Differential shop reccomendation

JPaul

Member
Location
West Valley, UT
So while down in Moab with my Hummer H3 this week I blew the spider/axle gears in my rear diff and chipped a few of the corners of the ring gear's teeth going up Metal Masher. My Eaton e-locker's pins are also rounded off so that would need to be rebuilt as well. I've done pretty much everything on a vehicle up to and including rebuilding several engines, but I have never touched a transmission or differential before. While I have all the tools I would need to rebuild my diff, except for a case spreader, I'm reluctant to mess with it on my daily driver.

Anyone have recommendations for a shop to take my axle to to have it rebuilt? I am planning on picking up an Ox locker to replace the Eaton, 4.56 gears to replace the 4.10's (if I can swing it I'll also get the front axle regeared at the same time, otherwise I'll just leave the front axle out and run in 2wd for a while), and I can replace the axle bearings/seals myself. I really just want someone that I can trust to install the new gears and locker for me for a fair price, but properly done. I am going to pull the axle out and bring it to whoever I get to do the work, same with the front axle since I can't really drive it right now.
 

JPaul

Member
Location
West Valley, UT
Talked to Ryan right after he posted, he's going to crunch some numbers and lookup parts for me since I threw him a curve-ball with it being for an H3. :D For some reason several manufactures try to list the 8.0 for the rear in addition to the 8.5, and on top of that they can't decide if we have 28 spline axles vs 30 spline, which makes it even more confusing trying to figure out the right parts.
 

JPaul

Member
Location
West Valley, UT
The carnage:

Spider gears:

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Passenger axle gear (about 1/3rd cracked off):

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Driver gear (didn't even see this until I got home):

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Unfortunately there was also damage to the ring gear and tiny nick to the pinion from what I can see.

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Looks like a chunk was wedged between the nose of the pinion and the carrier:

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A small flake is all I saw on the pinion:

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Video of the damage in the diff:



Fortunately a couple of the guys I was with were extremely generous and towed me home with their truck and flatbed, which was just as well since I apparently also sheared the driver side swaybar link completely off, and that apparently also popped the outer CV boot clamp off as well so I was losing grease.
 

JPaul

Member
Location
West Valley, UT
More pictures of the damage. I pulled the axle assembly completely out in preparation for taking it to Agility, and tore it the rest of the way down but left the carrier installed in case they wanted to check everything, plus I know you need to keep the caps with their respective sides and orientation.

Back of driver gear. Starting to see the slots rounding off.

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Locking pins. All starting to round off a fair bit from the looks of it.

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Closer look at the front and back of the passenger gear:

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Passenger axle bearing surface and splines:

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Driver axle bearing surface and splines:

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No apparent damage to the axles themselves and the bearing surfaces seem fine. The passenger axle splines look a bit excessively peened though, so I'm not sure if I am going to want to replace them anyway.

It's just as well that I am having the diff rebuilt, after getting everything pulled out and flushing it some more with brake cleaner I tried rotating the ring/pinion gear, and some little bit has apparently worked its way into either the carrier bearings or the pinion bearings and now it binds really badly. I can only turn the carrier maybe 20 to 30 degrees in either direction before it binds up.
 

JPaul

Member
Location
West Valley, UT
Ouch. How big of a tire are you running? Good luck!
Only 33's, but it's a 5.3L running through a 4:1 transfer case on a rig that stock weighs 4800 lbs, and probably with me, a full tank of gas, the UCP, winch, bumper, tools, fridge, roof rack, etc I bet it's more towards 5800 lbs. Really should get it weighed some time. With the way the axle gears broke, I think it was a combination of the previous owner beating on it (he apparently liked to do snow runs and drive through deep mud/water ) plus that driver gear was surprisingly thin in the back.

I think that is what gave out first and then the spider gear and passenger gear were cracked. The driver gear broke 180 degrees apart, so it was where the spider gears were at the time that it failed, but only one of the spider gears actually broke, and the passenger axle gear cracked either on the spider gear that didn't break due to shock loading, or on the spider gear that did crack and jammed up enough to pop the passenger axle gear. Could be totally wrong but I think I'm close.

This is the ledge I apparently broke it on initially:

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I'm still a bit surprised that I popped the gears like that, I have only used the lockers a handful of times. Once last year to get up a single obstacle, and I was very careful to not spin my tires then. And then this trip I had to use them more often, I think my tires are pretty much done and losing their grip but I still tried to be careful to not let the tires spin too much. On that ledge on Metal Masher I had an experienced guy spotting me, but I had to back up and retry getting my rear wheels up several times before they stacked rocks for me and I switched on my front locker as well. Of course the next H3 after me just crawled right up it and he only had a rear Lock Right but was on 35's.

