Shakes or Wobbles problem
1994 Ford Thunderbird V8 Two Wheel Drive Automatic 60,000 miles
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I am sorry if this has been covered, I could not find any exact symptoms.

My car is a 1994 Ford Thunderbird 4.6L with the auto transmission and 60,000 miles. Car has vibrated from the back end since I bought it about 6 months ago and is steadly getting worse. This vibration can be felt at 5mph and nearly shakes you off the road at 70mph (I haven't attempted any faster than this).

I am positive it is the rear because I replaced the entire front end - upper and lower control arms, brakes, shocks, sway bar bushings, etc. Car was alligned immeaditly after all components were installed.

I have balanced the tires twice, replaced rear drums and checked the rear axle shafts, (by lifting, then blocking one wheel and running the car, and visa-versa).

I think it is either the driveline/u-joints or torque converter. My question is; Am I completely looking in the wrong spot? Should I be checking the motor and transmission mounts? Could the rearend possibly be binding? There is no noise other than a slight thumping noise when almost stopped while braking, (the "noise" can almost be felt in the seat better than being heard). I would hate to drop the fuel tank and find that everything with the driveline is in good shape.

Throttle does not seem to have any affect on this shimmy, braking increases the shimmy slightly (can be felt in seat, and wheel vibrates - but car tracks straight). The only reason I am considering the torque converter is because it seems like on the highway if you let off the throttle completely then barely touch it again, it is a good 1000rpm until you can feel the car pulling again.

Putting the car in neautral on the highway has no affect on the shimmy either... I am sorry for the length of this post, I wanted to make sure that you had all the information.


Thank you,
Ryan

the rear half shafts went out they are similar to the ones found in front wheel drive cars. i would also change the u joints at the same time if you have not already changed them out the picture shows the same type of rear end that was in 89-96 tbirds this one is set up to be put in a kit car

I wanted to post a quick follow up.

I pulled the drive line, had it balanced and had the u-joints replaced, with no improvement.

I agree with Miller 92bird, that it is probably the half shafts, the rear ends noise is becoming a very distinct grinding sound. Someone on another forum said it is common for the rear end housing axle bearings to go out and tear up the rear end. If that is correct I assume that is what all the noise is.

I will pull the cover and investigate soon. Once the problem is solved entirely I will post another follow up.

Ryan