rear axle questions

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eran tomer

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Another alternative i’m considering is to replace the bad ARB with a detroit trutrac differential. They are much cheaper than a new ARB. Is it recommended? And how about the LSD ones?
 

stutaeng

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LSD is better than open differential, but not as good as a true locker. If you are into mild/moderate off-road, a LSD differential will be just fine.

Some LSD use clutches that wear out and must be serviced. But the Detroit TruTrac uses Thorsen gears. It's supposed to be a reliable unit. Only drawback is you get one wheel in the air, tap the brakes to get the differential to engage.
 
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stutaeng

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A LSD is not a locker, in the sense that both axles are not locked together when engaged. A LSD allows slippage between the axles, hence the name. They still get really good traction. "Posi" is a LSD. I think posi got it's popularity from the 70s muscle car era? ...so a lot of folks relate the G80 to posi.

A locker locks both axles 100 percent when engaged. There are several lockers: selectable (turned by air or electrical switch) or automatic (like some lunchbox lockers and the G80, made my Eaton).

I think that's correct. It's hard keeping all the different types of differentials straight.
 
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eran tomer

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eran tomer

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i'm totally confused here.
then the G80 is not a limited slip?
someone wrote in another forum that G80 was an lsd until 1974 and then changed to gov-lock.
and someone wrote on this forum that gov-lock is a very rare option from factory.
 

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WHICH "G80"?

That option code was used for decades. The specific equipment that it applied to was different between cars and trucks, and also varied over time.

In terms of GMT400, it's a clutch-type "posi" with additional gear-driven speed-sensing equipment that could engage the clutches at lower speed, while preventing engagement at higher speed. Comes in at least three flavors; the 8.5" axle, weak and troublesome. Then there's the 9.5" version, reasonably robust. The 10.5" version is strong but generates complaints of harshness.
 

df2x4

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That option code was used for decades. The specific equipment that it applied to was different between cars and trucks, and also varied over time.

X2. The G80s in these trucks are gov-lock lockers, where as the G80s in 90's F-Body Camaros/Firebirds were clutch type LSDs. It all depends on the specific application. G80 was basically just GM's RPO code for "not an open differential."
 

PlayingWithTBI

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Example of a 10 Bolt G80 GOV-Bomb :anitoof:

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It senses when one axle is turning ~100 RPM faster than the other, then engages. With hard acceleration, this happens. When over ~15 MPH it disengages so it's pretty much useless except for getting out of a mud bog...slowly
 
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