AndyAA

Hello out there, I continue to track down vibrations in my 78. I had replaced the motor mounts with some Checker ones when I first got the car two years ago. Last week I notced that they did not fit onto the frame mount for caca. There was about a half inch gap between the frame and the mount. Not good. I got a new set from Corvette Central and this has greatly reduced the vibration from the motor. All right, progress. But I still get a vibration at 55 to 70 when excellerating or decellerating. Also the front tires are cupping on the inside of the tread. Any thoughts or ideas?

7Bob3

Is this a new problem? I would check the idler and pitman arms and then get it aligned. A motor vibration will show all the time.

lou

I'm with bob, Have a shop check out the suspenstion for worn parts, then get it aligned. lou

AndyAA

Thanks for the ideas. The vibration is the strongest when excellerating up a hill between 45 and 65 mph. Then when you level off and coast it is smooth as silk. Would you find this type of problem with the front end suspension? I replaced the entire front end about two years ago. I also just replaced the U-Joints and rear whell bearings hoping to solve the problem. I had a similar problem with my truck and it ended up being the transmission pump.

Thx
Andy

lbell101

I have exactly the same problem with mine except it only lasts from 45-50 mph. It was much worse when I bought the car. So far I've replaced u-joints, yokes, front wheel bearings, tires, and one rim. All these things made an improvement except that vib under accel. I see the only obvious things left as a front enf rebuild and rear wheel bearings. I can feel mine in the wheel so I'm going with the rest of the posters and doing the FE rebuild in a few weeks. Hopefully I won't have to test drive it in the snow!
Good luck - vib fixin is no fun!

Larry http://www.larryscars.com/71vette.html

C5kid

Same problem here, it happens when I get on it going up a hill around 50-55. And I just put on new bushings and ball joints on 2 months ago. :confused:

jimduchek

vibrations that are road-speed dependant (ie, if you shift gears but stay at the same speed and the vibro doesn't change) is either rear drive train, wheels, or tire contact. Be sure your drive and half shafts are properly balanced. Be sure your tire/wheels are properly balanced and your rotors aren't too run out. Lastly, ensure your tires are in good condition and that your toe is VERY well aligned. Alignment is the most common problem. Just because you 'had it aligned' doesn't mean you had it aligned right, and if your tie rod ends and joints aren't in good condition a good alignment won't hold anyhow. Always get your alignment done at a reputable shop and demand to see the computer output and see how well they did your alignment. 'In spec' is typically a fairly wide range, and sometimes isn't even right if you're not running original wheels, tires, and suspension. Your average shop doesn't give a damn if your alignment is good, just if it's in spec for a stock model of your car. A query on the Forum or a call to a local speed shop will usually get ya the name+number of a good alignment shop who'll do it right.

Jim

Tom Johnson

Check your motor mounts. Mine was doin the same thing and that was the problem.

micks69

Easy to overlook drive shaft balancing. There are small weight tacked to the drive shaft front and rear.

AndyAA

Back at it again. Jacked the front end up and had my son jiggle the front wheels 3 and 9 oclock while looked over the suspension. The only looseness I noticed was about 3/8 of a inch at the power cylinder rod. Drove it to Phoenix this last week and the driver side tire is cupping quicker than the passanger side. Should the power cylinder have that much play?

Thanks again for the ideas.

AndyAA

Vibration gone. Had the car alligned. Rear camber on passenger side was way out. Car runs great, thanks for all your help.

Andy