I am confuse reading this complaint.

If I gather correctly, while stopped at a stop sign, idling, the car has a vibration. Further, during the vibration, the rpms are lower by 50 rpm than standard.

So this case would have nothing to do with driveshaft, tt, half shaft, bent rim or lowering.

You have an engine miss.

Now is it intermittent or all the time?

Keeping it simple, I ensure all my spark plug wires were on securely. Further, check that the wires are not damaged. One could upgrade to MSD wires or the like at this time.

As a step up, I would remove all the plugs and inspect for the sparkplug tip puck, that have a tendency to come off, and if a puck is missing replace the all the plugs, if not missing check the gap and reinstall.

Then find a new dealer. You are not alone in trying to find a competent repair man/ woman....especially if on warranty.

 

MIKe!!!!
Oh i'm glad you are here!!! I thought it was strange but they weren't willing to explore any other possibilities until she is restored to the stock height so I told them to jack her back up and realighn her. So I kinda felt like I didn't have a choice. Now i'm just waiting. :cry

 

:iagree:

 

I would have to agree with Kenny94945.
I don't think your vibration has anything to do with TT or rear CV axles.
The problem you describe is occurring when the car is not moving and engine rpm's are lower than normal. Could be you simple need to clean the throttle body or you have a small air leak somewhere in the intake system or the engine is miss firing which could be a bad coil or burnt spark plug wire. A bad coil has come up quite a number of times here. And the idea of the problem having to do with ride height is pretty obsurd. Maybe if you lowered it so much that the exhaust was resting up agianst something, but I find that hard to believe. If you are certain it is coming from the rear then it problem is the exhuast system vibrating due to a low rpm state of the engine. It could be you need to bump your idle up 50 rpm and see what happens.

 

That is :bs Once they do find the problem I hope you are going to make them pay you back for all the "fixes" they say your car needed. :mad

VR :cheers:

 

:iagree:

 

without feeling this vibration myself,it's hard to help.i doubt the car being lowered is the problem,but if it turns out to be the case,i would look at the rear inner drivers[especially if you have a slight rattle with your vibration].
as far as a misfire,possible,but i doubt it because if the motor is missing to put that bad of a vibration you should have a flashing check engine light or at least random misfires.this can be checked with a-tap,efi live,tech 2,etc.
it could be a prop shaft or rear bearing assembly[the prop shaft and bearing assembly are always spinning,regardless if you are moving or not].if you step on the clutch[manual]or shift to neutral[automatic]does the vibration change?if so,look at the driveline.
do you feel the vibration through the whole car?under you?in the steering wheel?

 

I tell you, there is one way to nail this down for good; but it would require a lot of time.

I would unbolt the entire rear assembly from the torque tube and run the engine. If the vibration is completely gone, then you've totally eliminated the engine, flywheel, and torque tube.

If the vibration is still present, then you have completely eliminated everything rear of the torque tube. Granted, all that is spinning back there (standing still) would be the torque converter; but for troubleshooting reasons - it's easier to unbolt the TT from the rear and get the two seperated.

I've got a suspicion that when the rear leak was initially repaired, something was damaged. .. and possibly unknown by the mechanic. Either the
drive shaft is bent inside the torque tube, or the protruding splined part of the driveshaft is out-of-round.

I'll ask again... are you sure the vibration is coming from the back half of the car?

LaDonna; I forgot - is your C5 an automatic or 6 speed manual?


.




[Modified by Mike Mercury, 11:40 PM 3/5/2004]

 

Her car is an automatic. I will say this much, the dealer admitted that they don't do much work on Corvettes, but that is no excuse. They did raise the car, aligned it, supposedly added some padding or something where they thought there might be a possible rattle(going to ask more detail and for them to show us this tomorrow when we pick Ebony up), and they flashed the computer for the pinging problem. The service manager said there is no charge for the things above. He thinks there may be an issue with the torque convertor that he wants to look into some more though. We are going to pick the car up tomorrow and see if it still vibrates and drive it some and see if it comes back after some driving. Thanks for all the input!! It's greatly appreciated, and we'll give everyone an update once we find out more.

 

Here is what the dealer did.....
Supposedly there is a vibration damper on the transmission, and he replaced this because he has seen quite a few of them bad on C5s and he thought that might be making the vibration seem worse if the damper is bad. They raised the rear of the car a little to get the correct rake of the car back, and he kept saying the correct pinion angle(but looking at the service manual, I don't see how that can change), and he left the front lowered due to noticing how much better the car handles lowered. The vibration is still there, so I still think they screwed something up when they fixed the rearend diff leak. They are going to schedule a time next week to work on her and see what all damage has been done to the tranny. They are trying to blame it on the lowering, but I still have my doubts about that as there are so many cars on here that have been lowered and have not had any issues. He stated that he never could hear the rattle from under the car, only the inside, and he could feel a vibration coming from the front of the tranny. Any idea why the bearing in the front of the tranny might would go out or could the torque convertor cause that?

As far as flashing the computer goes, the pinging is almost completely gone, and it was also flashed for the fuel gage being erratic, and HUD showing a different speed than the speedometer and DIC, and a transmission reprogram(he said reprogrammed to adjust to the number of miles on the car, but not sure why that would need done if it was right to start with).

And so far, there has been no charge, and that seems a little suspicious because I don't know of any dealer that is not going to charge you for working on a car if they know they are not at fault, and think the owner damaged it.


[Modified by CrazyMagMan, 1:13 AM 3/7/2004]

 

is this the "dampner" of which they speak?


black weight in upper left corner. I think the only way for that to of been a problem would be if the mechanic completely forgot to re-install it.

 

Nice pic Mike. That rear mount that the tech in the picture has his socket on would be good to check too. I'm thinking loose/missing nuts and/or damaged rubber om the mount itself. The two mounting nuts that go on the two studs hanging down in the pic were completely left off my car after a clutch job. I had to find this out myself and let the shop know. :rolleyes:

Robert

 

WHAT ?????? :crazy:

 

Yup! I know. That's what I said too! :mad

 

Well, we are taking her back to the dealer tomorrow. I'm not sure if that is the damper they changed or not, but considering it is the only one I saw, then it probably is. I'm going to ask them to explain to me how they think lowering the vette effects the pinion angle on the vette, because after looking at mine this weekend, and looking in the service manual, and all the correspondence on here, then I just don't see any way. It will change halfshaft angles, but not pinion, or torque tube, or torque convertor, etc. We'll see what they have to say tomorrow, and what their answer is, and then explain how I understand the drivetrain and suspension relationship working in the Corvette and see what they say.