*DIY How to take apart an LSD rear.

[Binjammin]

So I had this extra rear laying around, I decided to check out the condition of it and clean it up. Turns out it's in nice shape, could maybe use new clutches but I'll see if I can find 'em first, they're still holding though. Painted everything, and put it back together. I figured I'd write it up and post pics of it. If anything seems out of place for the instructions it's because I took the pics putting it back together, not taking it apart, but disassembly is reverse of assembly

Thanks to Matt at Sports Car Restorations for the use of the blasting cabinet to clean the stubs and rear cover, it would have sucked doing outside in 30mph winds and 25* weather.

http://www.trademotion.com/partlocat...25&catalogid=1




Start with the welding cart. It's tough, and can handle the weight of the diff. It's a heavy beast, like your mom.
Line it with rags, it's going to get gear oil everywhere, even if you drain it. Even if you take all the parts out and wash them in the safety-kleen tank, trust me.





I had all sorts of cans of paint laying around, the stub axles got white. Rear cover some sort of navy metallic, with red metallic bolts.





Pull the stub axles. They just come out, shouldn't need much more than a pry bar or some big, thick, meat mittens. Be a man, use your hands.



Pull the back cover.



Pop out the diff bearing races. It may take some persuasion with a hammer and punch, or it may pop out with a pry bar. Try the pry bar first, then use more force after. Really shouldn't take the BFH, if it does, you're doing it wrong.



Then the other side.



This is what you should have now. With both bearing races popped out the ring gear with the lsd in the middle will just fall out. Stupidly simple, and fairly beefy at the same time.

[Binjammin]

Pull all the allen bolts out of this flange. I recommend using an impact gun to save yourself the wrestling the diff around. I've never had one strip, and I've done like two of these




Pry the flange out. Use two pry bars, it's a piece of cake.



Then just pull the flange out. The next few photos will show the order in which the parts come out, there's no trick to it, just make sure you stack them when they come out so you don't lose the order.







Best tool for removal, stick a finger in and pull the whole stack out at once. Makes removal easy, and keeps the order for re-assembly too.




EEEK! Spiders!



There's that tool again.




Basically the diff internally is a mirror image, so one side is the same as the other.



That's the trigger wheel and bearing. Use a bearing separator and press to remove and install a new bearing, I have no idea how or why you'd want to remove the trigger wheel. It might be pressed on, it might need to be heated to be removed, but unless you've got some ridiculous reason to do it, it's not something you need to worry about.



That little ring on the inside is what holds the stub axle in place. It's always got the CV axle bolted to it so it can't come out, remove the CV and it will practically jump in your lap and ask for treats.

[Binjammin]

The last step would be to remove the pinion gear, but as I had a good pinion seal I didn't want to waste it for a write up. Basically once you've got the flange nut off the front (which people have written about already, nothing new for me to add) you rip the seal out. I believe you just tap the pinion out of the bearing after that. If someone wants to see it that badly beg me for it and I'll think about taking another diff apart



Start reassembly by tapping one of the races in partway, just enough to seat it. DO NOT forget to put the sealing rings in like I did, you'll have to take the whole thing apart and start over. Tap the race in enough to get a couple threads on the bolts that hold it in started.



The important thing to remember is NOT to put both races in all the way first. Put one in partway only, or you won't be able to fit the diff in afterwards. Once you've got the bolts started you can stick the diff in the case, and tighten the bolts on the race in a star pattern. Walk it in gently with just a little lube on the seal and you should be just fine. No need to go nuts with the hammer smashing the whole thing in, breaking stuff, and tearing seals, when a gentle hand will be do.



Turn the housing on its side and you can start tapping the other race in. This will align the diff bearing in the first race, and when you get the second race started it will be aligned with the other bearing. Same thing with the star pattern once you've got the race in far enough to start the bolts. Don't forget to put the metal seal in on this side either.

From there just put a new seal on the diff cover, I personally prefer a bead of "Right Stuff" RTV to seal the diff. I didn't take pics of that part of the process because I planned on taking it apart again sometime if I found clutches, and I didn't want to waste the time and effort doing something twice. Use your imagination for sealing it.

[Binjammin]

So I realized I didn't take any specific pics of the clutches. I guess I'll have to take it apart and do it again. Oh well, no big deal.

[MaloventEvil]

i am confused... where are the instructions / pics?

[Binjammin]

Pics are there, I DID have to write everything you know...

