bad vibration

[FTL40]

hows it going, i have a 1986 bonneville, 55k miles on it. i get a real bad vibration through the car from 55mph and above. it feels like its coming from the middle of the car, transmission or driveshaft. i pulled the shaft and the u joints were smooth with no play. i replaced the trans mount that had some play but it made no difference. i am planning on doing the u joints because it is cheap/easy enough to just replace it and rule them out. anyone else expierence anything like this? sorry for having a wordy first post to

Frank

 

[FTL40]

not sure if makes a difference but the car does it in 2nd gear at the same speeds. so it must be the driveshaft?

 

[pontiacgp]

if you put the rear up on axle stand and have some one start the car and bring it up to the speed where it vibrates you'll see if it is the drive shaft or a bad wheel that's causing the vibration and if it does not vibrate then you know it's in the from end

 

[SonOfRDgear]

if you put the rear up on axle stand and have some one start the car and bring it up to the speed where it vibrates you'll see if it is the drive shaft or a bad wheel that's causing the vibration and if it does not vibrate then you know it's in the from end

...Just be extra careful that you don't pull a Ferris Bueller!

 

[TODoubleD]

if you put the rear up on axle stand and have some one start the car and bring it up to the speed where it vibrates you'll see if it is the drive shaft or a bad wheel that's causing the vibration and if it does not vibrate then you know it's in the from end

...Just be extra careful that you don't pull a Ferris Bueller!

 

[t01blaze]

You can use hose clamps to balance a drive shaft. Put some on loose enough so they can slide a little and go for a ride.

 

[MonteCarloSS]

Had two vehicles with same problem different solutions. First vehicle did what you have done and found that the tail end of the transmission was bad and the mechanic replace it problem solved, he said while at the dealership they had a car with same issues and did all of the same fixes to it and still had the same problem. He was told by a friend (who work at a trans shop) of his to replace the tail piece on the trans and it worked. Second vehicle with same issue did all you had done and notice bracket from cat to the trans mount, we removed the bracket and it fix the problem!

 

[FTL40]

ok thanks, i think its from the tailshaft area if i remember what it looked like undere there the 200c is all one piece

 

[grandamman]

If the car has sat for a long time, it could be that the tires have flat spotted. If you put them on a spin balancer you will see right away of that is the problem.

 

[FTL40]

its def not the tires, its in the driveline