Several of y'all have followed my diff rebuilding thread (http://forums.bimmerforums.com/forum//showthread.php?s=&threadid=166399) and in there I promised I'd do a write-up on removing and replacing a differential (since I have yet to see a good DIY article on it). In this case, I'm removing the open 3.15 diff in my '92 325is for an M3 limited slip 3.15 unit.

Note: While you can do this alone (I have before), it's much, much easier with a second person. I recommend you supply a buddy some beer and have him give you a hand. You'll see why later.

Step 1: Get the car way up in the air safely secured on jackstands. I used a small jack to lift under one of the front jacking pads. Then I slid the large jack under the front of the car and lifted it. Insert two large jackstands under the front pads. Then I moved the large jack to the back and lifted it as high as I could. And, you guessed it....insert two large jackstands under the pads.

Step 2: Remove the sway bar. This isn't really necessary, but really makes things easier later on. It's easy to do, so as Nike says, "Just do it."

First remove the top mounting nuts from both sides (pictured is the driver's side):

Next remove the chassis mounts for the sway bar. Again, the driver's side is pictured. It won't fall right away, so don't fret....

Lift up on the sway bar to slide the mounting tabs from the chassis. Now the sway bar is free. The next step is to snake it out of position. Merely rotating the orientation of the driver's side endlink (as shown below) made it a no-brainer.

Step 3: Remove the cat-back exhaust. This can actually be done prior to step 2, it's up to you. The first thing to do is loosen all of the front muffler clamps. Looks like a previous owner of my car replaced one of the BMW clamps with one of those high dollar european ones. ;)

The next step in getting the exhaust out is to remove the two nuts holding the hanger clamps to the muffler. Feel free to use my patented "foot method" to aid in removing the exhaust. :stickoutt The muffler comes downward and the pipes slip off of the cat pipe.

Step 4: Loosen the diff from the driveshaft. Set the e-brake and/or put the car in gear. I used a QuickWrench to break these guys free. This is the first time having a buddy around will be helpful. Give him a beer and sit him in the car. It'll allow you to loosen all four bolts while your buddy releases the e-brake (or puts the car in neutral) so you can rotate the driveshaft for bolt access. Space is moderately tight, but you don't need to remove the flexible shield under the driveshaft.

Step 5: Remove the torx bolts. Now is the only time you'll ever use those inverted torx sockets you bought. ;) IMO, this is actually the hardest and certainly the most tedious part. The bolts are likely caked up with road grime. If you don't get the socket firmly onto the bolts, you will easily strip the heads of the bolts. Do not rush this! Only break loose the bolts you have easy access to (typically up top because the axle boot gets in the way down low). Then have your buddy release the e-brake (or put it in gear) as needed. He'll probably want another beer at this point, too. :D

If necessary, use a hammer and tap the socket onto the bolts to make sure you get them firmly seated. Again, do not rush this! I'd actually recommend buying a dozen new torx bolts for the re-install, but it all depends on how safely you remove them. Feelin' lucky? Well, are ya.....punk?? :cool:

Here's a better view of the torx bolts and plates coming out. Note the easy access with the removal of the sway bar and muffler!

When you get all the torx bolts out, I recommend zip tying the axle shafts up high to keep them out of the way when dropping the diff. Trust me... :)

Here's a close-up of the axle shaft pulled away from the diff. flange. You can't see the zip ties in the picture, but they're in there!

Step 6: Remove the Diff! There are three bolts holding it in. Two up top in the "ears" of the housing and one in the passenger side front of the the housing. I removed the front one first.

The bolt is long and may not want to come out easily. Push up on the housing to relieve some tension and the bolt will pull right out....

Now just barely break loose the two rear bolts, but do not remove them!

Now move your jack under the housing, then remove the last bolts in the "ears." Note the zip ties holding the axle shafts out of the way. Unplug the speedo sensor being careful not to break any of the plastic. The diff is about to come out!

:buttrock

Feed your buddy another beer 'cause now it's time for him to do some labor! :D Carefully lower the jack while supporting it from either side. It weighs about 85-90 lbs. so be careful. It's an easy job with two people, though. Wheel it out on the jack as such:

Free at last! Free at last! Thank God Almighty, it's free at last!

Okay, so it's out! Now bask in the glory of how naked the underside of your car is.

Allright, now it's time to get back to work, you sicko! :stickoutt

Depending on the car you have and what the diff came out of, you may have different input and output flanges. Mine had a four bolt input flange, as did the unit I bought. However, note how they are different shapes. No matter. I measured the critical dimensions and all were the same so I used the round one that came with the new diff.

Dig my groovy safety glasses, baby! :pimpflash

If you find that you do have to change the inut flange, impact the input flange nut off (securing the output flanges as shown below, preferably with the help from your buddy Otis) and use a gear puller to easily pull the flange off:

My flange wasn't torqued. And my socket was too large to fit, so I turned it down on my bench grinder. My kingdom for a lathe! :12: Torque according to the Bentley (129 ft-lbs, if I remember correctly) being sure to prevent the output flanges from spinning. It can be tricky, so ask your buddy for help securing the diff while you torque it. He should be drunk enough by now that you can push him over while he does it. :devillook

If you need to swap the output flanges (I didn't), it's super easy. Just use a pry bar and pry them out of the housing. There's a snap ring keeping them in place, but not very securely. The new ones just push back in place. Use a rubber mallet (softly) as needed.

In my case, the speedo sensor on the "new" diff was smashed so I replaced it with the one from my original diff.

Installation is the opposite of removal, so scroll up the thread. :D

BIG thanks to my buddy, Zac, for helping and grabbing pics. And, no, he didn't get drunk. He had to drive home in the snow afterall (yes, we're in Texas!). :)

As always, do this at your own risk and if you don't feel comfortable doing it, leave it to a pro....or someone you can con into it. :12:

Hope this helps some of y'all. Enjoy and happy burnouts! :clap:

Tommy

Man, That is a fabulous write up.
I am considering doing this soon and this will be a great help...
Pictures are worth much more than a thousand words when your trying something new.....


THANKS !!!!:D:D:D

Damn, that's a great write-up! Excellent job. I think even I could swap a diff after seeing this....


Mike

Very nice Tommy. Thanks for sharing this :)

Having two people to do this job is *highly* recommended. I had to get out from under the car for each bolt on the differential and axle flanges since they could really only be accessed in one position. Let's see (6 + 6 + 4)*2 = 32...just for these bolts. Add in all the times for the other bolts *and* wrestling the 100lb lump out and in, and you have one tired shadetree mechanic. Get a friend :)

As Tommy also said, the E12 Torx bolts can be a pain in the buttinski. If your axles have never been off from the factory, they will be *verY* tight. I stripped two of them before realizing that you have to be really careful with getting the socket on completely. I have the socket from Lisle, and it is shaped very much like your standard 3/8 drive 10mm socket...except that it has a larger diameter. This diameter is what makes getting it seated on the bolt perfectly a chore. Clean the bolt heads off really well before starting and find the position that allows you to get the socket in place straight. Be careful, or you will be cutting the bolt heads off with your dremel tool.

I am really tempted to go buy this socket for the next time I have to tackle this job. I think it would be well worth the $40...

Thanks again Tommy for the great write up :)

Butch

I'm still a little ways off from trading out my diff but I'll be back to this thread when I'm ready to do it!

Thanks for the write up...long live the zip-tie!

Originally posted by Tn325I
Pictures are worth much more than a thousand words when your trying something new.....

Hey! That's the excuse I can give my girlfriend for keeping all my porno mags.


Great write-up man. I'm leaning towards changing my differential and this is a big help.

Thanks, guys. :) Happy to help. I've gotten lots of good info from this site and thought this would be a nice way to "repay" the favor. Expect more soon... Bushing swap, custom cat-back, etc....

Tommy

Great write-up Tommy! I will be swapping mine out this coming friday and this is just what I needed. :clap:

No sweat, Mark. :)

Hey Butch, where did you see that tool? I definitely think that piece would be worth $40! :clap:

Tommy

That tool is made by Stahlwille and carried the part number SF 1067. The only site that I have ever seen it is http://www.zdmak.com though I can not find it there any longer. I would be willing to bet it is still available if you asked them. They have a bunch of other cool tools on that site as well :)

*edit* Found it on page 2 of the BMW tools at ZDMak

http://www.zdmak.com/stna1067.jpg

Nice DIY write up. But seriously, you probably spent more time snapping pics than it takes to swap diffs ;)

Originally posted by badmonkey
Nice DIY write up. But seriously, you probably spent more time snapping pics than it takes to swap diffs ;)

Nope, my friend Zac took the pics. ;)

A diff swap is a simple job, true, but is daunting to someone who's never done it before. Considering it only added about 10 minutes to the job to grab the pics and maybe an hour to write all the details, I figured it'd be worth it. I figured folks who haven't done it before would appreciate it.

