Driveline vibration

[RedNCStang]

My 94 GT (Auto) has a pronounced vibration on moderate-to-hard acceleration from a standing start, and hard accelertion from low speeds (5 - 30mph). No vibration on hard acceleration at higher speeds, or while decelerating. I checked the universal joints, and found that one was bad, so I replaced both of them (front and rear), but this did not solve the problem. It seems to be coming from the front part of the driveshaft. What else should I be checking? Trans or engine mount/mounts? Driveshaft slip yoke? Any suggestions would be most appreciated. Thanks.

 

[VibrantRedGT]

Two things seem to cause vibration on these cars.

1. Driveshaft-out of balance. Fix-Replace with light weight FRPP Aluminum. My car was only a year old when the driveshaft vibration started at 9,000 miles.
2. Harmonic Balancer-make sure the rubber isn't coming out the back. If this is the problem get it fixed before you vibrate the motor into oblivion. Fix- Replace with Romac Balancer.

 

[RedNCStang]

Thanks for the reply. I ordered an aluminum driveshaft from LRS (crazy expensive shipping to Hawaii), inspected the harmonic balancer, and it looks ok (It has about 30k miles on it). I also purchased an OEM style trans mount. Any tips on how to replace it? Thanks again.

 

[ProKiller]

that was going to be my suggestion was to replace the trans mount as well as the driveshaft

 

[toyman]

Is there any vibration while just revving the engine in neutral or while loading the engine by applying the brakes?