I have 79 L48 this is nice car with 66000 miles on it.This car drives fine and handles well at lower speeds.The problem is on the hot summer days after the car gets heated up after driving a few miles at 45 -55 mph the car starts to hop up and down like the tires are bad out of round.The faster you go the more the bounce.It also has some vibiration at the lower speeds.I have put new tires on the car,along with new front coils,rear leaf,shocks and u joints in the drive shaft.It`s like ther seems to be something is binding up after it gets hot and expands.the problem is not as severe when the t-tops are out.I love the car ,but I can`t drive it very far only about 20 miles at time.

I have 79 L48 this is nice car with 66000 miles on it.This car drives fine and handles well at lower speeds.The problem is on the hot summer days after the car gets heated up after driving a few miles at 45 -55 mph the car starts to hop up and down like the tires are bad out of round.The faster you go the more the bounce.It also has some vibiration at the lower speeds.I have put new tires on the car,along with new front coils,rear leaf,shocks and u joints in the drive shaft.It`s like ther seems to be something is binding up after it gets hot and expands.the problem is not as severe when the t-tops are out.I love the car ,but I can`t drive it very far only about 20 miles at time.

I'm fishing, but have you done anything with the drivetrain?

No I havn`t done anything to the drive train.I was thinking I might want to change the tranny and motor mounts,then again I also thought it may be the trailing arms.I checked the numbers on this car and they all seem to be correct.I don`t know if anyone else has done anything to the drive train before I bought the car.The car had 63000 miles on when I bought it in 97.

Any noise from the wheel bearings ?

when you say it bounces up and down, does it actually lift the suspension? and how high?

No there is no wheel bearing noise,when I say it bounces up and down it is like the belts have slipped in the tires or maybe the wheels are out of round,the problem is not there when the car is cold andit is less when I take the t tops out

i would get your tires and rim checked at a tire place to see if the tires need to be rebalanced or if your rim is bent from a pot hole or something.that should tell u. if they are messed up that all u need to do is get sone new tires or rims. if not than u know thats it is something else. that would be the cheapest way to go before u start replacing mounts and arms and stuff.

I have replaced the tires on the car.The bounce still came back ,but I didn`t replace the rims.Does anyone think that may the drive train could be bad out of line?If so how can that problem be corrected?

The tires should show ware if it was out of line.
Have you put the rearend up in the air and checked the movement of the assembly of each wheel ?
If you not sure about the tires have them re-balanced when their hot.

I had aluminum stock rim's get bent by the mechanic tightening the lug nuts with a 1" truck impact gum which made them shake/wooble above 35mph.

Did you have the problem right after the work was done ?

No I had the problem before replaced.I took the tires off myself took them to be mounted and torgued the wheels myself with a torgue wrench I thought the tire were out of round

My guess it to check your rear suspension bushings for any wear.
Ya don't want anything movin' about back there.
The temp and T-top thing don't make sence though. :confused:

The problem might be a bent drive shaft. Eliminate the tire problem by rotating first and see if vibrating comes from front or rear of car. May also be bent drive axle to one of the rear wheels.check u-joints too to see if properly installed. Let us know what you have done to remedy the prob.

I ran into this problem with a customers car. We changed the half shaft u-joints and the problem went away. We also went and replaced the driveshaft u-joints also.

Just a side note.....

Fly-n-C3,
That sure is one fine lookin' Vette cha got there. :cheers:

Just a side note.....

Fly-n-C3,
That sure is one fine lookin' Vette cha got there. :cheers:

Thank you!:cheers: You should have seen it 3 years ago. You wouldn't beleve it was the same car:lol: . Lets put it this way, it was heading to the crusher..........

:lol: Mine too! :lol:
"Bubba" got it from a police impound yard, no engine or tranny, and I saved it from him. She was quite a mess when I brought 'er home. :(
But she's gettin' better all the time. :cheers: