i just started (dis-)assembling and testing some aftermarket clutch-type lsd options for the M3.
competitors i got here so far:
- gkn viscolok (the stock unit)
- os giken superlock spec-s (and custom spec... see below)
- drexler gt4 light
- titan traction master
- bacci romano
- zf (which i modified and tuned to my own spec)
i put some pictures of each unit on my website:
(text only in german so far... maybe i'll translate it someday)
what i've tested so far:
after driving (and drifting) some thousand miles with my stock gkn viscolok
unit i was sure to need a proper torque sensing clutch-type lsd which will react and lock/unlock way quicker and with direct connection to gas pedal movements. the viscolok is a really slow performer who locks and unlocks slowly and smoothly.
quite ok for non-performance street driving and slippery, snowy road conditions. but annoying when driving on the track or drifting the car where you need direct control and quick response of your rear axle behaviour.
i first tried the os giken superlock spec-s
unit. it fitted perfectly into the rear axle housing, no additional shimming was required. build quality, materials used and the surface finishing is really thumbs up.
but once installed i was pretty much disappointed on the locking capabilities: it hardly locked at all... it simply felt like an open unit.
after discussing with the supplier and manufacturer we were pretty sure that the neg. preload setup was to high. i got some new pressure plates and a different setup suggestion. i am really curious an how it will perform in the new spec which i will assemble these days as i am pretty convinced of the general design and the negative preload idea in theory. i guess i will only need to find a proper setup (which should normally be done by the manufacturer but well...)
right now i am driving the drexler gt4 light
unit (out of the M3 GT4 competition model) with the steeper of the two rampsets, more lockup on decel and no preload. it performs a lot better than the above but still doesn't lock as hard as i would want to. so i will flip the center section to get more lockup on accel or i could use the other rampset... i am still thinking on what setup i will try next.
build quality is quite high as well... and it also fitted perfectly without the need to re-shim.
i have two more "competitors" laying around here already:
a titan traction master
lsd unit which i got with a set of sinter-coated discs. but as i know the sinter-stuff from my other cars already i am looking forward to get a set of carbon-coated discs soon. i will try this unit with the carbondiscs then! it has some preload and i opted for the symmetrical 2-way ramps.
and last but not least i have an old friend of mine here as well. an "old" zf lsd unit
from a M5 E39 which also fits into the E92 rear axle. but as this unit locks quite weak in stock configuration, i am massively modifying this unit to fit more clutchpacks and/or use different ramp angles. this unit is performing well if modified correctly (i did this kind of mods in other m-cars quite often yet) and is still a lot cheaper than all other mentioned units.
i will update this thread whenever i switch the units and have new findings.
when i will finally be happy with the configuration of the current units i have here, i'll get the next bunch of lsds like kaaz and cusco.
if anyone does also drive a aftermarket lsd unit i would be happy to read his findings on it. what manufacturer, what setup, what kind of driving, satisfied with the performance, ...?
would be great to collect all lsd units here which are available for the m3 and discuss about their pros and cons...