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2004 gmc
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Discussion Starter · #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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2002 gmc envoy_slt
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3,203 Posts
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.
 

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2002 gmc envoy_sle
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1,531 Posts
amazing carnage

glad you found a replacement though
 

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2004 chevy trailblazer_lt
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oh man roadie, thats some carnage! this is gonna be a good thread, since i plan on doing this at some point... at you keeping the g80 or upgrading it?
 

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2004 gmc
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Discussion Starter · #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.
 

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2009 chevy
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The locker appears to have exploded in the pictures.
That was my guess when we were reading the breakdown thread. I was picturing the 80 kicking in under-load and not being able to handle the stress.

Bill, do the locker parts in both axles appear to be the same size, or are the 8 1/2 parts heavier?
 

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2004 gmc
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Discussion Starter · #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.
 

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2006 chevy trailblazer_ls
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123 Posts
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
 

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2005 gmc envoy_sle
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129 Posts
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.
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
 

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2004 gmc
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Discussion Starter · #19 · (Edited)
Makes me really wonder what mine looks like. I don't do any rough driving, but 96000 miles of wear/tear might be churning that oil into sludge.
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.

 

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2005 chevy trailblazer_lt
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