Tommy

thats weird, mine doesnt have the torx bolts...they are just regular bolts....

Originally posted by poyntofdesign
thats weird, mine doesnt have the torx bolts...they are just regular bolts....

Interesting. Are you the orig. owner? Can you grab a picture of it?

Thanks,
Tommy

TommyR,
I want to thank you for making this writeup. I've been searching and searching all over to gather information on the differential swap I am about to do this weekend. Thanks for making me laugh along the way, too. I appreaciate it,
Peter Tyson

You're welcome, Peter, but what is up with your website?? I wasn't about to proceed beyond the front page! :95

Tommy

Woah, that is really messed up. I didn't put that there but I can imagine that I have a virus. I wouldn't put some nasty website as my homepage. Thanks for the heads up.
-Peter Tyson

No sweat... I don't think I'd want that as my website, either! :eek:

Tommy

How did you determine which diff to install? By year/ gear ratio? Because there are many different ratio LSD units, right? I'm just trying to determine which would work best in my 98 328is 5-spd. It's not like I'm looking for 4:11s to better the 1/4 mile, I'm really interested in just having a LSD rather than the open diff... I don't need a ratio so high that my gas milage goes out the window...any suggestions on what to look for and price ranges?
Thanks, Kutch
kutch_L@juno.com

How did you determine which diff to install? By year/ gear ratio? Because there are many different ratio LSD units, right? I'm just trying to determine which would work best in my 98 328is 5-spd. It's not like I'm looking for 4:11s to better the 1/4 mile, I'm really interested in just having a LSD rather than the open diff... I don't need a ratio so high that my gas milage goes out the window...any suggestions on what to look for and price ranges?
Thanks, Kutch
kutch_L@juno.com
You can get a used 3.15 LSD from a '95 M3 for around $400. If you want a higher ratio, you're looking at spending a few hundred bucks more.

TommyR, thanks for doing the write-up! I don't think I've come across one quite as thorough and well-documented. I have a 3.15 LSD sitting in my garage waiting to get swapped in for the stock open 2.93. This write up will help tremendously!

Happy to help... :)

Tommy

Just recently installed the 3.23 into my 328is, my acceleration feels good even with my heavy 18's on. And I am loving the LSD, accerating without the one wheel peel is so much better.

im looking for a 325is differential to do a m50 engine conversion on my 318is did you sell it already? becuase if you didnt i am interested

I just wanted to bump this thread (it's an awesome thread!) and add a few tips that I have for first-timers (or second-timers) because I just did this swap (2.93 Open -> 3.15 LSD) yesterday.

1. You don't have to get the Lisle External Torx socket set from Sears for $20.

I had already bought the set and was visiting Autozone to buy the steering wheel puller (which you also probably won't need, it turns out), when I happened upon an E12 socket sold by itself for $3.99. The socket walls were thinner than the Lisle socket, which made the fitment alot better than the Lisle E12 socket. I believe the Lisle socket is an impact socket, which explains why it has thicker walls.

2. Use some pipe tubing to get more leverage on the 3/8-in. drive ratchet for the external torx sockets.

Your average 3/8-in. drive ratchet won't give you enough leverage to easily break the torx bolts, especially when you're on your back under a car on jack stands. By using a length of pipe tubing slipped over the ratchet handle, you can break the bolts loose more easily. FYI, this trick works on many other tough bolts so it's always good to have one handy.

3. Make sure you measure/compare your input and output flanges.

I was quickly able to determine that the input flange was not going to be compatible (4-bolt vs. 6-bolt), but for some odd reason I just assumed that the output flanges would mate to the drive shafts. Big mistake. I had already gotten the new diff bolted onto the car - which was a monumental task by itself because I was doing the job by myself - only to find out that the output flanges did not mate up with my drive shafts! After 10 minutes of cursing, I calmed down and found out that I was able to get the output flanges out with the diff still in the car. I highly recommend that you do this *before* you put the diff back in, though.

4. Make sure your jack has a large diameter jack plate (the part that actually makes contact with your car) if it's going to be of any use to lower/lift the diff.

My jack from Sears has a jack plate that's about 3 inches in diameter. This is utterly useless when you're trying to balance a 90 lb (or smtg) hunk of metal. You need something that's at least as wide as the jack plate on one of those race jacks. I only used the jack for supporting part of the weight of the diff as I lowered/lifted it in place. Even if I had a buddy, he would have had a very hard time keeping the diff balanced on the jack I used.

All in all, it took me 7-8 hours to complete this job by myself. Dropping the exhaust/sway bars and putting them back on took about 3-4 hrs total by themselves. The UUC rear sway bars can be a real bitch to put in. I struggled with it the first time and it was still a bitch the second time.

As for the diff, it was a really easy job. It's just very hard to manage all the weight by yourself. I only used the jack to support the diff from time to time, but for the most part, I muscled it off/on the car. I'm pretty sore from all the awkward lifting I did yesterday.

The car accelerates faster, and I can definitely get on the throttle a lot faster on corner exit now (tested on a closed course ;)). I can't wait to try it at an auto-x!

Outstanding thread, thanks! I need to print all of these type of DYI threads out and make a book....

Outstanding thread, thanks! I need to print all of these type of DYI threads out and make a book....
Book? I've got two 3" binders completely full and alphabetically organized into sections and then chronologically ordered. :D

Then I've got my Bentley. But I've noticed that I hardly ever refer to these write-ups when I do the installs/replacements. I read them once and then it's usually pretty easy to figure out. ;)

Sweet write-up. Something in my Diff. is screwed up so I will be dropping in a 3:38. This makes mentally prepping for the job alot easier! Good job Tommy! :)

Great write up. Those who take the time to nicely document the procedures (with good pictures to boot) always get a :alright from me.

Some things i'd like to add......

What kind of lifespan do the LSD units have? Meaning, what kind of mileage can you get out of them? The friction plate kind can eventually wear out. Now if the LSD is of the Torsen torque-biasing kind (like a Quaife) then they "never" wear out. I'd just hate to see someone get a used LSD that was worn out.

If one chooses to replace the Torx head bolts, no need to reinstall the same Torx head kind. As long as you use the right shank length, thread length & thread size and the right property class (these screws are most likely 12.9 class) then you should have no problem replacing the screws with allen/inhex head screws instead of the Torx kind. Just use a quality brand. McMaster-Carr (www.mcmaster.com) and Metric Multistandard Components Corp. (www.metricmcc.com) sell high quality metric fasteners.

Tommy & others, I know this has been asked before, but please post the type of fluid you used for the differential.

Thanks,

Kevin

Great write up. Those who take the time to nicely document the procedures (with good pictures to boot) always get a :alright from me.

Thanks. Happy to help... :)

What kind of lifespan do the LSD units have? Meaning, what kind of mileage can you get out of them? The friction plate kind can eventually wear out. Now if the LSD is of the Torsen torque-biasing kind (like a Quaife) then they "never" wear out. I'd just hate to see someone get a used LSD that was worn out.

Given the nature of an IRS car, the clutch packs should hold up to a LOT of miles of street use. Put some race compound rubber on there and start lapping or autocrossing, however, and I'd expect a rebuild after a few years, depending on several variables. These cars have clutch diffs from the factory, BTW.

[Tommy & others, I know this has been asked before, but please post the type of fluid you used for the differential.

I've run Redline 75W90 N/S, I believe. Though running regular vs. N/S apparently doesn't net much of a difference in performance or longevity.

Tommy

Thanks Tommy.

Reason I asked about the lifespan is because of the early wear-outs i've heard of regarding factory Porsche ZF limited slip units. The later G50 units (mostly 993 units from what I understand) have poor longevity friction discs and wore out in 20-30K miles! :(

So I figured i'd ask about the BMW LSDs. Are they manufactured by ZF as well?

Thanks for the info. on the fluid. Sounds like the same deal with Porsche LSDs. They don't seem to experience chatter like other makes, so the friction modifier (for those who don't know, 75W90 has it, 75W90NS does without the fm) is not necessary. But I imagine the standard stuff is the way to go since it has the fm that most LSDs like to see, which reduces chatter and smooths the locking characteristics of the diff.

Thanks again!

