E12/E28 Clutch/Flywheel upgrade for E34?

[hakwuzhere]

Ok, so after searching and searching I hear people talking about doing this, it gets you a single mass flywheel and a heavier duty clutch for dirt cheap... but I cant find any writeups that talk about how to accomplish it. Does anyone either know whats involved or can they point me in the right direction to find out exactly what I need?

[gale]

I'm by no means an expert at this topic, but I saw it was going unanswered so I'll take a stab at it & perhaps someone will come along and criticize & help steer you to a viable option. With that said, one of our local club members put a non-dual-mass e30 m20 flywheel in his e36 m50 and it really opens it up & lets it rev freely. He was surprised at how much it improved the bottom end. I'm thinking about messing with this on my wife's e36.

He mentioned something about messing with the throw-out fork (different model?) and used a correction: e21 323 throw-out bearing (not e9 320). I would assume he also used the e30 disk & pressure plate. It was all nuts & bolts.

There are also numerous aftermarket light weight flywheels but I'm reluctant to going too light as it can cause driveability issues. It can suffer from annoying oscillations when taking off from a stop & actually lose a little top end.

As for the specifics for doing the job:

1. put all 4 corners up on jackstands
2. drop the exhaust
3. unbolt the front of the driveshaft & pivot it to the side & tie it out of the way
4. get a cheapie scissor transmission jack
5. support the trans & remove the crossmember
6. lower the trans slightly (make sure the fan clears the radiator, remove if necessary, make sure there's clearance for the head against the firewall
7. undo the clips on the shift lever link rod & remove
8. lower the trans enough to get room to reach the top bell housing bolts (see #6). With e32 & e34 m30's the engine will rest nicely on the swaybar. Use about 30"-36" of socket extensions & a mirror & flashlight to get to all of them. It's good to have a helper turn the wrench while you keep the socket on the bolt.
9. remove the trans. Be careful that it separates straight out without bending/stressing the input shaft. Note that there are 2 sleeves that act like alignment dowels on either side (the 2 larger hex head bolts). Make sure they're there when putting it back together.
10. remove the pressure plate & disk
11. remove the flywheel bolts. One of them also has an alignment sleeve, make sure it goes back in.
12. The pilot bearing comes out by hammering soft bread or playdough thru the center hole with a wooden dowel & hammer. Make sure you put a new pilot bearing in
13. good time to replace the rear main seal
14. ditto for the trans input shaft seal
15. the throw-out bearing simply pulls off
15. undo the spring clip that holds the throw-out fork
16. replace the plastic pivot dammit that the throw-out fork registers on

Some clutch kits come with a cheapie plastic pilot tool for lining up the new clutch disk, don't try to put it back together without using some sort of precision alignment of the new disk before tightening the pressure plate bolts.

Installation reverse of above steps. What else? New guibo: take note that there are arrows molded into the rubber on the guibo that point to the respective ears on the output shaft & driveshaft. If you clock it a hole off, it will greatly shorten the life of the new guibo. Turn the nut & not the bolt so you don't tear out the metal sleeve. That's pretty much it in a nutshell. Reference Bentleys to elaborate on any of the above.

[rob101]

removing pilot bearings: another interesting use for play dough i didn't know about.

[hakwuzhere]

What Ive been hearing is that this swap works with M20 and M30 engines, but not M50 non vanos... Is that true?

[Kalevera]

M20 and M30 flywheels are not interchangeable. All M20s use a 228mm flywheel, m30s are 240mm.

[hakwuzhere]

M20 and M30 flywheels are not interchangeable. All M20s use a 228mm flywheel, m30s are 240mm.

Ok, so I have an M50.... whats that mean? cause I know the E28 swap works with the M20.

[Paul in NZ]

Martin in Bellvue has done this on his M30 using a flywheel and clutch (i think) from an E28 535

[Derek A.]

Ok, so I have an M50.... whats that mean? cause I know the E28 swap works with the M20.

Your only choice is a UUC setup. None of the older BMW motor's flywheels are going to work.

[gale]

What Ive been hearing is that this swap works with M20 and M30 engines, but not M50 non vanos... Is that true?

I've been reading (aka Google) some more about putting an m20 non-dual mass on an m50 & have some more info. It seems putting an m50 into an e30 is a popular swap so those guys have a bit of experience. Looks like there are 2 resolvable problems:

1. The back side of a non-dual mass m20 flywheel hits some of the oil pan bolts on the back of the m50 engine. No big deal, a little machining will give it sufficient clearance.

2. The non-dual mass flywheel is 3/16" thinner than the dual-mass flywheel, and upsets the geometry for the slave cyl/throw-out fork travel. As it turns out, the e21 323 throw-out bearing is 3/16" thicker and takes care of the problem.

Another issue which I'm not sure of is whether the m20 flywheel on an m50 will require swapping starters as well.

None of these issues are a concern if using an aftermarket flywheel & clutch made for the m50 so maybe that's the way to go, except I can't get excited about using an aluminum flywheel for the long term in a daily driver.

[Herb]

This is interesting, the e34 I'm interested in needs a new man. tran., so I was looking for options. I hadn't even considered my answer might be my own car. e30 s52 with e30 trans, 323 euro fly with e30 m3 clutch assem. so I wonder if the 323 euro fly will work in the e36/e34 trans? 323 euro fly is like 12-16 lbs.

[etcetera]

Any aftermarket non dual mass steel flywheels out there for the m50? I don't want an aluminum one either.

If not there is a junk yard with a dozen or more older BMW's with m20 engines. If I could upgrade for the cost of a junkyard flywheel, machining and a new throwout bearing I'd be in heaven.

[Martin in Bellevue]

Martin in Bellvue has done this on his M30 using a flywheel and clutch (i think) from an E28 535
Paul, I put an e28 m30 flywheel behind my m30b35. Ended up helping Jeff & Erik do the same with their cars a while back. It is a great improvement in throttle response for a sportier drive. I'd be interested in knowing of a retrofit m20 flywheel for my supacharged s52 m3. I'd also like to know if a light flywheel is even a good idea with the vortech; friends have stalled it trying to get away from a stop as it is with the stock dual mass flywheel.

Here's the 15lb e28 m30 flywheel that went ionto my 535.
http://www.bimmer.info/bmw/Martin5er/e28stock&15lber.jpg