LT1_in_a_barn

Hello everyone.

I purchased a 2005 Z51 6-spd about a month ago. It has been making a strange noise, and I'm hoping I can get some advice or insight into what the issue (if there is one) might be. This is my first C6.

I'll try to keep this short, but I'll also be as descripitive as I can, and give the car's history, if that helps.

First of all, I've been reading as much as possible on this site for about three weeks. I've become very familiar with the search function. But I just haven't come across what I'm experiencing. Not enough to be sure anyway. I've also sent PMs to several people I've come across in different threads. I've read about the 'marbles in a can', springs in the clutch allowing chattering, torque tube noises, the torque tube amplifying other noises, etc. But I'm just not sure if it's any of those.

Ok, here we go:

I purchased this car from a friend. He purchased it new. He lives in Daytona Beach, and ONLY used it to commute to Ft. Myers, FL, which is a very long commute. The car has 110,000 miles, but it's LITERALLY 95% + highway. The car has spent it's entire life loafing down the expressway at 1700rpm. In addition, he treated it very, very well (he had planned to keep it forever, it was his baby), never tracked it, and had it maintained on schedule. Although it has high miles, it looks like new, runs excellent, shifts great, etc. I bought it, even though it has over 100K, because I know him, I know how he has treated it, and I know it's 95% highway. The price was great, and it's now MY baby

Ok, now onto my issue, as I'm a bit worried about my baby:

The car shifts smoothly. The clutch is nice and smooth. However, when the car is cold (say, after sitting all night), when I first back out of the driveway or start out in first, I hear a metallic, whirring, dry sound. It doesn't sound like "marbles", it sounds more like a "Rrrrr....rrrrrr...rrrrr" noise. Similar to a dry bearing noise of some type, like when a waterpump bearing is dry? Kind of like that, for comparison.

It only makes this noise at the point where the clutch is engaging JUST enough to actually begin to move the vehicle. Once the clutch is engaged and I'm underway, the noise is not there. Under acceleration or deceleration with the clutch engaged, there's nothing. Only during the slipping phase of getting the clutch engaged do I hear it.

Also, when this whirring/metallic noise is occuring, I feel a slight buzz in the shifter that accompanies it.

The car coasts in neutral with no noise, clutch in, or out. It's only when engaging it when cold-ish.

Now, I've experimented. If I hold the clutch to the point where it's making this noise, and then rev the engine, the noise does not change. No change in pitch, loudness, nothing.

Now, here's a critical piece of info: the noise is ONLY there when cold. If I drive the car in stop and go traffic (ie, the clutch/drivetrain is exercised...or warmed up (?) or whatever), the noise in GONE. Completely gone. It generally only makes this noise when it's been sitting, and when I start out initially. In fact, if I'm on the expressway in 6th, and stop for fuel....when I initially start out again, I'll hear it briefly, but not quite as bad as when it's cold. And again, if I start and stop several times, the noise becomes less and less noticeable, and seems to go away completely after enough stops and starts.

I hope someone has some ideas, it's on my nerves a bit.

Now, further experimentation: the noise only seems to occur under actual load, like when backing out, or starting from a stop (when cold-ish). If I let the clutch out in neutral, it's silent. No noise whatsoever.

Anyone have any ideas? I realize it's difficult to diagnose mechanical sounds through typing, but hey. I'm just *hoping* someone can relate to what I have felt and heard.

In summary:

1) Metallic whirring "Rrrrrrr....rrrrr...rrrrr" noise, like something is spinning (?) when the car is from a stop, when cold, first drive of the day.

2) Seems to be there until the clutch/drivetrain is exercised. In stop and go traffic, it is no longer there.

3) Does not sound like marbles.

4) Shifts fine, clutch does not slip. No complaints other than this noise.

5) When the noise occurs, if you hold the clutch at that point and rev the engine, the noise does not change.