I just love how easy it is to change out the diff. on these cars. Can't wait to tackle mine someday.

do you know any place where i can get the m3 axles because i have the 3.15lsd i just dont have the axles if anyone knows where i can get the axles i would appreciated it
thanks

hey tommy, i need to swap the diff cover and was wondering if i could do this while the diff is still on teh car. im assuming i would need to remove the swaybar and drop the exhaust... do u think i can get away with not taking off the diff? thanks.

hey tommy, i need to swap the diff cover and was wondering if i could do this while the diff is still on teh car. im assuming i would need to remove the swaybar and drop the exhaust... do u think i can get away with not taking off the diff? thanks.
I did this... I cracked my 3:38 diff cover so I replaced it with the one from my 3:15. If I remember correctly: Drain your diff, take off the sway bar, support the diff with a jack, remove the front diff bolt, and also the two rear diff mount bolts, drop it down some to access the top diff. cover bolts, take the cover off, put the other one on and tighten to specs, refill. I think thats all, I might have missed something. I'ts not hard though. Good luck

(might get a little messy) :)

When I replaced mine I did not remove the exhaust or the rear sway. I unbolted the sway on the one side so I could move it out of the way when necessary. It wasn't bad at all.

as far as the cover goes, first drain the diff using the special BMW tool to open the plug. When you put the new cover on, of course use a new gasket and the sealant they recommend. You should be able to get to the bolts but be careful to torque them in sequence slowly to properly compress the gasket. Buy two new drain plug gaskets.
Then just refill the diff. It is easier to do the cover when it is off but you might be able to do it when it is on.

yah, now that I think of it.. I dont think I removed the sway either.....

do you know where i can get m3 axles for this lsd swap?
thanks

do you know where i can get m3 axles for this lsd swap?
thanks

Why do you want M3 axles? Stock E36 axles will work just fine.

And sorry about not answering about swapping the cover with the diff in the car. As mentioned, it appears to be possible. Sure looks that way... :)

Tommy

I was going to say the same thing...don't bother changing the half shafts.

no i was swaping my M3 3.15lsd and my stock axles are too small to fit the diff
i have 328is axles and they are too small
i need the M3 axles to complete the swap trust me
so where can i get them

And you can't swap the cups (axle outputs) from the old diff to the new one?

Tommy

thanks all for ur help.

is it safe to drop the diff while its still connected to the axles?

thanks all for ur help.

is it safe to drop the diff while its still connected to the axles?
I did it... Axle was still connected, drive shaft was still connected... just make sure to support it with a jack.

just swap over the output flanges if the bolt patterns don't line up. I have a 328 and I put an M3 3.23 in there and the axles were fine.

And you can't swap the cups (axle outputs) from the old diff to the new one?

Tommy

dang it i didnt even thank about changing the output shafts
what a wonderful idea withough having to spend even more money
You dont understand how much i appreciate that thanks alot
i will do that this weekend
and again thanks alot

That'll be $5, please. ;)

Tommy

Get new seals with lock collars....make sure you have a device to apply even pressure to the seal as you tap it in place with a rubber mallet.

I just swapped them right over.

33 10 7 505 602 2 output flange seal $7.88
33 11 1 211 708 1 cover gasket $3.57
07 11 9 963 355 2 crush washer gasket for drain plug $0.07

don't forget loctite 270 for the diff cover bolts as well as the toquing pattern.

For everybody's info i have to replace a bent control arm and i was removing the axles... i found a set 7 of inverted torx sockets at napa for 25 bucks... it came with something like an E-4 through E-14 and it made an amazing difference... i would recomend the set for anybody messing with the axles.

Tommy:

Did my first diff swap and your DIY was invaluable. Thought I would add a few things that I found that might prove helpful to others, especially newbies like me. Used a couple of your pics, hope that's okay:

First, I found you do not need to remove the rear sway bar, although you do have to deal with it. The reason is that it runs directly in front of the two rear mounting bolts and prohibits getting a socket on these bolts. Rather than removing it, I simply removed the two stabilizer supports which allowed me to relocate the bar to remove these bolts. Seemed a much simpler solution than full removal of the bar.

Second, once the diff is unbolted you cannot simply lower the diff on a jack as described. The problem is that the front of the diff is over the Rear Axle Carrier, which prohibits lowering. Additionally, the trunk prohibits forward movement. See what I mean?

This picture shows the problem of the Rear Axle Carrier and trunk better. I found that you have to rotate the diff out onto the jack, and then lower it and remove. For all those that have done this by themselves, you qualify for "Super Hero" status. :eek:

glad to see you adding this info to the DIY hellrot325. makes sense to me to do it like you mention in the pics. nice :buttrock pic too :)

I did not experience the problems you and others encountered in removing the six torx bolts required to connecting the axle to the diff. On mine they were factory connections, and the buggers were tight, but here's what I did.

Because of the angle of the halfshaft to the diff when it is not under load (on jack stands) I found the inner boot prohibited straight access to the torx bolts, except one. This bolt was at the two o'clock poistion on the passenger's side, and ten o'clock on the drivers side. In this position I had easy use of a E12 Torx Socket (from the Sears 3/8 set), with a 6" extension and 16" breaker bar to bust 'em loose, and switched to a ratchet for removal. Use the e-brake or in/out gear technique desribed by Tommy to rotate the axle to get all six of these bolts in the proper position.

Because of the tedious nature of the breaker bar/ratchet technique above, here is a faster way. I put two 12" extensions and one 6" and reached this bolt without having to go under the car. You can access the bolt in the decribed position straight on by running it throught the spring. Even with all the extensions I cold break the bolts loose and quickly spin them off.

I also used this method to reinstall, although I did use the former to fully torque these bolts.

One other thing, I added fluid to the new diff before I put it in the car...much easier this way.

All in all the diff swap is not technically difficult, but is a lot of work. Lots of tight and/or rusted bolts. Removal of the exhaust, even with the Tommy R's patented foot method, is work and should be considered a two man job, and if you can get a third, even better!

Thanks for your write up Tommy. Hope these additions prove helpful to others.

Thanks or the write up! I'm about to putin my 3.23lsd.

Nice of you to add to the DIY Hellrot :clap

Good advice on the tool usage too. Sometimes people try to do things only one way and can have difficulty that way. I remove the axle screws on my 911 the same way you described. There's one "sweet" spot where you can get straight access with the socket. Kinda time consuming, but reduces the risk of stripping a screw head.

Enough people chime in with their experiences, and some threads end up becoming the ultimate thread on how to do something. This thread's one of those threads.

Hellrot,

Absolutely no problem! I welcome others' contributions. In the end, it makes future diff swappers' jobs easier. :) And you're more than welcome to use my pictures here. My only request is that if they're placed elsewhere that proper credit be given.

Yeah, the diff can certainly be swapped without removing the rear sway bar. In fact, I've done it that way......by myself.....and without even dropping the exhaust. It's just much easier and less troublesome to remove it, IMO. It's up to the individual. For me, it was worth the extra few minutes to drop the bar.

The torx bits can be a pain, but not so much so if they're clean. Stripping one would suck! The big issue, as you found out, was access. That's why I had a friend set/release the e-brake at my command so I could rotate the diff to gain proper access to the bolts. Made life much easier. I thought about using several extensions, but didn't want to risk buggering up a bolt head. If it works for you and others, more power to you! :)

And, yes, the diff has to be rotated upward in order to get out of its cradle and past the spare tire well. I just didn't think it warranted noting. :stickoutt :)

Tommy

Great write up!!!
Thanks for sharing!!

Hellrot,
Yeah, the diff can certainly be swapped without removing the rear sway bar. In fact, I've done it that way......by myself.....and without even dropping the exhaust. It's just much easier and less troublesome to remove it, IMO. It's up to the individual. For me, it was worth the extra few minutes to drop the bar.
Tommy I would definately remove the SB if I was doing the swap myself...but then again I wouldn't even attempt that...not when I have a 27 year old son that owes me big time! :devillook

LOL... :) Yeah, it was a pain going it alone. I was very appreciative of the help the second time around!

Tommy

I would definately remove the SB if I was doing the swap myself...but then again I wouldn't even attempt that...not when I have a 27 year old son that owes me big time! :devillook
Wow, your SON is 27? I thought I was old on this forum and I'm 27. Rock on! :buttrock

Wow, your SON is 27? I thought I was old on this forum and I'm 27. Rock on! :buttrockDid I put 27? He's 25, I'm 47...I must have been having a senior moment! He loves BMW's also, he was five when I got my first, a 1984 325e in Delphin (a dark gray) and remembers us driving fast with the stereo blasting. :cool Wasn't a high revver but man that car was a torquey lil motha! Put over 300k miles on it before...well you know...like my mom did with our dog... it lives on farm with a nice family ;)

Tommy,
Thanks for taking the time to do this write up. I did an auto to manual conversion and left myself with a 3.91 diff. Great off the line, but obviously not highway friendly. So, I bought a 3.15lsd (from a BFC vendor of course), and following your DIY to the T, managed to do the swap in all of 4 hours! A few observations:
1. The bolts holding the diff in place are 18mm (not something in every tool box, well at least my tool box)
2. This would have been a 10 hour job for a first timer w/o the extra man! So, for those planning on doing this, buy the beer and get your buddy on board.
3. Also for those *thinking about doing this* Don't be intimidated. It's not at all difficult. Just follow Tommy's DIY, and keep things organized.
3. This gave me an opportunity to see how shoddy my now former mechanic's work is. I found that when he did the tranny swap - which involved a new drive shaft - he replaced one of the prop flange bolts with a crappy hardware store bolt! I checked the rest of the install over and found other shortcuts, and less than quality workmanship. The words, "You're fired!" comes to mind....
Anyways, thanks again for the write up and pictures. I couldn't have done this in the time I did and also keep my sanity! :alright
Craig

The words, "You're fired!" comes to mind....don't forget to give him the Trump "Cobra" too :D

One other thing, I added fluid to the new diff before I put it in the car...much easier this way.

