Setting up differentials

I found a bum carrier bearing on my HP 30. And with the roughness in the pinion on my JY 27-spline 8.25, I am likely to rebuild my factory original 29-spline LSD.

I have read over several months many articles and write ups on doing this work and frankly it does not scare me. But I have never done it before. From what I can tell, all you need a few special tools, patience, and a good supply of beer and cigarettes. :cheers: :smoker:

At this point I am not looking to re-gear or install lockers, though the thought has crossed my mind many times to buy ARB lockers and 4.10's. Options are limited for the 8.25 and I am not interested in any lockers I can't manually control. Because I have never worked on diff before, I think it makes sense to do it with what I have the first time around and consider re-gearing and adding lockers later, possibly to my other XJ which I am eyeing for a lift as well, but remains stock.

To replace carrier bearings on the HP30, it looks like no shim changes may be necessary, but it is wise to check the backlash and plan for it if needed. The differential currently comes out with a little persuasion but a case spread is not needed. I am not even sure if it is worth changing ALL the bearings because one carrier bearing is fine, pinion is smooth, and seal does not leak. Any thoughts? It seems like carrier setup bearings may not be needed given the circumstances.

For the rear, I am going to carrier and pinion bearings. There was TONS of metal in the case when I first bought the XJ. I have already done the wheel bearings. No shims on the carrier bearings because it is done with side adjusters. I have a tool for that. The pinion bearing has a crush sleeve, but RATECH makes a spacer to replace it.

I have already changed the yolk on my 8.25 and have gotten used to measuring rolling torque. What I have not done is marked gears to read a pattern or measured backlash. It looks like the only tool I'd need is the Yukon carrier bearing remover or similar. Good tools make the job more straightforward and the way I look at it, if I can buy the tools for less than the labor of someone else doing it, I come out ahead.

Am I insane for trying this?

1) Give-er hell! If you don't rely on this vehicle for your DD, you can afford the learning curve.

2) Buy the bearing (service) kit for the front axle and be done with it. No benefit in wondering about the "should have" when you are driving around.

3) If you don't abuse your equipment, you just might be happy with the factory LSD. I'm not too familiar with the 8.25, but you might be able to "tweak" the clutch pack a little.

I like the way you think! I have 2 XJ's so I can afford to have the 97 off line for a little bit. Since the 97 came with the factory Up Country package, it has the Trak Loc LSD. My choice would be air locker since that's the only manually selectable option available.

I took the factory axle apart and was surprised at the level of damage to the carrier bearings. The cages were very loose. There was a line on the races and the rollers had both a line and heavy pitting. There was black gear oil build up all over the place and anywhere near the carrier bearings the black goo had metal in it. The pinion bearings actually looked fairly decent by comparison. But it validates what I read online, rumbling over 20 MPH under any any throttle condition is usually worn carrier bearings... All bearings were Timken. I am certain someone was in this differential before because of the yellow gear marking residue on the gear. I don't know if it was to change the clutches or something else.

The OX locker is also available for the Chrysler 8.25 ( http://www.ox-usa.com/chrysler-825/263-chrysler-825.html ) . I think it is a little more fool proof than the ARB (as there are no air lines to damage, solenoids to fail, etc.). Personally I run Detroit TrueTracs LSD front and Rear (clutchless design, with no need to run friction modifier) and love them for their ease of use and low maintenance, although I understand that they are not full lockers.
If you have time and a spare XJ, I say give it a shot. I think having that skill set would be very valuable if you plan to work on other jeeps in the future. The only reason I would hesitate, is I know a lot of garages only trust certain ASE mechanics they employ to set up differentials. I think this may just be due to efficiency; but it does make me think twice. The beautiful thing about XJ's is that you can run to your local U-Pull it and get a replacement axle usually for cheap. Good luck :spin1:

I tore the rest of the factory axle apart ... took the ring gear off the carrier and so forth to clean up all the black residue that was filled with metal. I replaced the clutches in the Trac Lok with new Spicer clutches. Tomorrow I need to drive out the old pinion bearing races and see about getting it all setup. Worse case is I throw the axle I bought off puttzer under the Jeep until I get the rest of this one worked out. I know LSD is not ideal, but I already had the carrier and the clutches and did not have a selectable locker. ;-)

I did this for the first time over the summer. Spend the Xtra money and get your master shim kits from randy ring and pinion. There may be another vendor that sells the same thing going but I'm not sure.

I took advice from a few guys on here on my contact patterns and so far driving mine daily I have had no issues what so ever. The big thing is take your time and have patience.

Oh it was my only vehicle and it took me a week working on it in the afternoons just on set up for both diffs. Get a cpl of Xtrap pinion seals also.

I finished rebuilding the axle and installed it. I used a RATECH solid pinion bearing spacer instead of crush sleeve (see thread in Modified section). Drove it 200 miles today and it seems fine. Once I go the rolling torque figured out, the rest was a piece of cake.

Many people do their gears on their own, just make sure you have all the parts and tools you need before you tear it apart. If you haven't done this yet, here is our installation guide that has many detailed pictures and lots of information:

http://www.nitro-gear.com/installation-guides/

Good luck!

Since you're referencing a Nitro installation guide, how do you explain the Jeep FSM providing different values for backlash and pinion preload?