99 explorer Shaking at 70 miles an hour

[bigdawg703]

I just bought a 99 explorer and under hard acceleration it starts shaking bad at 70 miles an hour, the steering wheel shakes and the whole truck, if I tap the brakes it stops and if I accelerate slowly it does not do it, I just had the wheel bearing replaced when I bought it, I dont know if that could have anything to do with it.

Thanks

[shorod]

I'd suggest rotating the tires front to rear and see if the vibration changes such as the steering wheel no longer shakes, etc. If there is no change, then you may want to consider a vacuum leak or engine misfire. Could also be an out of balance driveshaft, but I wouldn't expect that to be dependent upon aggressiveness of acceleration. Of course, wheel balancing wouldn't likely be aggressiveness-sensitive either.

Does the vibration change if you coast at 70mph, or only under acceleration?

-Rod

[bigdawg703]

It only happens under hard acceleration.... and if it starts and I tap the brakes it will stop. It did not do this before I had the wheel bearings changed, is it possible that the bearings have to wear in or something, or could they have knocked some weight off of one of my tires while they were doing this work?


Thanks

[shorod]

I'd suggest making sure the lugnuts are properly torqued ASAP. It sounds like something is shifting when torque is applied to the wheels -- forward torque causes it, and torque in the opposite direction (braking) changes it.

If lugnut torque is not the problem, then you may want to have the shop inspect the ball joints and such to make sure everything was properly tightened. Sounds like a good chance something is a bit loose somewhere.

-Rod