G80 = Locker or just some kind of LSD?

daevans315 · Post by **daevans315** » Wed Jan 17, 2007 12:45 pm

I have the G80 option code in the glove box. I do have some LSD going on in the rear end but on wheel lift I never get a full lock. The wheel off the ground just spins. I assumed ( I know) that i just had some other LSD dropped in the rear end from chevy that would never lock(normal LSD). After bidding on slammed98gmc's Eaton on Ebay I started doing some serious looking into the available options. I'm now suspicious that I may have a locker and its just broken and defaulted back to clutch packs only. It has never locked since I have owned it but I bought it with 30,000 on it so it could have been broken before I ever saw it.

Does anyone else have a LSD that isn't a locker? I changed the diff fluid a year ago when I did the Boisie Spring kit but didn't even take much of a look at the possi. I would have noticed if it was a zextel but other than that I'm pretty sure I wouldn't have been able to tell the difference anyway.

BobbleSmitty · Post by **BobbleSmitty** » Wed Jan 17, 2007 1:17 pm

I'm not much of an expert in this area, but could it be possible that the previous owner switched out the axle or removed the locker?

quickbiker · Post by **quickbiker** » Wed Jan 17, 2007 1:43 pm

What I was stock, I had the G80 also, wich is GM's version of a "locking Differential". It worked fairly well, but they do wear out. They never really lock up. And it requires a bit of spinning at low speeds to get it to add some friction. I would never really call it any sort of locker, but it does help off-road allot. Mine was about toast by the time I replaced it with a Detroit. And now the whole axle is replaced and sold.

huntsman2002crew · Post by **huntsman2002crew** » Wed Jan 17, 2007 2:15 pm

Mine has got 56,800 mileson it and it works great...i push it pretty hard and it never lets me down

killian96ss · Post by **killian96ss** » Wed Jan 17, 2007 4:00 pm

It sounds like the engagement pin on your locker is broken.

The engagement pin is by far the weakest part and could be broken very easy if the wheels are spinning and one tire suddenly gains good traction.

I would jack the truck up enough to get both rear tires off the ground and then have a friend hold one tire while you spin the other.

The 2 axels should lock together fairly easy if nothing is broken.

I have done this on a few G80 Gov-Loc equipped vehicles and the locker engaged every time.

It is also possible that the previous owner switched out the Gov-Loc for an LSD, and if the clutches in the LSD are bad one tire will spin forever while the other one stays put.

Snoman002 · Post by **Snoman002** » Wed Jan 17, 2007 6:03 pm

If/when you test the g80 using the above method remember that the needs to be a fair difference in wheel speed to get the locker to engage, so make sure to give the free wheel a good healthy spin.

JaVeRo · Post by **JaVeRo** » Wed Jan 17, 2007 6:20 pm

I have gotten the axle on my wife's truck to lock by jacking up one back wheel and putting the transmission in neutral. Spin the wheel that is off the ground as fast as you can and it should lock up in less than one turn.

daevans315 · Post by **daevans315** » Wed Jan 17, 2007 6:59 pm

I'll give the suggestions a try but I had the truck at full articulation a few months ago going through a ditch. The passenger rear wheel was several inches off the ground and spinning and my drivers front didn't have enough weight on it to pull me on through. Had to get a buddy on the back bumper to set the passenger rear back down and then it went right on through..... I'm betting its a broken locker now.

I doubt the previous owner swapped out the rear end. They put 30,000 miles on it in 14 months before I bought it. That doesn't leave a lot of time to play.

daevans315 · Post by **daevans315** » Fri Jan 19, 2007 7:28 am

Ok.. google is failing me or maybe I'm not looking for the right thing. I can't seem to find a rebuild kit for the Govlock \ G80 \ Eaton Locker for 7.xxx GM rear end. Is it only available from GM or am I looking in the wrong place?

2kwik4u · Post by **2kwik4u** » Fri Jan 19, 2007 9:37 am

daevans315 wrote:I'll give the suggestions a try but I had the truck at full articulation a few months ago going through a ditch. The passenger rear wheel was several inches off the ground and spinning and my drivers front didn't have enough weight on it to pull me on through. Had to get a buddy on the back bumper to set the passenger rear back down and then it went right on through..... I'm betting its a broken locker now.

I doubt the previous owner swapped out the rear end. They put 30,000 miles on it in 14 months before I bought it. That doesn't leave a lot of time to play.

Lightly applying the ebrake will accomplish teh same thing as your buddy on the bumper

I have to do that all the time in the winter in the Xtreme. One tire will be on ice, and have Zero torque applied to it to transfer over through the Zex. A little ebrake does wonders.

killian96ss · Post by **killian96ss** » Fri Jan 19, 2007 9:40 am

daevans315 wrote:Ok.. google is failing me or maybe I'm not looking for the right thing. I can't seem to find a rebuild kit for the Govlock \ G80 \ Eaton Locker for 7.xxx GM rear end. Is it only available from GM or am I looking in the wrong place?

