Two other recent threads have contained this subject.

I do not do burnouts because I am aware of the weakness of the G80 (gov loc).

In pulling my truck up on ramps yesterday, one rear tire spun a little on leaves and the G80 apparently locked.

Later, while turning around in the driveway the rear crabbed badly because the G80 did not unlock. This included both forward and reverse and left and right turns in the driveway.

After getting out onto the road and above 17 to 20 mph, it apparently unlocked and everything was fine. This is only the second time it has happened.

Someone said that changing the fluid and adding the additive stopped theirs from doing this.

Why? The additive is not used for the G80. Besides, the G80 is purely mechanical in operation and does not respond to a friction modifier additive as would clutch plates.

I bought this truck used six months ago and there may be something else in there besides a G80, however I do not think so, a positraction like an Eaton would not stay engaged and other lockers make routine noise that this rear does not.

Is there something about the G80 that causes this that I can take care of?

 

My old truck used to do that same ****.

 

Drain oil, clean well, I think I heard with brake cleaner, but call the dealer ship to make sure thats what they use. must use same type that is in the manual.
My dad was doing the same thing. He took it to have it done because it was still under warranty. It fixed it.

 

Mine does this also once in awhile Really scares the **** outta me, ive also flushed it twice. Only 22k on my truck

 

I just had my g80 replaced i had the same problem, it would lock up all the time and not disengage. until after 30 mph. I was offroading on day and the rear end just started make a horrific grinding noise. well i had to drive back home (4hr) drive on a bad rear end and it only got worse, every time i hit a crack in the road, speed bump, anything it would gring like crazy. i had the g 80 replaced for an *** reaming price of $1700, what happened was my emergency brake was falling down and causing the axel to bind thus causing the g80 to lock. well the grind was from the emergency brake. they opened up the diff cover and it was like sludge with a crap load of metal shavings. to make a long story short, check you e brake and if it is fine crack open the diff and inspect it. my truck only has 49000 miles on it.

Peace

 

replace the g80 and get an eaton. thats what i did. i also got bent over on the price of the replacement

 

I only had this happen to me twice in my 04 crew cab. Both times were at the track. Hard launched at the track and it locked up and at the far end on the turn off lane, it crabbed and chirped as turning. Really kinda embarrassing to happen there. But it never did it again and I never had any problems with it. I don't think changing the fluid would really matter either, both times this happened to me it was less that 25,000 miles on the truck.

 

My truck has 94,000 miles and generally runs great, consumes only gas and that is 16 city 20 highway at 75 mph.

The only two times the G80 has locked and failed to unlock have been very slow speed. First time was on ice, it locked and I continued in the parking lot but it only unlocked after 20 mph on the road. Second time was one wheel slipped on leaves while pulling on ramps. Truck sat for several hours, was backed off the ramps, turned around in the driveway, crabbing all the time and then unlocked at apparently 20 mph on the road.

The rear is perfectly quiet, has not noticible backlash, and otherwise seems ok. I just ran it 800 miles to FL @ 80 mph, everything seems normal.

Should I be concerned since it is 2WD and I do not try to do burnouts. Although it runs good, I am sure it would not even do a burnout anyway.

 

The G-80 will "lock" when a certain amount of differientation between the two axle shafts occurs and will generally stay locked until you get faster than 20 mph(ish). I don't know that you can do anthing to change it other than to replace the unit with either an open diff (YUK!) or a limited slip. What you described sounds normal and won't hurt anything.