Lightened Flywheel Chatter

[ACHTUNG]

Why do lightened flywheels make the "chattering/marbles in your gear box" noise? I'm curious to know what causes the noise because the wheel is lighter.

Thanks

[erik325i]

Why do lightened flywheels make the "chattering/marbles in your gear box" noise? I'm curious to know what causes the noise because the wheel is lighter.

Thanks

Are you running an alluminum flywheel, or a shaved down stock flywheel? how light is it?

[ACHTUNG]

I don't have one. I'm looking into the aluminum ones right now. Kind of pricey. I wanted to know what causes the chattering noise. I don't understand why it would make a noise just because it's lighter. I don't really care if it makes the noise. I'm just curious.

[permit]

Lighter, so its more prone to vibrations? Possibly the reason.

[Brew]

I believe that the rattle is from the gears, as the noise is usually only with the clutch engaged (pedal released). The lighter flywheel doesn't smooth out the power pulses of the engine as well as a stock flywheel.

[mspiegle]

I believe that the rattle is from the gears, as the noise is usually only with the clutch engaged (pedal released). The lighter flywheel doesn't smooth out the power pulses of the engine as well as a stock flywheel.

That's how I understand it, and you can lessen the noise by using different tranny fluid. My friend just got the UUC flywheel+M5 clutch kit for his '99 M3. Had mad chatter coming out of the shop, but a 50/50 mix of ATF and gear oil from redline cut the chatter in 1/2.

[bimmer8604]

Are you sure its coming from the gears in the tranny?

I always experienced chatter in nuetral. The flywheel acts kindof as a balancer to smooth out your motor. With the less mass there, the vibrations are going to be more, there fore causeing anything and everything to chatter thats loose or has clearence.

I guess I answered my own question - HAH, but hopefully that gives you some more food for your thought.

Kyle

[joshh]

I have a 8.8 lb flywheel on my Acura and I don't have any chattering. I don't see why the flywheel would cause this at all. Unless it's during slip. Or if you have a stage 3 clutch.

[Brew]

Are you sure its coming from the gears in the tranny?

I always experienced chatter in nuetral.

When your transmission is in neutral and your foot is off the clutch, the input shaft is spinning because the clutch is engaged, and the power pulses cause it to rattle.

EDIT: Here you go: http://www.uucmotorwerks.com/flywheel/gear_rattle.htm

[ACHTUNG]

When your transmission is in neutral and your foot is off the clutch, the input shaft is spinning because the clutch is engaged, and the power pulses cause it to rattle.

EDIT: Here you go: http://www.uucmotorwerks.com/flywheel/gear_rattle.htm

Nice link. That's the answer. you get an A.

[Kilomph]

My friends 92 325i has very bad chatter, with a 12lb flywheel. My 89 325iS with a 7.5 lb flywheel doesn't have any chatter. I guess i'm just lucky :)

[bimmer8604]

Thanks brew. Makes sense now. So its the input shaft thats rattling, or is it the mainshaft/countershaft thats rattling?

I think a part of it was also my crankshaft endplay... the noise would go away as I applied the clutch

Kyle

[Brew]

Thanks brew. Makes sense now. So its the input shaft thats rattling, or is it the mainshaft/countershaft thats rattling?

I think a part of it was also my crankshaft endplay... the noise would go away as I applied the clutch

Kyle

When you say "as I applied the clutch", do you mean as you press the pedal towards the floor? Because thats when the clutch disengages and the input shaft becomes disengaged from the engine.

[bimmer8604]

When I say apply the clutch, i mean pressing the pedal, disengaging.

Kyle