I'm not sure about a rebuild kit, but I did find a few used Eaton Gov-Lock's on E-Bay that will fit our 7.625" rear ends.

Eaton Gov-Lock (E-Bay) Starting Bid $140

Eaton Gov-Lock (E-Bay) Buy It Now Price $120

Steve

daevans315 · Post by **daevans315** » Fri Jan 19, 2007 10:09 am

killian96ss wrote: I'm not sure about a rebuild kit, but I did find a few used Eaton Gov-Lock's on E-Bay that will fit our 7.625" rear ends.

Eaton Gov-Lock (E-Bay) Starting Bid $140

Eaton Gov-Lock (E-Bay) Buy It Now Price $120

Steve

I was hoping not to have to setup another rear end. I've done 2 but I still can't get the hang of reading the paint patterns so I have to call a friend over to help every time.

I found a post on S-series.org that talks about rebuilding a Gov Lock. I've got a post in to see where he got parts.

killian96ss · Post by **killian96ss** » Fri Jan 19, 2007 6:59 pm

daevans315 wrote:I was hoping not to have to setup another rear end. I've done 2 but I still can't get the hang of reading the paint patterns so I have to call a friend over to help every time.

If you replace your Gov-Lock with another one the wear pattern should be very close if not dead on because the ring and pinion settings are usually unaffected by swapping carriers.

Pinion depth is already set, so all you really need to do is check the backlash which should be pretty close as long as you reinstall the original carrier bearing shims the same way they came out.

Even though I'm confident you could do this swap the way I mentioned above, it is still a good idea to check the wear pattern with some marking compound after you get the backlash set.

Steve

daevans315 · Post by **daevans315** » Mon Jan 22, 2007 12:25 pm

Looks like my Gov Lock falls into the "works sometimes" category. We got some snow over the weekend and I decided to show the wife why I needed to spend a few hundred dollars on "a truck that works just fine". I stopped on a nice steep driveway that had been cleared and put one tire off in the snow. I left it in 2wd and stepped on the gas and what do you know..... The tire on the pavement chirped and I accelerated up the driveway. When I got to the top to turn around I could feel the drive train binding up with the rear end locked. I did it twice more and it locked each time. I then drove around the block, got it up over 30mph. I tried again. One Wheel Wonder... The tire in the snow just spun. I let off the gas, let the wheel spin stop, and got back on the gas 3 times. Each time getting a little more aggressive with the throttle. Every time, no locking. I backed up about 6 inches and tried again. Locked up and went.

I guess I see why so many serious off roaders are replacing the G80 with something more reliable.

killian96ss · Post by **killian96ss** » Mon Jan 22, 2007 5:29 pm

The Gov-Lock WILL NOT engage at speeds over 30 mph.

They are designed this way for safety.

You DO NOT want your rear end to lock axels while going through a turn on a slippery road, especially at higher speeds

Steve

2kwik4u · Post by **2kwik4u** » Tue Jan 23, 2007 4:46 am

killian96ss wrote:The Gov-Lock WILL NOT engage at speeds over 30 mph. They are designed this way for safety. You DO NOT want your rear end to lock axels while going through a turn on a slippery road, especially at higher speeds

Steve

Sure you do

.....Makes for all kinds of drifting excitement

If/When the G80 dies in the ZR5, I'll be ditching it in favor of a Zexel unit. The "somtimes works" category is not somewhere I enjoy being.

crew cab sonoma · Post by **crew cab sonoma** » Tue Jan 23, 2007 5:05 am

killian96ss wrote:The Gov-Lock WILL NOT engage at speeds over 30 mph. They are designed this way for safety. You DO NOT want your rear end to lock axels while going through a turn on a slippery road, especially at higher speeds

Steve

exactly.... thats how they work, and for one of reasons they work that way...
for the majority of the driving public, an open type std. diff. is actually safer... you may get stuck more easily, but at least they wont suddenly find themselves going sideways at higher speeds, when they hit a slippery spot in the road....

the Govloc has to be under a certain speed, and there has to be a certain ammount of speed diferential between the wheels before the mechanism engages the clutch.

plus, i think they also did it for fuel economy reasons too.
a conventional clutch type LSD typically has some extra drag on the drvetrain, anytime the wheels arent traveling at EXACTLY the same speed.

and even when driving in a perfectly straight line, there can be several factors that can cause a very slight speed difference, such as slight differences in tire pressure, weight balance, ect. so there is a slight fuel economy benefit to not having a "full time" clutch type limited slip, but rather one that engages only when needed....

