a bit of clarification on M20 flywheel/clutch conversion

[bflan2001]

It isn't, the stock m20b25 flywheel is something like 18lbs whereas the 323i flywheel is 13lbs. I don't know if they are the same dimensions. I just remember that the parts I collected were, at the time, supposed to be the only way it would work, but from reading through this thread I can see that's not the case. Unfortunately I'm still having trouble making sense of it all.

[bmwman91]

Well, one thing that you can do is take the full M42 clutch/flywheel assembly out and measure thisknesses of the stack-up. Then do the same for your E21/E30 M20 assembly. See how close they may be. Looks like you are going to get the privilege of being everyone's guinea pig with this!

[bflan2001]

Well I guess I am due for a contribution of my own. I'll dig all the parts out and get things measured up this weekend.

[jwal]

I hope I am not asking a dumb question...but does the m20 flywheel setup require a different pilot bearing? I am ordering all my parts and I am not sure how this change affects that decision. I know that the clutch alignment tools only work for particular bearing sizes, so it would be nice to know definitively which bearing to use. Thanks

[ForcedFirebird]

I hope I am not asking a dumb question...but does the m20 flywheel setup require a different pilot bearing? I am ordering all my parts and I am not sure how this change affects that decision. I know that the clutch alignment tools only work for particular bearing sizes, so it would be nice to know definitively which bearing to use. Thanks

Pilot matches the trans. To use a g240, use a m42 pilot. Spline count is the same, so the tool will work fine.

[jwal]

Ok great, that makes it easier :)
Thanks firebird

[roguetoaster]

Be aware that if you are using an M42 G240 there are two different pilot bearing sizes.

[jwal]

Yeah, I saw that too. Just one more thing to check I suppose

[brads2002]

yes the M42 bearing has a wider center so while the M20 tool will fit the spline it will not work to align it correctly.

[ForcedFirebird]

yes the M42 bearing has a wider center so while the M20 tool will fit the spline it will not work to align it correctly.

Not all of them. ;)

The time you would need a different tool would be if you changed your transmission since the bearing has to match the trans. A lot of kits don't come with the tool.

[roguetoaster]

^
Exactly. For reference, two different M42 G240s, although it's a bit hard to see the comparison:

[brads2002]

Interesting. I didn't know there were 2. Mine has the larger one for sure.

[jwal]

I am going to measure mine so I can know for sure. I hope its the larger one so the m20 clutch tool fits :P

[jekas619]

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[ForcedFirebird]

I am going to measure mine so I can know for sure. I hope its the larger one so the m20 clutch tool fits :P

Getrag 260 has the small diameter bearing.