Sorry to be so long-winded Any insight is appreciated. Thanks in advance.

JJC5

Throwout bearing.

LT1_in_a_barn

Hmmm. I thought I read a throwout bearing was typically noisy as the clutch pedal was to the floor. I'll search for that again, maybe I'm wrong.

Also, a piece of critical info I left out in my initial long-winded post: I talked with the original owner, and he said it's been making that noise for a long time....over two years....and never got worse, so he never had it checked out.

Ideas?

JLargo

LT1_in_a_barn

Thanks for the input.

Any other ideas, besides the throwout bearing? Any ways I can check or confirm this without tearing into it?

agmaustin

I have a 05 Z51 with the exact same symptoms so curious to see if someone responds with a remedy. My Vette has 80K miles with an extended power train warranty so will be taking it to the stealership later this week. I'll let know what their initial diagnose is, however I'm sure that I'm going to have trouble regenerating the noise because it only does it for about 2 miles of cold driving.

I'm also having some trouble with rough shifting and sometimes struggle to engage into first gear. This also seems to improve after warm up but occasionally scratches when thrown into second gear, feels like a bad synchronizer but wouldn't it do this all the time? Not trying to hijack your post, but somewhat relevant. I'll report back after talking to Chevy if you wish.

LT1_in_a_barn

Yeah, definately let me know what you find out. Feel free to send me a PM, too. I talked with the owner today, and he basically said it had been doing it for several years, and didn't get any worse, so he didn't really check into it. That made me feel a little better. I was concerned that it started doing it when I drove it home (I drove it from Daytona Beach to Michigan. I didn't hear the noise until the first full day it was home. Of course.)

Definately let me know what you find. Mine can be a little stubborn getting into gear when cold, and shifting, but I think every stick car I've ever had has been like that. I've found that you can just put the clutch pedal in, and cycle through a few gears to get into first, when cold. When at a stop, go, 3-2-1, and it usually goes right in.

But yes, let me know what you find. I'll be very curious. Thanks.

Chevy Cust Svc

Congrats on your new Corvette! If you decide to go to the dealership for this concern, please keep me updated and let me know if you have any other questions.

Thanks,
Laura
GM Customer Service

agmaustin

So here is the update. I wanted to speak to a service tech at Chevrolet before just dropping my car at their shop because I had it in there once before for the scratching in 1-3 gears. They claimed that they couldn't replicate the problem and charged me $100, hence stealership. The problem has only got worse so I decided to try a different dealership in Austin so I called to speak with a service tech about the new grinding noise. The nice lady assured me that someone would call me back but nobody ever did. I called a local transmission shop who has been in business for 30 years and they were familiar with my extended service plan (ESP) and were very helpful. He was able to replicate the scratching issue and said I had a problem with the synchronizers. They pulled the transmission late this afternoon and will dig into it tomorrow. I'm going to know for certain tomorrow when they have everything taken apart, but they feel that the noise we're hearing is the clutch or throw out bearing. Both wear and tear items that ESP will not cover. The synchros will be covered by the ESP but I will be looking at $1600 for a new clutch kit, throwout bearing and other misc parts. I'll let you know what they finally determine the noise to be. I'm going to have them look at the torque tube as well.

LT1_in_a_barn

Hmmm, interesting.

$1600...that's a bummer. Sorry to hear.

Thanks for the update though, I really appreciate it. I'll be looking forward to hearing what they find as they tear into it.

I drove mine today, and it's definitely temperature-affected. That goes for the outside temp, too. I'm up in Michigan, and on cold mornings, the initial car-moving is SO loud. It's awful. But, on warmer mornings, it's about 1/2 as loud. And of course, and I drive it and exercise it......it becomes silent. Very strange.

