My 2004 Mountaineer AWD V8 has a shimmy in the steering wheel which I can’t figure out what is causing it.

I purchased the SUV used with 40k miles 3 years ago. I drove fine, no shimmy. Last year it got some front nose damage, air bags did not deploy, most of the damage was at the bumper or above. Collision shop stated no frame damage. 9 months ago I replaced the front shocks, rotors and pads and had the alignment checked. The shop that did the alignment said the alignment was nearly perfect, no adjustments were done. 2 months ago I purchased 4 new Bridgestone Dueler HL’s, had them mounted and balanced. I took the SUV out for a drive on the highway a week ago and noticed a slight shimmy in the steering wheel that seemed to appear between 64 and 75 mph. I never noticed this before with the old tires. The new tires only have about 2,000 miles on them.

So later in the week I took the SUV to company that mounted and balanced the tires and they took off the front wheels and rechecked them on their machine, stating that the rims were not bent, the tires ran true, and when they put them back on the SUV they said the wheel/tire assemblys ran true.

I took the SUV to another tire shop and they checked the balance on all 4 wheels and stated they were not out that much. I asked the tech to test drive the vehicle with me and when we got on the highway I showed him the steering wheel was shaking. He said it could be alignment. When we got back to his shop I noticed the tires on the back of the SUV has feathering on their outside treads. The tech said they had rotated the tires after balancing so these tires go their feathering when they were on the front of the SUV, which leads me to believe the first shop that checked the alignment missed something.

Recently I’ve noticed that I can sometimes feel the wheel shimmy when driving a slow as 35 mph, the shimmy is not as severe and seems to come and go, however at 65-75 mph its always there.

Placing the trans in neutral or another gear while it is vibrating does not make a difference. Nor does touching the brake pedal.

I’m baffled at this point at to what the problem could be: these are new and rather pricey tires and they have been balanced twice, the alignment might be a problem, the SUV has new shocks, rotors and pads (the brake pedal does not pulse when applying the brakes).

If anyone has had a similar problem with their Mountaineer or Explorer and you solved the problem, or if any experts have the solution then please chime in.

 

Jack each wheel up and personally check the tire as you rotate it.

 

If you are seeing feathering on the front, that is an indication that they are scrubbing. Get the alignment checked again, particularly the toe.

 

the alignment numbers are a starting point. most shops will look at the tires after 20k miles and "see how they are doing" they might change the toe in or toe out slightly to compensate for some wear. I would have thought that after they put the fronts on the back end, then vibration would have quit. Vibration is normally from worn tires "due to worn ball joints or alignment". If the tires are just worn on the outer edge, thinner tread than the center, then that is normally caster/ camber. If there is scrubbing or cupping on the tread, that is normally toe in / out and will cause a vibration as the tires get worst, thats why putting them in the back normally helps reduce the problem. If the tires are cupped on the outside, the tires have too much toe in, if cupped on the inner edge, they are toe out too far. THis assumes the ball joints and tie rods are all fair condition and no excess movement. I have changed the "toe in" measurement a little past the "max or min" range depending on how they are wearing. If the tires scrub on the outside and you are "in the range" you still need more toe out, that should be obvious to the alignment guys.

 

PROBLEM RESOLVED:
The problem ended up being the lower ball joints (thank you Steve). I had taken this SUV to 3 different repair shops. The first and second both did alignments and said they checked the ball joints. Finally, I took it to a third shop where the owner said "its probably the ball joints, do you know how they checked them?" Frankly I did not, so he showed me how he checked them. He left the vehicle on the ground and jacked up the chassis to get the front wheels off the ground. Then he took a large pry bar placed in on the ground under the tire and used it as a lever to lift the tire up and down, loading and unloading the lower ball joint. Sure enough you could see the excessive movement in the lower ball joint. This SUV only had 50k miles on it. He replaced the lower joints, did another alignment and PRESTO- Problem solved.