gvns8

I need some help troubleshooting. My rear differential (chryco 8.25) always has a relatively annoying turning sound which gets louder with speed. Kind of a howling sound. It's not a vibration like the drive shaft would make and sort of quiets down when turning left.

Do you think I need new diff bearings? Or do you think the diffs need to be reshimmed? Or.... any other ideas? By the way I have a lunch box locker back there. Thanks for your help!

Gee oh Dee

Have you pulled the diff cover and inspected?

I'd start there.

gvns8

yup here is a picture. Nothing seemed loose and all the teeth looked fine. I didn't pull the carrier though.

_StationWagon_

Is it regeared? Ever since the regear mine howls loud enough to drown out my aftermarket muffler & my tires.

gvns8

yup it is regeared with yukon 4.56 gears. I bought it with the howling sound though and the new gears so I can't determine what led to the sound. I don't really want to pay to have it re-shimmed (im guessing that is your problem) and replace the bearings if only one of these is causing the problem.

Gee oh Dee

Mine whines as well, I've got 4.11s. That could be.

gvns8

yea its pretty annoying. At first I thought it would go away after I got my SYE installed, but that just cured the vibrations, not the loudness from the rear. Did you guys set the shims yourself? or have a shop do it? I am assuming the PO got it done by some cheap place, so they probably didn't set the shims correctly.

gvns8

I guess it could also be my axle bearings. Anyone had any experiences with axle bearings going out or how to tell the difference between axle bearing noise and diff bearing noise?

Choo_31

I had the same howling sound only when under load. It turned out to be the axle bearings and a bad u-joint in the drive shaft.

Gee oh Dee

Anytime I've had a bad U joint there have been vibes as well as the howl.

Never had axle bearings go, though. My buddies F150 had some that went, his made noise, but I never felt any vibes. I never drove the truck, though, so it can be different as a passanger.

gvns8

yea i might pull the shafts and just look at the wheel bearings to see their condition and replace them if bad for about $60 i think they run. If thats not it, its probably the diff bearings/shims...so I guess I will just live with it until I upgrade to a ford 8.8 or d44 because I don't think its worth spending another $250+ to get the job done right at a diff shop.

Xjtim

The 8.25 sucks *** to do a ring and pinion on. I did it with a mechanic buddy of mine. After it was all done it howled like crazy. The 8.25 doesn't have shims. It has this stupid adjuster wheel at each end of the carrier. You have to torque the Carrier bolts to 70ft/lbs and the adjuster wheels to 75ft/lbs. Only problem with doing that is that you have to have a special tool from chrysler to torque the adjuster wheels down once you've torqued the carrier down. You have to acsess the adjuster wheels through the axle tube, so you need like a 36mm male socket that has an extension of about 36". Ive seen some people make one out of all thread and a couple 36mm nuts by double nutting them to get the torque to 75 ft/lbs. If someone did a half *** job on your diff, I can almost gurantee they didnt do this step, it will shift your carrier to one side or another when turning causing your howl. Plus the carrier is loose at all time causing howl constantly. Hope this helps! Good luck!

gvns8

Thanks for that info. I was wondering why I couldn't find any rebuild kits with shims for the 8.25. From everyone's posts I believe that it is probably the differential. I might try to see how much it would cost to have someone replace the bearings for me since I don't have the time to do it myself. I was guessing about 250 but maybe I can get it done for less... I wish I could just get a new ford 8.8 but I really need long arms before a new axle.

maverickdan

A good way to make that tool is go to the junk yard a get a torsion bar from I think it was a 90's chevy pickup cut the end off and weld a cheap socket to the end.
do you know what the set the pinion bearing pre load to?

gvns8

not sure what they are set to right now or exactly how to check...supposed to be something like 12-15 Inch pounds though I think.