Anyway, I'll be looking forward to what they find. Thanks.

agmaustin

After the tear down, it was diagnosed to be the torque tube. Luckily this defect and the synchronizers were covered under the extended service plan. Total repair job $7500. The new clutch kit, throw out bearing other misc parts were not covered so I'm paying $1600 out of pocket and the ESP is paying 6K.

phatmaxx87

I am a for tech for a living. It sounds like a normal characteristic of a clutch. clutches always seem to make a slight "rubbing" noise when you slowly engage the clutch, more so when the clutch disk is cold. thats why the carbon zr1 brakes suck when they are cold but are incredible when hot. the rotors are basicly the same materaial that a conventianal clutch disk is made of. Now in respect to if it is abnormal, i would say if you can hear it clearly with the windows up, over the exhaust of the engine it is probably another issue like a throw out bearing or a pilot bearing. with the torque tube set up and all, i am assuming the clutch is atatched to the engine flywheel like a normal clutch so i would say this theory would apply to your car. unfortunatly my vette is a A4 c6 so i cant say if all 6 speed vetts make this noise. hopefully this is of help.

-Vance

LT1_in_a_barn

Thanks for the replies everyone. Any info is good info as I try to figure out what's going on in there, if anything.

Good info on how a clutch can be noisy when cold, thanks. And yeah, I can hear the rubbing noise with the windows up (when it's cold). Definitely. I mean, it's not as loud as having the radio on at a "normal" listening volume or anything, but with the radio off and windows up, you can definitely still hear it. A dry bearing, spinning, rubbing sound. "RRRrrr....RRR......RRRrrrrr......" is all I can type that might resemble it. I think it's become my least favorite noise of all the car noises I've heard over the years.

Agmaustin- do you recall specifically what about the torque tube it was? Did they explain what specifically was causing the noise?

agmaustin

Hey there - since an extended warranty was involved, they were reluctant to replace the torque tube. They researched whether the bearings could be serviced and/or replaced but eventually they told the tech that it would cost more to service so the agreed to replace it altogether. I researched on eBay and they range from $350 to $800 used. The noise that you're explaining is exactly what I have, in fact I have an iPhone video clip if want me to text to you. I wanted to be able to show the symptoms to the repair shop. Once I have the invoice break down, I'll be glad to send you a parts cost and R and R. Torque tube is on order and won't arrive until next week.

LT1_in_a_barn

Agmaustin,

Yeah, if you could send me the sound clip, that'd be excellent. I'd be very, very curious to hear it.

My email is cbabb@cablespeed.com

I'll look forward to hearing it, and thanks so much!

Chevy Cust Svc

LT1_in_a_barn,
I'm sorry to hear you're having issues with your Corvette. What I would recommend is taking it to the dealership and having them run a diagnostic on it. They should at least be able to indicate if it's something trivial or if it may be an indication of a more serious problem. Regardless of the diagnosis, you can decide where to go from there. If you need help locating a dealership, setting up an appointment please let me know and I'll be happy to help. Also, please don't hesitate to contact me with any questions, comments or concerns.

Chevrolet Customer Service,
Justin

SEVETGO

I have an 06 Z-51 six speed with similar problems. When the car is cold and I back out of the garrage I hear this clanging noise that comes from the rear axle area of the car. It get worse if I cut the wheel as I back up. The problem disappears after the car warms up, any ideas as to what may cause this?

WildBZ06

I have 01 Z06, and I am having the same dry bearing noise from torque tube (prob resonance) only mine does it even while driving, but not every time I drive. It seems if I put it in neutral before starting eng it doesn't do it. On a separate note I have had some vibration from the rear accompanied by bad odor. Any ideas? Also have heard some clicking from rear at low speed.

b4i4getit

Check your axle nuts. They are known to be loose.

JBrunoJSBC6

I have this same exact noise, although my 2008 C6 Z51 is an automatic.

Same symptoms, when backing up and the car is cold you can hear a grinding noise on every rotation of the axles/wheels. When cutting the wheel it is much louder. The thing that troubles me is that my car only has 3,500 miles on it.