No chatter in 1st or reverse that I can hear. I thought it should chatter here?

However, the Chevy mechanic heard it while servicing the car and he should only have only been in 1st or reverse AFAIK. But, if he shifted to second - yeah - he'd get it.

I made one shift down to 3rd at 40 mph to compression slow the car and got a very uneven engagement, enough to put the clutch back in and re-release only to have it do it again (no noise, just uneven engagement). I thought that fit the description of chatter but it's only happened once.

On a side note, this car was probably lugged to death by the previous owner. "1 to 4" engaged too soon and forced a shift to 4th at way too low of speed and it would lug. Even shifting "1 to 3" it would lug. So I had "1 to 4" disabled right away. But who knows how long it was doing that?

 

Describe the rpm range you used under big loads.. it 2000 to 3000 rpm add 2000 more. It's an LT4 not a L98. Getting rid of the bad gas is no doubt a good idea. If you can find 93 octane in your area all the better. If where you live is over 1000ft above sea level it makes less difference. This might be a silly question but what do you drive when you are not driving the Corvette? Possibly the PO glazed the first clutch and did the same to the replacement. If it is possible to getthe service records from the PO at least you would know what was done and if it was all new or just a patch job with a new disc and some scotchbright to the flywheel and pressure plate.
Dave

 

Yes. My first small block - And it shows in how I drive it. I always think I'm over revving it. Keep in mind that I'm still on my first tank of gas. The throttle housing also needs cleaning. It has a gas pedal that feels like it's stuck in cement. So you often push too much or too little and the "too little's" could be the problem.

The last time I drove it was the first time I ever watched the tach. On a level road, 2K was fine but not less. Otherwise, I watched the speedometer for the shifts (easier to see.). Uphill happened only twice, once in 6th gear when it dropped to 50 mph, got knock, and I shifted to 5th. I took the other in 4th at 40 mph with no knock. That was as close as I came to a "load" situation.


I'm at 450 feet above sea level so it probably makes more.


That's quite possible. "1 to 4" was out to kill the car. Who knows how long it's been doing that? In "in town" driving, it would engage on about 30% of my shifts to 2nd and there was zero chance of 4th pulling it or even 3rd half the time. PO probably didn't think to try "1 to 3".

It didn't matter to me. After two days of that, I ordered the disable kit. that clutch has undoubtedly gone through a rough 1,000 mile break-in.

I can ask him.


I contacted the Chev dealer that put in the clutch but they won't reply. I can ask PO to try.

Thanks for your interest.

 

OK. Problem, or problems, identified. The engine was knocking due to my adding HEET to the gas tank. If you have water in your tank and add HEET, although HEET is 108 octane, with water dissolved in it, it's now minus 3 octane. Drove it down to half a tank, filled it with 92 octane and the knock was gone in the time it took me to pull out into traffic.

The clutch will chatter on shifting down into third to make a compression stop. It does it for about one second. Does that justify picking up a resurfaced flywheel?

The amount of water in my tank has to be at least a pint as HEET dissolves three times it's own volume. And I may still have water in there. I added it because another poster here reported his tank and fuel gauge were both rusted out. Not wanting the same thing to happen to me, I added the HEET and I OBVIOUSLY had water - Lots of it. The engine ran like hell. I would STRONGLY recommend that, if you haven't ever dried your tank out, that you do so. And, if you do, know that if you do have water, you'll lose 3 octane. An LT-1 can probably handle that but not my LT-4.

 

Forget the Heet. Siphon out the old gas and use it for your lawnmower. Fill it full with 91 octane. Clutch chatter happends when a clutch is slipped just before engagement. If the clutch pedal is all the way up, and you are hearing/feeling something, it is not chatter.

 

clutch chatter is a function of the friction plate making initial contact with the flywheel when moving a vehicle from a stopped position.......and its something you "feel" as the car will shutter or shake a bit.....once the car has momentum and you shift, if you "hear" something and not feel it, I believe you have something other than clutch chatter........

I think you need to just learn the car.....

 

I am having chatter engagement problems after 3 back to back clutch jobs with spec clutch, and carolina clutch, Done first time by dealer, second time by trans shop, 3 rd time by me. I have a new ZF trans ordered from ZF doc, I bought it as a low mileage used car that needed a clutch. $5000 grand later, it needs a clutch and?

 

OMG!

This is like reading a horror story!

But there may be a discussion here of your problem. When your engine is cold does it back up or go forward smoothly? But, after freeway speeds, does it then chatter?

If so, you might get some helpful opinions.

 

Chatters severely upon start off forward and reverse, I have only driven it a couple of miles because the chatter on start off is so bad - scary bad, but once at speed, seems ok but I have driven it enough to say a confident "yes, drives ok once up to speed"

 

Wow. Hey everyone. I too have clutch chatter. I had a new clutch put in my 96 LT4 by a reputable corvette shop 3 weeks ago, and starting out from a stop really chatters. Its much more noticeable when starting out on an incline. My driveway is slightly inclined, and putting it in the garage I stop in front of the door, raise the door and drive in, and that is when it chatters the most. Only in 1st gear from a complete stop. The previous clutch was grabbing rather high, it also chattered, but somewhat less. It was worn, but looked reasonable. The DM flywheel was cleaned up and checked out, no issues were discovered. I'm planning to call the shop and try to get this chatter problem solved, its very annoying!

BTW, the new clutch has less than 300 mi on it.

Opinions?

 

You don't state what kind of clutch was installed. By now you probably no longer have the original flywheel but a Spec extra mass possibly installed just 3 weeks ago too. It would not be unusual to order a Spec clutch to go with a Spec flywheel. If so, Spec clutches can chatter (especially Spec II). If this is what you have, unless you change the clutch the Spec will continue to chatter for 2-10K miles. Then, for some reason, it goes away.

 

Thank you Sam. I didn't realize that the thread I was following was 8 years old - I am so focused on the problem, I simply want to find the cure. We (my mechanic) feels the flywheel is original, and was not showing any unusual wear. The new clutch is shown below, a standard clutch.


I was trying to remember before I had work done on the car if I experienced the chatter (more like a shutter), and I do remember a similar behavior. Is this something that is inherent with DM flywheels, or maybe the 96 LT4 engine?

Thanks for your feedback.

 

Dont use a dual mass, ‘extra mass’’ (ie. ‘Worthless mass’ ) style flywheel.

use those as anchora for your boat
I like the lightweight louis fidanza flywheel.

the picture of the clutch above is a non sprung hub which should ONLY be used with a dual mass flywheel and Never a single mass style flywheel.

you must install a sprung hub clutch, to dampen driveline vibrations.

some of this chatter in the original post may be gear noise. A lot of it (not all though) can be eliminated with thicker countershaft shim on the zf trans

and yes i realize this thread is 8 yrs old

 

They probably used greasy hands to install it.Did you stand there and watch them? If not you got what you paid for a flywheel that is not true.

 

I read through this before I realized it was old. Some familiar names from back then.

Anyone who find this, call ZFdoc web site here (602) 319-6575

Last time I was on the phone with him for a completely unrelated part, he told me when (not if? ) my car needs a clutch to send it to him so they can do some machining to get it flat. He stated "all replacement clutches are not flat" in reference to something on the surface, but not the friction material. I forget the details, wish I would have wrote it down, but... call him. He knows his ZF's. He did mention I could machine my own.

 

Thank you all, I'll keep an eye on this as I put more miles on the new clutch. The mechanic ***** cloves, and no, I wasn't present, they took photos. The corvette shop is a very well known shop, known for quality and thorough work. I have to believe that they would know not to contaminate the clutch, but you never know.