Another m20 flywheel conversion question

[thejimlab]

I did some searching and couldn't come up with an answer. Do both flywheels have the same diameter? If so, wouldn't it be possible to heat up the toothed ring on the m42 wheel, remove it, and then install it on the m20 flywheel? That way you could still use the m42 starter. I took a look at the flywheel I have at home and it seems like it will come off, I've helped do it on  other vehcles. Put the flywheel in the freezer overnight, heat the crap out of the ring with a torch and knock it right off. Anyone done this, or tried it?

[dude8383]

I think that the rings are not interchangeable.

[Wise Old Dog]

M20=228mm.
M42=215mm
That's what a Metric Mechanic flywheel is. But they machine the flywheel to make the ring gear fit. The ring gear will come off the M42 by tapping with a hammer and a piece of steel to spread the blow. I took 3 of them off last week and sold them to MM. Then you mount a M20 clutch with a sprung hub disc.