I have an 89 Mustang coupe with 174,000 on it. My problem is whenever i get to around 65-70 mph, the steering wheel shakes like the tires are out if balance. Ive already had the tires balanced twice. The steering wheel shaking isnt constant, it seems to vary by the road surface or something.

 

Interesting... hm...

Warped rotors maybe?

Also, that age a car and that mileage, could it possibly be shocks?

And other general suspension questions... worn out bushings causing the geometry to change at speed causing the tires to go "toe out" and therefore snap back and forth... or something...

Past that, I dunno... does it change if you go down a gear? If so, it may be something to do with the steering pump pressures or such...

Just throwing out ideas... that's really an odd one, to me anyway.

/bet someone says "it's this" and it is.

 

hmm, worn suspension components? loose/worn wheel bearings? maybe a tire/wheel issue?

 

...and it wouldn't hurt to check the condition of the steering rack bushings, wheel bearings, + inner & outer tie rod ends for play while you're at it.

 

Have you had all 4 wheels balanced? sometimes the rears can affect the whole car (happened to me when I had some mud on the inside of one of my rears).

Does the vibration stop / lessen immediately when you come off the gas or does it only stop when you drop below 65?

TBH, it still seems like a balance issue because of the speed it is occuring at, but as you have had the wheels balanced, I am stumped.

 

I had snow tires on the rear last winter and the vibration was still present. It only stops when I drop to below 65.

I doubt its a balance issue, maybe the tires are bad or something.

 

I had the wheel bearing repacked when I got the car. One of the tie rods is kinda of stiff.

where are the steering rack bushings located?

 

Could worn out ball joints cause steering wheel vibration?

 

i say it seems possible. maybe an alignment issue? my guess is either tire/wheel issue or alignment issue...although u stated u dont think its a balance issue.

 

Does the car sit a lot?

My '82 will shake at highway speed until it is driven a few times in the spring. Caused by flat spots in the tires, I suppose. It's fine now that it's been driven some.

 

Good point and I would also check the u joints, I had a bad one and only felt it occasionally until I took off the drive shaft and it fell apart...

 

If the inner or outer tie rods are worn you would be able to move the front wheels a bit side-to-side using your hands while the front wheels are raised up off the ground.

You can find the steering rack bushings inboard of the rack's rubber boots, on the bottom part of the tube. The rack is bolted to the lowest portion of the K-member and should be the only aluminum-colored thing attached to it. If there is/was a constant source of oil leaking on them, like from a power steering fluid or front seal leak, the bushings can deteriorate and the rack would move around as bumps from the road and/or steering inputs go through the suspension. Age also plays a part too. However, it doesn't sound like the rack bushings could be a problem. Doesn't hurt to go underneath to inspect all of your steering components for any parts failures though. Good luck finding the source of your problem and keep us updated if you can.

 

I noticed yesterday that if i drive faster than 70, the wheel shakes less.