ike

I have a 2014 with almost 15k miles (purchased used 2 years ago w/5k miles). There's a fairly annoying clutch chatter when starting out relatively slowly in 1st gear. It gets worse when the car is warmed up. When it's cold, it's fairly smooth. I've had multiple manual C4's, C5's and a C6 before this car and never experienced this.

On a level road, I tried starting out in 2nd gear and it's smooth. No chatter.

I did some searches here and the few threads I found said that chatter normally gets better when the car is warm. Mine gets worse. It's not terrible but it's bad enough that my girlfriend asked if something is wrong with the car. I've tried starting out at different RPMs. It seems to chatter worse above 1k RPM but still does it below. And again, not at all or barely starting out in 2nd gear.

Is it worth taking to a dealer since it's out of warranty? Or maybe the powertrain warranty would cover something still? Or is this condition just "normal".

JerryU

^^^

My 2014 and my Grand Sport don't chatter - never did. Worth trying the Ranger Method of a clutch fluid change. I do it at each oil change.

Option is having the dealer do what it says in the Owner's Manual to do every 2 or 3 years (time changed with model year for no apparent reason.) However that requires removing the driver's side CAT and exhaust pipe from the manifold. Then the sheet metal to expose the clutch throwout bearing bleed screw. Cost is >$150.

Below is a pic of the change made using the Ranger Method in my Grand Sport at oil chage (I do my own) after 1 year. This is a PDF with full details: http://netwelding.com/Clutch_Fluid.pdf
May help but you should do it anyway so why not! 10 minute job, cost < $10.

Summary of method: 1) Remove fluid from reservoir under hood. 2) Fill with clean fluid from new unopened container; 3) Pump clutch 30 times, 4) Repeat steps 1 through 3 about 6 or 7 times. Only buy a small bottle of brake fluid as you should toss it when finished!

ike

Thanks. I can't fathom that changing clutch fluid would have any impact on chatter but agree it's worth doing anyway.

SK360

Mine has done it since I got it. Notice it in 1st and R the most, find I can stop it with more RPM. I was going to have a dealer check it out then figured I'd be better off just leaving well enough alone and seeing what happens rather then let a dealer touch it. at 600+whp now and still no other issues.

JerryU

Search the Threads and you'll see folks saying the clutch stuck etc. Ranger drag races and does it after every race. He shows pics of the clutch pieces in the fluid! Been using that at each oil change in my C6, 2014 and now my Grand Sport.

Cheap and as you say worth doing. Report if any better.

pickleseimer

x2 on the fluid.

If that doesn't do it, consider several other causes of clutch chatter. When chatter develops after warm-up, it makes sense to look at those areas that would be most likely to either generate heat or absorb heat. Excessive slipping of the clutch generates heat pretty quickly or a warped flywheel that gets worse as it gets hot (perhaps from excessive slipping) may be a cause. Once this starts it usually doesn't go away until parts are replaced. Although you may be using good clutch procedures, it would be difficult to know how the car was treated during the first 5k miles put on the car before it was yours.

Some other causes of chatter are a damaged throwout, damaged or missing pilot bearing, warped pressure plate, suspension issues, improperly torquing flywheels or pressure plates, lubricants contaminating friction components, missing or broken springs on clutch disks - these would probably cause chatter hot or cold. Good luck to you.

Internets_Ninja

Changing the clutch fluid will not help the chatter at all. MY 2015 Z51 does the same thing. Some say it is normal some say it isn't. I bought my Z51 with 4000 miles on the odometer and it has done it since I got it. It has not gotten any worse or any better no matter how many times I've used the Ranger Method. I've heard it happens because of the clutch design but I don't think it should happen at all. I'm torn with living with it or having it fixed. I still have a warranty but with my car being modded I assume the dealer will not cover replacing it. If I keep the car for a while I will prob end up putting in an aftermarket clutch and lighter flywheel. I have found that if I modulate the clutch a certain way and bring up the RPMs, it won't chatter. It actually reminds me of my modded C5 Z06 with a Textralia clutch that would chatter a little if you didn't treat it right.

ike

How painful is clutch replacement on the Stingray? Anyone pay to have a dealer or indy shop do it?

Internets_Ninja

Very, the entire drive train minus the engine has to come out.

The HACK

With advanced apologies to my buddies over at McLeod Racing...Need to use their image to illustrate.



Almost all clutch friction plates come with these springs highlighted in the picture. What these springs do, is they dampen the centrifugal action between the input shaft of the transmission attached to the central spline, and the spinning action of the pressure plate. When the clutch engages and the outer plate spins up, the springs take the initial hit and then transfer that force onto the central spline and thus onto the input shaft of the transmission.

The Corvette has an exceedingly easy to operate clutch. I've driven a ton of different manuals in my lifetime, from a variety of BMW clutches, to aftermarket clutches, and the C7 clutch rank near the top for the easiest to operate. Part of the ease of use is how the springs in the friction material is tuned. A soft spring allows the two spinning masses to have some "lash" and come up to speed together smoothly, while a very stiff spring like what's equipped on my BMW Z4 M Coupe results in a fast delivery of power from standing still. The end result though, is the BMW has a tendency to "buck" in first gear if you don't get on the throttle quick and aggressively.

