Somebody to the rescue please!

[drilzzz]

1997 GT...I am up to my neck with this rear end. After allowing two weeks for the rebuild of the rear diff and having to go back to drop the car off for another week in order to address the whining noise (from ring and pinion) I finally get the car back with more problems.

I went out this morning to pick up some parts and on the drive home i decided to take the car out on the highway in order to open her up a little and to see how the rebuilt rear diff would perform at higher speeds. When I got the car to about 80mph i start to hear a pulsating humming which turns into a loud vibrating pulsating sound at about 95mph and the sounds just gets louder and more obnoxious as I hit 100mph. I was afraid that the rear end was about to cease up or fall off so I decided to slow back down and drive home slowly and immediately.

What should I do? What could be cause of this issue? I got new axles, bearing, spider gears, trak lok rebuilt, and new 3.73 gears. I don't want the shop owner's mechanic to touch my car again. So far he has given me back the car twice with issues on a $2,000 rebuilt job Please give me some advice.

 

[drilzzz]

I was doing some research and discovered that my symptoms may be related to a bad Universal Joint (U-joint). THe backlash on the car was reset a few times and the rear diff was taken apart and put together at least 4 times in the last three weeks. Could this be my issue?

 

[Rusty67]

After reading your first post, I was going to suggest that you have the drive shaft checked. How long have you had the car for and how many miles are on it ? It might be time for new u-joints as it is.

You might want to go to the junkyard and get a drive shaft out of a crown vic police/taxi car. They are really nice aluminum units. Strong and light. Just have a drive shaft shop build a new one out of the donor and have them reuse the trans and pinion yolk off of your existing drive shaft. It would be a nice, cheap upgrade. Then you would have new u-joints and a nice aluminum drive shaft.

 

[drilzzz]

I have had it for about 5 years now and it has about 156K on it. Never replaced either. Do you think that the u-joint and or drive shaft could have been damaged because of the rebuild?

I'm going to check out a local shop and see what they can do for me. I appreciate the advice.

 

[Rusty67]

With that many miles it may have been close to needing new u-joints as it was depending on how hard the miles were. You said the backlash was adjusted a few times. You might have put the finishing touches on one of the u-joints because of the vibration from the diff being off.

You can always pull the drive shaft and have a shop check it out. New u-joints and a rebalance on a drive shaft should be easily less then 200 bux.

 

[drilzzz]

Thanks for the information Rusty. I will bring it in somewhere tomorrow to see exactly what the problem is. This rear end rebuild has been a disaster for me. Will update as soon as i know...

 

[fast97gt]

might oghtta check the flange mounting bolts. improper torque will reek haveck on the pinion flange. thats what mine was, i swapped my ujoints and got a vibration, didnt have one before but after i chanded i did. bought a new D/S it was a miracle it was fixed.

 

[Kilgore Trout]

Stupid mechanics do not mark DS position prior to removal guaranteeing it will not go on the same way it was and that causes DS imbalance. One little chalk mark would have prevented this.