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Ouch. Bad juju with those.
I wonder if that could be from using the wrong fluid like that article suggested. Seems possible I guess.
There’s a reason they call for different fluids. I’m pretty sure you’d be more bothered if your front diff wore out from using the wrong stuff.
You mean Limited Slip additive.
WTF?
I think he is referring to the munched up spider gears. Saying they are shot and either scrap or could be welded up to make a Lincoln Locker.
Ill try...
LOTS of heated debate and confusion out there about this. It doesn't help that GM used the G80 RPO code to designate both posi/limited slip differentials (on cars) AND Eaton Gov-Lock locking differentials (found on trucks).
My personal conclusion after spending around 10 hours on the subject reading forum conversations, phone calls, opinions and hypothesis's I could find, and like you said following those links further into there individual rabbit holes......
The G80 Gov-Lock does not require any friction modifier or additive.
GM considers any additive introduced into the G80-GL a contaminate that may cause the diff to fail by delaying the engagement of the locking mechanism (bad) and or causing chattering/shuttering (also bad).
While the Eaton G80 Gov-Lock does have differential clutch plates and works like a limited slip diff, it was not designed to need or use a friction modifier/ additive.
Several service bulletins from GM have been released on this matter.
BUT......
Upon calling a few local shops I found that most if not all of them still use an additive when replacing fluid in a G80 Gov-Loc.
When I asked why they said.... "because its a limited slip differential and that's what limited slip differentials take!"
furthermore, the internet is full of people claiming that they have used a additive in their G80GL and it works just fine.
So I call other lube shops, in other cities and states and received a motley assortment of answers but non that were definitive.
The best answer I got ended up being from an old friend of mine who I had called and left a message with. A regular at the racetrack, the old gear-head type...
He said....
"The reason people are not having problems when an additive is used, is because their not using the locking portion of the differential. Most of these people drive around to work and back and wouldn't know what "diff chatter" was if it bit them in the a$$.
Now people who actually USE their Gov-Locks locking feature, like those who 4x4 or have a heavy foot (especially on loose soil, gravel or snow),..."
He went on to explain that this diff locker works with RPM and the additive (just like the service bulletin said..) will keep the locker from engaging when its supposed to. When and if it DOES engage at a now higher RPM it was designed for... BOOM!
"You now have what has become known as the GM Gov-bomb."
"Run a 75/90 in the rear with no modifier and it'll be good to go!"
He also noted that the reason most "professionals" or lube techs say they run a additive in the G80 is because the "screen" tells them to. Somewhere along the line the confusion of the posi-track G80 RPO code is getting crossed with the Gov-Lock G80 RPO instructions....(imagine that) maybe even at the time the information was written into the system to begin with.
Mostly at highway steady speeds. 275k will do that.
I hear a lot of diff noise at 70 MPH + but my Tahoe only has 74k on it.
I don't have 400+ HP like you do. The only thing locking at Wide Open Throttle is my power door locks.
