Lightweight flywheel? - The Unofficial BMW M5 Messageboard (m5board.com)

rcalvin · 30th September 2002, 19:40

Just wondering if there are any aftermarket lightweight flywheels for the 93 3.8L M5 Touring? I have seen all kinds of aftermarket products for the M3 but very little for the M5.

Rick
93 M5 Touring 3.8L 5-Speed

jrturbo · 1st October 2002, 15:05

Hi there

I am not aware of anyone having lightweight flywheels off shelf for the M5 engines, although a competent machine shop could make one.

I have heard of some people in some cases fitting the flywheel from the earlier M5 which wasnt a dual mass unit, and it should be possible to lighten it further, but the problem your are going to encounter is that most engine machine shops will requiere a crank to bolt the flywheel on to, so that they can rebalance the flywheel after lightening it.

beware of anyone who offers to lighten your flywheel without rebalacing it, it will introduce vibrations which will shorten the life of your engine components ie crank, conrods, etc.

I would be interested to hear about your findings on the matter.

regards

Joe Rubido

rcalvin · 1st October 2002, 16:31

Yes, I have heard that the 3.6L M5 flywheel, which is lighter, can be used.

However, I have also been told that the 3.6L flywheel installed on the 3.8L might "rattle" in nuetral. I don't know if I would be comfortable hearing that.

But, I have also been told that by using LubriMoly, instead of the factory gear oil, the rattle could be eliminated.

Any of you guys fix rattling flywheels by using a different type of gear oil.

Rick

dmenheere · 1st October 2002, 23:02

Hi Rick,

It is not the flywheel that rattles but the transmission. With the lighter flywheel I believe there is less dampening of the input shaft and the gears in the transmission will rattle. There is no damage done by this.

cheers,

Dave

rcalvin · 14th October 2002, 06:32

Thanks for the clarification Dave.

Also, do you know if the 3.6L M5 flywheel is interchangeable with the 3.8L M5 dual mass flywheel?

Rick

dmenheere · 14th October 2002, 15:58

Hi Rick,

The 3.6L flywheel will bolt to the 3.8L engine. The respective clutches may be different but a 3.6L flywheel with a 3.6L clutch will work. I will check tonight whether the part numbers for the clutch changed. The 3.6L flywheel weights ~12 lbs versus ~20 lbs for the 3.8L.

Dave

dmenheere · 15th October 2002, 21:55

Hi Rick, please check the link for info on someone who has already done it. I just remembered I had been though this discussion already. At the bottom of the thread he explains how he used the 3.6 flywheel and cltuch on the 3.8 engine.

cheers,

Dave

http://www.bmwm5.com/vbulletin/showt...threadid=20133