Which year C5 do you have. I had read, I'll try to find it with search when I get to a computer, that some years were balanced at the flywheel. If that was the case for your ride a zero balance clutch may vibrate. The stock flywheel would have had a bit of weight added to it for balancing reasons. Of course I could be way off, I'm kinda nuts.

Later

Darion

 

2002

 

Hmmmmm, thought it was earlier years than that. If ya can do some searches on clutch balance or engine balance and I'll check later. Maybe somebody will check in on this also.

I just had my clutch swap done end or last week and waiting for other work to get done. Fingers crossed it all goes smoothly and hope ya get this straight sooner than later.

Darion

 

Start with this, I did a search on "engine balance" found it on about the forth page, there are others.
https://www.corvetteforum.com/c5-tec...balancing.html

Darion

 

I have a 2002 with the same issue, new FW and centerforce clutch. My starts at about 2000 rpm and goes away about 2800. Not torn into it to see whats causing it yet. I still have the factory FW and it did have weights and the one I put is is neutral balance so I am sure thats the issue

 

Check this out go to post 14, thanks to Bill Curley.

http://forums.corvetteforum.com/c5-t...h-install.html

Darion

 

If I am reading this correctly, you do not transfer the weights from a prior clutch to the new one. It seems that the weights are there to balance the clutch assembly, not the drivetrain as a whole. So if you install a LS7 type clutch that is balanced from the factory, then it should come pre-balanced (with weights already attached if necessary). Or am I missing something?

 

You will be reading for years if you search for this on here, and will drive yourself crazy with all the conflicting information you find. This has been an issue since 1997.

I have researched this topic extensively. The most concise way to summarize it is:

All LS engines are internally balanced. They do not require external balancing for proper engine operation. This is true for all LS engines from 1997 up to now. They are factory assembled with as-machined parts. There is no component matching or balancing the crankshaft with the actual parts your are using as would be done in a one on one aftermarket rebuild, or building an engine yourself. This is not a criticism of GM. It is how they build the engines in an economical and efficient way in order to keep the cars affordable. The parts are all made and held to pretty tight tolerances, such that when they are assembled, the overall internal balance of the engine is within an acceptable range of imbalance. This is a fact. Let's call the net build balance acceptable if it is 1.5 oz∙in or less. This is fine for the operation of the LS engine.

Now put the engine in a MANUAL TRANSMISSION CORVETTE. The unique drivetrain of all C5 and C6 corvettes are more sensitive to small imbalances than a traditional design where the transmission is attached directly to the engine. In MANUAL TRANSMISSION CORVETTES the sensitivity is even greater due to the vibration transfer path of the gear shift from the torque tube. Small imbalances can create vibrations that feel terrible and can make you think something is wrong. To minimize these potential vibrations, GM engineers do a final assembly HOT BALANCE procedure. It is only done on the manual transmission corvettes. They bolt up the FW and clutch/PP, and run the engine on natrual gas. The balance machine then tells them where to put external weights if necessary in the harmonic balancer, and or flywheel as needed to get the total assembly balance down to within .5 oz∙in at both planes. This is also a fact and anyone can verify it by taking a tour of Wixom, getting in touch with someone there, or speaking with someone who actually does the procedure. This procedure is done to FINE TUNE imbalances so they are at a lower level as to minimize unwanted vibrations. They are NOT making up for a crappy engine balance. The engine is fine beforehand, it just may be at a level of imbalance that is too high for the sensitivity of the manual transmission corvette.

SO, when your manual transmission corvette comes out of the factory, it has on it a harmonic balancer and FW/PP combo that MAY OR MAY NOT have some external balance weights in them. I would bet that most people are pretty happy with the smooth operation of their factory engine. The only way that you are going to MATCH that operation when you replace your factory clutch and FW is if you take your stock FW/PP together, have a good machine shop measure the state of balance (it could be perfectly zero balanced, slightly imbalanced, or quite a bit imbalanced, but when mated with your stock engine, the whole assembly is .5 oz∙in or better), and have your replacement FW/PP combo MATCH what you took off. It is as simple as that. If you do anything else, you are guessing. Most people will tell you, "aww that's BS, just make sure you have your stuff zero balanced". That is very good advice if you want to make sure you ONLY have a final assembly imbalance that is only what your engine alone would have, which is 1.5 oz∙in or less. When it left the factory, the whole assembly was down below .5 oz∙in!! So this just opens up the chance that you may feel new vibrations you didn't before. Your engine is fine, but it will feel like something is wrong, and who wants new vibrations?? If you just slap in a new FW/PP out of the box, without checking anything, you have an opportunity to get imbalances above the 1.5 oz∙in, and now you could have vibrations that feel very bad, and bad for your engine as well.

Anything other than match balancing your stock stuff is a crapshoot to one degree or another.

This applies to all year manual transmission corvettes. Not just early Z's, not just a few, but all, including the current manual corvettes being built today.

 

I forgot to mention, my only true criticism of GM on this issue is the half a$$ way they deal with it in the service manual.

 

Thanks for all the feed back,the front balancer was changed today with no change.We are going on 4 weeks with the car at the shop.I told them today this is not right, I know they are not working on it all the time and they need to,they allready got paid and this is not important to them as the new work comming in is.I dont know how to put it to them in a nice way any longer.HELP !!!!!!!!!! HOW LONG SHOULD IT TAKE TO SOLVE THE PROBLEM ????????

