G80 Locking Differential in K5

[wazzabie]

Was the G80 an upgraded differential for the K5 from the factory?

 

[1-ton]

My guess is it was an option. Some people on this site may know better if it was standard equipment or not. My 1-ton with a Corp FF 14-bolt came with a G80 Gov Loc.

 

[dyeager535]

It was an option. Not sure if there was a package that it was included with as well or not.

I wouldn't necessarily consider the 8.5" gov-lock an upgrade, but GM did lol.

 

[muddybuddy]

I believe it typically came with tow package, but yes was an option.

 

[tarussell]

Way back before the “Z/71” opt became just a sticker package on the half ton trucks the G80 came standard with it along with the LD 3/4 Ton torsion bars , whatever kind of upgrade shocks , largest tire size offered with a little more aggressive Goodyears and ( I think ) minimum 3.42 gear and skid plates - and of course those damn stickers on the sides that added more horsepower.
Like said earlier a G80 in a 10-Bolt eventually will loose its upgrade status… ( KABOOOM )and over the years that package was whittled down to a glorified decal display - GM should be ashamed for that.

 

[wazzabie]

What would be better then the G80 in the rear differential?

 

[tarussell]

Damn near any aftermarket LSD diff has a longer life expectancy than a Gov-Loc ( some will argue but history has shown that the G80‘s life span ain’t that good - especially with any increase in tire size ).

All kinds of types offered - just depends on what you are after. What are you looking to do with the truck ?

 

[scouthead]

Ive had one in my semi float 14 bolt since i put it in the truck. it rarely engages unless i'm playing prerunner in 2wd, or doing donuts in a field. Ive not hear of any of the SF14 going kaboom... but I did it to the original 10 bolt rear, and still have those side gears laying around somewhere... UGLY. Ive had an entire 10 bolt carrier shear in half when one of these locked up, and I had a friend with a lifted 454 trying to spin 305's in a parking lot that susSPLODED a full float G80 (but seriously thats a lot of torque and traction right there!)

the G80 has been in my SF14 for about 10 years and 70K miles now, and was used out of a 1997 Z71 when i got it...
its probably about time to pull my cover and take a look at those side gears. Ultimately i would rather have a good used Eaton E-locker out of an H2 in there, or the eaton aftermarket version that was pricier but stronger than the GMH2 version, but, this particular G80 is still kicking, and the budget for the eaton has been spent several times on new engines!

 

[scouthead]

removing a G80 typically means the whole carrier needs to come out and get replaced. if you want an inexpensive lunchbox locker you need to go find a factory open diff carrier to install it in...

so, if you already have a G80, and need to replace it, might make sense to look at an ARB, OX, or Eaton that replaces the carrier as part of the new locker?????

 

[muddybuddy]

Not that I’m pro G80, im not (tho im fortunate enough to have one in my k5), but are there really issues with them in stock truck, with only occasional use? Sure they arent meant to be beat on and you need to tip toe around with 35’s and offroading. Said another way, will they crap themselves in a “normally” driven stock truck?

 

[scouthead]

Not that I’m pro G80, im not (tho im fortunate enough to have one in my k5), but are there really issues with them in stock truck, with only occasional use? Sure they arent meant to be beat on and you need to tip toe around with 35’s and offroading. Said another way, will they crap themselves in a “normally” driven stock truck?

well, mine locked up on the street, during normal driving, with 45,000 original miles, on a stock truck that was not used to tow, that had never been lifted, and never seen bigger than 31 inch tires.

 

[muddybuddy]

well, mine locked up on the street, during normal driving, with 45,000 original miles, on a stock truck that was not used to tow, that had never been lifted, and never seen bigger than 31 inch tires.

And that answers that.

 

[scouthead]

My advice to anyone thinking they will keep one in their ten bolt "because they have not had problems before", is that there is a reason these are nicknamed the "GovBomb", and HAVE YOU SEEN WHATS GOING ON IN THERE WITH YOUR OWN EYES -RECENTLY?????
if not, might be time to plan an oil change and have a look in there.


centrifugal weights in the carrier actually move the side gears so that they bind with the spider gears, and therefore couple one shaft to the other... incredibly hard on the individual gear teeth, and any material that comes off of them poses a threat to all the other teeth and bearings in that housing. The torque and stress is transmitted to a carrier housing that may be too thin for the job...

If nothing is damaged already, an oil change and gasket, and back on your way... wary of what is in there and how it works. Probably not a good piece of hardware for a truck that will be receiving "standing death drops" and seeing air time... or just making regular use of the locker!

If you open one up and the side gears are chewed up... at least you have an opportunity to replace those and clean housing out... might give it a "save" for a while.

 

[scouthead]

And that answers that.

the one that sheared the carrier in half was trying to control 33 inch tires, and had seen some off-road use by the previous owner that I was not privy to... there was likely bits and pieces of side and spider gear teeth already loose and in play when that one went kabloooey

 

[nvrenuf]

Damn near any aftermarket LSD diff has a longer life expectancy than a Gov-Loc ( some will argue but history has shown that the G80‘s life span ain’t that good - especially with any increase in tire size ).

All kinds of types offered - just depends on what you are after. What are you looking to do with the truck ?

@wazzabie I know Tom (@tarussell) is a fan of the Eaton clutch type LSD and the torsion type diffs. He helped me pick a decide on what I eventually went with in my front D60 (Power Lock) and I'm very happy with it.

 

[tarussell]

the 14 S/F's on up fare much better than the 10-Bolts do by a wide margin. KABOOM !!!

 

[Blue85]

Well when the trucks were built, it was an upgrade from both standpoints. It added locking function and also cost GM more money. I don't think they offered anything but open and gov-lock for several years in the trucks.

Over the years, something must have improved because there are millions of gov-locks in 8.5/8.6" rears of GMT800, GMT900, etc going hundreds of thousands of miles and the trucks got heavier with taller tires over the years.

 

[tarussell]

@wazzabie I know Tom (@tarussell) is a fan of the Eaton clutch type LSD and the torsion type diffs. He helped me pick a decide on what I eventually went with in my front D60 (Power Lock) and I'm very happy with it.

That's because we put way more clutches & hardware in that D76 P/L from a D80 T/L

 

[scouthead]

That's because we put way more clutches & hardware in that D76 P/L from a D80 T/L

interesting!


powerlocks have been around a long time... i had quite a bit of seat time in front of a Dana 27 with tapered n keyed axleshafts...all original as from IH in 1962... only thing i changed was the leather axle seals. STRICTLY kept it to the stock tire sizes and treated that toothpick like it was made of glass!

but, that toothpick still had the origional powerlock, and it engaged and disengaged as it should. no real complaints on my end! got a few good years of light wheeling in some vintage iron.

the 14 S/F's on up fare much better than the 10-Bolts do by a wide margin. KABOOM !!! View attachment 432474View attachment 432474

 

[wazzabie]

The RPO on my 78 K5 shows G80 Locking Differential with HE4 3.40 ratio Rear Axle. So far 140K miles on the original rear axel and locking differential. I just don't want it to go kaboom.