325 flywheel on 318is

[alloyproducts]

im thinking of putting a 325 flywheel on my newly acquired 318is, as ive been old the flywheel on a 325 is lighter. what other parts do i need, i know clutch, but do i need a 325 starter as well. thanks.

[monkey]

yes you will need to change the starter . i think you can use a flywheel from a 316 m40 as they are lighter than the m42s and use the same clutch and starter . i dont know how much lighter though .

[hoshy]

I think you need some e21 323 bearing also.

I'm doing this conversion also. Just started to get the fly and starter.

There's a very good website that details the entire conversion with lots of photos. but I can't find it now of course

A little info is here: http://bmw.e30tuner.com/my318is_mod_1.php

and more can be found on google too.

[Daf318is]

I did this on my 318is - you need:

M20 flywheel
M20 clutch + pressure plate
E21 323 release bearing (get it from BMW dealers - most places will get the wrong one in!)
New flywheel bolts
325 starter motor

To make it fit you may have to get the back of the flywheel skimmed to make it miss the sump - there is a lip on the flywheel. I have photos of this if you want me to post them.

Alternatively you can use a spacer which is attached to either the M20 or M42 I cant remember where it came from to be honest. Best bet is to have it skimmed though cause then it will be lighter.

The website was black forest engineering, or black forest autos or something like that - can't remember off top of my head!

Daf

[e21Jason]

Hi


Was this not a US thing as most m42's have dual mass were aas the UK one has a standard flywheel, so a m40 one is an easier option

Jason

[JungleGus]

the m40 flywheel and the m42 ones have been the same I've found..

still, the m20 fly isnt a bad swap, just make sure you lighten it

not sure how light the m42 one can been lightened

[n1tr0_9]

Ive done this conversion on my 'is with the M20 flywheel. I had it machined down to reduce the mass even more, but make sure you get it balanced properly after. I went for the M20 over the M40, as although there isnt much difference in overall weight, the 'meat' of the flywheel is closer to the centre on the M20, so it takes less energy to accelerate it.

I did the 323 e21 release bearing thing, but if you actually measure the distances using the standard 325 bearing its not much different. Memory is a bit sketchy now, but at the time i thought i could probably get away without using the 323 bearing. If you are able to have the car off the road long enough, i would suggest trial fitting with the 325 bearing before ordering the 323.

[Daf318is]

Dug out some pictures of when i did it. They might be of some use:

325 vs 323 release bearings:


This is 323 release bearing on 325 cluch on a very light M20 flywheel compared to the standard M42 gubbins



Daf

[alloyproducts]

thanks for all the info,

[shorty73]

will this newly aquired 318 be racing at all next year?

[djs325]

Much easier to do is swap over to a 316i or 318i M40 Flywheel. Uses same size clutch, but different friction plates (318iS is solid plate, 318i is torsion damped). Need the 8 different length bolts for mounting the flywheel as well, but thats it. No starter motor or release bearing change. Did this on my road 318iS, and it flew! Clutch kits are cheaper too!