Differential Z3, who knows something?

M

mirco.slepko

Newbie
Joined
Nov 22, 2021
Points
3
Hello to all,
I have to refurbish the differential of my 1996 BMW Z3 1.9.
I have never put my hand to this differential and at first sight I find it different from the standard LSD ones where on the cabinet there is the letter "S" while in that of the Z3 there is the letter "R" someone knows what the letter "r"?

To understand more, I opened it and found a strange situation.

It is a clutch disc differential only that unlike other differentials inside I did not find the preload discs but only 4 clutch discs coupled to the 4 dog's ear discs.

I have a feeling that the owner before me has somehow "tampered with" by replacing the preload discs with 2 other clutch discs to have a greater locking but these are just my hypotheses and I ask you if you have ever experienced this type of differential.

I am attaching a photo of the components of the differential lock arranged in a disassembly sequence and if anyone notices any additional or missing components, I thank them infinitely for the help.

thank you all
 

Attachments

  • 20211121_090710.webp
    20211121_090710.webp
    45.9 KB · Views: 446
  • 20211122_080650.webp
    20211122_080650.webp
    135.5 KB · Views: 466
Hi, could it be a Z3M diff? Same length output shafts as the 1.9 and I think the M diff is a 4 clutch arrangement.

@Lee @Pingu any ideas?
 
thank you for the tip!
my strong doubt is that there are no plate springs

in fact, without the plate springs there is no initial holding torque and it behaves as if it were an open differential.

therefore this is the original configuration?
 
Do you have a photo of the aluminum diff tag under a rear cover bolt, or the bar code (with number)?
 
Last edited:
It looks like an M diff. I have a video that I haven't edited yet that shows me rebuilding my diff.

When you bolt it together, you test it by measuring the torque required to turn the diff. I made a tool to lock the diff - it is basically a long bar that locks one output shaft - you measure the torque required to turn the other output shaft.

If you need new clutches, you can get them from Porsche. They are ZF, but ZF won't supply them, but you can get them from Porsche. I didn't need any, so I don't have any links, but Google is your friend. I think they are used on the 924 or the 944 - I can't remember.


A quick google found this...

www.eeuroparts.com

Upgrade Your Stock BMW E36 LSD With Porsche Parts! – eEuroparts.com

The OE BMW E36 LSD came on multiple cars, from the 325s up to the venerable M3. But, this LSD only has 2 clutches. Here's how to fix that!
www.eeuroparts.com www.eeuroparts.com
 
Last edited:
Althulas said:
Hi I don’t know if this video will give you any insights on how it should be assembled.
View: https://youtu.be/pVG-RUfXo4Q


Maybe the previous owner tried to upgrade to a 4 pack clutch. In this thread discussing about z3m diffs a poster mentions that his has a four clutch pack and has thinner plates compared to the thicker plates on a 3 or two pack. https://www.bimmerforums.com/forum/showthread.php?2090803-188mm-Diff-Build-3-Clutch
Click to expand...
I followed that video last year when I rebuilt the LSD diff of my other BMW e36 in fact the one in the video is a 188 while that of the Z3 coming from an e30 size 168.
 
mirco.slepko said:
I followed that video last year when I rebuilt the LSD diff of my other BMW e36 in fact the one in the video is a 188 while that of the Z3 coming from an e30 size 168.
Click to expand...
?? the Euro 2.8, 3.0 & M are type 188 diff not sure about the other engine sizes. The "R" I'm reasonably sure stands for Remanufactured, as in factory replacement.
 
R is thought to mean 'Rutschsicher' or non slip. Older E30 era stuff has 'S' for Sperre or 'lock'.

Reconditioned in German is 'Ueberholt'.

1996 is about the last year of the metal diff ID tags before the white plastic ID sticker on top of the diff.

That looks like a 3.45 ratio small case (168) Z3 1.9 LSD. Some more photos of the casing and rear cover would be helpful.
 
Many thanks to everyone for the info I received, they were very useful to me ...
I go through the photos of the case ...
20211121_083425.webp
20211121_103036.webp
20211122_080650.webp
 
ok do you think this 4-disc clutch differential is equivalent to a classic LSD 25% or worse?

finally: from this photo do you think the discs are in what condition? I think they still look good...

20211122_191347 (1).webp
20211121_103041.webp
 
mirco.slepko said:
Hello to all,
I have to refurbish the differential of my 1996 BMW Z3 1.9.
I have never put my hand to this differential and at first sight I find it different from the standard LSD ones where on the cabinet there is the letter "S" while in that of the Z3 there is the letter "R" someone knows what the letter "r"?

To understand more, I opened it and found a strange situation.

It is a clutch disc differential only that unlike other differentials inside I did not find the preload discs but only 4 clutch discs coupled to the 4 dog's ear discs.

I have a feeling that the owner before me has somehow "tampered with" by replacing the preload discs with 2 other clutch discs to have a greater locking but these are just my hypotheses and I ask you if you have ever experienced this type of differential.

I am attaching a photo of the components of the differential lock arranged in a disassembly sequence and if anyone notices any additional or missing components, I thank them infinitely for the help.

thank you all
Click to expand...
This may answer your question as to why there are 4 clutches and no pre-load? ........ found on another forum

I can provide a partial answer: only the later LSDs in Z3s seem to be Torsen. My 1998 2.8 6-cylinder has a clutch-pack LSD, as I believe they all did. The VIN decoder says: "S209A, SPERRDIFFERENTIAL 25%, Differential lock 25%." The bar code tag on the diff says: "1428258/E3204J;3.15." It turned out to be a Msport version with 4 clutches instead of the standard 2 clutches, along with asymmetric ramps and no pre-load.
 
Last edited:
great thanks for your availability and preparation on this topic.
I will try to investigate a bit about the history of this diff also based on the answer you gave me.
Thanks again
 
I have yet to see a clutch type LSD in a UK registered 2.8. I've had R reg ones with TorSens as well as S and T plate. The spec sheet from BMW always says 25% lock. The 1998 S plate car was a written off 1 owner 38,000 mile car.
 
You must log in or register to reply here.
Back
Top