On the Corvette, if you don't get on the throttle enough, those springs, instead of transmitting that force smoothly to the transmission, allows the clutch friction plate to "capitulate." It releases the energy back into the engine side as the spring bounces back and forth if the throttle application isn't forceful enough and consistent enough. That's what causes the "clattering."

While disconcerting, it's not outside of the operating parameters of a clutch friction disc. They're designed to do that, so instead of the car bucking like you're learning to drive a manual for the first time (not insinuating at all guys. Don't jump down my throat and tell me you've been driving manuals your entire life), the lash is taken up by the softer springs to make for a much smoother clutch engagement experience.

If you guys have ever driven a car with a light-weight flywheel, you'll experience that same clattering upon take off. Physical principals are the same, except on a car with light weight flywheel, the flywheel's mass being reduced means the spring's rebound energy can easily overpower the light-weight flywheel and cause the clattering or chattering between the flywheel and the friction disk.

Although, for the OP, I don't know what's going on, but typically this type of chattering is more common when the clutch disc is cold. What you're hearing is the friction plate struggling against the spring's rebound tension and the frictional surface's struggle to keep grip between the flywheel and the friction plate. As the frictional plate warms up, the grip level between the two frictional surfaces increase and you eliminate the clatter/chatter because the force transmitted from the flywheel should keep the tension on the springs consistent. IF you are experiencing the clatter/chatter more as the car warms up, it's possible that the surface of the flywheel may have some hot spotting, score marks from the friction disc transferring frictional material unevenly onto the flywheel causing it to hop, skip, and chatter as both materials heats up.

I'm not a clutch mechanic/engineer, I'm just a Internet forum keyboard monkey, so take what I say with a huge grain of salt. If chattering continue to worsen over time when warm, it could mean the hot spotting on the flywheel is getting worse. But if it only does it while cold, and only does it once in a while on a poorly executed launch in first, I wouldn't worry about it.

Perf n Restore

Prevention and sometimes cure for clutch chattering? Worked for me.
Having driven manual transmission cars forever and having clutches last over 90kmiles with hard driving here are my tips for what its worth.
When "upshifting" as the clutch pedal is released, the flywheel, spinning faster than the clutch disc, is trying to turn the clutch disc at the same rpm. . It slips briefly and then fully engages. It does over time create hotspots on the flywheel, which can cause chattering.
When "downshifting" the opposite happens. When down shifting to a lower gear the clutch disc will be spinning faster than the flywheel. As you raise the clutch pedal the clutch disc is trying to turn the flywheel at the same rpm.
I have always felt that this reverses the upshift effect.
Active Rev Matching minimizes this by raising the engines RPM.
What I do frequently is to downshift, slowing bring up the clutch to reverse the upshift burnishing of the flywheel.
It has worked for me on all of my vehicles. I have never had clutch chatter.
I have replaced many clutches on friends and customers cars and know what clutch chattering is. When I asked them if they frequently downshift and occassionaly slowly raise the clutch, they usually say "no". They do now.
Worked for me.
Not all will agree with me, that's ok. Just wanted to share my time experience.

The Chev

Are you saying you slip the clutch during a down shift?

ike

I watched Ant Anstead of Wheeler Dealers, change the clutch on a C5 Z06 (which I once owned) and he groaned about how difficult it was, lowering the rear suspension to allow the trans/torque tube to be moved rearward. I was hoping that maybe they've engineered a way to make this a little easier by C7, but I guess not.

ike

That's how I read it. I'll give it a try to see if it has any effect.

JerryU

Watched that show as well. And he did as a good mechanic does to make commission, cheated a bit! Recall when they showed him pushing the rear assembly away "just enough" and his face cringed a bit as the rear he had on a trans jack looked like it might slip! And he had lots of folks around him like the camera and sound person, lightly person and perhaps a director or producer. He probably rehearsed that move!

If you follow the C7 Service Manual it will take longer! That is what a dealer will charge even if the mechanic uses short cuts to make more commission!

Perf n Restore

The Chev:
"Occassionally" I will slowly let up the clutch during a downshift.
If you are now having chatter I would do it quite a bit to see if it helps in this situation.

dbirdhouse1

I also have a '14 Z51 1lt 7mt conv I've owned for almost two years bought with about 5K miles when I bought it and about 15K now; some difficulties with shifting
into first and a bit of clutch chatter. I have a great mechanic (Mark @ Titus-Will in Olympia, WA) who said let's change the tranny fluid (not under warranty) and
it has helped markedly, has not completely eliminated it but measurably improved it which is exactly what he said would happen.....

ike

Red86Cfour

I assume the C7 has a dual mass flywheel. I assume that is really where the chatter is coming from.

JerryU

^^^^

Good point! Certainly a possibility. It's really needed for those who let their car go into 4 cylinder mode! My Grand Sport never has!

I recall early in 2014 there were reports of one of the dual mass flywheel springs falling out! Pic below is not one from the C7 but certainly a spring issue in the dual mass flywheel could cause chatter!