Lightweight Flywheel Chatter - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Cloudsurfer · 07-31-2007, 08:44 PM

To those of you who followed the post a few months ago, I recently installed an Aasco lightweight flywheel and Sachs Sport clutch in my 02 S. Work was performed by a very qualified shop. Since the first time I cranked the car when I picked it up, it has had a decent bit of chatter while in neutral and the clutch up. I've heard from many that this is a normal problem encountered on these cars when doing this mod because you are going from a dual mass to a single mass flywheel in a clutch hub designed for a dual mass. Lately, however, I've talked to a few other techs that I"ve had the car around, and a few of them suspect either a bad throw out bearing (both pilot and throw out bearings were replaced with OEM during the clutch job, along with RMS and clutch slave) or a damaged diaphragm.

Can anyone give some insight on this? Chatter normal, or is something not quite right in my driveline? The clutch actuation is beautiful, and the car drives great.

Patrick

Tool Pants · 07-31-2007, 10:12 PM

Does the noise go away when the clutch pledal is down it idle?

Cloudsurfer · 08-01-2007, 10:15 AM

Yes.

Patrick

skip_168 · 08-01-2007, 11:27 AM

well, if the noise goes away when you press the clutch in, then the throwout bearing should be ok, as this is when the load on the bearing is the greatest..

I would probly look at a defective part, or an installation error..

how bad is the noise? we talkin' overly obvious, or you can hear it if ya listen for it?

Cloudsurfer · 08-01-2007, 04:06 PM

Yes, the chatter goes away when you press the clutch in in neutral. I would best describe the noise as a true chatter, very similar to the dry clutch on a Ducati for us bike guys out there. Def obvious...

The real problem, is I have absolutely no interest in pulling the gearbox off the car AGAIN to deal with this.

Patrick

NickCats · 08-01-2007, 04:40 PM

bmwm750,

Seems like the chatter is common with the lightweight flywheel :

http://986forum.com/forums/showthread.php?t=12420

You might want to PM edevlin and compare notes...

Nick

Gelbster · 12-31-2016, 12:52 PM

As you probably realize, the chattering is just a symptom of uncorrected imbalance. There is no harmonic balancer on the front of the crankshaft so depending on the severity of the imbalance, your engine is experience gross,momentary overloading of various bearings and sundry other items.
The best remedy would be to get a good,used DMF balanced (with the clutch assy)and fit it.
You may be more interested in refitting the DMF if you consider the potential problems that will emerge from ignoring it.
There is lots in Search on this subject.

10/10ths · 12-31-2016, 01:12 PM

....once his crankshaft snaps in half, the chattering will stop.

Real sudden like.

Gelbster · 12-31-2016, 01:16 PM

I was trying to be gentle.
When we have discussed this issue ,some get really nasty about having the reasons for it being a poor idea explained to them. Even when Jake has gently explained why he does not use LWFW ,we still got unpleasantness. It may require the financial pain of c/s breakage for people to be grateful for such advice. But I hope not.
It is worth noting that some LWFW uses claim no ill effects but they never gave details of any other mods they made to alleviate the problem. Even when we tried to separate the issue for them into harmonic and dynamic imbalance we got grief. In theory ,even a professionally balanced flat 6 will have some (harmful?) vibration w/o a DMF or harmonic balancer.

Lapister · 12-31-2016, 03:38 PM

Having come from the Nissan 350z world I can tell you this is a common problem with the newer cars that came with A Dual mass Flywheel. Cement grinder was more of a descripter of the sound our cars made with Light weight FW. One of the reasons I passed on the idea.