Gear Set-up Question

Hi all,

My question is pretty simple. Here is the background info. I obtained a set of axles from a 96 XJ with the 4.10 gear ratio, a front D30 and a rear 8.25. Unfortunately, the 8.25 was 27 spline. So I got a 29 spline carrier, a set of shafts, and a No-Slip locker for the 8.25. I also have an OX locker 30 spline unit with alloy shafts for the D30. These are going under a 98 XJ, auto tranny, whenever I get the new carriers swapped in and the gears set up.

Here is the question, then: since I am not required to pull the pinion shaft--the same gear set is being used again--will I theoretically be able to complete the ring gear swap onto the new carriers and get away with just setting the backlash rather than both that and the pinion depth, which will remain unchanged since the pinion isn't moving anywhere? I realize the mesh pattern will tell all in the end, but I just want to get an idea of what to expect as far as how involved this is going to get.

I'm not ready to do the work yet, but I'm gathering the proper tools now, so I figured now is a good time to pick up some advice as well.

Thanks in advance for your consideration of this topic!

--wavingpine11

each housing is different. If I did that i'd only want to do it once, and do it right. Don't want it blowing up on you on the trail hours from home. Just my .02

Yes it is possible not to reshim the pinion but be prepared to if the gear mesh indicates it. read your gear pattern before you pull it apart take a digital pic for reference.

I don't want to give the impression that I'm trying to do less work than the situation requires. I'm just trying to perform a thought experiment here and seeing if your conclusions match up with mine. If the mesh pattern indicates a need to reshim the pinion, I will certainly do so.

I just wanted to have you quality check my thinking. The key to my interpretation of the situation is that putting the same ring gear on a different carrier, unless the carrier is out of round (and therefore unusable), should leave me with the exact same ring gear position height, since the ring gear will still be concentric with the center line of the axle shafts. What may be different is the side to side clearance, which will affect the backlash only.

Overall, my plan is to check the pinion depth as it sits, the backlash as it sits, and then take a good set of photos of the mesh pattern and try to duplicate that set of values and the mesh pattern at the end as exactly as possible so that the gears don't whine from being set up differently than their original X-1000 miles.

This will be my first time setting up gears, however, so I wanted to be sure that my analysis wasn't missing something obvious. So even if everyone totally agreed with me, I would still be buying full install kits, but my expectations would be different for the actual set-up.

--wp11

I agree with you and have done what you are thinking of doing. just match the pattern that you get before taking it apart and enjoy your cheap DIY.

Sponge Bob--did you have to reset backlash, then? I'm taking it as a given that I'll need to do that given the very close tolerances required, but just wondering. Your experience encourages me in my planning. Thanks for posting.

reelbigdundy87--thanks for expressing your concern on this approach. I feel exactly the same way about it, but was just looking for people to critique my thinking on the pinion depth issue before I got started. I'll probably have my install kits early to mid Feb. and I'll post up with any snags that I hit, and also if the install is successful without reshimming the pinion.

As I said before, I'm interested in doing this correctly for a long life, but don't want to do more work than is needed.

A side issue is that originally I had planned to stick with the 27 spline rear set-up and put in a lock right, then after a later lift and tire change, I was going to regear the front (from 4.10 to ?) and add the OX locker, and then regear a Ford 8.8 that I have lying around to match, probably with an OX also. I was going to leave the OX out of the front until that time since I was originally not going to regear (past the 4.10 these are already set up with) until I lifted the current ride and went with larger tires. So I currently have a 98 Classic with D30 front/D35 rear (because it has ABS--all ABS equipped XJ's came with the D35 IIRC). So the idea was to do the least amount of work as possible to step from stock gearing to the 4.10's, then from the 4.10's to whatever will be next. I wouldn't have had to worry about the gear set-up on the rear at all on the 8.25 as originally I was going to stay with the 27 spline rear, but since kicks a$$ so much, I was able to pick up a 29 spline No-Slip, a 29 spline carrier, and three 8.25 axle shafts for hardly more than a 27 spline lock right from another user here. Clearly, it was meant to be. So the 8.8 may sit around for a while before I'm built up enough to need it, but that's fine with me.

So as I was thinking about this carrier change in the rear, I stumbled upon the thought that I was changing carriers rather than gears, and that the pinion should be able to be left alone since ithad already been set to the correct height. That made me think that I'd be better off planning on putting the OX in now while the axles are still sitting in my garage, given the potentially simplified set-up procedure. I plan to do the rear axle first, though, and if I need to change pinion depth, it may inflluence whether I go OX sooner or OX later. Not that I don't want that extra capability, but I was running with an Aussie locked rear in my previous XJ and that provided plenty of traction for most of the places I've gone so far.

