Rear end pulls/wiggles under hard acceleration/up-shift.

[Shawn819]

I just recently installed a new driveshaft, which fixed a problem I've had for months with the car vibrating terribly above 75MPH. During that time, I also replaced both rear wheel hub bearings since they were shot.

Anyway, now that the vibration is gone, I did a few hard pulls and noticed that when I shift up in any gear, it feels like the back end of the car jerks out to the left when I hit the throttle. I know I said pulls/wiggles in the title, but it's more of a violent twist/jerk. Under normal driving conditions (i.e. not WOT), the issue is almost unnoticable.

Mine still has the factory IRS and nothing aftermarket in the rear end. Goodyear GS-D3 315's on the rear with 3/8" spacers.

Could the new wheel hub bearings already be ruined as a result of driving around for almost a month on a bad driveshaft with vibration? Any suggestions on what else to check?

 

[ac427cobra]

I just recently installed a new driveshaft, which fixed a problem I've had for months with the car vibrating terribly above 75MPH. During that time, I also replaced both rear wheel hub bearings since they were shot.

Anyway, now that the vibration is gone, I did a few hard pulls and noticed that when I shift up in any gear, it feels like the back end of the car jerks out to the left when I hit the throttle. I know I said pulls/wiggles in the title, but it's more of a violent twist/jerk. Under normal driving conditions (i.e. not WOT), the issue is almost unnoticable.

Mine still has the factory IRS and nothing aftermarket in the rear end. Goodyear GS-D3 315's on the rear with 3/8" spacers.

Could the new wheel hub bearings already be ruined as a result of driving around for almost a month on a bad driveshaft with vibration? Any suggestions on what else to check?

Jack up the rear of the car and feel the rear wheels for play in ALL directions and report back with your findings.

:thumbsup::coolman::beer:

 

[01cobravortech]

I just recently installed a new driveshaft, which fixed a problem I've had for months with the car vibrating terribly above 75MPH. During that time, I also replaced both rear wheel hub bearings since they were shot.

Anyway, now that the vibration is gone, I did a few hard pulls and noticed that when I shift up in any gear, it feels like the back end of the car jerks out to the left when I hit the throttle. I know I said pulls/wiggles in the title, but it's more of a violent twist/jerk. Under normal driving conditions (i.e. not WOT), the issue is almost unnoticable.

Mine still has the factory IRS and nothing aftermarket in the rear end. Goodyear GS-D3 315's on the rear with 3/8" spacers.

Could the new wheel hub bearings already be ruined as a result of driving around for almost a month on a bad driveshaft with vibration? Any suggestions on what else to check?

Interesting I just took my car in to do a lot of suspension work because one of the problems was that I was getting a violent twist/jerk to the left as you described, when slamming it into 2nd. I replaced the IRS diff bushings with FTBR alum ones and also added the FTBR rear toe links. Will let you know if that problem has left the building.

 

[Shawn819]

It turned out to be as simple as a loose tie rod bolt. Amazing that being loose about 2-3 turns caused such a significant driveability issue.