Eaton G80 Locking Differential Keeps GM Pickups Moving


Traction is always an important issue for pickup truck buyers and owners, especially when towing, carrying payload or just exploring the roads on the way to your favorite campground. A spinning wheel usually means that's as far as you get, unless you have some kind of smart technology inside your axles or controlling your brakes.

One solution to prevent a progress-killing spinning tire is a traction control system that uses the vehicle's existing brake setup to slow or stop a spinning wheel in order to transfer more of the engine's torque to the wheel with the most traction. The benefit? These systems use high-tech computers to control the input signals and the resulting brake action, leaving the driver to simply control steering and throttle. The downside can be some unnerving vibrations and groans from under the vehicle.

Another less complicated and even more invisible way of dealing with lost traction is to use a limited-slip or locking differential that sits inside the axles. In their simplest form, rear-axle traction devices can sense wheel spin and with a series of plates, clutches or gears, make sure the most amount of traction gets to the tire with the least amount of slip. Because these devices try to sync up right and left axle shaft speeds, it's not a good idea to use one for the front axle on a four-wheel-drive pickup because it will restrict your turning abilities.

Eaton Vehicle Group has been making locking differentials for GM pickups for more than 40 years; they are available on GM's full three-truck lineup as standard or optional on select trim packages. And because this technology is largely unseen, we thought sharing this GM video about how and why locking differentials work would be of interest. It's worth noting the G80 locking differential is designed for extra traction in low-speed situations like driving on ice, getting stuck in the mud or crawling through or over rocks.

The real value of this type of traction-aiding device is how simple the design is and how effectively it works. Another benefit is how relatively inexpensive the option is for the midsize, light-duty and heavy-duty pickups, usually somewhere between $300 and $400 when not included in a package.

To pull up the GM video, click here. photos, Joe Bruzek


IMG_8537 II



I have to say I have had this on a few of my Chevy trucks, and all I can say is it works! and I have never had any problems with either that, or any other systems in my GM trucks! I can run on the beach in 2wd for the most part, all I have to do is not come to a complete stop, but just try to keep on moving! also in the snow, and mud, and most off road tracks/trails I have driven on, the G80 always comes through! I will not buy a truck without some type of lmt/slp, or locking device in the rear axle. It would be nice to be able to get a Power Wagon, with the switchable f/r lockers! maybe next time! I have had a vehicle, a MB ML 320, that has the braking systems that use a computer to stop the wheels with no traction from spinning, the main problem with those are brake heat, and wear, as it seams like in the winter (and we get a lot of snow in my area) it was every other year I was going through the rear brakes, and the fronts in 30-40K! where in my GM trucks the brakes lasted for at least 70-80K! The ML? I ended up trading it in on a 2005 Avalanche 1/2t 4x4, with the G80, and I owned that truck for 80k, and never had to replace the brakes! and when the tires and brakes finally wore out I traded for a 2011 Silverado Z-71, which comes with the G80, and now has over 60K, and the brakes are still fine and just passed inspection! Also do not think I am all to easy on my trucks, as I regularly tow a 7k trailer with another 1k loads all the time!

Why is it GM cannot build quality parts themselves? First, they form a joint venture with Isuzu to design and build their diesel Duramax after failures of their own. Then they buy their pickup transmission from Allison. Now they're buying someone else's differential. Also, is it just coincidence that those are the only high quality parts in their pickups?

Another GM article. Imagine that.

The "Gov-Loc", also called "Trac-Loc" or "Trash-Loc" on the proven to be the weak link in these trucks. It'll break and grenade your differential under any heavy use whatsoever. There are even many reports of them snapping on the boat ramp trying to recover a boat on wet uphill pavement.

Typical GM garbage.. yet the lemmings keep buying this junk. And as long as it's selling...they'll keep spitting it out.

Have one in my 99 two door Tahoe 4x4 and it works great. I rarely have to engage 4wd when I'm off raod. It's been completely reliable even after 180,000 and 16 years it still works fine.

I was very pleased to see my 2015 2WD Sierra had the G80 in it as well.

Great product and an option well worth the money.


PUTC tested this a few years ago and it didn't work.

The Ford F-150 and Toyota Tundra performed best. They were the only trucks to make it off the slippery surface without having to stop and engage four-wheel drive.

The Chevrolet Silverado and GMC Sierra both had locking mechanical rear differentials that engaged automatically when wheel slip hit a certain rpm. While both pickups performed excellently in the autocross, they were challenged by the wet surface and fishtailed backward as power was applied. We had to put both trucks into 4-High to get off the basalt.

Extreme Traction-Control Test at the GM proving grounds.

Gm needs to do away with the square wheel houses already.

