How much friction should I feel with an LSD at low speeds?

[Racerhoze]

I somewhat recently installed a used LSD on my car, and never really having driven a car with an LSD, I am not sure what to expect. When driving around in my parking garage and going around turns slowly, I can feel and hear the LSD putting a lot of drag on the driveline every once in a while. I would not discribe it as "chatter" like a lot of people on here do. More of a smoother friction. And it is not 100% of the time, and usually when everything is warmed up. I have royal purple 90w-140 in there. Is this diff about to explode? or is this normal.

[screwbiedoo15]

I somewhat recently installed a used LSD on my car, and never really having driven a car with an LSD, I am not sure what to expect. When driving around in my parking garage and going around turns slowly, I can feel and hear the LSD putting a lot of drag on the driveline every once in a while. I would not discribe it as "chatter" like a lot of people on here do. More of a smoother friction. And it is not 100% of the time, and usually when everything is warmed up. I have royal purple 90w-140 in there. Is this diff about to explode? or is this normal.


Can't say I have too much too offer. With the current LSD on my car I almost never hear anything coming from it when I'm driving around. I will be installing a 3.64lsd on my car sometime soon and am interested to know if I'll be hearing some noises from that one.

Did you put the friction modifiers in your diff with the Royal Purple oil or did it already have the lsd additives in it?

[TouringDan]

I think it depends on the diff... I've had 2 BMW diffs that groaned around corners and one that is silent. (The LSD on my old chevy used to make a hell of a lot of noise) It could be something as simple as the weight of the oil, the clutches, or just something specific to that diff.

[Racerhoze]

The royal purple already has the friction modifiers in it. And shrike, would one of those two bmw differentials you spoke of happen to be this one? :stickoutt

[TouringDan]

Why yes it would.. I am really sorry that you are unhappy with it! I've gone ahead and sent you a refund of 1/2 the purchase price. That way, you can drive around on a $100 3.64 LSD and feel ok about it. Really though - I honestly think it's fine or I wouldn't have sold it. PM me and let's get this figured out.

[screwbiedoo15]

Wow, that was generous of you, Shrike.

On another note, Racerhoze how are you liking the 3.64lsd? Did it wake the car at all up from the 3.46?

[Racerhoze]

Woah, damn shrike, that was VERY generous of you. My purpose of this thread wasn't really to complain, you sold me that diff for cheap as it is! I was just trying to figure out if that was normal for an LSD. I wasn't trying to drag your name through the mud or anything either, I can tell from dealing with you that you are good guy. If you ever need anything that I happen to have, be sure and let me know!

screwbiedoo15, it did wake up the car some, especially when you punch it in 2nd or 3rd. But don't expect it to be a HUGE difference.

[screwbiedoo15]

screwbiedoo15, it did wake up the car some, especially when you punch it in 2nd or 3rd. But don't expect it to be a HUGE difference.

K, yeah I'm not expecting huge things. But figure 2nd and 3rd is where I would like the extra pick up.

[slocar]

I was under the impression that our diffs took 75w90, not 90w140. I'm surprised that stuff is still a liquid. :eyecrazy

[screwbiedoo15]

I was under the impression that our diffs took 75w90, not 90w140. I'm surprised that stuff is still a liquid. :eyecrazy

I think you're right. I bought 75w90 redline for my diff...

[Racerhoze]

I was under the impression that our diffs took 75w90, not 90w140. I'm surprised that stuff is still a liquid. :eyecrazy

Just checked and it is actually 75w140. I remember doing some research and finding that the thicker stuff was better for people who drive their cars really aggressively.

[screwbiedoo15]

Just checked and it is actually 75w140. I remember doing some research and finding that the thicker stuff was better for people who drive their cars really aggressively.

oh ok. when I called up redline they said 75w90 was what they recommended for the car. I think 75w140 is the weight bmw recommends for their specific oil?

[TouringDan]

My purpose of this thread wasn't really to complain, you sold me that diff for cheap as it is! I wasn't trying to drag your name through the mud or anything either, I can tell from dealing with you that you are good guy.

I didn't take it as such, so no worries! I have been on the bad-end of a deal before and know how it feels. I want everyone I sell something to to be cool with whatever happens.

I am happy that "it's all good" now.

