I've been noticing some strange vibrations that peak in strength at 77mph. I have swapped wheels (different rotational diameter) and the problem occurs at the same speed. I found cracks on my a-arm brackets, and after having them welded the vibes are still there.
The nature of the vibrations is like two instruments playing slightly out of tune on the same note...the vibrations fade in and out as I maintain speed. Doesn't matter if I turn or stay straight, accelerate or deccelerate, the vibes only occur around 77mph. The gear I am in does not make a difference either. I tried shaking the wheels (check bearings) and nothing feels loose when I do that. I am going to get an alignment done today. No play in my driveshaft CV joints and diff functions properly. I hear no rattles or ticking that could indicate the source of the problem. Anyone have any ideas? Everyone else I've asked is at a loss as well.

 

Seems to be getting common, in one case an alignment worked another was a CV joint.

 

One thing to try is to go around corners at about 30-40mph in 2nd under acceleration and see if the shaking is more pronounced. If its harsh on a right turn and none-very little on a left turn then its 99% a CV joint issue.

 

i already said i checked my CVs and that's not the problem. i've had to replace those before and know what it's like, this is different.

At first I thought the cracks in my Aarm brackets were the cause, now I think they may just be an effect. That leads me to believe that it's a problem in the front, not the rear, but that could be an incorrect belief.

 

and pinky, I said in my first post that it's not noticeable until 77+-5mph range, and that turning the wheel or leaving it straight does not change a thing.

 

True true.

 

I know you changed wheel combos, but balancing of tires themselves?

just fishing......

 

Did you check if the hubs are loose?

 

Does it change when you put the brakes on? Do you have any spare brake rotors that you could put on? Maybe you have a warped rotor or two on the rear.

 

Perhaps it is the ?