engine and drivetrain m10/m42 flywheel ? Am I missing something?

[Rozz]

I am in the process of swapping in an M42. I pulled the M10 drivetrain yesterday, and I compared the flywheel/clutch assembly from the M10 with the dual mass setup from the M42. Aside from being about 1/8" taller overall, they seem to be the same everywhere else (overall diameter, clutch disc diameter, starter ring, throwout bearings, and crank bolt pattern) My M10 flywheel is a JB Racing lightweight flywheel, and I'd like to use it on the M42. Can anyone see a problem with this?

Thanks,

Ross

[eurotrash]

Hit up Jake at Classic Daily.  He does a lot of M42 swaps into 2002s.  He may know something about this.  google his business. 

[Rozz]

I'll give that a shot. I am waiting for him to send me my mounts and header anyway.

Thanks

[TobyB]

Depth.  The depth that the crank flange sits at relative to the ring gear.  Check that.

Also, it'd be smart to see where the clutch bell sits relative to the crank flange for the throwout.

 

It probably won't mess with anything other than your starter engagement, but it's worth checking.

 

The only reason I mention this is that an M42 starter sticks into the bell about 6mm less than an M10, even though it bolts right up.

 

And count the teeth on the ring gear- the M20 is slightly different, but I never checked the M42.  This matters because of gear pitch.  A bit.  

 

Unrelated to all that, I have had trouble with the clutch bell you show with the single mass flywheel you show above.

In hard usage, the radial straps fracture.  It's a real problem in the ClubRabbit world, where they can't get circumferential straps, like you have on the dual mass flywheel.

Not sure how much that matters, just something that's bitten me.

 

t

[cwlo]

Check previous discussion:

Let us know the end results.

 

Thanks,

Chris

 

[Rozz]

I'll check the tooth count tomorrow, and if I can switch the m42 and M10 around on the engine stand and hoist, I'll compare the difference in relation to where the starter ring gear sits.

[jakeb]

The m20 and M42 starter gears are different...I have never compared the M10 and M42 So you might be on to something.  Is that a 228mm m10 clutch or 215?

[Rozz]

OK, the results are in. I bolted up both flywheels to the M42. The M10 FW fouled against the rear seal housing bolt heads. I then removed the 1/8" spacer from the dual mass FW, drilled it out to fit the dowel on the crank, and bolted up the M10 FW. The ring gear sits .03" farther away from the engine than the M42 FW. Looking good, but then I checked the tooth count, and the M10 has 3 more teeth than the M42, so the pitch is slightly different. I don't know if it is enough to matter, but I'm going use a RHD engineering flywheel

and an M20 clutch setup. I had already gotten it when I started checking the usage of the M10 setup, so I'll just sell the aluminum M10 flywheel. It is a 215mm clutch.

 

http://racehead.com.au/products-page/engine-components/bmw-light-flywheel-m50-m52-m42-m44/

Edited November 17, 2016 by Rozz