My 90 L-98 has 32,000 miles on it. About a month ago, it developed a knock after driving on the highway for some miles. It sure sounded like a rod. One of the members of the club told me it was my dual mass flywheel. It only knocks after "heating up". I checked with the dealer. About $2500.00 to replace the flywheel, clutch, pressure plate, & throw out bearing. Doh! I can replace with a Fidanza aluminun single mass flywheel & kevlar coated clutch disc. I can handle the mechanical labor, so the whole job will only be about $800.00. I have heard about the rattling noise. I know there was a thread on the forum somewhere in the past, but at the time I didn't read it. Can someone enlighten me on what to expect if I go the single mass flywheel route? I can't see $2500.00 for a flywheel every 32,000 miles! :eek:

 

dual masses usually don't knock, i really have no suggestions without hearing the car but i know a single mass clutch will sound somewhat like rod knock. mine does at least out of gear with the pedal out.

 

You are right there but when they wear out/fail/whatever, they do knock.
Well, mine did anyway. As best as I can recall the sound of mine when it went, it sounded like a clicking sound at high idle. Does the noise go away when you hold the clutch down?

Mine also made a ratcheting sound when I shut the motor off (man I hate trying to describe noises). When I was doing my single mass conversion when I pulled the clutch and still had the dual mass attached to the crank I twisted it by hand and heard a 'click' just as the dual mass reached the end of it's free play between the two halves. As best I could figure it, that translated to my clicking noise when hot with the clutch out and the ratcheting noise when I shut the car off. The ratcheting noise as shutdown went away after I reinstaled my new single mass.

There are a ton of single mass flywheel threads in C4 tech. As a first measure I would do a search in there and then post with any specific questions you still have.

As far as I know there isn't a sound file of the SM noise on the web although I did read in the ZR1 forum that the aftermarket aluminium single mass wheels are supposedly quieter than the generic f-body single mass flywheel conversions (the sort I have). You can usually drown out the single mass noise with a rumbly exhaust. :D The noise is a very subjective thing, it's not an issue for alot of us but some cannot stand it.

Oh, and lastly the early ZF's with the differently cut gears are supposed to be a little noiser with a single mass then the later models where the change was made to the angle the gears were cut at to quiet the boxes down.

HTH

 

Red 90 asked the right question. Does the noise go away when you press in the clutch? If not, then I would look elsewhere.

Jason

 

It is less noisy when I depress the clutch pedal, but still noisy. Once, I engage the clutch in gear, the noise goes away. I am quite confident that it is the dmf. I just wanted to get opinions of those who have converted so I can get an idea of the noise of the trans.

 

Do a search...:)