crew cab sonoma · Post by **crew cab sonoma** » Tue Jan 23, 2007 5:24 am

2kwik4u wrote:Lightly applying the ebrake will accomplish teh same thing as your buddy on the bumper

I have to do that all the time in the winter in the Xtreme. One tire will be on ice, and have Zero torque applied to it to transfer over through the Zex. A little ebrake does wonders.

i agree. the Zex is an awesome differential for most typical driving conditions.
but like you said, if one wheel comes off the ground, or has very low resistance from being on ice, ect., it acts like, or possibly worse than, a std. open diff. but if you apply the brakes slightly to give the wheels enough "resistance", the Zex will apply power back to the wheels again.

daevans315 · Post by **daevans315** » Tue Jan 23, 2007 6:10 am

killian96ss wrote:The Gov-Lock WILL NOT engage at speeds over 30 mph. They are designed this way for safety. You DO NOT want your rear end to lock axels while going through a turn on a slippery road, especially at higher speeds

Steve

I was aware of the, "will not lock over 30" feature. Thats why I got it up over 30 and then tried again. I was hoping to kind of reset everything and see if I could get it to fail. Which it did.. kind of.

purduecrew · Post by **purduecrew** » Tue Jan 23, 2007 7:55 am

killian96ss wrote:The Gov-Lock WILL NOT engage at speeds over 30 mph. They are designed this way for safety. You DO NOT want your rear end to lock axels while going through a turn on a slippery road, especially at higher speeds

Steve

i dunno if i buy that

i was out the other day with my buddy playing in the snow on county roads, and we were kickin my ass end out at 40-50 mph

( which by the way is asking for some crunched fenders, really gets the blood pumpin)

daevans315 · Post by **daevans315** » Tue Jan 23, 2007 8:52 am

purduecrew wrote:
killian96ss wrote:The Gov-Lock WILL NOT engage at speeds over 30 mph. They are designed this way for safety. You DO NOT want your rear end to lock axels while going through a turn on a slippery road, especially at higher speeds

Steve

i dunno if i buy that i was out the other day with my buddy playing in the snow on county roads, and we were kickin my ass end out at 40-50 mph ( which by the way is asking for some crunched fenders, really gets the blood pumpin)

Thats where the hybrid part of the Gov Lock comes in. There are clutches that work at every speed giving you a basic LSD. The clutches transfer some torque from one wheel to the other when one slips. This works well as long as the amount of torque each wheel can handle is relatively close to the same. (both tires on dry pavement, or both on snow and not going around fast corner so the weight on both is about the same.) This is what you were feeling at higher speeds. Once you get to extremes: wheel lift, one wheel on ice one on pavement etc. The clutches can't overcome the differences so you are back to just spinning one wheel. Thats where the lockers work well. You want to be able to have 100% of the torque availabe a the tire with traction. The problem with locking the tires together is the same issue as you feel when you are in 4wd and you go around a corner on dry pavement. You get binding and scrubbing as the tires slip on the pavement. The forces it generates stress the drive line components. Things want to move at a different speed (front and rear axle in 4wd or inside and outside tire on a locked rear end) LSD will allow this Limited Slip. A Locked rear axle will not. The Gov Lock "Governor Locker" gives you a automatically engaged locker a low speeds but once you get up to higher speeds it will not lock. (when it working right)
This is an attempt to give you the best of both worlds. On paper and really when in 'normal' use it really does a pretty good job of giving you the best... Its just complicated and fragile so they break when abused or sometimes they just break....

FYI... Most of the above stuff I didn't fully understand about the Gov-Lock until the last few days of "google'ing" so feel free to correct me if I don't quite have it right.

Post by **Walt** » Tue Jan 23, 2007 11:23 am

My G80 locks.

I've been in the aforementioned situation only a few times, and it's locked every time. I also get a bit of chirping if I turn my wheels all the way left or right from a dead stop, and take off slowly.

crew cab sonoma · Post by **crew cab sonoma** » Wed Jan 24, 2007 9:42 am

its not a true "locker"... it only engages and disengages a clutch pack.
it`s a "limited slip" when "locked", and basically a std., open diff. when not "locked"...

Govloc`s will freewheel like an open diff. when the rear wheels are off the ground.
take the wheels off, and spin one axle, and the other rotates in the opposite direction.
now quickly turn it in the other direction, and you can trigger the engagement mechanism. now both wheels turn the same direction.

the mechanism simply applies, and releases pressure on the clutches...

just about any clutch-type limited slip in good condition, will cause some tire chirping on a tight turn...
the Govloc will do the same, when engaged...