Noob Help - Rear End Questions

Just picked up this piece for five hundies. '94 2.5l 2wd 5sp 189k

You'll have to bare with me, I've only learnt Fords and Hondas, so Jeeps are new to me. So far, Iv'e been happy with ease of maintenance and access to key areas (spark plugs for instance, damn all fords for that). It runs strong, has even compression, but there are few kinks. The rear end, the 8.25, is humming. It sounds like it's coming from the middle, and only makes the noise under positive torque (gassing it). It goes away when you cruise, or when you declerate. I'm guessing bearings and gears will need to be replaced. I'll be moving to Colorado, and I'm thinking POSI would be nice to have since it snows a lot and all I have is 2wd.

Should I:

1. Rebuild the rear end in my carport, yes carport, because I have all the basic tools (sockets, wrenches) and I can probably borrow the specialty tools I don't have from the local Oreily's.

2. Pay a local shop $200 labor to rebuild the rear end because I'm a noob and I'll probably fudge the whole deal.

a. Go with a posi, because 2wd open diff is the anti-jeep.

b. Go cheap with the sand because...it's cheaper..

So option 1a, 2a, 1b, 2b. Please also suggest brands to stay away from, and brands to go with for the replacement gears and LSD. I'm an e-bay'er, so please guide me well. Also, what would my spline count and gear ratio be? Thank you for help with my first post. Please learnt me good. :wierd:

I would first diagnose the problem before sinking money into a rebuild. WHo says it needs one? Could be something as simple as a u-joint. If it's humming...I wouldn't suspect a diff problem.

Figre out what is wrong and go from there. Simplest thing to do is get on your back and check u-joints for play.

Good luck

PS: If you're serious about owning a Jeep...do some research. Don't take that the wrong way, asking for help is one thing, but asking the specs of your own vehicle sounds lazy to me.

PPS: I didn't say I wouldn't help...now all you have to do is read http://jeephorizons.com/tech/xjstockspecs.html

If I just bought a new XJ, and it was humming like you described, I would personally start by just replacing the fluid in the diff.

I'd check for metal shavings and do a quick visual while it was apart.

Go TO THIS LINK and request a "Build Sheet."

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p.s. Welcome! :thumbup:

Creamy - Well, if I hadn't of asked, I would've never found that useful link. Thank you.

RTicUL8 - What is a build sheet? Thanks!

There is no play in the u-joints (first thing I checked). I did also changed out the rear fluid, and the hum didn't change tone or nothing. I'm probably gonna dump some Lucas oil stablizer in there just to see if it changes the noise at all. The local 4x4 shop said it's probably the bearings going out, and since it's been like this (the noise) for a while, it's gonna need new pin and ring gears. My hypothesis is that the previous owner negelcted it, and wore some nice patterns into the gears. When I changed out the fluid though, I did a quick siphon job, so I can't tell you about any shavings (didn't see any).