Enjoy

[ross1]

The owners manual of my '89 states "Brand name hypoid gear oil SAE 90(GL-5)"
no mention of friction modifiers for limited slip
Are BMW limited slip differentials clutch type or Gleason worm/spur or planetary type?? It has been my understaning they are gear type and do not use clutches.
Shrike, the one in your Chevy chattered likely because of worn out, wrong or poor friction modifiers. The original modifier was from whale oil and when it's use was stopped the replacement additives took a long time to catch up and work well enough.
It did it the worst after a long straight ahead drive, as in first turn after exiting a freeway, didin't it?

[CleanE34]

mine makes minimal noise. and yes it does put a small amount of friction. if i let up off the gas down my block, i can feel a tiny bit of resistance from the car. but it could also be the sound system and 18 inch wheels i got.

[SchnellerE34]

Edit below. Up-dated information.

[robisconfusedd]

The recommended Gear Oil for BMW differentials is:

Non- Locking: 75w-90 or 140
Limited Slip or LSD: 75w-90

If you put 140 in your LSD, you will burn up your LSD clutch packs. 140 is too viscous and does not allow for the correct amount of slip, therefore locking up your rear end. This is why your car feels like it has resistance. Change it to 75w-90 immediately. Your LSD Diff will be much happier. Also, use Redline or Amsoil gear oil. Do not use Royal Purple. I have run tests with all three fluids. Royal Purple will foam up on you after awhile. Redline and Amsoil do not. I am running Amsoil currently as they have a new synthetic 75w-90 Gear oil, and my S3.64 loves it.


1st of all, Shrike is awesome, that was very generous!

And just curious, when I searched for what fluids to use when I did my diff oil, I came to the conclusion that 75w140 was correct for LSD and the w90 was for non-LSD... per these threads:
http://forums.bimmerforums.com/forum/showthread.php?t=840066&highlight=lsd+diff+fluid+75w140
http://forums.bimmerforums.com/forum/showthread.php?t=841324&highlight=lsd+diff+fluid+75w140

so that's just what i went by, is it different for e34 LSDs?? I didn't know! I assumed 75w140 was the way to go, which is what I told racerhoze when he filled his diff...

[SchnellerE34]

Edited information below.

[seventhstoned]

+1 on the amsoil, I've used it in several different LSD diffs.

[SchnellerE34]

Amsoil offers a Slip Lock Differential Additive for LSD units that Chatter:

http://www.amsoil.com/StoreFront/ada.aspx

[SchnellerE34]

I called Amsoil again seeing as they now offer the Slip Lock Additive. They have changed the Application of their Gear Lubricants to as follows:

75w-140 for Locking Differentials, if chattering or what feels like "friction" from the rear end occurs, apply the Slip Lock Additive.

They originally had 75w-90 listed for locking differential prior to the additives release since the more viscous oil was causing failure and chattering in LSD units.


The OP states that he has 90w-140 and not 75w-140. I would change it to 75w-140 and purchase the Slip Lock Additive.

[attack eagle]

just go to autozone and pick up some friction modifier.

sometimes the amount put in the gear oil is insufficient for the older diffs.

mine was chattery for a little bit, but I went out and cut some figure 8s to work the diff and it quit after that.

[Racerhoze]

The OP states that he has 90w-140 and not 75w-140. I would change it to 75w-140 and purchase the Slip Lock Additive.

It is 75w-140, there was a typo in my initial post. So can I get the amsoil slip lock additive at autozone?

[SchnellerE34]

Not sure if they sell it at AutoZone, but they should have something similar. If not order from the link above, shipping is usually pretty fast.

[screwbiedoo15]

So the Amsoil additive can be added to any diff oil? Can it be used on a diff oil that already has the friction modifiers?

[Grush]

Hmmm
talked to a local motor fluids specialized shop and he told me that he has the Castrol 75w140 for the dif (imported and very expensive btw) in stock. He also mensioned it was for LSDs, so he knew what he was talking about.

But he dosen't knows anything about aditives. Well. I have chattering noises in the dif. Let's see.

Btw, it's almost 2L of oil for the dif, right?

[SchnellerE34]

The additives allow for the clutches in the LSD unit to slip correctly, the chattering you hear is from them locking up. The Diff takes, 1.6L, so your correct, almost 2 liters.


Hmmm
talked to a local motor fluids specialized shop and he told me that he has the Castrol 75w140 for the dif (imported and very expensive btw) in stock. He also mensioned it was for LSDs, so he knew what he was talking about.

But he dosen't knows anything about aditives. Well. I have chattering noises in the dif. Let's see.

Btw, it's almost 2L of oil for the dif, right?