Amen to that - just be sure to add the fluids with the diff level to prevent overfilling... I put in my 3.46 LSD (from Dan at diffsonline) over the holiday week and aside from a few hurdles replacing the center bearing (tip - get a local driveshaft place to press the old one off and press the new one on) the hardest thing was finding a 14mm allen key to get the plugs off. I got a hex bolt from Grainger but it was too long to use with the diff on the car. A allen key from NAPA did the trick.

After doing the M50 manifold swap, this was not too difficult by comparison. The writeup definitely helped - I used the version from someone's website and wish I'd seen this thread first!

In my case, the speedo sensor on the "new" diff was smashed so I replaced it with the one from my original diff.

does the sensor need to matched to the gears?

does the sensor need to matched to the gears?

Not to my knowledge. I believe there is only one P/N for it.

Tommy

Not to my knowledge. I believe there is only one P/N for it.

Tommy I believe the sensor measure axle rotations thereby working with any diff...wheel/tires have the only effect

thanks a LOT!
just made my diff swap much easier
great writeup!
-JoSH

Hey Hellrot325....which end of the Sway did you undo? Or does it matter...about to tackle this myself in a couple days....

Thanks!

Hey Hellrot325....which end of the Sway did you undo? Or does it matter...about to tackle this myself in a couple days....

Thanks! Look at post 69, you'll see that I did not remove the sway bar. I simply removed the two sway bar support and pulled it doen out of the way. I would recommend this only if someone is helping you remove the diff, and I would recommend that you get help. Wether you do what I did or remove the SB like Tommy R...its heavy and ackward taking it out.

awesome DIY write up man....definitely makin this a subscribe in my book

You are the man. I wish I had this when I was swapping my diff, but instead took it to the shop :(

You are the man. I wish I had this when I was swapping my diff, but instead took it to the shop :(
now the question is....what diff do i want.....im still learning tho...

You're welcome, guys... Happy to help. :)

Tommy

That is one good heck of pictures, Tommy, it is very helpful. though it is a bit too much for me, but Ill try with the help of this thread. B y the way, how are you able to post all these beautiful pics, am trying to post some pictures for some DIY I did, the forums won't let me, I always go beyond the 150KB limit. thnx

Make sure they're jpeg...you can thow them into MS Paint and resize them and change format...

I've got two Teenagers to help me! :D Just waiting for the new (used) one to show up, need to do some prep work today. I don't look forward to the heavy part, I'm a skinny dude! My boys should be able to help though. Need to fab a better platform for the Jack Head too, it's too damn small....

i did it in 3 hours including jacking car up and setting it right... you don't need to take off sway bar .. just loosen 2 rear-most bolts and lower it down and let output shafts hang on it ... no zip ties needed.... its simple

i did 2.93 to 3.15 LSD on a E36 328is

i did it in 3 hours including jacking car up and setting it right... you don't need to take off sway bar .. just loosen 2 rear-most bolts and lower it down and let output shafts hang on it ... no zip ties needed.... its simple

Yup, that's all been covered already in this thread. :) Personally, I found it easier with the bar removed and with zip ties (having done both ways), but to each his own...

Tommy

oh ok ...hmmm didn't read that, cool

Just got started on mine (been sick all week...ugh....) and so far just loosed all the Axle Torx Bolts...was quite easy. Know that mine is a CA/AZ Car (first year in GA though) so it's not that messy underneath, plus I have a AA Gen III Ex and custom springs, so my clearences may differ.

First, trip to Autozone. Picked up there:

1- 24" 3/8" Extension $9.99

1- Female Torx Socket E12 $3.99 Pt# 085903 2027 26830

I added my own 4" extension, and a large Torque Wrench for power. The night before I hit each one with some "PB Blaster". (smelly, but way better the Liquid Wrench IMO)

I moved the axle so I saw bolts at 11 & 2, placed the extended (28" total) socket on it (through one of my Red Vogtland spring coils) and used a Rubber Mallet to make sure it had solid contact, then pushed on the Torque wrench, pushed hard and "SNAP"...each one gave a crisp sound when breaking loose. Gave a few hand turns to make sure they were loose, then on to the next one. I was able to do two at a time this way no problem. Piece of cake! Thanks for the ideas! Next up the sway bar supports.....

Look at post 69, you'll see that I did not remove the sway bar. I simply removed the two sway bar support and pulled it doen out of the way. I would recommend this only if someone is helping you remove the diff, and I would recommend that you get help. Wether you do what I did or remove the SB like Tommy R...its heavy and ackward taking it out.


Are these the two SB attachpoints that secure the middle of the Bar? If so, how did you do it, by removing the large bolts that go up into the chassis, or some how seperate the bar from the tabs? (I have TMS bars in place, they came with the car. Have only adjusted them, never removed/installed)

Thanks!

Hi Tommy,
Read your write up and with the pix the job was a breeze! Thank you, I had never worked on a Bimmer diff before I looked at your article!!
I pulled it out in 3 hours myself but now I have to redo the seals any helpwith that?
You Rock!
Brent

This is a great writeup. It helped a lot when I pulled my LSD from my parts car. Thanks again!

B

No sweat, guys. Happy to help. :) No idea on the seals as mine have been fine. If you're talking about the output seals to the axles, I wonder if you even have to drop the diff to do that?

Tommy

Thanks again Tommy,
But actually I need to do the driveshaft one... it is the worst, but while I have it out I could probably do the axles as well.
Any one know of link to do the seals?
Thank you
Brent

Hi All,

I finished my FIRST Bimmer rear diff including the seals (two sides and the main pinion seal!!!!) :buttrock :alright :eyecrazy
If it wasn't for this forum it would have taken me 10 Hours but it took 3hrs (to remove the diff with lots of help from TommyR's write up) + 2Hrs to rebuild and clean and replace all seals 2 hours to reinstall and torque everything down!!! I am still greasey from the undercarriage but You can't wipe the smile off of my face :D . Time for a test drive :redspot

THANK YOU ALL!!!!!!!!
Brent

How long do you guys reckon it would take to switch the diffs of 2 cars at the same time? 5 hours with a helper?

This should be stickied.

Also does the car HAVE to be on jack stands at front and back? Or can I just have the rear jacked up? I ask because I only have 4 jackstands and have to swap the diffs of 2 cars, so they both have to be up in teh air at the same time. Can't put 1 down with parts all apart.

Also does the car HAVE to be on jack stands at front and back? Or can I just have the rear jacked up? I ask because I only have 4 jackstands and have to swap the diffs of 2 cars, so they both have to be up in teh air at the same time. Can't put 1 down with parts all apart.
Just buy 4 more jackstands. They're like $10/pair at Kragen. :dunno

If anybody knows what size socket is needed to remove the input flange please let me know!

The one shown here:

http://forums.***************************************?attachmentid=57562&stc=1

30mm.

Just make sure you get a thin wall socket or "turn" it like I did to the one in the picture. Otherwise it won't fit in there.

Good luck!
Tommy

i did it in 3 hours including jacking car up and setting it right... you don't need to take off sway bar .. just loosen 2 rear-most bolts and lower it down and let output shafts hang on it ... no zip ties needed.... its simple

i did 2.93 to 3.15 LSD on a E36 328is
Sweet. I'm about to attempt this tonight (and tomorrow).

What size "reverse torx" sockets do I need to remove those axle bolts?

Also does the car HAVE to be on jack stands at front and back? Or can I just have the rear jacked up? I ask because I only have 4 jackstands and have to swap the diffs of 2 cars, so they both have to be up in teh air at the same time. Can't put 1 down with parts all apart.

Two Jack stands is all you need leave the front on the ground.
And yes if you like you can put one car down in peices, just block the wheels so it doesn't roll away on you or use the hand break.
I also didn't have to remove the sway bar just loosen it were the tabs are and got my helper to push it towards the floor out of the way while I loosing the rear bolts.
Took me 1 hour and 45 min to drop my old diff out and install my new one for the first time (with a good helper).

Two Jack stands is all you need leave the front on the ground.
And yes if you like you can put one car down in peices, just block the wheels so it doesn't roll away on you or use the hand break.
I also didn't have to remove the sway bar just loosen it were the tabs are and got my helper to push it towards the floor out of the way while I loosing the rear bolts.
Took me 1 hour and 45 min to drop my old diff out and install my new one. Handbrake works on rear wheels...

Handbrake works on rear wheels...

Mentioned while the car was down, you do not need to remove the rear wheels to swap a diff.

