Lighter Flywheel on the Cheap?

[riverdale21]

I've got a M42 that needs something lighter than 29lbs. I was exploring the option of using the 325i clutch/flywheel until I heard mention in another thread about someone using an M10 flywheel with his M42.

How much does a M10 flywheel weigh stock? Can it fit in an M42 engine/transmission? I was also planning on having a machine shop lighten the flywheel before installation.

[rs4pro3]

I've got an 84 318i 5 speed flywheel for sale it's ~12lbs according to the bathroom scale, not sure if it would work or not. But let me know what you find out.

[arnoldgtr]

ETK says 14 lbs for the M10 flywheel. I checked it out because I noticed that the M10 certainly loses RPMs quicker than the S14, which has a 17.4 lb flywheel.

[e9nine]

....I noticed that the M10 certainly loses RPMs quicker than the S14, which has a 17.4 lb flywheel.

..very noticeable with the m42...you push the clutch in and you can take a nap as the revs drop, when I had the single mass f.wheel on my 2.7...it was 8) till it gave me probs and I had to go back to dual mass :roll:

[SlammedE30]

If there is a surface on your stock flywheel that can be machined to take weight off, that is a very cost-effective way of lightening the flywheel. My local machine shop took my 325i flywheel from 19lbs to 13lbs for $110 ($55/hr labor cost only). Might look into that.
-Ted

[LowR3V'in]

..very noticeable with the m42...you push the clutch in and you can take a nap as the revs drop, when I had the single mass f.wheel on my 2.7...it was 8) till it gave me probs and I had to go back to dual mass :roll:

lol! So true, there's about a 3 second pause inbetween shifts..

It's like....

VROOOMMMM!!!!! (*waiting for the rpms to go down.... *still waiting...) VROO-VROO-VROOOMM!

[riverdale21]

Can the M10 flywheel fit? If so what modifications if any would I have to perform to make it fit?

[riverdale21]

Any takers on the M10 flywheel question?

[Rob]

i'm interested in hearing as well

[riverdale21]

It sounds like it may work in theory. I was doing some research and they are the same diameter at 215mm just different thicknesses. That should be obvious because the M10 is a single mass and the M42 being a dual mass. I don't really know how many teeth the starter ring has on both and I don't know what effect having a thinner flywheel would do to the throwout bearing and such. I just plain don't know. I don't have the money to experiment and I dont have a M10 flywheel or M42 flywheel laying around to compare measurements. Any takers?

Who has a M10 flywheel they can count the teeth in the starter gear and measure the thing for us?
And who has a M42 flywheel that can do the same?

[riverdale21]

I talked to Ireland Engineering if it would fit and hopefully he will get back with me on that.

[rs4pro3]

Like I said Earlier I have the 318i flywheel sitting here I'll measure and count for you.

[rs4pro3]

Here is a crappy Paint drawing at the 140mm spot is where the clutch surface area starts My caliper dosn't go large enough to measure the outside diam.
The only problem I can see is the locating pins for the pressure plate are 15degrees of rotation from the 6 hold down bolts. Where as on a m20 flywheel the pins and bolts holes are very close together. I've never seen an M42 flywheel so I'm not sure how the locating pins are arranged.

[e30evolution]

that doesnt look like any flywheels i would want in my car

[riverdale21]

That picture of the flywheel is beautiful. Coincidentally my favorite artist is Picasso.