Author Topic: DIY M20 flywheel conversion (Read 125292 times)

Cobra Jet · « **Reply #75 on:** March 06, 2008, 12:05:28 PM »

Just a quick question w/ regards to the flywheel "upgrade":

When swapping out flywheels, is there no need to be concerned with the flywheel weight in relation to the engine's harmonic balancer or overall engine balance?

The reason I ask is this - when wanting to install a lighter flywheel on a Mustang, you also have to change and match the harmonic balancer to the flywheel's weight in order to retain overall engine balance and to avoid premature wear (or destruction) on the internal bearings. For example, a stock 5.0 flywheel is 50oz, so is the harmonic balancer. If wanting to swap out to a 28oz flywheel, the 50oz harmonic balancer would need to be removed and a 28oz balancer installed so that the total rotational mass was still balanced. You can't install a lighter flywheel and not change out the balancer or visa versa.

When installing an M20 flywheel on an M42, there is no need to change the harmonic balancer out as well? Going with a lighter flywheel over the heavier dual mass flywheel has no impact on overall engine balance if leaving the factory M42 balancer in place?

Does the M42 balancer weigh the same as the M20 or visa versa?

Please enlighten me a little more... I understand swapping out the flywheel in order to increase the spin up wanted for spining the rotational mass faster and the fact of "losing weight" (as this is a common upgrade or mod for MANY vehicles), however, I'm not seeing any mention of the impact to overall engine balance or any mention of the need for also upgrading the harmonic balancer. I'm only assuming that the M20 harmonic balancer and the M42 balancer weigh the same, therefore there would not be a need for swapping out this part...

mgold · « **Reply #76 on:** March 06, 2008, 02:05:41 PM »

I'm not sure how to answer that. What I do know is that there was no noticeable increase in vibration, even with the solid M30 motor mounts. That being said, it was recommended that I not lighten up the stock M20 flywheel, probably for that very reason.

josephb983 · « **Reply #77 on:** March 16, 2008, 05:09:16 AM »

I'm thinking of doing this conversion. The post above about the harmonic balancer has me worried. Has no one thought about this? Is there a solution?

Frankie · « **Reply #78 on:** March 16, 2008, 12:28:42 PM »

What is the verdict? What is the easiest way to do the flywheel conversion? Just to lighten the original or what?

Shift_Now · « **Reply #79 on:** March 16, 2008, 06:58:06 PM »

well, I lightened the m20 flywheel to just over 16 lbs (minimal lightening), and right now I'm in the process of re-assembling (tranny mounts are on their way) I'll let you know how everything worked out as soon as its up and running. And abotu the harmonic balancer... Metric Mechanic originally came up with theis little mod, you don't think that they would have thought it through? I don't know though, oh well, it's too late for me to go back now...

pwforprez · « **Reply #80 on:** March 18, 2008, 07:00:51 PM »

i picked up some 22mm flywheel bolts are they going to be too short for me?

also was i supposed to get the m20 clutch tool? because i did. im hoping if it clears up outside tomarrow to get this knocked out.

Shift_Now · « **Reply #81 on:** March 24, 2008, 09:15:47 AM »

Well, you need teh m20 clutch tool (i just used and adjustable one). This is a very good mod. the engien revs up much quicker, and it definatley feels faster. The idle has smoothed out completely, but it did get harder to drive smoothly but maybe thats my combination of this flywheel and a 4.45 diff haha.

pwforprez · « **Reply #82 on:** March 24, 2008, 10:41:36 AM »

well if i was to reuse my old tranny which was busted it had the smaller shaft and would have needed the m42 clutch tool. but for some reason the newer trans i got had the larger m20 shaft so i had to replace a couple things. we shaved the flywheel down and bolted the m20 starter right up. everything went together much easier then it came apart and the results were great.

daqqer · « **Reply #83 on:** July 14, 2008, 02:31:17 AM »

I have most of it now, but are those really needed ?

323i Release Bearing BMW PN: 21 51 1 204 525
M20 Pressure Plate

Does it really have to be 323i release bearing ?
And the pressure plate is from 325i ?

dvmotorsports · « **Reply #84 on:** July 17, 2008, 05:35:04 PM »

Here is what I just did and I love it.

323i Full clutch setup.

323 Flywheel (12.9lbs)
323 Clutch and PP
323 T/O Bearing
323 Starter gear

I love it. Highly recommended.

Bunta · « **Reply #85 on:** July 24, 2008, 07:38:33 PM »

I think this is going to be the next thing I do to my car.

Ive already got a 325 clutch and pressure plate.

So ill need a
-Single mass flywheel(lightened)
-323 TO bearing
-325 Starter gear

Hunter

daqqer · « **Reply #86 on:** July 29, 2008, 03:17:00 AM »

guys 323 and 325 have same flywheel and clutch, check the code.
so the 323 or 325 is just what you sayed in the shop when you bought you stuff, no difference there

dude8383 · « **Reply #87 on:** July 29, 2008, 07:25:17 AM »

The 323i flywheel was lighter from the factory.

KenC · « **Reply #88 on:** September 08, 2008, 11:28:25 AM »

I have a few questions before I slap mine together tonight.

1. Does the spacer from the M42 flywheel go on the crankshaft before or after the flywheel?

2. Can I use the flywheel bolts from an automatic? According to the Blackforest write-up, the threaded portion of the bolts should be just under 1", and that is just about how long the ones from an auto are.

Thanks,
Ken

nickmpower · « **Reply #89 on:** September 08, 2008, 06:51:13 PM »

inbetween the crank and fly and as long as they are the right length? they should be a good deal shorter then the m42 bolts