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Grenaded Differential - Upgrading to 8.6" LWB

47K views 102 replies 41 participants last post by  rentalcarsuae2 
#1 ·
As you may have read, I broke the differential helping out a van stuck in Colorado snow. 4LO, good traction on the rear, marginal on the front, 1/2-2/3 throttle. It went click, and just quit. Limped down off the mountain 20-25 miles at 8-12 MPH, all the way making horrible noises from the rear and intermittently locking up, breaking loose, and I was always worried it would lock up permanently.

Here's the start of the axle replacement thread.

Replacement on jack stands, ready to open up. Oh, it weighs 230 pounds, and I *did* kill my back this time. Ick.



Oh, very nice. Unknown mileage, but it's a 2003, and the oil looks very good. Almost no particles on the drain plug. Oh, this has a drain plug - my 2004 did not.



Remember what this G80 carrier looks like.



Oh, I have a leaky BDS gas shock, too. Time to upgrade the shocks as well.



Cover damage without the Purple Cranium Spider





Inside the cover



Fragments that fell out at first.



Note bearing way out of position due to missing G80 housing and no spider gears



Fragments in the bottom



After clearing out fragments, saw the passenger side c-clip was missing. Driver's side was as well! All that held the shafts (and wheels) from walking out of the axle was the brake calipers.



Overall view of the mess.



Fragments collected. Wonder if JB Weld can put them back together?



Why I should have worn surgical gloves. Sigh.....

 
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#12 ·
...Are you going to change the oil in the new one anyway ...
Oh, yeah. Unknown miles, and less than $20 for new oil. No brainer.

Do'h... I saw the pinion still in there. I guess I was wrong about the pinion shearing off... blast.
Still have to examine the pinion for all its teeth, but the prime suspect right now is the G80 housing can.

The locker appears to have exploded in the pictures.
So far, it really looks like that. Spider gears survived. As far as I know, I wasn't spinning either rear tire, so it exploded from something other than engagement shock.
...you keeping the g80 or upgrading it?
If I was working, I'd be pulling an AlekG and upgrading to an ARB or Eaton Elocker for sure. As it is, I'll leave the G80 for now. Not that the axle would have cost less without it, since the parts recyclers don't seem to put much of a premium on it. (They almost all seem to call it a POSI, though - their software doesn't seem to deal well with it being a locker.)

What the recyclers seem to charge extra for rarity is the 4.10 ratio. Again, if I was working, now would have been a great time to get both front and back diffs in a 4.10 ratio. Or jump up to Alek's 4.56. But for the money, the most needed mod for me soon is more underbody armor. You will not BELIEVE what my gas tank skid plate looks like right now. Pics tomorrow.
 
#7 ·
Its amazing, the ring gear actually looks to be fine in the pictures.....not that I would trust them, after having all that debri in it. Sure looks like your Grenade-80 lived up to its knick name though. The locker appears to have exploded in the pictures.
 
#14 ·
The EXT locker has 30 splines for the axles, and is supposedly beefier than the 28 spline version in the SWB.

I have been so ultra-careful for years to not stress the locker when I expect it to engage, by spinning the wheel with less traction. I tickle the throttle until it engages, then get on the power if I need it.

There's a chance that while I had the power on this time for the tow, a tire broke loose and the root cause was locker engagement shock. I didn't think so, but I can't rule it out. Whatever it is, it's going to be a great lesson for me and the rest of you, too.
 
#18 ·
The Roadie,

Having seen enough broken metal in my day job, I don't think you shocked the G80 cage apart. In the ninth picture down of your first post, it looks like ductile fracture on the broken cage piece to the right. This could be caused by the engagement of the G80 if it pushes against the posts like it looks like it does. You just engaged it more often than most people that get the G80 would.

You may have found the usable limit of the G80 in real world, high use environments.

ct_mike
 
#15 ·
Grind me a pound while you are at it....

Holy crap!

This is a standard differential, no reason for it to depart in such a fashion. It is an interesting observation about the "C" clips. No sign of them in the fine grind? Sounds to me that either they weren't there at the factory, or your last service was less than stellar.

