Hey guys,

I have a loud whine when I let off the gas. Definitely coming from the rear axle area (not sure if differential or not), and it is pretty loud.

I was just wondering, should I start by replacing the axle shaft bearings and then see if it goes away, or should I just go for the whole kit and rebuild the whole thing. I have the Chrysler 8.25 axle.

I took the cover off and drained it, and the fluid definitely looked metallic. The gears all look good, but I really don't know what else to check.

This is a 91 XJ btw.

Thanks in advance

 

Noise from the rear when decelerating (letting off the throttle) is usually a bad pinion bearing. Chrysler 8.25" are known to get noisy with age, though since you are seeing metal in the fluid it is likely something that needs to be addressed sooner rather than later (if left go the pinion will get loose enough to mess up the pre-load and gear contact pattern, tearing up the gears). Your options are to replace the bearing(s) (it really doesn't make sense just to replace the pinion bearing once you get the differential apart you might as well replace them all), if you are not familiar with setting up gears it would be best to have a shop do this (usually $500-$700, though it can get to $1000+ if gears need replaced) or replace the axle with a used one from the junkyard (usually $150-$300), only takes a couple hours with basic tools (this is the option most people go with if they have stock gears).

 

Thanks. I was afraid of that. Looks like next weekend is junkyard weekend. Only $110 at my local yard.

Sounds like a good time to do disc brake conversion too.

Question: If I am planning on re-gearing soon (gonna go bigger tires), then should I still get the new axle, or should I just rebuild the current one? I may be planning on getting a locker if I can afford it.

 

If you're planning on re-gearing soon (next few weeks or a month or two) there may not be much benefit in replacing the axle as long as you are only doing local driving (no long trips). Re-Gearing should also replace the bearings (if done right) and take care of the issue, worst case scenario the bearing fails completely and the differential gets torn up and you replace the axle anyhow (if the carrier or shafts are damaged it will likely be cheaper to replace the axle than to repair the damage unless you are upgrading these anyhow).


With that being said if you are planning to go on a long tip anytime soon or can't afford having an unexpected breakdown it is probably best to replace it as it certainly can leave you stranded if it fails (you may be able to "limp" it in 4WD using the front axle but you don't want to go very far or fast like that).

 

X2 if you can wait till you have the money to replace the gears/lockers at the same time for both the D30 and the Chy 8.25.