[MaloventEvil]

oh i thought it was just a browser issue or something . nice writeup!

[themadhatter]

nice work, thanks for sharing.

[Binjammin]

No worries, I'd like to do a few more write-ups as I have more projects to do. If only more stuff would break on my car...

[silver36]

cool.. ive been meaning to replace the seals on my lsd for my 3er.. this gices me a better idea of what it looks like inside!

[Rozboz]

great writeup.

i need to rebuild my diff as the clutches are worn out. do you know where i can buy a clutch plate kit and shims? bmw want stupid money

[Binjammin]

Everyone here can thank Schitzo for doing the legwork and finding this link

http://www.trademotion.com/partlocat...25&catalogid=1

with a link to an exploded view and a listing for clutches. I've been swamped lately and hunting clutches got put on the back burner, if I can find a little time sometime soon I'll see if I can find them cheaper.

[Rozboz]

thanks very much to both of you. that's awesome

[Blauanzug]

On the subject of LSD is it possible to add it to your car even if it didn't originally have it?
Next question if i am just learning how to repair my car where do you think I should begin?

[Binjammin]

On the subject of LSD is it possible to add it to your car even if it didn't originally have it?
Next question if i am just learning how to repair my car where do you think I should begin?

I think it's possible, but for the money you're going to spend buying an LSD, you can probably get the whole unit for hardly a couple bucks more.

For repairing, I'd say fix the stuff that's wrong first, then start upgrading.

[r1101r]

amazing write-up..

[Rozboz]

ok so how many clutches do i need to buy? it seems they don't sell a 'kit' as such and when i emailed them they just replied to me with a link to the parts locator

also what shims do i need to buy to make it more active and how many?

thanks

[Binjammin]

Shouldn't need any shims, if you managed to wear the steel plates that butt the clutches out then you're probably going to be facing other problems as well. A pair of clutches is all you need, one for each side. I don't know about upgrading these units with more clutches, you'll need to call a pro diff builder for that type of thing. Try diffsonline.com

[Blauanzug]

Next question if one can add an lsd is it worth it? And what exactly does it do?

[Binjammin]

Ever seen the movie My Cousin Vinny? There's a simple explanation that's the whole basis of the plot of that movie, but basically, it's a limited slip differential. A differential takes power in from one direction and via gearing changes the direction of the path of motion. In this application it means the driveshaft turns the pinion gear in the rear end, which turns the ring gear in the rear end, you can see these parts in the pictures. The ring gear puts the power to the axles.

The thing about differentials is that an open diff will always put the power to the inside wheel in a turn. Take a right turn, and the right wheel will peel out on an open diff. This is usually perfectly fine, and it makes sense to have this setup, as the outside wheel in a turn has to travel further than the inside wheel. A spool is a differential that is always mechanically locked, it always applies power to both wheels equally. This is good for drag racing, but bad for street driving, as it means you'll be lighting up the inside wheel in a turn.

A limited slip differential means the differential will lock in a straight line, applying torque to both wheels evenly, but in a turn it will allow slippage in the clutches in the rear, unlocking the differential so the wheels can turn at different speeds. As soon as you're traveling straight again and under power the rear will lock again. It's a good solution to the problem of not wanting the wheels fully locked all the time, but wanting them locked almost all the time.

[Binjammin]

So far as worth it, yeah, if you don't have one you'll end up doing the one-wheel-peel. It's a really decent upgrade, it also helps in adverse weather conditions, giving you more grip in wet, snow, and dirt. If you're upgrading to an LSD rear you can also pick a ration that's more suited to your driving style, something shorter for more acceleration.

[Blauanzug]

if i install one do i have to install the switch as well? Or just keep it on?

[Rozboz]

Shouldn't need any shims, if you managed to wear the steel plates that butt the clutches out then you're probably going to be facing other problems as well. A pair of clutches is all you need, one for each side. I don't know about upgrading these units with more clutches, you'll need to call a pro diff builder for that type of thing. Try diffsonline.com

thanks

[Rozboz]

turns out that place doesn't ship internationally

there goes that idea

[Binjammin]

if i install one do i have to install the switch as well? Or just keep it on?

No switch. The wiring on the doff cover is for the speed sensor. The trigger wheel you see in the pictures passes through the sensor to tell the ECU and ABS how fast the car is travelling.

turns out that place doesn't ship internationally

there goes that idea

You can probably find someone that will take your money and ship it internationally for you, I just don't know if it's worth the megabucks for you.