Stewart

Starting at 75+ I get some driveshaft vibration on decceleration. The faster I go the worse it gets, and at 100 I don't want to go any faster since it starts vibration pretty badly. I've got lower springs/tokicos and 4.10 gears in there so either mod could be the culprit. I'm not positive if the vibration started after the lower since I didn't have the gears in then and I would have to go 100 + to even feel the vibration but I'm 90% sure I only started getting the bad vibration after the gears.

To remedy this, I ultimately plan on fixing my pinion angle, but in the meantime does this sound like something a driveshaft balance could remedy? Or will the only way to stop this be taking care of the pinion angle? I just got it back from the dealership who put in a replacement driveshaft under warranty, it helped a little but the same vibrations happen at the same speeds.

CrazyAl

What kind of driveshaft do you have? Stock or a 1-pc? Any aftermarket parts in the rear end?

I seriously doubt it is your gears. If a gear change would make things fibrate it would be accompanied by a horrible whine/grinding noise, unless they did something stupid like left out a ring gear bolt.

My guess is pinion angle, at least for right now. When you lower the car, you need to fix the pinion angle.

Stewart

It's a stock driveshaft, only aftermarket parts in the rear are the springs/tokicos. By gears I didn't mean it was caused by the actual gears themselves, I meant that the driveshaft vibrated at 110+ with stock gearing, with 4.10's the same vibration would come at a lower speed, so I was thinking maybe the driveshaft was a little off to begin with but I think now that a new one got put in there and the problem persists that it's the pinion angle. I was just wondering if that sounded like something an off pinion angle could cause.

07GT

From what you've described it sound like the pinion angle is off. The low gears can make the vibration come in sooner. Get some adjustable lower control arms and let us know.

CrazyAl

Your logic is correct, if something is out of balance, the vibration will happen at a lower RPM if you switch to those gears.

It could be the driveshaft but that is unlikely.I think it isthe pinion angle. If you lowered your car and you didn't install adjustable control arms and reset the pinion angle then it WILL be wrong and that will cause vibration.

moosestang

What springs do you have in the rear? Do you get a clunk when shifting at low rpmsfrom 1st to second gear? With the stock arms and a 1.5 inch drop your pinion angle would be around 0 to -1 and should cause some clunking when shifting and may cause a vibration. I'd get some adj. lower control arms. They should come set to the stock length. Install them at the stock length and then lengthen them about 1/4 inch. Test drive the car and if there's no change go another 1/4 inch longer. You'll need an angle finder to check the actual pinion angle.

Stewart

They're the steeda Sport springs which I remember are about a 1 inch drop. No clunking, going through the gears is smooth it's just that high speed vibration. I'll get some lower control arms soon.