LSD diff not working - confirmation needed

[deni2s]

Local mechanic says LSD diff is not working on my automatic Z3 2.8 and sent me this video - turning one wheel while on lift and the other is not turning at all. Can you please confirm, that means LSD is not working and diff needs maintenance?



Just want to be sure, that he didn't miss something (like checking should be done in gear only, or in neutral only or under load or something like that).

P.S. There are no doubts that car has LSD diff - confirmed by VIN and by mechanic too.

[scenturion]

I believe the non-M's have Torsen differentials.
Due to the way a Torsen works, if there is no resistance on one of the wheels, it will not lock up.
You can read more about it here.

This ties into your locker question; the simple formula is that the high traction tire receives (up to) whatever amount the low-traction side can sustain, multiplied by TBR. So, T(high) = T(low) X TBR. This does necessarily mean that the Torsen requires some amount of reaction torque on both outputs to be able to act against. This is typically the result of tire contact with the ground.
You probably see by now that in extreme situations, such as when a tire is lifted off the ground completely, that zero X TBR is still = zero. So, yes, in that case, the Torsen is limited.

Therefore, the video that you have posted is not conclusive.

[deni2s]

I believe the non-M's have Torsen differentials.

Any reference to source of this knowledge, please? I think some late production non-M z3 might have Torsens, according to this: https://www.bimmerforums.com/forum/s...5#post28931275

But my car has clutch type limited slip diff.

[Schreier]

This is the first I've heard of non-M Z3s getting anything but 25% Torsens, but my knowledge is not complete.

Maybe the mechanic could drain the diff and slip off the cover to take a look? Nice opportunity to drain and replace the gear oil, if anything.

edit: For what it's worth, RealOEM seems to indicate four different differential used in the 97 Euro Z3 2.8 at http://www.realoem.com/bmw/enUS/show...diagId=33_0385

3,15 (33101428439)
4,10 Automatic (33101428445)
I=41:14=2,93 Hot climate manual (33101428435)
3,91 Hot climate automatic (33101428437)

[deni2s]

This is the first I've heard of non-M Z3s getting anything but 25% Torsens, but my knowledge is not complete.

Maybe the mechanic could drain the diff and slip off the cover to take a look? Nice opportunity to drain and replace the gear oil, if anything.

edit: For what it's worth, RealOEM seems to indicate four different differential used in the 97 Euro Z3 2.8 at http://www.realoem.com/bmw/enUS/show...diagId=33_0385

3,15 (33101428439)
4,10 Automatic (33101428445)
I=41:14=2,93 Hot climate manual (33101428435)
3,91 Hot climate automatic (33101428437)

Car is not in workshop anymore. Wanted to confirm if I should order diff clutch parts for next visit in shop.
That is US car (not Euro) with 4.1 diff (33101428445), options S209A (Differential lock %25) and S205A (Automatic transmission).

[scenturion]

If you look at "Z3 E36 Z3 2.8 DIFFERENTIAL-LIMITED SLIP DIFF.UNIT" it shows a 25% lock up Torsen: http://www.realoem.com/bmw/enUS/show...diagId=33_1075
I think they were also available with open differentials, however. If your car does have an LSD, it is almost certainly a Torsen as per the parts diagram.

For reference:
My 01 Z3 has a Torsen with 25% lock up: http://www.realoem.com/bmw/enUS/show...diagId=33_1075
I confirmed this when I cracked it open and rebuilt it.
My 99 M Coupe has a 25% lock up clutch type: http://www.realoem.com/bmw/enUS/show...diagId=33_1075

[deni2s]

If you look at "Z3 E36 Z3 2.8 DIFFERENTIAL-LIMITED SLIP DIFF.UNIT" it shows a 25% lock up Torsen: http://www.realoem.com/bmw/enUS/show...diagId=33_1075
I think they were also available with open differentials, however. If your car does have an LSD, it is almost certainly a Torsen as per the parts diagram.

For reference:
My 01 Z3 has a Torsen with 25% lock up: http://www.realoem.com/bmw/enUS/show...diagId=33_1075
I confirmed this when I cracked it open and rebuilt it.
My 99 M Coupe has a 25% lock up clutch type: http://www.realoem.com/bmw/enUS/show...diagId=33_1075

You might be right, couldn't find that diagram... Maybe it is Torsen then. Thanks!

[Luftwaffe1O1]

If you look at "Z3 E36 Z3 2.8 DIFFERENTIAL-LIMITED SLIP DIFF.UNIT" it shows a 25% lock up Torsen: http://www.realoem.com/bmw/enUS/show...diagId=33_1075
I think they were also available with open differentials, however. If your car does have an LSD, it is almost certainly a Torsen as per the parts diagram.

For reference:
My 01 Z3 has a Torsen with 25% lock up: http://www.realoem.com/bmw/enUS/show...diagId=33_1075
I confirmed this when I cracked it open and rebuilt it.
My 99 M Coupe has a 25% lock up clutch type: http://www.realoem.com/bmw/enUS/show...diagId=33_1075

I think the early Z3s had Clutch pack LSDs, in 99 or something they switched to Torsens. I don't recall when the switch happened, but I do recall some of the early ones had clutch ones. It should say it on the diff itself, if it is something like S315 or whatnot.

edit:

For a 97 Z3 2.8, REALOEM lists it as a Torsen 25% as well. So maybe someone has more detailed knowledge, but if that is the case, you also prolly have a torsen.

[scenturion]

You might be right, couldn't find that diagram... Maybe it is Torsen then. Thanks!

On the plus side, this means that your diff probably works great. The clutch type wears pretty quickly, but the 250k mile torsen in my Z3 still works like a champ!

[deni2s]

On the plus side, this means that your diff probably works great. The clutch type wears pretty quickly, but the 250k mile torsen in my Z3 still works like a champ!

Yes, agree.

[Tim95M3]

Both my 7/98 and 10/98 build non-M's have Torsens that work great.

[robrez]

https://www.bimmerforums.com/forum/s...ntial-Question
See post 15 re Motorsport LSD

[me77]

My 12/98 build non-M Z3 has no locking differential at all, according to a VIN decoder and turning the wheels.