 

See post #7 & #8. Do they still have the original parts? If not, they may not be capable of solving the problem at this point and this may be why it is not getting any attention.

 

As vettenuts mentioned, you may be at an impasse. If I understand your previous post, it sounds like when they replaced the clutch the second time, they installed it right out of the box, and did not check it for balance. Is that correct? Yes, the kits are supposed to be balanced, and they are to a certain degree, but the manual corvette is much more sensitive to small imbalances.

Since you do not have your original flywheel or PP, your chance of matching the original balance is gone. Completely.

The best thing they can do at this point, which unfortunately would require taking the clutch out again, is to take the new stuff and have them zero balanced together as close to zero as possible. This will give you a total assembly that will only have the imbalances of the engine internals, with no contributions from the FW/PP. This may bring your vibrations down to an acceptable level. This means that your engine will be fine, even though you might feel some small vibrations. If you still have vibrations bad enough to make you uncomfortable, there are ways to fine tune balance the FW/PP/engine assembly while still in the vehicle. The method will be determined by a few more things.

1. Does your new FW have the 12 circumferential balance provisioin holes? They are through holes located at the outer perimeter of the FW, equally spaced.

2. Do you have long tube headers on your car? You had a cam installed, so I'll guess you have headers as well.

Once your shop goes through and tries replacing things one at a time, hopefuly they may stumble on something else that is the cause of the vibrations. Chasing vibrations can be a nightmare, as you are fingding out. but if they exhaust their efforts, and you still have vibrations, I know a shop close enough to you that has experience with fine tune balancing the assembly while in the vehicle. Of course, if you have enough access, you can do the process yourself. PM me for more specific information if you like.

 

If you put the car in gear, sitting still with the clutch pedal depressed and rev the engine to the rpm's at which you get a vibration when driving, do you still get the vibration?

If you do, you have a balance issue that involves the clutch assembly. If you don't, it's probably an issue with the torque tube. Another possibility is that they screwed up the pilot bearing. Worst case scenario they bent/sprung something during the R&R.

 

Anyone get this problem fixed? I too have the mysterious vibration and I replaced everything.

 

I may have this same issue on a 6 speed with 17,500 on it. Please explain more regarding the couplers. Where are they located, does the clutch have to be pulled to install them, how much are they.
My problem is a rattle in first and second gear; most noticeable there. Had all exhaust bolts and nuts tigthened (sp) so that doesn't seem to be the problem. No one can seem to help. My next resort is to have B-Quiet installed under the seats and in the transmission tunnel

Thank you.

 

I had the same vibration issue a few years ago, my hydraulic slave died so I just decided to go ahead and replace the clutch assemble as well with an LS6 kit while I was in there. Little did I know my car had the added weights in the flywheel, when it was all said and done I pulled the drivetrain a total of 5 times…ughhh. Trying to get the vibration issue taken care of. I ended up just having to use my original flywheel I had it resurfaced; I could not get the other flywheel to work in my car without some sort of vibration. I feel your pain it was a major PIA. I did get where I could tear it all out in a little over 2 hours though on jack stands in my garage. Is there any way you can get your original flywheel?

The best of Luck
Rich

 

I don't have my original flywheel unfortunately. My car never vibrated once with the stock clutch or flywheel. When i replaced my clutch, i started getting vibration only 300 miles after the install. Along with the vibration came shift problems(grinding when shifting felt in shifter). I thought it was a hydraulic problem and changed my clutch fluid and it went away after i got all the fluid clear. It ran fine for 1000 miles when it all of a sudden came back alot worse, and i started to get a loud grind comming from the clutch area if i let the clutch out a liitle aggressively, especially if i was rolling backwards.
Took it into a shop to have the clutch replaced again and they found the pilot bearing to be completely ground up, and damaged the input shaft, slightly bent the driveshaft and damaged the torque tube. I had everything replaced with brand new oem parts along with an ls7 clutch and ls2 flywheel.
The car drove fine with no vibration and the shift problems were gone. 300 miles later i'm getting grinding and rejected shifts again and the vibration is back.
I talk to a few people and they say it has to be something internally wrong with my trans, so i make arrangements to have a new trans installed. Two or three days before i have to drop the car off the shift problems and vibration disappear.
I ended up getting the car back last week with a new trans, and after driving it for about 30 mins the shift problems and vibration are back yet again!!
It's back at the same shop which is a reputable performance shop, and they say they will get the problem fixed and not charge me for it.
I'm clueless as to what this can be. I have well over $7k in this car right now chasing this problem and it's driving me nuts! It's been back at the shop for 5 days already and i haven't heard from them yet,which means they haven't figured it out yet. I can't seem to find anything after lots of extensive searching that is close to what i'm experiencing.
Anyone have any ideas before i jump off a bridge? lol

 

Have you heard back from the shop yet? Is it fixed? Just a guess, but intermitten vibration would likely rule out a FW balance problem. If that were the case, you would feel vibrations all the time, and they would increase with engine speed.

Let us know when you hear from the shop.

 

I spoke to them earlier this week and saiid they wouldn't be able to take it aprart till today because of being so booked. They are pretty quick when it comes to gettng me in and out, and said they will get my car back to me with no vibration by the weekend.
I did not suspect the viibration to be a balance issue at fiirst but now that I have replaced everything, I don't see what else it can be.
We'll see what they say, I'll keep eveyone posted.

 

Who is them ? What shop