--wp11

yes on the backlash because of the new bearings and carrier. what size tire do you think you will run now and in the future

Sponge Bob said:

yes on the backlash because of the new bearings and carrier. what size tire do you think you will run now and in the future

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I'm running barely above stock tire size now with 235/75-15 BFG AT's. I expect to be running no more than 33's in the foreseeable future. However, I may go up to 31's with some kind of bastard lift set-up before going to a real lift (thinking RE 5.5 HD for summer 2010) and 33's. So the 4.10's are for the 29-31" tire range, and I'll go lower when I go to 33's. I'm looking at a 2 year build-up plan given what I'm willing to budget between now and then for the project. I have most of the armor and recovery equipment I'm interested in already, as most of what I wheel in central PA doesn't require mega-clearance and I figured I'd put my money where it was most needed for performance (lockers/gears) and protection (front/rear bumpers and rock rails) first since clearance is less important for my current usage.

It seems that most people here usually lift first, then regear and lock later, but I took the opposite approach given my expectations. I don't do much rock crawling, for instance, although I'd like to be able to do so with confidence at the 33" stage of things. I run some muddy slop, some dirt trails, and occasionally rocky stuff. The state forest land in central PA has highly variable terrain, but most of it isn't nearly as demanding as some of the trails that a lot of people here seem to be running.

What I'm hoping for the current situation is to be able to get the 4.10 axles set up, then in the background while I acumulate funds for the real lift and tires, I can obtain the other OX and set up the 8.8 with lower gearing, correct bracketry, and a super 88 kit (all in hand now except for the gearing and OX), and finally finish off with the original 30 that will have been lying around all that time since being swapped out. Then I'll swap them in when I do the lift, since there's no better time to do so than when the axles need to come off anyway. I've been trying to plan this carefully so that I don't have to do too many things twice. I like doing this work myself, as I'm sure everyone does once it's finally done, but I see no reason to do things more than once, and in that regard, I understand exactly where reelbigdundy87's words of caution are coming from.

--wp11

the shim packs should be housing specific. if you are swapping different matching depth pinions into the same housing, you can keep your shims. if you are going to a new housing, i would mic the pinion depth again

tomcat said:

the shim packs should be housing specific. if you are swapping different matching depth pinions into the same housing, you can keep your shims. if you are going to a new housing, i would mic the pinion depth again

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I'm using the same gears, same housing, with different carriers. Going from a 27 to a 29 spline carrier in the C8.25 and from an open to a 30 spline OX in the D30.

--wp11

i dont mean to hijack this thread, but there a write up for setting up gears? i want to go with 4:56's and i havent really found one. never done gears before.

76ANTHONY said:

i dont mean to hijack this thread, but there a write up for setting up gears? i want to go with 4:56's and i havent really found one. never done gears before.

Click to expand...

If you have to ask gear are not for you. Find as friend that does them or pay someone.

WaXJ_Skier said:

If you have to ask gear are not for you. Find as friend that does them or pay someone.

Click to expand...

that bad huh?ok i look around and see who knows whats up and maybe watch them and learn for next time. thanks.

76ANTHONY said:

that bad huh?ok i look around and see who knows whats up and maybe watch them and learn for next time. thanks.

Click to expand...

Its more time and tools. If you want to get a book, buy tools and spend a full day or more. Probably cost you as much as paying someone to do it just for the tools (not to mention the extra time).

Imho pinion depth shouldnt change between the two carriers. I think your on the right track with just adjusting backlash. just remember to intstall the extra shims for preload during final assembly.. things will get noisey other wise..(i know from experiance)

I performed the same thing with my 8.8. The original housing and 4.11 gears were installed but with a new carrier and master install kit. The original shims (carrier and pinion) gave me a good starting point but I had to adjust everything. Keep in mind your axle might not have been set up perfectly the first time, which may have been my case. Also, I found brinelling on the factory carrier bearings which could have accounted for the difference.

So it seems like the general feeling is that I might get lucky due to the geometry of what I'm changing vs. what I am not changing, but that I should be prepared to go through the whole procedure. Sounds like a plan to me!

Sideshow--did you check the mesh pattern and pinion depth before you disassembled the 8.8 so you'd have a reference point?

Everyone who's posted up so far--thanks for all the input. I'm probably going to find out what's what in the first couple weeks of February after I've assembled the rest of the tools I need.

--wp11

wavingpine11 said:

Sideshow--did you check the mesh pattern and pinion depth before you disassembled the 8.8 so you'd have a reference point?
--wp11

Click to expand...

Nope, I never checked the pinion depth. I checked the backlash and it was at the high end if I remember. I figured the factory shim packs would get the pinion close enough for the initial setup, and it worked. I believe it took me 5-6 full setups (cap torquing and everything) to get the backlash at the low end and a slightly competition pattern.

I used Randys Super Shims without the $20 install tool and it worked great.