Drivetrain Vibration At 70mph Plus

[chilleblanco36]

I'm getting a vibration at 70mph plus and I'm not sure where it's coming from. I've swapped wheels and tires and it still does it. I don't feel it in the shifter either.

Car is a stock 1993 GT. Automatic with 273 gears.

 

[mikestang63]

driveshaft would be my guess or bad u joints

 

[chilleblanco36]

driveshaft would be my guess or bad u joints

U think so even though I can't really feel it in the shifter? I'm thinking of swapping those this weekend.

 

[rbohm]

try having the tires balanced first.

 

[chilleblanco36]

I pulled the driveshaft today. Inspected the u joints and they look good. It may be the tires

 

[mikestang63]

Eyeballing it is useless. You can take a tape measure and go from front to back at the same point in a straight line and mark it with a grease pen or permanent marker. Put it back on the car and see if it is rotating straight or if it's twisted. The only way to check the driveshaft is still balanced is to have a driveshaft shop check it.

Tire vibration due to imbalance normally is within 50-60 mph. Unless you recently hit a curb , threw some weights off or the tires are wearing uneven, I doubt that'sthe culprit.

Small possibility -I'd check the wheel bearings and ball joints. Jack up the car and see if you can wiggle the front tires side to side with your hands on the tire at 3 and 9 oclock-to test the wheel bearings. If you can wiggle it with your hands on 6 and 12 then its the ball joint.

 

[chilleblanco36]

I meant to post back. Upon further inspection, I noticed the balance ring on the driveshaft had moved. The rubber was pushed forward in 2 places. I think this is on automatic transmissions only. I called around to see if any part stores had a new slip yoke avail. None did, so my buddy decided to try something. He cut the balance ring off out of curiosity to see what happens. To my surprise the vibration is gone.

 

[mikestang63]

Told you it was the driveshaft. The weight is only for AOD driveshafts and you can use a T5 one in and AOD. The Ford Racing aluminum driveshaft fits both stick and AOD and has no balancer on it.

 

[chilleblanco36]

Told you it was the driveshaft. The weight is only for AOD driveshafts and you can use a T5 one in and AOD. The Ford Racing aluminum driveshaft fits both stick and AOD and has no balancer on it.

Good call.