Topic: high speed vibration

[Andy78TA]

Hello All,
   From last year I noticed that I have a vibration at about over 60 mph in my car. I was hoping the wheels were out of balance so i got them balanced but no luck. I opened up the rear to install a new diff cover with bearing support and to change the fluid, still no help. I talked to someone and they said check the tires, maybe they are old and starting to deteriorate. Did that and found out the tires were 9 years old so replaced them. Today I took the car out for a drive and I still have the vibration. What should I check next? It really only happens above 55-60 mph. Trans Mount? U Joints? Im going nuts here. Any ideas are appreciated!!

Thanks.

[Tin Indians Rule]

where do you feel the vibration? in the seat of your pants or hands while on steering wheel? Does the rear view mirror shimmy when car is vibrating?

[Andy78TA]

i feel it from the rear, i can feel it everywhere really but not the steering wheel. It seems like it goes on for a few seconds, then stops for a second, then repeats, almost harmonic. As for the rear view mirror, im pretty sure that its not vibrating.

[LOMILETA]

Sounds like it maybe a drive shaft problem. Check to stt if it is bent or the balancing weights fell offf.

[RENOVATIONS]

Remove the driveshaft and take it for a drive...see if that fixes it lol

[Tin Indians Rule]

i feel it from the rear, i can feel it everywhere really but not the steering wheel. It seems like it goes on for a few seconds, then stops for a second, then repeats, almost harmonic. As for the rear view mirror, im pretty sure that its not vibrating.

Knock it outta gear next time while rolling and see if the vibration stops. Just slip it into neutral and let the engine ide. See if the vibration goes away. You'll have a good idea after you find out.

[Andy78TA]

I will try that tomorrow. If the vibration goes away in neutral that would point to something engine related correct? And if not maybe try the u joints?

[Tin Indians Rule]

Thats what I'd think. If you return the engine to idle, take the load off the transmission and the driveshaft and you still have the vibration then I'd check bent axles, warped wheels (but you had balanced, right) etc... If the vibration goes away then I'd check play in U-joints.

[Amtrak]

Check your trans tailshaft bushing

[Andy78TA]

how do i check for play in the bushing? After work today I plan on taking the car out for a drive. If it seems to be vibrating still I will drive to the parts store and get some u joints.

[joe d]

is the vibration there on acceleration or deceleration? sounds like pinion play to me although most vibrations/shimmys over 55 point to rear tires, where are the t/a experts on this one, does the t/a have a damper on the diffy

[Andy78TA]

the tires are brand new, like 9 miles on them ha, and they were just balanced. It happend at the speed, doesn't matter if i am cruising at the speed or accelerating around there. I am goingto pull the driveshaft and have it checked/balanced and do the U joints most likely. From my research that seems like the most likely cause but first i am going to drive it and put it in neutral and see as suggested above.

[Andy78TA]

well i stopped and picked up the u joints this afternoon and plan on taking out the drive shaft tonight or wednesday. I stopped by a shop that we used to bring our cars to and talked to the guy and he said it didn't sound like a U joint or the drive shaft off balance, but instead the rear differential bearing or something like that. He said these cars were notorious for this and that in order to replace them you have to rip apart the entire differential. Has anyone else heard of this? I did some research on this and really didn't find anything. All input is appreciated!

[joe d]

check the ree play in the pinion up and down and yes you do have to disassemble to replace carrier bearings and you SHOULD disassemble to replace pinion bearing to rebuild the diffy you could be faced with a $1500 tab

[Andy78TA]

ok driveshaft is officially out, was much easier then expected. The U joints look worn to hell. but I can't tell if there is excessive play or anything, but this is the first time I did these so im not sure. What I think is good news is that I found zero or very close to zero play on the input yoke to the differential. Everything on the yoke seems tight and the differential spins smooth as butter. I inspected the driveshaft and didn't find any indication of lost weight tabs or anything to put it off balance. I am crossing my fingers that it was just the u joints. I will work on replacing them on Wednesday most likely when I get my press in. Until then is there anything else I should check out?

Thanks for all the help everyone!