Mentioned while the car was down, you do not need to remove the rear wheels to swap a diff. Misunderstood your post....my bad. Just didn'tr want someomne thinking that the e-brake would help w/ the back up on jacks

Okay, I just did this tonight (removed it, anyway). Not hard AT ALL. The hardest bolts for me, however, weren't the 6 E12 bolts on each axle flange. It was the four bolts connecting the differential to the driveshaft. 16mm.

I couldn't get a socket to fit so I had to use a 16mm wrench. I had to loosen two of them with my FOOT! Tough suckers. And I weighed the differential with my old bathroom scale. ~80lbs. FYI: I weighed myself right after. ~100lbs!

So yeah, if I can do this MYSELF, anyone can do it. :D

Now to get that bolt drilled/lasered out and the differential put back. :(

Great thread!!! Im about to attempt to do this swap in the next week or two with a 3.23LSD that I just purchased, but first I have a few questions. I bought the differential without the output flanges becuase the seller informed me that the 99 M3 output flanges that came on the diff would not fit with my 325 axles. I know swapping hte output flanges is relatively simple, but I want to make sure Im not missing a gasket or anything that would come with the diff if the output flanges were still on the diff. Here are some pics of my differential, I would really appreciate if someone could identify anything thats missing from these pictures as it would help me tremendously.

Sorry for the pic size...

http://img.photobucket.com/albums/v242/sgray944t/birthdaydiff075.jpg

sorry for the blurryness...
http://img.photobucket.com/albums/v242/sgray944t/birthdaydiff067.jpg

So if you see any snap ring or gasket or anything I need before I stick my 325 output flanges in there I would really appreciate a heads up!! Thanks alot everyone!

Also does the car HAVE to be on jack stands at front and back? Or can I just have the rear jacked up? I ask because I only have 4 jackstands and have to swap the diffs of 2 cars, so they both have to be up in teh air at the same time. Can't put 1 down with parts all apart.
Not sure if this has been answered but I didn't use four jack stands. Jacked only the rear up.

Did this all by myself too. The hardest part, BY FAR, was getting the differential back in. I used my 3.5 ton jack and managed to position the diff vertical on the edge of the jack. Then slowly jacked it up while tilting the front of the diff down as it went up. Slid it in that way.

I removed the sway bar and found it VERY helpful. In fact, I don't think I would have been able to do this if it was still there. I have aftermarket sways (UUC) so they're pretty stiff/thick.

Anyway, good luck! Great thread.

Might I add some suggestions though?

It would have been nice to have a list of ALL the tools used for this DIY, as well as the torque specs for each bolt.

Oh, and it took me about 5-6 hours total for this job (over two days). I am a VERY slow worker (clean stuff, paint stuff, etc. :stickoutt ). I also took pictures and stuff. Sure was a major PITA and I really don't want to do it again. :(
The worst part of it is that I wasn't even swapping my diff. Only removed it to get my broken bolt out. :(

Did this all by myself too.
Did it alone the first time I did it, too. Much easier and faster with a second person. If for no other reason to hand you tools and, of course, to put the diff back in.
It would have been nice to have a list of ALL the tools used for this DIY, as well as the torque specs for each bolt.
Go for it! :)
Tommy

Did it alone the first time I did it, too. Much easier and faster with a second person. If for no other reason to hand you tools and, of course, to put the diff back in.

How did you manage to put the differential back in yourself? This is what I did (post #112 & on):

http://forums.bimmerforums.com/forum/showthread.php?t=414611&page=2

I just lifted it and put it in the carrier.

Tommy

I just lifted it and put it in the carrier.

Tommy
How high up did you have your car? That's pretty impressive. Even if I had it in the carrier, I would need to support it while I connected the driveshaft bolts. I used a jack to support it though.

You can see how high I had it in the first pics of the thread. It wasn't fun and it's one of the reasons I suggest doing it with two people, but it's possible.

Tommy

It sure feels like the diff has its own gravitational pull when you're struggling to put it back into the carrier! I had my car probably around 20" off the ground when I eased it back in with the assistance of a jack. I was using Griots Garage jackstands, which don't have that much lift. Also, I did it alone, except for the toggling of the e-brake which during installation I had my brother do. :D

You can see how high I had it in the first pics of the thread. It wasn't fun and it's one of the reasons I suggest doing it with two people, but it's possible.

Tommy
Ahh. Just realized this was your thread. :D

Anyway, yeah, no fun. :( Great write-up though. If you could update the first post with tools and sockets used, that would be VERY helpful for future DIYs. :D

If you could update the first post with tools and sockets used, that would be VERY helpful for future DIYs. :D
Nah. I think I've done enough including answering the countless questions, e-mails, and PM's I receive as a result of this thread. I don't mind helping (it's why I posted this in the first place), but all the tools required and torque specs are readily available in the Bentley or other shop manuals. I think the readers can bare that responsibility.

Or you could contribute and post that information here for everyone else.......

Tommy

Can anyone help me? I havent been successful finding pics of differentials with the output flanges removed so I'm not sure if I am missing anything on there.

Nah. I think I've done enough including answering the countless questions, e-mails, and PM's I receive as a result of this thread. I don't mind helping (it's why I posted this in the first place), but all the tools required and torque specs are readily available in the Bentley or other shop manuals. I think the readers can bare that responsibility.

Or you could contribute and post that information here for everyone else.......

Tommy
Haha, true. But I couldn't find the sockets needed in my Bentley.

You can copy and paste this if you want. :D

-Jack (3.5 ton or greater is recommended)
-Jack stands (at least 2)
-3/8" and 1/2" drive ratchets (the longer the better for more torque)
-Torque wrench
-13mm socket for exhaust bolts (x6 total) and sway bar bushing bolts (x2)
-13mm wrench (or socket for holding the other side of the bolt)
-16mm socket (for sway bar links) - if you can get a short one, you could use it for the driveshaft to differential bolts but I couldn't fit mine in and they're VERY tight
-16mm wrench (for sway bar links and driveshaft to differential bolts x4))
-17mm socket (for sway bar links)
-17mm wrench (for sway bar links)
-18mm socket (for front and rear differential support bolts x3)
-E12 socket (for axle to differential bolts x 12, 6 on each side, cost me ~$20 for the entire E socket set at Sears)
-One OEM BMW bolt, part #33176750780 (cost me ~$2.00)

I wasn't sure the torque specs since the Bentley listed these bolts as M8, M10, etc. :(

I torqued my differential to axle bolts to about 45lb-ft., my exhaust hanger bolts to about 15lb-ft., my rear differential bolts to ~60lb-ft. and my front differential bolt to 74lb-ft. I couldn't get my torque wrench to the other bolts though. :(

I hope those are the appropriate torque specs. I'm REALLY worried that, when I change my front diff bolt (to the AA DSB next week), I'll either break the bolt or strip the threads. We'll see. :(

Um I just did mine last night took bout 3 hours. Wasent to bad you really dont need to remove the sway bar to do this job but it might make it a bit easier but if you just undo the two rubber bushings that support it across the back and pull it down when accessing the rear two diff bolts its fine. THe torque settings I used to put it all back together I found in the hanes manual. Torqued all the half shaft bolts to 74 ft/lbs and the front diff bolt to that the rear two diff bolts to 50something cant really remeber just go out and buy the hanes manual its. As for tools used other than the E12 socket and the 14mm allen wrench for the diff oil plugs everything else should be pretty self explanitory. If you cant figure out what size metric socket to put on all of these bolts and how to get them out then you probably shouldent be attempting to put in a new rear diff by yourself. :) Mabye find a freind thats got some mechanical intuition to help you out. All and all you read through this thread should answer all the questions you have and then your pretty much all set to just tackle the job. THanks for the DIY guide though found it nice to read about before actually doing the job.

Um I just did mine last night took bout 3 hours. Wasent to bad you really dont need to remove the sway bar to do this job but it might make it a bit easier but if you just undo the two rubber bushings that support it across the back and pull it down when accessing the rear two diff bolts its fine. THe torque settings I used to put it all back together I found in the hanes manual. Torqued all the half shaft bolts to 74 ft/lbs and the front diff bolt to that the rear two diff bolts to 50something cant really remeber just go out and buy the hanes manual its. As for tools used other than the E12 socket and the 14mm allen wrench for the diff oil plugs everything else should be pretty self explanitory. If you cant figure out what size metric socket to put on all of these bolts and how to get them out then you probably shouldent be attempting to put in a new rear diff by yourself. :) Mabye find a freind thats got some mechanical intuition to help you out. All and all you read through this thread should answer all the questions you have and then your pretty much all set to just tackle the job. THanks for the DIY guide though found it nice to read about before actually doing the job.
Nice. Do you have stock sways? My UUC sways are super thick and I couldn't even move it lower to access the top diff bolts. I HAD to remove mine. Plus, it made it a LOT easier to put the diff in and take it out.

