Author Topic: Lightweight Flywheel Options (Read 8139 times)

Flatsix · « **on:** May 21, 2007, 06:58:57 PM »

Folks,

I am looking to replace my hideously heavy dual mass flywheel. After some research there appears to be two options. One is the JB lightweight, an aluminum option which weighs approx 8lbs but is has a very complicated design (multi-piece) plus lots of screws/bolts. The other is the Metric Mechanic flywheel from a 325 6 cylinder which has been machined down to approximately 10lbs and which uses the m42 ring gear. Any thought on either? Personally I favor a solid mass steel wheel over a multi-piece aluminum wheel as it is a simpler unit, has less �moving� parts and less likely to warp.... but then there is the ~2lb weight penalty. Other experiences, thoughts or input. I am basically building a mild street racer with possible occasional use on the track.

1991 318is (under construction)

Shocker · « **Reply #1 on:** May 21, 2007, 07:40:11 PM »

Do a search there are plenty of threads about this.

I'd recommend the 325 one because it has a sprung clutch disc so it wont have the rattles like mine does.

b318isp · « **Reply #2 on:** May 22, 2007, 07:19:46 AM »

There is a third option - use the one piece flywheel from a Euro 316i/318i with the orginal clutch. Not as light as the M20 flywheel, but a simple swap though.

bar73k · « **Reply #3 on:** May 22, 2007, 07:51:02 AM »

Quote from: b318isp;26298

There is a third option - use the one piece flywheel from a Euro 316i/318i with the orginal clutch. Not as light as the M20 flywheel, but a simple swap though.

this is what im running (flywheel that is, the rest is custom) just need to change the starter ring that is on the flywheel. i.e take the ring off the old duel mass flywheel and put it on the new 318i single mass flywheel. very easy to do, with a little heat

johna · « **Reply #4 on:** May 22, 2007, 06:43:25 PM »

The M40 (Euro 316i/318i) flywheel weighs around 9.7 kg (21.4 lbs) but can be machined down to 7.7 kg (17 lbs), possibly more.

Quote from: bar73k;26301

this is what im running (flywheel that is, the rest is custom) just need to change the starter ring that is on the flywheel. i.e take the ring off the old duel mass flywheel and put it on the new 318i single mass flywheel. very easy to do, with a little heat

I don't understand... My M40 flywheel fitted without any modification.

gearheadE30 · « **Reply #5 on:** May 23, 2007, 04:55:10 PM »

Someone here is attempting to put an E30 M3 flywheel on his car. If this works, it may be a bit more economical.

bar73k · « **Reply #6 on:** May 23, 2007, 09:42:22 PM »

Quote from: john318isau;26361

I don't understand... My M40 flywheel fitted without any modification.

I had a shop do mine and they said they changed them over (starter ring on the flywheel), it is quite possible that isn't necessary.

the pressure plate and clutch plate were custom made to cope with the power
my car puts out..

johna · « **Reply #7 on:** May 24, 2007, 01:24:12 AM »

Ok, I used a standard LuK M40 clutch and pressure plate kit.

kramerica5000 · « **Reply #8 on:** May 24, 2007, 01:55:38 PM »

I've never heard good things about going with aluminum flywheels, at least for a street car. I think they are too light for daily driving and are not very durable (flywheels do crack, had it happen to me with another vehicle). So I would either go with the metric mechanics kit or an m20, etc conversion.

fabe · « **Reply #9 on:** May 25, 2007, 02:35:18 AM »

Quote from: john318isau;26361

The M40 (Euro 316i/318i) flywheel weighs around 9.7 kg (21.4 lbs) but can be machined down to 7.7 kg (17 lbs), possibly more.

I don't understand... My M40 flywheel fitted without any modification.

I am using the M40 single mass flywheel machined down to 7.6kg... been using it for 3 years aledi. No problems watsoever..

vpilarry · « **Reply #10 on:** May 25, 2007, 08:10:27 AM »

What US available clutch can be used with the M40 single mass flywheel?

Boyracer · « **Reply #11 on:** May 26, 2007, 04:10:28 AM »

I have standard M40 flywheel waiting for lightening and installation and my understanding is that it will fit straight away to M42.

gearheadE30 · « **Reply #12 on:** May 28, 2007, 10:31:36 AM »

Those of you who have the M40 piece, what clutches are you using? Looking to do an LTW flywheel swap, but M40 parts are difficult to come by in the US

Wise Old Dog · « **Reply #13 on:** May 28, 2007, 11:36:59 AM »

I have the M40 flywheel also. Machined to 17.6 lbs. It was also used on the non-AC M42. I used the clutch assembly listed for a non-AC 1991 318i. Works great.

Shocker · « **Reply #14 on:** May 28, 2007, 11:51:39 AM »

Quote from: Wise Old Dog;26698

I have the M40 flywheel also. Machined to 17.6 lbs. It was also used on the non-AC M42. I used the clutch assembly listed for a non-AC 1991 318i. Works great.

Does that clutch have a sprung hub?