I'm a bit concerned with the amount the splines on the passenger axle have been peened, especially when the driver axle doesn't show anything close to that.

I'm working with Ryan at Agility to first get the rear rebuilt before my trip down to Overland Expo West, I'm going to go with an ARB air locker (since I really don't like how the Eaton has so much takeup in order to actually lock, and then if you need to roll backwards it unlocks, plus I'm really iffy now on the design of the driver axle gear and the Eaton only has the two spider gears. The ARB has three and with the V8 and lower crawl ratio I want the extra strength. The base model H3's have a 3.7L I5 and 2.64:1 transfer case ratio with 4.56 gears) and a Nitro ring and pinion in 4.56 instead of my current 4.10. Pricing was better than I was anticipating so I'm looking forward to working with him. Front will have to wait but that's going to be redone with an ARB and matching gears as well. I'll just drive it in 2wd until then.
 

Omgbecki

Well-Known Member
Location
Ogden
All I can say is ouch. I have to ask though, do you feel it was a combination of weight, torque of the v8 and 4.1 t case that did it or do you feel it was poor quality? I ask because I am looking at a Eaton as well as doing a crawler box in my jeep as well as a power adder in the next year and would like to know if I should go a different route? I like the idea of limited slip until I lock. Right now I have a spartan in the rear and a ARB up front but with the weight in the front and the spartan I have a lot of understeer in slippery conditions.
 

JPaul

Member
Location
West Valley, UT
All I can say is ouch. I have to ask though, do you feel it was a combination of weight, torque of the v8 and 4.1 t case that did it or do you feel it was poor quality? I ask because I am looking at a Eaton as well as doing a crawler box in my jeep as well as a power adder in the next year and would like to know if I should go a different route? I like the idea of limited slip until I lock. Right now I have a spartan in the rear and a ARB up front but with the weight in the front and the spartan I have a lot of understeer in slippery conditions.

The Eaton isn't a limited slip, at least mine isn't. It's either open or locked. I know there are plenty of other H3's running the Eaton (since that is the factory locker) that only have issues with the pins wearing out, though most of them are the 3.7L. Personally I feel that for my rig with the V8, weight, and crawl ratios the Eaton for my rear axle is a bit under designed, especially the driver axle gear thickness and only having two spider gears. I think if either there were more spider gears or the driver gear was thicker then it wouldn't have been an issue. I think the Eaton e-locker is a fine design, especially for those not using them very often, but for my rig with the GM 8.5" axle it's apparently not strong enough. The rear axle has over 160K miles on it, though I have no idea how often the rear locker was used, I didn't get the rig until beginning of last year when it had 150K miles.
 

bryson

RME Resident Ninja
Supporting Member
Location
West Jordan
Have you considered just building a beefier axle altogether? Something more up to the task of staying alive under your rig? A Dana 60 can be had for reasonable money and can be configured to match your width, bolt pattern, etc...
 

JPaul

Member
Location
West Valley, UT
Have you considered just building a beefier axle altogether? Something more up to the task of staying alive under your rig? A Dana 60 can be had for reasonable money and can be configured to match your width, bolt pattern, etc...
It's definitely something I've thought about, but I don't have the time or inclination right now. It's really not that common to break the rear axle on these unless you're pushing it hard on obstacles and with larger tires which really isn't a goal of mine. My rig is my daily driver and more for offroad camping and whatnot, I really only go down to Moab once a year currently and this is the first year I've actually broken anything. I just need to get it back on the road with some upgrades as quickly as possible. Later on I may upgrade the rear axle to something stronger and then sell my old axle to someone looking for a good stockish upgrade. Another H3 guy is working on a HD front IFS that should be coming out this year so I'm going to be looking into that as well. The front end is the real weak point on these trucks, though with my CI front diff it's a little bit tougher than the standard aluminum front. Then of course there is the option of going SAS, but that's way down the road for me at the moment.
 

JPaul

Member
Location
West Valley, UT
Big thanks to Ryan with Agility Customs, my rear axle is all rebuilt and the truck is back on the road! I was up until 4AM last night (this morning?) getting it all back in (plus replacing the front swaybar links that were apparently pieces of garbage). Had to run to Lowes and Home Depot first thing this morning for some metric bolts for the ARB cover since they only include standard threaded bolts. It's all buttoned up now and I took it around the block, seems to be good. Going to drive it for a bit and then on Tuesday evening change the fluid before I leave for Overland Expo West.

Ryan was great to work with and even put up with my paranoia about some metal flakes I found. I already have my front diff with him to get matching 4.56 gears and a new ARB locker put in. Hopefully I shouldn't have any more issues with the diffs breaking now.

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