The tools, sockets, torque, etc., needed are in the post above yours. #132. ;)

OH awsome yeah mine are stock id imagine the UUC's coudl be a bit different. I was thinking of getting those UUC sways how do you like them did you get them in the front and back or just rears. And what shocks/springs you runnin with yours. I just did the H and R sports with the Koni yellows but probably need to look into some new sway bars as well.

OH awsome yeah mine are stock id imagine the UUC's coudl be a bit different. I was thinking of getting those UUC sways how do you like them did you get them in the front and back or just rears. And what shocks/springs you runnin with yours. I just did the H and R sports with the Koni yellows but probably need to look into some new sway bars as well.
I can't really tell. I wouldn't really get them unless you plan to track your car. I only got it because I was doing work down there and just decided to do it all at once (rotors, pads, suspension, x-brace, etc.). My car's very stiff now.

I have Ground Control coilovers with Koni adjustables and camber/caster plates. 500f/550r spring rates. Pretty stiff for my daily. :(

Oh, I have UUC front and rear sways with rear UUC links and front GC links.

So no one can identify if I'm missing a lockring or washer or something in my pics?

clumpy, what is the BMW OEM bolt listed in your post #132?

I am hoping to do the swap this weekend and I have a few questions.

Do I need to get new torx bolts and/or diff bolts?
Do I need to use any compound (I forgot the name, locktite?) to keep the bolt secured in?

thanks
--h.

It is recomended to get new cv axle bolts, their ment to be tourqued only once.
I think it's a waste of $$$ IMO but be carefull their easy to over tourque and break in the axle hub, done it before......
You do not need locktight either typical tighten it up snug then a 1/4 turn is what worked for me. and has been holding ever since.

It is recomended to get new cv axle bolts, their ment to be tourqued only once.
I think it's a waste of $$$ IMO but be carefull their easy to over tourque and break in the axle hub, done it before......
You do not need locktight either typical tighten it up snug then a 1/4 turn is what worked for me. and has been holding ever since.
What torque did you use?

clumpy, what is the BMW OEM bolt listed in your post #132?
The OEM bolt is the bolt to replace the lower bolt (in case it's bent or broken in the differential).

What torque did you use?

I geusstimated......
Officialy I beleive it's 18 ft/lbs for each bolt on the C.V. axles.

I geusstimated......
Officialy I beleive it's 18 ft/lbs for each bolt on the C.V. axles.
18lb-ft? Are we talking about the same bolts? The ones that require the E12 socket? I torqued mine to ~45lb-ft. :dunno

Do not know what an E12 socket is. I'm talking about the 12 female torx bolts (six per side) that hold the CV Axle's to the diff their easy to break and a pain to remove if they do.
Think your talking about the bolt near the input flange in the front of the diff by the driveshaft & 45 ft/lbs sounds about right for it.
Wish I could get you the exact #'s it says for you but lent my bently away.

Do not know what an E12 socket is. I'm talking about the 12 female torx bolts (six per side) that hold the CV Axle's to the diff their easy to break and a pain to remove if they do. Those are torx bolts...males, not females. E12 means external torx socket. Torque spec depends on size of bolt...M8 is 47 ft-lb, M10 is 62 ft-lb.

i torqued mine to 70lbs thats what the haynes manual said to do and none of them broke on me or striped. those things are flying around pretty fast so id imagine you dont want them flying out on ya. 25lbs i dont think is enough. the lug bolts on the wherls are torqued to 74ft lbs so it makes sense the half shafts are so tight.

Do not know what an E12 socket is. I'm talking about the 12 female torx bolts (six per side) that hold the CV Axle's to the diff their easy to break and a pain to remove if they do.
Think your talking about the bolt near the input flange in the front of the diff by the driveshaft & 45 ft/lbs sounds about right for it.
Wish I could get you the exact #'s it says for you but lent my bently away.

Female? Do you mean male? These are what I'm talking about:

http://www.bimmerboard.com/members/clumpymold/original/Resize%20of%20PICT9530.JPG

The front 4 bolts I couldn't even get a socket on those. Those are pretty tight though. I'd suspect something around 70lb-ft., at least. :dunno


Those are torx bolts...males, not females. E12 means external torx socket. Torque spec depends on size of bolt...M8 is 47 ft-lb, M10 is 62 ft-lb.
Yep. So which one are those? That's what I couldn't figure out. M8 or m10? :(

^^ Yeah their what I'm talking about, Males my bad,
74 lbs way too much I doubt I even had 40lbs when one snapped in the hub I remember reading in the Bently a 88lbs hence why I snapped the first one, re read and found it was really supposed to be around the 20 lbs mark.
Geuss that is why they recomend you change them, single torqued.
I'll try to get it back tonight and post all the proper specs from the Bently.

I used a 3" extention and was really only one position I could easily crack & tighten them, just spun the wheel to that location for each bolt for easy access for all.

^^ Yeah their what I'm talking about, Males my bad,
74 lbs way too much I doubt I even had 40lbs when one snapped in the hub I remember reading in the Bently a 88lbs hence why I snapped the first one, re read and found it was really supposed to be around the 20 lbs mark.
Geuss that is why they recomend you change them, single torqued.
I'll try to get it back tonight and post all the proper specs from the Bently.
I used a 3" extention and was really only one position I could easily crack & tighten them, just spun the wheel to that location for each bolt for easy access for all. I posted the proper spec's above. And they are not stretch bolts, they can be reused. Way earller in this thread I indicated where to position them for easier access.

I posted the proper spec's above. And they are not stretch bolts, they can be reused. Way earller in this thread I indicated where to position them for easier access.
So which is it? Are they M8 or M10?

I guess M10, take a look at :
http://www.realoem.com/bmw/showparts.do?model=BF93&mospid=47486&btnr=33_0468&hg=33&fg=25

I did the swap tonight, and only thing left id putting in the fluid. How many qts diff fluid should I buy?

2 qts takes 1.8

.2 goes on the ground ;)

ok, filled in w/ the fluid and test drove the car. Either my prev diff was a 3.46 as well, or it will get better after the break-in period. I didn't feel a huge difference (at least for the 1st gear). I am scared to push the car before break-in.

frankly, how do you know if a diff is 3.15 or 3.46 or whatever?

Jack it up. Count the number of driveshaft revolutions per one wheel revoltion. Also, you could check your rpm at a certain speed in a certain gear. A 3:15 ratio in a BMW with a 1:1 high gear turns right around 3000 rpm at 70 mph.

Tommy

ok, filled in w/ the fluid and test drove the car. Either my prev diff was a 3.46 as well, or it will get better after the break-in period. I didn't feel a huge difference (at least for the 1st gear). I am scared to push the car before break-in.

frankly, how do you know if a diff is 3.15 or 3.46 or whatever?
Where did you get the 14mm allen socket? I bought one off eBay but I noticed it's too long to even fit in that small space (let alone get a ratchet in there). I really don't want to take my differential out to add more fluid. Any suggestions?

Autozone sells a three pack of these allen sockets and they're made for a 1/2" ratchet. Put the socket in a vise and punch out the allen key portion of the socket. It takes very little effort. Insert it into the drain/fill plug and use a wrench to turn it. Very easy.

Another option is to get a 14mm allen ley and cut it to taste.

Tommy

another option is -what I did- buy it at zdmak.com

They sent me a FACOM brand socket (3/8 drive), and it fitted perfectly. (They ship pretty fast as well)

-h

Autozone sells a three pack of these allen sockets and they're made for a 1/2" ratchet. Put the socket in a vise and punch out the allen key portion of the socket. It takes very little effort. Insert it into the drain/fill plug and use a wrench to turn it. Very easy.

Another option is to get a 14mm allen ley and cut it to taste.

Tommy
I'll try taking that piece out. Or maybe cut the tool to fit? Is that going to be too hard?

ccblanket: Wow, they're pretty expensive. $20 unshipped. I paid $14 shipped for my one. And I'd prefer to not spend any more money. Besides, those look just as long as mine. :dunno

Oh, what's interesting is that, on the 10mm and 14mm page link, the two tools are identical. They just resized one to make it look larger. That's pretty shady instead of taking actual pictures of the item. :nono

it's a bit pricey. I paid a lot for all the little tools etc to do the swap. I was wondering if I should have spent more and get it done at a shop to save my arms and chest from the pain of lifting that heavy block up.

I think the cheapest (low quality) part of all I bought for this thing was the fluid pumps. I bought two, one of them didn't pump anything at all, and the other one was leaking from top or bottom. What a lousy workmanship.

Bumping this because I'm doign the swap in 2 days. Can anyone tell me if I am missing a lockring or washer or something on output flanges? Heres a pic of the diff I am installing, it didnt come with the m3 output flanges becuase they wouldnt fit my 325 anyways. So does it look like anything mising from this pic?
http://img.photobucket.com/albums/v242/sgray944t/birthdaydiff075.jpg

Yes, you're missing the diff output flanges. You should be able to pop the ones out of the current diff and put them in.

