Single flywheel – will it remove rattle and clanks at clutch engaging?

[Alexen]

Hi all!

Looking throughout the forum I’ve ruled on that it’s common for our 6MT clutch to clank and rattle when engaging and disengaging clutch at a low speed especially when engine and transmission are hot. As I’ve learned from different threads the key possible reason of this annoying sounds and instability in power train is the construction of OEM dual mass flywheel used in our cars. Since the construction of dual mass flywheel supposes the damping of torque from crankshaft to train line - it obviously has some rotation head room for spinning of two parts of flywheel relatively to each other.

Considering this I want to clear it up will the installation of single mass flywheel make it to feel the engine, clutch and train line like one common unit without any stray rotations and instability inside of it?
Those who has already replaced OEM clutch and flywheel with aftermarket ones (for ex. SPEC or something different) could you please share your experience and tell about your feeling?

[rcracin]

Regardless, any twin plate clutch will rattle. It will have mutiple discs loose when you disengage the clutch. My twin plates on past cars used to ring like a bell.

As far as the factory flywheel goes, I would be weary about replacing it. It was designed to dampen torque for a reason. One reason that comes to mind is to alleviate stress on the crank when engaging the clutch. You run the risk of thrust bearing wear and ultimately crank walk when a clutch is too aggressive. I would run the factory clutch unless you're exceeding it's power limit.

Also, say you had a traditional flywheel and clutch, it would have to be aggressive enough, most likely with a heavy duty pressure plate, to handle the torque. This will make for a stiffer clutch pedal, more uncomfortable engagement from a stop, and you might have some clutch chatter.

[Alexen]

BTW could any other parts of transmission be the cause of bumping sound coming from gear box when
-playing accelerator on 2d or 3d gears or
-when moving slowly and engaging clutch or
-when turning slowly or
-when moving slowly on worndown road?

[anom3]

I too have thought about the many sounds the E9X M3 6MT transmisisons make.

Someone on here reported that the transmission quieted down quite a bit when they had installed a carbon fiber drive shaft.

As you probably know, the stock one is 2 parts joined in the center. The CF one is a single long shaft.

I feel there are 3 "parts" that make the transmission quite noisy:

A) The dual mass flywheel
B) The drive shaft
C) Throwout bearing

Originally Posted by Alexen

BTW could any other parts of transmission be the cause of bumping sound coming from gear box when
-playing accelerator on 2d or 3d gears or
-when moving slowly and engaging clutch or
-when turning slowly or
-when moving slowly on worndown road?

[pbonsalb]

Dual mass flywheel should not make any noise. BMW has been using them for 20 years.

Lightweight flywheels transmit more transmission noise. The E9xM3 uses a lightweight dual mass. At least relatively light.

Twin disc clutches are known to rattle since the plate in between the discs floats. Even if I was changing clutches, I would continue with a twin disk because they are more driveable than the stiff pressure plate big single that would be required to hold the same power.

Driveshafts can clunk, especially if the center support bearing is worn out or the u-joint or CV joint or rubber connecting guibo is worn out. Single piece driveshafts don't have a center support bearing but they still have u-joints or CV joints or rubber connecting guibos. Those can wear out. However, even a brand new single piece driveshaft can clunk -- I run one in my turbo E36M3 and it is noisier overall than the two piece one that it replaced. A carbon fiber one piece driveshaft might be quieter. Go drive a new M3 to find out since they have them from the factory.

Worn axles, differentials, diff mounts, diff bolts, subframe mounts, trans mounts, motor mounts, suspension bushings can all cause noise.

The trick is isolating the problem. Sometimes you need some load on the car and that is hard to achieve on a lift.

[Alexen]

Thanks for your responses guys! Will try to fix the problem if any.