if it wasn't happenning before the new rear then I don't think the rotors are likely to be the cause.

 

has anyone got an update on this? I am having the exact same problem. I am running a 12 bolt with the Spohn Torque arm, stock balanced driveshaft. So does the driveshaft have to be shortened? I feel the vibration right at the transmission/center console area. But it sucks. I feel it really bad right around 60-65. At 70 mph it lessens. Any ideas?

 

I should have my new driveshaft very soon. I'll let ya know if that takes care of it.

 

I've got bad vies too, so please keep us informed. Mine shakes like hell at about 80mph and just doesn't let up. I barely notice it until I get to 75 mph.

 

the new driveshaft fixed my problem...smooth as butter @ 120+. I went with a new DS from Denny's . Not only do they back their shafts like no one else I've seen but this was hands down the #1 customer service experience I've had.

 

Bingo, you got it. I took my driveshaft to my friends place to have it rebalanced, for the second time, adn it was way off. My friend has been in business for 25 years, and all he does is driveshafts. He said that if you notice the "harmonic balancer" looking thing on the front of the driveshaft, he said those were placed on the driveshaft to absorb small vibrations, from the sloppy balance job that GM preforms on them from the factory. Well turns out, these "balancers" are pushed in and held together through a rubber bushing. He said with just enough power, you can spin the driveshaft, and the balancer would stay steady, causing the driveshaft to unbalance itself. He told me to retry mine, and if no luck, im going with a Denny's as well.

 

I think you had mentioned the vibration continuing even when you were'nt in gear? Could that be engine vibration and not DS, Pinion angle or wheel balance? I had a buddy who had vibration and spent a ton of money trying to pin point the problem. He finally realized it was an engine mount that had broke.

I have vibration as well after I changed my tranny mount to a poly, by Energy Suspension. Pretty sure mine is an unbalanced harmonic balancer. Possibly a chasis dyno can help give you more answers.

 

Mine was perfect until I lowered the car. By dropping the rear ride height, the pinion angle was changed. It ended up being roughly +1º.... the vibration was worse with added weight in the rear, confirming yet an even greater change in pinion angle. I adjusted the torque arm for -2º and no further vibrations.

 

Joe, how much did you lower your rear end. Mine is down only one inch.