Wheel Vibration

[99 Expy]

Hey guys,
The other day while I was up wheeling in the mountains, I got stuck in a pretty good size snow bank, and it took some digging and rocking to get it out, and when we got back to town, I backed up, and I got a really bad vibration out of my rear wheels, and when I put it in four wheel drive, all wheels did the same thing. In normal driving, it drives and shifts fine at all speeds, but when I put it in reverse, it makes a small clunk, kind of like u joints, and from 0-5 mph, I have a bad vibration. If I go any faster in reverse, it stops. When I go forward after that, it vibrates a little then stops, and wont vibrate until I go in reverse again. I stopped by Ford today, and the mechanic told me he thinks it is probably u joints or possibly my rear pinion, but is probably the u joints. My dad said the rear joints haven't been replaced since its been in the family, about 5 years. I am going to replace the u joints sometime when I can find someone to let me use their shop for a little bit. What does this sound like to you guys?

Thanks
Zerick

 

[Racenut]

The easiest way to check your u joints is to get under the truck with it in park and try to "twist" your drive lines back and forth. If the u joints are bad you will see the bad one right away. If the drive line moves a little but you cannot see a bad u joint then it could possibly be slack in the ring and pinion.

There should also be a "vibration damper" right after the front yoke on the rear drive line (looks kinda like a harmonic balancer) check the rubber in between the two pieces and make sure it is not seperating.