Jim Strathearn

At 210K miles, the '95 finally needs a new clutch. GM doesn't make the clutch kit anymore so I get one from Ecklers, who has it dropped shipped to me from Carolina Clutch. My mechanic, a general mechanic and not a trans guy, drops the trans and says it also needs a flywheel. GM doesn't make them anymore either. So I get a billet steel flywheel from Carolina clutch and have it drop shipped to the mechanic. While it's there it gets a new clutch slave cylinder and lower ball joints, plus an alignment, etc. This is a mechanic who does 90% of my work and one whom I trust. I get a call saying everything is done but it makes a noise in 6th gear and he thinks it's a bearing or chipped tooth in the trans. The trans did not make any noise when I brought it in, although I did think it needed a u-joint or two... So he wants me to drive it and see what I think. Well, the car shutters when you let out the clutch and he tells me that's normal because the new flywheel isn't a two-piece flywheel. Otherwise is shifts the smoothest it has ever shifted... Running through the gears you get a loud vibration-type noise - almost like a very loose cat heat shield, when passing through 1500 RPM's in EVERY gear, not just 6th. Sounds rather obnoxious actually. They put the car on a lift and let me hear it from below. With the car in gear it sounds like someone is in the trans with a hammer. The mechanic tells me I didn't hear this before because of the dampened flywheel. I think I would have heard the little man with the hammer regardless of the flywheel... They had the trans out of course for the clutch, but otherwise did not open or do anything to the trans. They did not match balance the new flywheel to the old flywheel. The engine does not vibrate when the clutch is disengaged so the mechanic says it can't be the flywheel causing the chatter. So now we have to get a new clutch plate to match the billet steel flywheel. But he insists there is a bad bearing in the trans. Would a bad bearing make chatter-type noises only at certain RPM's?

Any advice/insight would be greatly appreciated.

Samhain

The sound you are probably hearing is the gears in the trans chattering. The stock flywheel is a Dual mass unit, which means it has two parts and a dampener in between to absorb the chattering that you now hear. If this is the problem, you really don't have to worry about it, it's just annoying.

96GS#007

Typical of a single mass flywheel. If they didn't use a clutch disk with a sprung hub, it's even worse. At idle it'll sound like a box of rocks rattling around as well.

The only options are to turn up the stereo, get a louder exhaust, or find a dual mass flywheel you can install.

Btw...The dual mass has a weight cast into it. Single mass flywheels come with a weight that is bolted in place in order to replicate the balance of the dual mass flywheel. Hopefully the shop installed the weight or you'll make short order of your main bearings.

ccford

I'm on the verge of changing the clutch in my 93 to a McLeod dual disc and steel flywheel. My understanding is the single-mass noise is only an issue sitting at idle. There should be no change under load. Is this correct?

J

96GS#007

It is not correct. Like the OP, you will hear some noise up to ~1500-2000 rpm. It's not obnoxious, but it is noticeable. In my case, I have full length headers, bullet cats, and a Corsa exhaust...ie the noise will definitely stand out on an otherwise stock car.

Kubs

And like GS said earlier if they installed a stock type solid disk there is now ZERO dampening and the noise will be more noticable.

SJW

As others have noted, you need a sprung-hub disk with a SMF. Because your clutch install did not originally anticipate a flywheel change, I strongly suspect you have a solid-hub disk in the car now, which, when combined with a SMF, I would expect would deliver unbearable engagement chatter and a hell of a lot of gear rattle.

FWIW, I recently replaced the clutch and flywheel in my stock '94 LT1 car, with blue-tag ZF6. I installed the new Spec extra-weight billet steel SMF, and Spec's Stage 2 sprung-hub kevlar clutch kit. Engagement is very smooth, and I have no gear rattle. YMMV.

Live well,

SJW

Jim Strathearn

Thanks for all the replies...