Just recently I was driving my rx7 and I came to a light with a Subaru WRX beside me. after the light the lanes merge into one.. he was in the merging lane. When the light turned green he thought he would try to cut in front of me but I couldnt have this so I ran it out and he couldnt pass.. but right after this my car started to shake violently. I pulled over worried that I had blown a seal or something. But it idled perfectly. I got back onto the highway everything seemed to be fine until I got up to 80(kms) and the vibration came back. The wheel doesnt shake.. the whole car shakes..

I have noticed my rear right caliper locking up>? u think this has anything to do with it? also the roads where very wet maybe on take off i could have done some damage to the rear end?

any ideas would be great.. oh.. and the vibration has majically dissappeared im worried that it might come back.

 

Ujoint, tranny mount, unbalanced tire, poor alignment. Weird that it went away like that, but I would guess that you strained/broke something while you were messing with the subie. I would bet that you broke a ujoint, but like I said it's weird that it went away...

 

Since it only happens, or is felt, at higher speeds it sounds like something that is rotating so I'd start looking at u-joints and tire balance first like what Kentetsu has suggested. After that start checking motor and trans mounts, steering linkage bushings and mounts.