Tommy

It should look like this. See how your missing the output flange all together. But luckfully you can just use the ones off your old diff so your in luck. :)

Your ok they just press in & out no lock washer.

Ok great thanks guys. I know I was missing the output flanges themselves, just wanted to make sure there was nothing in between that I didnt have. Thanks alot!

I bookmarked your thread a while back and just did the swap today. Very good write up, thanks:redspot

I bookmarked your thread a while back and just did the swap today. Very good write up, thanks:redspot

Glad it helped. :)

Tommy

Well I just did the swap last night and took the car out for a drive and am incredibly pleased. I do notice 1 thing though. When I take really sharp turns at low speeds the diff seems to make a very low hum sound. Is this normal? The differential is a 3.23 with 55k miles on it so I dont think its going bad, I hope not anyway. Its running some heavy duty shockproof oil right now and I think that switching over to some redline may help smooth it out a little. The diff was also sitting for about 4 months without being used and my garage gets pretty cold, maybe it just needs to be driven a bit? Thanks

You dident put new oil in before you installed it? Why not ? Change the oil put some new oil in and put the addative in for positraction rear ends. Or get the redline that is made for the posi rear ends.

I didnt change it becuase the guy I bought it from changed it right before he sold it to me. He also opened it up and tightened everything back down to spec. I need to change the tranny and engine oil anyway so I'm probably just gonna put some new redline in the diff at the same time.

Um well sounds good to me. I dont trust anybodys work except for mine. Id change that oil asap. ITs cheap and is peace of mind knowing that its done right .

I don't know why he'd put a shockproof oil in there since it's a clutch pack diff. Of course, I'm assuming it's the OEM diff. I use Redline 75W90 NS. Yes, the diff may occasionally make a moaning noise when making tight turns. That's not very uncommon.

Tommy

Great thanks for the help!

Mine did too, don't notice anymore.

I'm doing this tomorrow and away from home so I don't have my tools aside from a ratchet and jacks and whatnot. Will have to go and buy everything from Autozone or whatever. Can anyone tell me what size wrenches are needed? I have the E12 torx, looks like maybe 17mm for the diff bolts, 16 mm wrench for the driveshaft to diff, 14mm for the sway bar bolts and 10mm for exhaust bolts?

Anyone? So I don't have to buy all kinds of stuff I don't need hoping it works.

Thanks.

I'm doing this tomorrow and away from home so I don't have my tools aside from a ratchet and jacks and whatnot. Will have to go and buy everything from Autozone or whatever. Can anyone tell me what size wrenches are needed? I have the E12 torx, looks like maybe 17mm for the diff bolts, 16 mm wrench for the driveshaft to diff, 14mm for the sway bar bolts and 10mm for exhaust bolts?

Anyone? So I don't have to buy all kinds of stuff I don't need hoping it works.

Thanks.

18mm for diff bolts, need a 13mm wrench and a ratchet for head and nut on the sway bars. 16mm is correct for the driveshaft, a 1/2 lenth extension helps with removal of the C.V. axles, 14mm hex for filling the diff fluid (do before install PITA after). Some advise first thing disconnect the speed sensor conector get's in your way when you forget.
For a 318 diff this is all that you need.

I'm doing this tomorrow and away from home so I don't have my tools aside from a ratchet and jacks and whatnot. Will have to go and buy everything from Autozone or whatever. Can anyone tell me what size wrenches are needed? I have the E12 torx, looks like maybe 17mm for the diff bolts, 16 mm wrench for the driveshaft to diff, 14mm for the sway bar bolts and 10mm for exhaust bolts?

Anyone? So I don't have to buy all kinds of stuff I don't need hoping it works.

Thanks.
A breaker bar for the 16mm wrench would help tremendously too. ;)

Yeah and just so you kjnow I dont think you can get a socket on those Driveshaft nuts, so id get a box end wrench for those.

Yeah and just so you kjnow I dont think you can get a socket on those Driveshaft nuts, so id get a box end wrench for those.

Yup. I used a Quickwrench. (http://forums.bimmerforums.com/forum/showthread.php?p=1902171&postcount=7)

Tommy

Yeah using those quickwrenches woudl help tremendously. I had to use a regular box end wrench of the driveshaft bolts and it took forever, only to find out after completely removing and installing the diff. that my dad had a full set of those quickwrenches.

sorry to bring up an old thread but I'll be replacing my torx bolts however I'm not sure which ones to get:

I have
33-21-1-227-664 (325) 45mm long
33-21-7-507-845 (325) 43mm long
EDIT: found this part Number: 33-21-1-227-279 (from M3) 50mm long
dealer says they've updated the 33-21-1-227-664 to the 33-21-7-507-845. but the 664 bolt is longer by 2 to 3 threads.

I'm upgrading to a 3.38 using the m3 output flanges and bolting it to a 325. which torx screws do I need?

EDIT2: another thing noticed is the following:
http://www.realoem.com/bmw/showparts.do?model=BF93&mospid=47486&btnr=33_0468&hg=33&fg=25
for the M3 the Drive Shafts have the following: LK=94MM/D=27MM
http://www.realoem.com/bmw/showparts.do?model=BF33&mospid=47484&btnr=33_0468&hg=33&fg=25
for the 325 the Drive Shafts have the following: LK=86MM/D=27MM

so what does the LK mean?

I'm assuming that the output flanges are different from the 325 but is that only in thickness? Maybe the LK=94MM means that its thicker and that you should use the 50MM bolts?

nice Al Pacino quote... lol

Bump - I bought also the M3 Torx Bolts just in case. any idea's what LK means?

I know its kind of late but I think the LK means length followed by D for diameter.

On another not, I stripped 2 axle bolts trying to get them off, I will be grinding those heads off tomorrow unless someone has and easier way? I couldnt fit my little dremelt cutoff disks in there.

Update: I had to use my 325 output flanges the diameter is larger on the m3 output flange. I ended up using the standard 325 torx bolts.

Just finished taking notes and will be doing this tomorrow. :buttrock Just need to pick up some royal purple diff fluid and torx sockets. I can just fill the diff using the speed sensor hole cant I?

-Serge

Just finished taking notes and will be doing this tomorrow. :buttrock Just need to pick up some royal purple diff fluid and torx sockets. I can just fill the diff using the speed sensor hole cant I?

-Serge
You can? I thought you had to remove that diff bolt using the really random torx socket. Something like 40 or 44. Don't remember now but I DO remember buying one on eBay only to find out I can't even fit my socket wrench in there. :(

Um the only torx socket required is an E12 for the half shaft bolts everything else is standard metric heads.

Um the only torx socket required is an E12 for the half shaft bolts everything else is standard metric heads.
He was talking about refilling the differential fluid. It requires a 14mm hex socket.

http://forums.bimmerforums.com/forum/showthread.php?t=477572&highlight=diff+socket

So I cant use the speed sensor hole to drain fluid in? So I gotta find a 17mm allen.

-Serge

Got my diff out today, hoping to only see some allen bolts backed out and instead I find 1/3 of my pinion gear missing and large chunks of it all over my diff!!!

The weird part is I cant see anything that worked loose to cause this kind of damage.

Sorry about the noob question but the search is down. What is the point of putting in another differential? I really appreciate your response

4life that is NUTS. Was it making any crazy noises before you removed it?

wcbimmer, a higher gear ratio will improve acceleration quite a bit!

Must be the massive horsepower my stock 328is with a Dinan intake is making LOL.
I noticed a faint barely audible clicking noise for about 10 minutes, then it suddenly turned into a loud clunking noise. I drove the remaining 2 KM home with no problem aside from the noise. After taking it apart and assesing the damage Im surprized I was able to drive it home.

JB weld, I swear it will work.

-Serge

So I cant use the speed sensor hole to drain fluid in? So I gotta find a 17mm allen.

-Serge
I read about one board member who created a work-around by putting a bunch of 17mm nuts on a bolt with a 17mm head. I've never changed the diff fluid myself, so I can't vouch for whether this would work or not ...

^^^ 17mm no.
A 14 mm yes.
Just need to lock two nuts togeter or weld one.
Although the proper hex tool only cost 5 bucks.

Thanks. Ill let you guys know how it went. I think Im going to miss a meet I wanted to go to cuz of this... oh well

-Serge

Missed the meet I wake up too late, but the lsd is in. Took less than three hours, pretty simple swap. There is def. a diffrence driving the car.

