So when i'm on the interstate doing 70 or so my car has a terrible vibration. i did an alignment, checked the tie rods, and had the motor mounts replaced (two were bad). None of that made a difference. So then i checked my transmission fluid. It was dangerously low. I filled it back up and it's still driving the same. So i was wondering if a bad axle could be doing this. It seems to be a temporary fix if i jack the rear of the car up and set it back down. my only issue with this being the problem is it seems to go away if i'm in neutral or make it to where there is no torque on the drive train. Any ideas?? It's driving me insane!!

Tranny? Engine? Stock? If you get the trouble going and ride the brakes does the noise change? If you get the noise going and sway the car side to side does the noise change?

If none of those seem to make the noise/vibration change considerably, I'd be thinking bad tranny. Hows the fluid look now that you added some and its stired up with the rest?

Yeah, the bearing would just make noise if it was going bad... not unbalance. If you're sure nothing's attached to the CV shaft, I would unfortunately also tend to lean toward the tranny from this point.

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* 1984 Black Fiero SE (1995-1998) blown tranny - rest her soul
* 1988 Black Fiero Formula (2001-2004) Was to be a 3800SC, badly rusted rear frame.
* 1988 White Fiero GT (2009 - Present) This one's a keeper!

jack the car up and put it in gear, with the wheels on accelerate. but please make sure your safe about this. if it is the cv shaft you will see it wobbling. ive had drivers shafts go bad before on cavaliers and they shake something fierce.

My bet is on the Hub bearing going out!

quote Originally posted by kikinz24: jack the car up and put it in gear, with the wheels on accelerate. but please make sure your safe about this. if it is the cv shaft you will see it wobbling. ive had drivers shafts go bad before on cavaliers and they shake something fierce.

This is an excellent way to blow out the inner CV boots. The rear wheels can be off of the ground, but the spring must be loaded. The lower rear suspension must be resting on something, so the axles are almost straight. The boots are not made to function at a real extreme angle.