kennedy759

I have a fast buzz type vibration on my 97, thought maybe tires, but notice when it shifted up and rpms went down, so did the vibration. I feel it on the gas pedal, any ideas? this is with or without a/c running. also previously when coming to a stop lite, it would vibrate in gear at idle.

SaberD

is the vibration still present with the clutch disengaged?

If not, I'd check to make sure the outer hub is aligned with the inner hub on the harmonic balancer. The elastomer wears out and causes them to wobble.

If the vibration does go away, I'd say the culprit would most likely be the torque tube bushings.

kennedy759

sorry, should have said its an automatic

dadaroo

Still check the damper for wobble. If not that, then when it is doing it in gear at idle, try putting it in Neutral and see how that affects it.

kennedy759

how do you check the damper for wobble? will I be able to see it white its running or do I need to take the belt off and see if it moves?

73Corvette

Pop the hood with it running... get a flashlight and take a looksy... if, it's much of a wobble you'll see it.

Bill Curlee

It could be any one of several issues. The harmonic dampener (as stated ) is a good place to start. If the outer ring on the dampener is loose or rotates on the inner hub or you see it wobbling excessively,,,,, replace it as soon as possible.

The second suspect is or could be the RUBBER COUPLERs inside the drive train Torque Tube. If they are rotted and start to shred, they can cause weird vibrations and noises. When the engine is running, the torque tube prop shaft is ALWAYS spinning.

When you LOAD the drive train with torque, does the vibrations change??

This is what a good used coupler looks like when the prop shaft is removed from the torque tube:



BC

nitrouspaul

Resurecting. Hi Bill thanks for all your past electrical help

My shifter vibrates and i get a vib in gear (6spd) at all speeds gears, its consstent in nature no better or worse with speeed. I can go 100mph then put it in nuetral and it runs butter smooth. My torque tube was out and the guibos are good. bearings good, clutch new old clutch same vibration?
how do i figure if its transmission, rebuildt by promotion ft lauderdale or what?

Bill Curlee

Paul


SOME QUESTIONS:

- Does it vibrate at IDLE?

- Is the shifter lower body tight in its V notch and are the two bushings on top properly securing the shifter?

Are the two bushings on top stock or aftermarket?

- What engine mounts are you running?

- What differential mount are you running?

- Is there a difference in vibration with the clutch depressed trans in N and clutch out, trans in N??

When the drivetrain is in N and coasting, everything from the wheels to the output shaft and countershaft inside the trans is rotating. If its smooth, that part of the trans/drivetrain is not having any issues.

If you have the trans in gear, engine running, clutch depressed; do you get the same vibrations?

If you are in gear and depress the clutch car coasting, everything from the clutch disk to the wheels are rotating at coasting speeds.

If you are sitting still, trans in N clutch OUT, everything from the crank to the INPUT shaft of the trans is rotating.

I am guessing that you are running an aftermarket clutch. What one?

If I had to give a diagnosis, I would have to say you have a slight NVH condition caused by a slight engine off balance caused by the clutch flywheel/pressure plate.

Normaly at the factory, they add small weights to the outer ring of the flywheel to bring the balance down to almost nothing.

If you use all of the senarios I described above, you can hopefully isolate the vibration source to a specific part of the drive train.

IF,,,,,,,,, it comes down to a slight engine off balance issue, there are people who can dynamically analize and balance the drivetrain/engine in place.

If you want to talk about the issue, feel free to give me a call. PM Sent

Bill

PM Sent

nitrouspaul

hi bill

let me try to go thru your points one by one

no idle vibrate
shifter mounted tight
2 bushings are harder plastic type b@m short throw
stock engine mounts replaced with hinson poly. same vib both times.
diff mount stock rubber. tried that phadt copy one thats a alum bar with the mount in the middle but the noise thru the chassis was unbearable took out after a week.

not sure if i recall on the clutch in out in neutral is this at a stop?

it just feels harsh when i driving, if i go fast then go neutral its smooth as butter. It did this with another driveshaft torque tube i had thats solid bushed and heavy duty drive shaft, so im thinking thats not it.
old clutch was a texralia exosckell new clutch is a mantic twin.

i dont think its engine as its rebuilt forged 377 zero balanced the vibs seem to come from under the car not from the front. im running hoosier r6 but it was the same with the michelin pilots.my half shafts feel tight too.alignment is good but if i give more rear tow it gets worse.

jjc508520

I heard about something called "driveshaft whip" and I may have experienced it on my last track day - downshifting from high speed....

MAJ_Charlie

Sounds exactly like what I was experiencing two months ago. In my case the vibration in every gear under acceleration turned out to be the half shafts. I just replaced them with OEM half shafts over the weekend. Vibration cured!

This was the OEM half shaft...


Cheap Carquest replacements...


Went back to OEM...problem solved in my case.

nitrouspaul

thanks for that Charlie i wonder if there is a way to check halfshafts before throwing money how much were they maybe its worth a try. i need remove anyways the seals are leaking

MAJ_Charlie

I found them on eBay from a Vette guy. I paid $110 shipped for the pair. I'll PM you his info.

Bill Curlee

Paul

Grab half the shaft and see if the half shaft has any excessive deflection in any direction. The ball berings in the constant velosity carrier inside the boot shoud not have very much if any SLOP/lost motion!!

I would also do a comphrensive deflection check of the rear wheel bearings to insure that they do not have any SLOP.

Jack the rear off of the ground. Apply the brakes and apply TORQUE to the drivetrain in reverse & forward and see if the half shafts make any movements other than CW or CCW.

I woould also check the half shaft splines and the spline nut for being properly tightened. If the nut is loose any movement in the HUB/CV Output Shaft splines can cause vibrations.

Please let us know what you find.

Bill

apex26

GM issued to each dealer a "vibration analyzer" many years ago. The tech sticks electric sensors around on the chassis and it's supposed to triangulate the vibration and ID it. I spoke to our local dealer Corvette tech and he said he hasn't had it in his hands since the training years ago. However, maybe as a last resort, some techs actually do use it, because I spoke to one who did.