I search around but could find a spec on the 9-bolt pinion depth. I had the gears install by a trusted mechanic but they wine on accel and decell and viberate for a sec then quite for a sec at about 55-70. There is a slight viberation below that speed while normal driving. Anything higher than 70 and the whole car viberated really really bad. I took it to the MFBA US41 track rental on Sat and at the end of the 1/4 I thought the car was going to viberate apart. The wheels were balanced and the drive shaft is new and balanced. The reason I ask about the pinion depth is when they were installed the mechanic couldnt find a spec on it so he set it using the marking compound. I have an appointment next week to get it fixed but what should I have him look at specifically.........

 

find another mechanic you and your car's rear have been sodomized as rb likes to say. there is no spec for pinion depth and any mechanic that's ever done a ring and pinion would know that. the contact pattern means very little in reguards to pinion depth. each gear set is differant, and the key word is set, as in matched set. the gear maker figures out the optimum depth and back lash and etches it on the pinion and ring gear.

 

The mechanic aside.....what should be done to set the rear right?

 

at this point i'd suspect start over with new parts, at the very least start over with the old parts. one things for sure i wouldn't drive it.