Rear End Roar

[blaz246]

I would like to put up another question - My 2001 with 155,000 miles has a roar under load and it sounds like it is coming from the rear end. I pulled the cover off, drained the fluid and replaced with synthetic as it called for. The fluid was relative clean. I also greased the half-shaft fitting. The roar did not change. If I am going down a slight hill and let off it completely goes away. It is not terribly loud just annoying. Is this something that can be adjusted out or should I find a complete axle assembly from a wrecked truck? What $$$$ am I looking at to fix? Also, mine has disc brakes. Thanks!

[99silverado1500]

Sounds like the rear is on its way out. My moms expedition made a roar/whistling noise, and it was a few bearings bad in the rear, and she just had the whole thing rebuilt. A junkyard rear is a option, and then you can get what gear ratio you really want if you dont have the one you want already.

[omegafiler]

Find a good local mechanic or even better, a drivetrain or some other speciality shop that knows all about rear diffs. Have them go for a ride, they can probably tell you what it is right away.

[RyanZ71]

That roar you hear is the supercharger kicking in!!!

[blaz246]

That roar you hear is the supercharger kicking in!!!

I wish it was that!!

[pm26]

If the noise was a whine, that could mean improper gear backlash adjustment.

[Zembonez]

Your noise is certainly center diff related judging by your "it comes and goes" description. Might be able to get away with replacing the carrier and pinion bearings.

 

I had an S10 Blazer years ago that did that from day one. At about 10K, it got louder so the dealer replaced pinion bearings and it went away for about 30K... and then came back as loud as ever. It never cratered, just made racket for another 50K. I always suspected the rear end was not set up properly when built.

[fixitmann]

I agree with Jim sounds like a pinion bearing, just did one on a ferd before Christmas with same symptoms "under load roar goes away upon coast"When you had the cover off did you happen to notice the mesh pattern where pinion and ring teeth contact.?Replaced a worn out rear u joint lately?

[blaz246]

I agree with Jim sounds like a pinion bearing, just did one on a ferd before Christmas with same symptoms "under load roar goes away upon coast"When you had the cover off did you happen to notice the mesh pattern where pinion and ring teeth contact.?Replaced a worn out rear u joint lately?

 

I looked at the pattern and it appeared to be normal from what I know. I haven't owned the truck that long, but the u joint looks to be the original one.

Thanks! Gary

[marko]

I agree with Jim sounds like a pinion bearing, just did one on a ferd before Christmas with same symptoms "under load roar goes away upon coast"When you had the cover off did you happen to notice the mesh pattern where pinion and ring teeth contact.?Replaced a worn out rear u joint lately?

 

I looked at the pattern and it appeared to be normal from what I know. I haven't owned the truck that long, but the u joint looks to be the original one.

Thanks! Gary

 

 

Start with the cheapest thing first. Clearly it is a driveline problem (this you can tell from the fact the noise comes from that area and under load only), but the rearend is the most expensive thing. Check the ujoints first and replace if needed. Then check slipjoints. Then check pinion bearing (when driveshaft is off and wheels raised try to push up/down side/side on the pinion, then check end play (in-out).