1997 ford thunderbird LX . Rear Wheels - Upper control arm bushings.

this is probably from a failed suspension bush and or spring/ shocky . Have it inspected by an accredited suspension specialist . When done ensure that the rear wheels are properly aligned as their alignment affects the front wheel alignment.

Here's a link on your upper control arm.

UPPER CONTROL ARM:

Do not disassemble the upper arm. If the ball joint or bushings are faulty, or the upper arm is damaged, the entire upper arm must be replaced.

1. Raise and support the vehicle safely.
2. Remove the front wheels. Support the lower control arm assembly with a floor jack.
3. Separate the upper ball joint from the steering knuckle using a ball joint separator tool.
4. Remove the self-locking nuts from the upper arm anchor bolts. Remove the upper arm from the vehicle.

Do not disassemble the upper arm. If the ball joint or bushings are faulty, or the upper arm is damaged, the entire upper arm must be replaced.

Replace front shock absorber upper pad both side

REMOVAL AND INSTALLATION Upper ball joints are not replaceable. The upper ball joint is part of the upper control arm bushing joint and is not serviced separately. If the upper ball joints are found to be defective, the entire upper control arm bushing joint assembly must be replaced. Lower Ball Joint INSPECTION

1. Support the vehicle in normal driving position with ball joints loaded.
2. Wipe the grease fitting and checking surface, so they are free of dirt and grease. The checking surface is the round boss into which the grease fitting is threaded.
3. The checking surface should project outside the cover. If the checking surface is inside the cover, replace the lower arm assembly.

Had a similar problem with a different car. Rear struts / spings were worn. Caused rear to sag enough to push wheels out and wear out inside portion of tires.

I had the similar 'wobble of death' for these late 90's pathfinders. Just change all 8 bushings on REAR lower and upper control arms. That is main problem. Everything else has marginal impact like front control arms, wheel bearings, shocks, etc.

UPPER CONTROL ARM:

Do not disassemble the upper arm. If the ball joint or bushings are faulty, or the upper arm is damaged, the entire upper arm must be replaced.

1. Raise and support the vehicle safely.
2. Remove the front wheels. Support the lower control arm assembly with a floor jack.
3. Separate the upper ball joint from the steering knuckle using a ball joint separator tool.
4. Remove the self-locking nuts from the upper arm anchor bolts. Remove the upper arm from the vehicle.

Do not disassemble the upper arm. If the ball joint or bushings are faulty, or the upper arm is damaged, the entire upper arm must be replaced.
To install:
Use new self-locking nuts when installing the upper arm and strut.

1. Install the upper control arm assembly into the strut tower.
2. Connect the upper ball joint.
3. Install the front wheels and lower the vehicle.
4. With all four of the vehicle's wheels on the ground, torque the upper control arm nuts to 47 ft. lbs. (65 Nm). Torque the castle nut to 32 ft. lbs. (44 Nm); then, only tighten it enough to install a new cotter pin.
5. Tighten the wheel nuts to 80 ft. lbs. (110 Nm).
6. Check and adjust the vehicle's front end alignment.

The bushings on the front lower control arms are replaceable on most models.
This procedure requires the use of a press and may be above the skill range of the average driveway enthusiast. It is recommended that this procedure be done by a qualified machine shop if you are not skilled in the proper use of a press.

1. Remove the lower control arm that is in need of new bushings.
   

It is recommended that both the left and right lower control arm bushings be replaced at the same time. The vehicles handling may become unstable if there are new bushings on one side of the car and worn ones on the other.

1. Set up the control arm in a press.
2. Using a impact socket of the correct length and size, press out the old bushing.
3. Install the new bushing by slowly using the press to push it into the control arm.
4. WARNINGExcessive force could cause the bushing to bend or tear so be careful.
5. Once the bushing is properly seated in the control arm, remove the arm from the press and install it on the vehicle.

Very common BMW problem. The front lateral arms that support the front to rear motion of the wheel. BMW calls it the upper, lower support arm. Two arms connect there. one left to right (think typical lower control arm, and this arm) It has a ball joint that connects to the lower most part of the strut and extends rearward to the rear crossmember and has a large bushing pressed into the arm. You can replace just the bushing if the ball joint end is ok. Bushings are about $45 each and you will need a press.

have you checked you brake rotors. they could be warped.