Car suspension problems

I bought an 87 Mustang 5.0 2 years ago, and while it has been a good car, and fun to drive, there is a persistent shimmy in the front end that is hard to diagnose. I drove the car 2500 miles cross country two autumns ago, and during the trip there would be periods of annoying vibration from the front end, and the steering wheel would oscillate side to side. Sometimes it was very bad, sometimes barely noticeable. After the trip, I noticed the front tires were feathering at the edges. These were installed brand new before the trip. I suspected loose wheel bearings, and I was right. When I took off the wheels, I could get about 3/16 deflection on the rotors by pulling on them side to side. I replaced the bearings and snugged them up, but the oscillation persists. Thinking that maybe the tires hadn't been properly balanced at the store I bought them from, or maybe a wheel was bent (alloy rims) I rotated the tires front to back, but still there is a shimmy. The wheel will shake left-right-left-right at highway speeds. Sometimes when crawling along the freeway during rush hour, when I am braking at low speed, the steering wheel, and the car, will pull slightly left. Also, a hard application of the brakes will sometimes result in a noticeable veering to the left. All ball joints seem ok. Tie rods ends seem snug. I am wondering if the steering rack is bad, as there is a slight click when moving the steering wheel (although it feels like it is in the column). Are there inner tie rod ends on the steering rack, and can they be replaced? Would bad ball joints cause a shimmy? Also, the manual I bought for the car says the ball joints are not replaceable, and that you must replace the whole control arm at about $300 a pop, yet a local auto store stocks replacement ball joints for this car.

I would just bring it to a shop if money wasn't an issue right now (back in school), but I am doing all my own maintenance for the forseeable future (replaced a heater core last fall, 8 hours! And just after recharing my AC.....) A 5.0l v8 doesn't make a lot of sense right now, especially with gas at $3.80 a gallon, but I would like to keep this car to have some fun with in a few years time ( 460 v8.....heads....pipes....)

• MacPherson suspension

The ball joint is riveted in place from the factory, and the factory regards it as non-replacable. Aftermarket has you drill out the rivets and install the new one with bolts.

The inner tie rods are a ball joint that screw on the ends of the steering rack. They do wear out. Ford used a tiny roll pin driven into the tie rod end behind the threads to safety it. If you try to unscrew the rod end from the steering rack without removing this pin, it will damage the threads on the ends of the rack. I used a tiny 4-40 tap to screw into the roll pin and it caught and I was able to spin the pin and pull it out. Replacement ends will use allen set screws to safety the end on the steering rack. All of this is under the boots on the ends of the rack.

Use a large adjustable wrench to grab the flats on the rack to keep if from trying to rotating and damaging something while you break loose the inner tie rod end ball joints.

Charles

The inner bushings on the lower control arm as well as the outer ball joint must be snug with no looseness under any condition.

The front end Caster, Camber, and Toe must be set correctly but can only be serviced after all of the other pivot points are inspected or replaced to provide good and firm snug fits.

The steering rack has an adjustment which sets the centering torque or fit between the rack and the pinion. If this is loose then oscillation may occur. The steering rack itself must have mounting bushings which are in good condition and no looseness must be observed at the rack housing to frame mounting location.

The front wheel runout must not exceed +/- 0.002 Total Indicator Reading when measured at the wheel rim edge using a dial indicator and the wheel assembly lifted off the ground. All other related support systems must be in excellent condition so that you are measuring the wheel runout only. You have already started this by greasing and snuging the wheel bearings. Causes for runout may be the wheel bearings, the brake rotors, rusty scale between the rotors and the spindle, rusty scale between the rotors and the wheel, incorrect torquing of the wheel lug nuts, and bad wheels.

Finally you indicated that the tires were recently replaced. If the problem started coincidentally with the tire replacement then it's a good bet that the tires are the problem. No amount of balancing will fix a badly constructed tire. There are a lot of good looking bad tires out there. If the tires are bad and there is a lot of wear in the front end parts then you have a recipe for disaster as the tires will lead to eventual wearout and breaking of the front suspension parts and an accident.

That 5.0 Mustang has a limited slip differential, right? There's a good chance it's binding. Change out the differential oil, and add the Ford brand LSD additive when you refill.

If this doesn't fix the problem, well you needed to do it anyway.