-Serge

nice write up, lucky me my 328 has a LCD first owner ticked all the boxes when he bought the car

i got a 3.23lsd... i'm in the middle of putting it in.. almost done, and i find out my axle shaft holes don't line up to the input flanges on the diff... what's wrong?

i got a 3.23lsd... i'm in the middle of putting it in.. almost done, and i find out my axle shaft holes don't line up to the input flanges on the diff... what's wrong?
Its probably because you have the wrong output flanges on the new diff swap them with your old diff.I postedmore detils in the other thread you posted.

can i fit or convert my e30 4 stud to e36 5 stud
as there is a better choise of mags about thanks
keith

(AKA vintageholden or bmwdude)

thanks for the great directions...i was wondering if you could tell me how to remove the axles from the hub area.?? also, where can you buy the E12 torx socket and new torx bolts? that would be sooo helpful! thank you

Thanks for all the information. I have a quick question

Behind the output flange (for driveshaft) from the differential there is a dust cover. Is it supposed to rotate with the shaft. If I need to replace it how do I do it?

I have a Z3 with a similiar diff as everyone.

Thanks,

Mike

Great article. Thanks for the info and pics.

great write up

Thanks, y'all... Just about forgot this thread was still here. Glad folks are still getting use out of it. :)

Tommy

Could you update links on pics?

great thread, I plan to do this in the near future!

Thanks for the post, you saved me a lot of agrivation

I've done this twice now and was going to post up a DIY, but that was simply not necessary thanks to this thread.

It's funny. I've been subscribed to this thread for ages and forgot about it when I actually underwent this swap.

Sure was a MAJOR PITA to do by myself though. Damn differential weighs almost as much as me (I'm only about 115lbs). Was pretty difficult but I did it. Sure feels good to accomplish something like this. :stickoutt

It's funny. I've been subscribed to this thread for ages and forgot about it when I actually underwent this swap.

Sure was a MAJOR PITA to do by myself though. Damn differential weighs almost as much as me (I'm only about 115lbs). Was pretty difficult but I did it. Sure feels good to accomplish something like this. :stickoutt


yeah me too ive been subscribed for at least a year... :D That diff is a bitch I just kinda put it on my chest and bench pressed it up there then threw a bolt in the back to hold it rested and started bolting it back up :D

Followed this DIY with no probs except for the heavy diff. My alligator jack has a big bicep to help me out.
Thanks for the DIY !!! :D And I dont have the growling noise coming from the rear anymore.

Cheers

Take a rubber mallet to the E12 socket. I got off all 12 bolts without a problem, so did my buddy.

Excellent thread everyone! I'm excited/nervous for tomorrow...DIFF SWAP TIME! Is it necessary to replace the seals when swapping output flanges?
~Phil

So the fluid doesn't need to be drained? That makes things much easier for me.

Take a rubber mallet to the E12 socket. I got off all 12 bolts without a problem, so did my buddy.

Do you mean you just gave each of the bolts a few taps before removing them to loosen them up?

Excellent thread everyone! I'm excited/nervous for tomorrow...DIFF SWAP TIME! Is it necessary to replace the seals when swapping output flanges?
~Phil

Nope.

So the fluid doesn't need to be drained? That makes things much easier for me.

Correct. It'll just be a tick heavier. ;)

So the fluid doesn't need to be drained? That makes things much easier for me.



Do you mean you just gave each of the bolts a few taps before removing them to loosen them up?

Tap the bit into the socket to seat it more tightly. This will help keep it from rounding.

Correct. It'll just be a tick heavier. ;)

Tap the bit into the socket to seat it more tightly. This will help keep it from rounding.

Thanks and thanks, I'm really hoping to get this done this weekend, along with RTAB's.

Not to revive the dead/old, but how hard is it (and can someone post clear instructions) on how to change the driveshaft flanges? My 328is has a 4 bolt 2.93 Open diff, and the one i was is from a 95 M3, and is a 6 bolt 3.15 LSD. how hard will this be?

Reviving an existing thread should be ENcouraged, not DIScouraged. People create too many new threads as it is....but I digress. ;)

I've swapped an input flange. It's a matter of removing the nut, using a puller to remove the flange, inserting the new flange, and torqueing the nut down to the proper specs and with the proper thread locker. It may require a new nut to be safe. I would measure the preload on the pinion flange before removing it. When you install the new one, torque the nut until the same preload is reached.

I would verify this with the Bentley.....or a good manual if you have one. ;)

Good luck,
Tommy

Not to revive the dead/old, but how hard is it (and can someone post clear instructions) on how to change the driveshaft flanges? My 328is has a 4 bolt 2.93 Open diff, and the one i was is from a 95 M3, and is a 6 bolt 3.15 LSD. how hard will this be?

It isn't terribly hard. you need to take your 328 output shafts out of your 328 diff. Pretty straight forward.

Then you need to inspect the seals and bearings in the output shafts of the M3 diff. The best bet is to replace these. Then just press the 328 shafts in.

When it is on the car I would drain and refill the fluid as well.

Not to revive the dead/old, but how hard is it (and can someone post clear instructions) on how to change the driveshaft flanges? My 328is has a 4 bolt 2.93 Open diff, and the one i was is from a 95 M3, and is a 6 bolt 3.15 LSD. how hard will this be?

You should also inspect the innards of that 3.15 diff--check the link in tommy's sig. The factory omitted threadlocker on a few of the bolts and they have a tendency to back out, bounce around and get stuck in the gears. You should verify that everything is as it should be.

thanks! Im needing this right now.

Great great writeup. If I get my 3:15 replacement this weekend, I'm ready to do this thanks to the quality of the pics and narrative. Thansk! *Crosses fingers*

Speaking of, can anyone confirm that the E12 TORX is available for $3.99 from Autozone, and if so, perhaps show a link? I'd rather not waste the money on the extra Sears set if I don't have to. Thanks!

I can confirm it was 4 or 5 bucks. Just call whichever store you're planning on going to.

Not sure whether this has been mentioned already in this thread or not, but the exhaust and sway bar do not have to be removed from the car inorder to swap the diff.

I just swapped mine this past weekend, and I left the exhaust completely bolted in place (a few extensions are required to get at the drivers side halfshaft to diff bolts). I also only unbolted the swaybar from the frame, not the suspension. This allows you to push the swaybar up enough the get at the rear diff mount bolts, and lower the diff out of place.

Reviving an existing thread should be ENcouraged, not DIScouraged. People create too many new threads as it is....but I digress. ;)

I've swapped an input flange. It's a matter of removing the nut, using a puller to remove the flange, inserting the new flange, and torqueing the nut down to the proper specs and with the proper thread locker. It may require a new nut to be safe. I would measure the preload on the pinion flange before removing it. When you install the new one, torque the nut until the same preload is reached.

I would verify this with the Bentley.....or a good manual if you have one. ;)

Good luck,
Tommy

so how do you measure preload?

I was told that there was quite a bit of "timing" when it came to installing the new diff as far as spinning it a few times until input and output shafts were synchronized. This isn't the case?

Great write up by the way

Not sure whether this has been mentioned already in this thread or not, but the exhaust and sway bar do not have to be removed from the car inorder to swap the diff.

I just swapped mine this past weekend, and I left the exhaust completely bolted in place (a few extensions are required to get at the drivers side halfshaft to diff bolts). I also only unbolted the swaybar from the frame, not the suspension. This allows you to push the swaybar up enough the get at the rear diff mount bolts, and lower the diff out of place.

Yep, it was mentioned in the first or second page, if I recall. :)

Tommy

so how do you measure preload?

There are several ways. You could get a torque wrench that measures in in-lbs. and simply use a socket that fits the input flange nut. Increase the torque setting on the wrench until the flange rotates. That's youre preload.

Or you could use a fish scale in a hole on the input flange. Measure the amount of "weight" required to get the flange to turn. Then use some math to determine how that force (applied "x" distance from the centerline of the flange) correlates to the amount of torque in in-lbs.

Tommy

I was told that there was quite a bit of "timing" when it came to installing the new diff as far as spinning it a few times until input and output shafts were synchronized. This isn't the case?

Great write up by the way

Nah, 'cause the input and output flanges will all change relative to one another as the differential does its job.

And thanks. :)

Tommy

This is a GREAT write up, thank you! It is a job I look forward to doing sometime this year!!

My pleasure.... :)

Thanks for the write-up and pictures. As mentioned, pics do a world of justice when us DIY'ers want the challenge/satisfaction of doing something ourselves....now if I can only find an LSD that'll balance my auto trans(ugh) with better low-end take-off power....anyway, the search continues. Peace. PG

great job, i'm considering swapping but it looks like a lot of work

If you have doubts about the DIY nature of this for a relatively new DIY mechanic - let me say from experience - DO IT!!! It took my dad and I approximately 2.5 hours with air tools and no prior experience with BMWs. There were a couple of times when we got stumped, and of course the natural profanity when one of the half-shafts smacked him in the face (I always manage to escape injury), but other than that it's well worth it and fairly straightforward.

is it normal to go 65 mph at 3500rpm I did a manual swap on my 93 325is dont know if I also had to swap the differencial

is it normal to go 65 mph at 3500rpm I did a manual swap on my 93 325is dont know if I also had to swap the differencial