G80 not unlocking

[melms23]

My lmm has 130k miles with roughly 10 hooks, lots of burnouts and general hard abuse. I hopped last weekend and broke the drivers side axle. Got a used one with 90k on it. Pulled the cover and found some shavings and 2 very small chunks about the size of a pencil led. I put 4 1/2 quarts of synthetic 75-90 in it.

Now the g80 is not unlocking. It has always been very strong in this truck and I've never had an issue before. Did I miss something on how to install an axle shaft?

 

[Bonestock]

The 80 will inevitably fail with 500+ hp it seems to happen quicker. I ran mine near 800hp and havent had a problem. I didnt have it @ that power level with much abuse. I have had several of the 80's crap on me in the older trucks below or @ 500. I am guessing you may have found a pin laying in the case. I always wondered if the lmm units were stronger than the lb7/lly units? It just seems like the lmm diff takes more punishment before they fail. I have been told they are the same units so who knows? Sounds like its time for you to step up the rear end to another style. We have run the grizzly with great success so far. Good luck on the 80.

 

[melms23]

Just seems odd that it broke the g80 and axle in the same run. I figured it's on borrowed time anyway.

There's a pull tonight and I'm not going to bother if it is going to break. I don't drive the truck much and would rather just do a spool if they are cheaper.

 

[melms23]

After talking to the tech at the dealer he said he has seen one do it before. I pulled it and drove it a little bit.

I guess stuck locked is better than having it not lock up!

 

[Molly]

Mine was locked up after some abuse, lol. After trying every way I could think of to get it to unlock, I gave up and just rode it like that. Felt it was better actually, the skipping while turning didn't bother me. It unlocked like a month later and just the other day I did a burnout and I left two tire marks so I'm thinking it's still working...


Sent from your girls iPhone.

 

[clrussell]

Had a gm tech tell me one time to put one tire on pavement and one in the gravel and brake torque it. Something about freeing up the clutches inside


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[melms23]

Thanks guys. Going to drive it like it is for a while.

 

[TheBac]

My lmm has 130k miles with roughly 10 hooks, lots of burnouts and general hard abuse. I hopped last weekend and broke the drivers side axle. Got a used one with 90k on it. Pulled the cover and found some shavings and 2 very small chunks about the size of a pencil led. I put 4 1/2 quarts of synthetic 75-90 in it.

Now the g80 is not unlocking. It has always been very strong in this truck and I've never had an issue before. Did I miss something on how to install an axle shaft?

If you hopped it hard enough to break an axle, the G80 was not far behind, if not done at the same time.
Hopping is one of the most sure-fire ways to grenade a diff.

I once broke the pinion in half on the 7.5" in my Mustang from one wheel hop over a crack in some pavement.

 

[melms23]

If you hopped it hard enough to break an axle, the G80 was not far behind, if not done at the same time.
Hopping is one of the most sure-fire ways to grenade a diff.

I once broke the pinion in half on the 7.5" in my Mustang from one wheel hop over a crack in some pavement.

I'm sure it won't last long. Before long the truck will be down anyway for the new motor. I have a bunch of little things that need attention including the diffs.

 

[melms23]

I actually hopped again at the last pull. Someone snapped a pic. This is after the new axle and seems to be because I tried a little bigger bump stop up front. They are coming out before I pull again.

Sorry about the crappy pic but its the only one I have.