[LEOWife]

Hey Gang,
I have a 1990 YJ that is my daily driver.
About 3 weeks ago, I made the off handed comment that 'Nothing has broken on the Jeep in a while.' Wish granted.

I was driving to my parents house to get the kids after a long day at work when I ran over a man hole cover. The sound that resulted sounded like a tire popping.

I pulled over and saw the tires were fine, nothing was hanging down, and the sound was not happening at idle. After I limped it the mile down the road to my parents house and then home with the aide of my husband here is what we know:

The sound is coming from the back of the Jeep.
It is a very rhythmic sound, a deep metal sound vs. a high tinny 'ping'. The faster you go, the faster the rhythm is.
When the Jeep is under acceleration the sound does not happen. If you let off the gas or push the clutch in to shift, then the sound happens.
It only happens after you shift out of second, into third (speed I am assuming) and then every gear after that. And again, when you are coming to a stop.
The transmission was replaced two years ago. I have no problems shifting into or out of any gear.
The axles and driveshafts were completely rebuilt as well about 2 years ago. (the transfer case was not.)
There are no loose parts on the drum breaks.
There is no play in the drive shaft at all.

We are stumped and we don't have the time or the money to have it sit at a shop and be diagnosed. We need it fixed and don't have an idea of where to start.
Can someone point us in the right direction?

[jbolty]

best bet is to get under there and look for something with a fresh bang mark on it. The only things rotating in the back are the drive shaft, the connections on each end and the wheels. I would look for something contacting the drive shaft or perhaps a bent brake backing plate.

put it up on jack stands and rotate the tires by hand to try isolating the source

[Anticanman]

Pop the diff cover on the rear end and take a look around.

[LEOWife]

Originally Posted by jbolty

best bet is to get under there and look for something with a fresh bang mark on it. The only things rotating in the back are the drive shaft, the connections on each end and the wheels. I would look for something contacting the drive shaft or perhaps a bent brake backing plate.

put it up on jack stands and rotate the tires by hand to try isolating the source

We did put it on Jack stands and rotate the rear end. It did make the sound.