I did the front differential on my first service, used the oil additive program. Now I will get the rear done on the next service. Don't want this happening to me.

The nice thing about getting your hands dirty, is good clean grease will remove the black stuff. I learned that rebuilding the front end of my 1978 Chev 4x4.

Tobruk
 
#19 · (Edited)
The transfer case fluid interval is 50K miles, but the manual says nothing about differentials. I did mine at 50K anyway.
This is a standard differential, no reason for it to depart in such a fashion.
I tend to use mine hard, especially in 2-3 yearly expeditions. Been expecting something like this for some time. Assume you've seen my trip reports. ;)
It is an interesting observation about the "C" clips. No sign of them in the fine grind? Sounds to me that either they weren't there at the factory, or your last service was less than stellar.
I'm sure their fragments were there, or they were ejected through the hole. If they weren't there before this incident, the disc would have been constantly been pushing on the caliper as it tried to escape the axle tube. The drive back felt very loosy-goosy. I know it was intact before. The rotors are also scored freshly. Time to turn them and put in new pads.

And I did the diff service myself at 50K (now 75K), and never extracted the axle shafts before, so I'm certain the clips were there.
... it looks like ductile fracture on the broken cage piece to the right...
Agreed. I plan to clean them up and post good macros. There's enough MEs on the forum to look over my shoulder. It should be pretty easy to tell the initial stress fractured parts from subsequent mechanical grinding action. If I had been alone on the trail, setting up camp for the night, I would have taken it apart sooner to prevent subsequent damage and preserve evidence.

 
#22 ·
some crazy pics, and looks like you got a damn good clean deal ... i was expecting a crap looking diff(the new one)... is the G80 worth getting, or just save up for an ARB or eaton?(since you kinda degraded it bill),

and time for a dumb question- how do you know when your locker has engaged?? (will it click or will you feel it or what for future terms..)

good luck bill
 
#24 ·
some crazy pics, and looks like you got a damn good clean deal ... i was expecting a crap looking diff(the new one)... is the G80 worth getting, or just save up for an ARB or eaton?(since you kinda degraded it bill),
Ask the guys that went to TECORE. There is a notable difference in the abilities of a TB with and without a G80. I still believe that a decent driver with a G80 and 2WD could run circles around an open 4x4 in any off camber terrain (rocks or ruts). However, a G80 is not as valuable in mud or sand as a 4wd is.

and time for a dumb question- how do you know when your locker has engaged?? (will it click or will you feel it or what for future terms..)
It sometimes provides a slight jar or click. You normally know when it engages because your slipping wheel suddenly stops slipping. But no, there is no ultimate indicator directly to the driver that the locker has engaged.
 
#23 ·


I don't think the failure was due to engagement of the G80... or at least it wasnt due to over-torqued because the clutch tangs are still intact. Bent, but intact. The bend is probably due to the housing hitting it after failure.

It's interesting to note that the side gear cam plate has teeth missing from where it engages with the governor assembly. Again... that could be subsequent to the main failure. It still doesn't explain suddenly losing all torque, but I thought it was notable.

I need more pictures of the parts to really determine a root cause.
 
#32 ·
The axles are indeed AAM, but the gears themselves may be Auburn or other mfrs.

The looseness was definitely after the incident. Not at MORA. HOWEVER, I have been thinking for a while that I took a number of stairstep dropoffs while loaded in Sedona. I may have bent the axle tubes up. I'll get a straight edge on it after removal. What you may be seeing is rear axle camber. Not desirable.

I will do a total stripdown, and display the clutchplates and tangs and everything else.

For a demo of locker engagement while climbing a hill, my best example is this:

 
#34 ·
The looseness was definitely after the incident. Not at MORA. HOWEVER, I have been thinking for a while that I took a number of stairstep dropoffs while loaded in Sedona. I may have bent the axle tubes up. I'll get a straight edge on it after removal. What you may be seeing is rear axle camber. Not desirable.
That's exactly what we were thinking, only way you get that is with an independant rear... not a solid one...:x
 
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