This is real simple. For my turbo car I rebuilt one going from 25% to 60% lock by machining and fitting 4 clutches/dog plates in place of 2. For my daily driver '95 525i I decided to fit an LSD diff and rebuilt it for 3 clutches/dog plates which will result in a more calm 40% lock up. 60% is nice in the turbo car but tight radius turns result in tire chatter since the axles are so locked.


'93 3.23 LSD Differential by Jon Kensy, on Flickr

Old clutches were in good shape:


IMG_0055.jpg by Jon Kensy, on Flickr

Replacement clutch set:


BimmerDiffs.com 3-Disc Upgrade by Jon Kensy, on Flickr

You just remove the end plates and then remove the ring gear/LSD carrier. You make sure that your carrier depth is ~96.8mm and your LSD cover plate is about 14.0x mm inset. Then, just swap out a spacer plate and old clutch/dog plates with new. ZF used a spacer in the diff that can be removed and is the exact same thickness as an additional clutch/dog plate. So, going from 2 clutch to 3 clutch is easy. 2 clutch to 4 clutch required machining down the carrier cover by the stack thickness difference, still not hard, though.

Old parts out:


3.23:1 LSD 40% Lock-up Setup by Jon Kensy, on Flickr

Measuring backlash:


3.23:1 LSD 40% Lock-up Setup by Jon Kensy, on Flickr

Spec is 0.06 - 0.014mm (0.0023 - 0.0055"). Mine measures in at 0.0041", well within spec.

Measuring backlash:

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1992 700RWHP Pump Gas BMW

Nice Jon,
I did the same (3 clutch mod) with my 4.10 e30 diff in my ti. Did you use thicker Porsche plates or the stock thickness BMW plates? I went with 2.1mm Porsche Motorsport dog ear plates rather than the standard 2.0mm BMW ones for a bit more lock-up.

Simon I used a kit from www.bimmerdiffs.com they measure a hair over 2.0mm

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1992 700RWHP Pump Gas BMW

I need to rebuild my e46 m3 diff it's knocking like crazy the oil leaked out, I wonder if they have any rebuild kits for mine.

The E46 M3 uses the larger 210mm unit and they are rebuildable. Contact Dan at Diffsonline (http://diffsonline.com/) and he should be able to help you out.