1995 pontiac vibration 60-80 mph

[steepcreaker]

I have a 95 pontiac grandam 3.1 lit. automatic trans 155000 miles.
the car started vibrating about a month ago and hasnt gotten any worse or better. It really only happens above 50 mph and smooths out over 80mph. i have replaced almost everthigng all new suspension new tires, roters, calipers, plugs,wires,fluids passanger cv joint. The engine light isnt on and i had it put on a computer at the dealership and they couldnt find anything. They told me to buy a new car.
I could really use some help.

Thanks Austin

[Ridenour]

Welcome to the forum. It sounds like either A) tire wear/fit or B) a bad wheel bearing.

Could you be any more specific about the vibration? Is there any kind of noise?

[steepcreaker]

Originally Posted by Ridenour

Welcome to the forum. It sounds like either A) tire wear/fit or B) a bad wheel bearing.

Could you be any more specific about the vibration? Is there any kind of noise?

No there isnt any noise, the vibration is bad you can feel it in the floor board and steering wheel. There isnt any pulling and the car tracks fine. ive already replaced my wheel bearings i forgot to mention that sorry. There is some strange tire where on the driver side the outer edge of the tire is wearing faster then the rest??? Dont know if it is related or not. Ive tried putting the car in 3rd and it seems to quiet the vibration own just a little. Oh yeah it seems that if you accelerate thru the 50 to 70 mile an hour range you dont really feel the vibration. Thanks for the responce and i hope you have some more ideas

Austin

[Ridenour]

Originally Posted by steepcreaker

No there isnt any noise, the vibration is bad you can feel it in the floor board and steering wheel. There isnt any pulling and the car tracks fine. ive already replaced my wheel bearings i forgot to mention that sorry. There is some strange tire where on the driver side the outer edge of the tire is wearing faster then the rest??? Dont know if it is related or not. Ive tried putting the car in 3rd and it seems to quiet the vibration own just a little. Oh yeah it seems that if you accelerate thru the 50 to 70 mile an hour range you dont really feel the vibration. Thanks for the responce and i hope you have some more ideas

Austin

This could be a simple case of your wheel being un-balanced. I would highly reccomend taking it to a tire place, and having them do a wheel allignment. It should be very cheap, and if it's an actual problem with the tire, they'll be able to diagnose it and fix it.

[skibum1111]

I agree, it sounds like you have a wheel out of balance. I had one out a little, caused a shake around 60mph and went away around 70ish, got progressively worse until I had the wheel balanced.

[GMMerlin]

Originally Posted by steepcreaker

No there isnt any noise, the vibration is bad you can feel it in the floor board and steering wheel. There isnt any pulling and the car tracks fine. ive already replaced my wheel bearings i forgot to mention that sorry. There is some strange tire where on the driver side the outer edge of the tire is wearing faster then the rest??? Dont know if it is related or not. Ive tried putting the car in 3rd and it seems to quiet the vibration own just a little. Oh yeah it seems that if you accelerate thru the 50 to 70 mile an hour range you dont really feel the vibration. Thanks for the responce and i hope you have some more ideas

Austin

With the tire wearing, I would have the alignment checked before addressing the vibration.
The two issues sound like they are related.

Here is a simple test to determine if your vibration is related to MPH or RPM.
Drive your car at the speed you feel the vibration the worse, while at that speed, throw the shifter in neutral..if the vibration is still there, then it is related to MPH.
If the vibration goes away then the vibration is related to engine RPM and you could have an engine related problem.

[xeroinfinity]

Does sound like alignment or tire balance, thats a good trick about the mph or rmpthing, GMMerlin .