I have a 99 1500 with an 8.6 reared. I had to do some work to the center section a while back. Cleaning, gears, and oil. Everything has been fine until recently. Now the rearend is howling. I believe it's outer bearings and my seals need to be replaced. Should I do inner and outer bearings or will it be safe replacing just the outer bearings?

 

Were the carrier bearings replaced?

When I had my 411s put in the races were scar'd pretty bad and I opted to replace them at that time.

I suspect the chunk is coming out again.

 

No I didn't replace the carrier bearings. They still looked good. It doesn't sound like the usual gear howling that I've had in the past. It sounds more like the roar from a hub assembly that is going out. I had my wife drive beside me and she couldn't hear anything. You only hear it in the cab.

 

Do you have a 2pc driveshaft? If so, what about the center support bearing?

 

What was pinion preload and you shouldve replaced carrier bearings and pinion bearings when installing gears axle bearings/seals arent bad idea to do either, cheap insurance compared to having to pull it all back down and risking tearing up new gears

 

Pinion preload is a pain if you don't have a good in-lb torque wrench that stores the max reading. On my np246 I had to do a billion spins with my cheap in-lb tool to feel confident on preload.

Great points, OP listen!!!

 

Ive always done preload with beam type inlb torque wrench... How i learned!! Not to mention some people think im nuts way i setup a rear end, but not getting into that right now!!! Mines been holding up with no issues for about 10-12 years and probably 120k so far

 

I replaced the carrier bearings and one had a few pitted areas. The other side was fine. Found that it was my pinion bearing that was making all of the noise. So for anyone that reads the post. If you replace anything in the differential. Spend the extra 24.00 for races and bearings for the carrier and pinion. It might take a little longer but is worth the time.

 

Did it look a little like this? (from my front diff)

 

Not to mention when you pull the inner pinion bearing off to get the shim thats behind it you usually destroy the bearing anyway, on occasion you can get away without carrier bearings but if theres any markings on bearing rollers or races they should be replaced.. Just for the sake of sanity make sure they are back on all the way before you try to put em back in the housing. Fought more than one carier bearing i thought was on all the way until i smacked it one more time with the bearing installer and it slid right in!!!