Ok, so I recently went from being a car guy to getting into the whole 4wheeling aspect of motorsports, so I'm not retarded when it comes to vehicles, just not completely used to Jeeps yet. That being said, here is my problem:

I have a 99 xj, lifted about 4.5" on 31's with a stock rear end. Recently upon acceleration from a dead stop I am hearing a metalic popping noise coming from the rear differential. If I am making a turn while accelerating its not as loud, but it kinda makes a tinging sound. Anyone have any idea what this could be? My immediate thoughts are pinion bearing. Any other ideas?

 

Are you sure its not one of your u joints, that includes your front axle jounts

 

Axle bearing possible or brake issue or rear u-joint .

 

Oh wow, never even thought of those, but they all make sense and are so much cheaper and easier than digging into the rear dif!

 

When was the diff last serviced? If all u joints look good id pop the rear cover and check for metal shavings and go from there. Sure doesn't sounds like u joints to me

 

Check you brakes first, sometimes drum brakes can let go and make some nasty noises accelerating from a stop

 

Diff regularly has fluids changed, last time was a few weeks ago.

not the brakes, checked those. had my roommate crawl under and listen while stopped, shifted from park to OD, to reverse. Said sounds like it is coming from the u-joint.

 

not to sound like a retard, but how do I tell by looking at the u-joints if the look good or bad?

 

Bump

 

Start by looking to see if they are deformed or any cracks in the caps also check to make sure the lobes don't look they they are deformed the joint could have play in it also

 

If both are in bad shape you can usually grab it and twist it with your hands. You'd be able to see or hear play in the joints. It might just be the rear though, so if it looks really beat and rusty I would pull the driveshaft. If any of the caps are seized or grind when you move them it needs to be replaced.

 

Get your wiggle on. Shake the shaft back and forth. You will easily be able to track down if a u joint is bad

 

All of you guys are awesome, thank you all for the help. Here is the latest update: so I "dropped down and got my wiggle on" lol, and couldn't get any of the u-joints to move. Could it still be the u-joints or should I start looking at the rear differential?

 

Bump

 

Do you have a sye?
Check the centering ball on your yoke. Mine had a "pop" I thought was ujoints but they wouldn't budge. Didn't find it till it totally broke.