Clutch issue with m20 flywheel on m42

[Papasta318is]

Hey guys,

I recently did the common m20 flywheel swap into my 90’ 318is, using the m42 spacer ring, m20 starter and a 323 tob (21511204525) and the clutch pickup point is very high, at the top of the throw of the clutch pedal. Contrary to what people say, that with this combination of the parts, the pickup should be low, as it should be with a new clutch.

Maybe I’m doing something wrong? I’ve now removed the trans, and am thinking of using the 325 tob that was included in the clutch kit, as from the base of the bearing to the shoulder of the tob it is 4-5mm shorter than the 323 tob. This should mean that the tob has to travel further, hence a lower pickup point in the clutch pedal. My only concern is that I’ll run into issues with the slave cylinder having to travel too far with the shorter tob.

if that makes any sense. My thought process could be wrong so please correct me if this isn’t how it works.

the image attached shows the taller 323 tob on the left and the shorter 325 tob on the right.

thanks,
nick.

[jsnppp]

Wish I could help from experience but haven't gotten there yet. That few mm difference will indeed changes things. Hopefully someone has done it here!

[THEGr8insiDEMAN]

Following. Getting ready for the m20 fly 323 tob and going to use a zf320 on my m42. let us know how it goes. I’m going to shave the rear m20 fly use no m42 spacer and measure everything befor I do the install

[bmwman91]

Using all M20 clutch parts is fine and is the recommended setup. I forget how the 323 TOB became part of the "conventional wisdom" but it should not be needed for any reason. I am running an all-M20 setup now and it feels fine to me. Many many years ago I ran a configuration with the 323 TOB because the flywheel swap was new to the M42 world and one guy did it that way (so everyone else decided to go with what seemed to work). If I remember correctly the pickup point was sort of high, but I cannot say for sure "how high" since that was at least 15 years ago.

The pickup point is higher than it is on most newer cars, but I do not find it problematic. At this point you may as well stick the M20 TOB in and give it a shot.

[Papasta318is]

Using all M20 clutch parts is fine and is the recommended setup. I forget how the 323 TOB became part of the "conventional wisdom" but it should not be needed for any reason. I am running an all-M20 setup now and it feels fine to me. Many many years ago I ran a configuration with the 323 TOB because the flywheel swap was new to the M42 world and one guy did it that way (so everyone else decided to go with what seemed to work). If I remember correctly the pickup point was sort of high, but I cannot say for sure "how high" since that was at least 15 years ago.

The pickup point is higher than it is on most newer cars, but I do not find it problematic. At this point you may as well stick the M20 TOB in and give it a shot.

thanks for the reply man. That’s what I’ll do. I’m sure the shorter 325 tob will make a difference, my only concern is that the slave cylinder will reach full extension before the clutch is engaged, but if you’re using the same setup without issue then I should be fine.

[Shangsta]

Using all M20 clutch parts is fine and is the recommended setup. I forget how the 323 TOB became part of the "conventional wisdom" but it should not be needed for any reason. I am running an all-M20 setup now and it feels fine to me. Many many years ago I ran a configuration with the 323 TOB because the flywheel swap was new to the M42 world and one guy did it that way (so everyone else decided to go with what seemed to work). If I remember correctly the pickup point was sort of high, but I cannot say for sure "how high" since that was at least 15 years ago.

The pickup point is higher than it is on most newer cars, but I do not find it problematic. At this point you may as well stick the M20 TOB in and give it a shot.

yup Im also running all m20 parts. The 323 tob came about when people were not using the m42 spacer and were grinding down the bolts for clearance.

[Papasta318is]

Thanks for your help guys. Now using a 325 tob without issue, with the m42 spacer, the clutch picks up around halfway. through the clutch's travel, much better than before.

[ForcedFirebird]

m42 with m20 clutch needs the rear oil seal housing shaved down, or, use the anti-galling plate behind the FW (engine side), which will give you clutch release right off the top stop. When bolting the m20 FW right to the m42 engine, even the two center oil pan bolts will have to be shaved (clutch will release closer to the floor stop). Ideally, shave the FW on the back to meet the ring gear, install an m20 clutch kit, use the m20 starter (or swap the apex from m42 starter to m20 starter).

I don't see what gearbox you are running, but the m20 box with m20 clutch, and m42 doesn't have a good drive shaft combination (the m20 DS splines barely engage with the shorter engine).