Trac-loc is not the same as a Gov-loc. Trac-loc is s simple clutch LSD. The Gov-loc used a centrifugal mechanism (thus GOVernor) in the carrier, to engage a set of gears, like what's in a detroit locker. The Eaton selectable rear locker in the H2 replaces the governor assembly with a solenoid and some other brickerbrack.
IMHO, The Gov-loc or G80 is junk- seen too many that wouldn't lock anymore, and the clutches are then under sized for the application.
Helical gear diffs like the True-trac perform way better.

@ Marc

It looks like the square wheel housings are working great on the GM trucks since they are outselling everyone else.

If you don't like it don't buy it!

I wouldn't buy another truck that doesn't have a locking rear dif as my truck loses traction really bad in wet weather. I think weight and tires play a big part in it. I am looking at an ARB air locker.


So mis-informed. You are crying about the old design eaton Gov-Loc. The Gov Loc was bad because it was machined with bigger interior holes and weaker materials. That teamed up with the vehicles people were dropping them in and how they were being used/abused and they got a stigma of Gov-Bomb.

The updated and improved G80 "Eaton MLocker" was redesigned to be more durable and robust and has had very few problems. This is great for mild to medium off roading and street use. These still aren't the diffs to use as a regular moab vehicle or flooring it with 38's through mud bogs where wheels can spin at different rates and lock. Abuse will lead to breakage in anything.

Where other lockers need to be manually engaged and be in 4wd already this works great in 2wd on slick surfaces and up boat ramps and such. Haven't heard much of them breaking at the ramp...

They are far from junk and work great for what they are designed to do, if you want call them crap because you hear stories of people install them on their 10.5 slick tire drag car and break them with that power and traction or mud bog types trash them because of all the high rpm mud slinging on their 38's and won't last that is your problem.

For the millions of these on the roads and the few (in relation) threads you see or hear of issues, it isn't bad at all. None of ours have ever had an issue and we have had them on our trucks since the early 90's and regularly towed a boat at or above our weight limit.

Locking diffs are great. I use mine as a backup when I do get stuck. This saves much winching.

My pickup already has a raft of traction aids available, so when off roading it can get into quite sticky situations without the aid of a locking diff.

When I do go beyond my vehicles capability and get bogged, I pull myself out by engaging my rear diff.

It has worked so far. But I'm waiting for the day when I'm stuck and my locking diff won't get me out of trouble.

So, my advice is use your vehicle as you would normally, without the rear diff locked. Only use it when you do get stuck. Nine times out of ten it will pull you out and you can find another way around the obstacle.

I put 300.000 miles on my 2wheel drive GMC Sierra with G80 locker without problems,works like a dream never got stuck on ice or deep snow yet...

@Dale- It's ok if you don't like GM, but get your "facts" straight. GM owned a majority of Isuzu's truck division at the time of the creation of the Duramax. Every 6.6 Duramax was/is built in Moraine Ohio. GM also owned Allison from 1929 until 2007- well after the point when GM started putting them in pickups. Sounds like you're a Ford 6.0/6.4 man who wishes he had a Duramax or a Ram Cummins owner who could really use an Allison tranny. I've had two G80 diffs (9.5" and 10.5") that never gave trouble through lots of abuse.

Love my G80! It's nice that it engages automatically when you need it. I also like that it disengages over 25mph. I had a Dodge with limited slip and gentle high speed curves on snow or ice can sneak up on you. Nothing against Dodge, just commenting on the way in general that limited slip doesn't disengage. I'm used to driving on snow, so it wasn't a surprise. Just like the G80 :)

I'm sure the grenading can happen under abuse, but I don't think an open diff would last that much longer under the same conditions. Besides, that might be the excuse you need to go get a Detroit TrueTrac.

And as a GM guy, I'm jealous of the Ford eLocking axle. I think an Ecoboost with the 3.73 eLocker would be a great truck!

Oh Yea?
My F-150 Eco-Boost has an E-Locker and its the bestest!
My friends say: "Tom you're so cool cause you have an F-150 with an E-Locker"
I tape a dollar bill to the dashboard and when I take my friends for a ride I tell them if they can grab that dollar bill they own it, then I FLOOR IT with that awesome Eco-Boost POWER and with that EXTREME acceleration they are pushed back in the seat so hard they can't get that dollar bill!
My friends say "wish I owned a cool truck like you got"

I think Dodge (edit: Ram) has a big opportunity; with their air suspension, they have a compressor on board and could run an air locker. Their limited slip is back of the pack right now. I don't know if air lockers have a maintenance schedule or not.

I had a gm with the g80 and after having it behave like the gm trucks in the pickup 2008 test I vowed that I would only get a locker that I could control and not be dependent on a difference in rpm between the two wheels. If you have lost traction then it's too late in some situation. That is why I now drive a ford with an elocker.

I had 2 Chevy's with the G80 and hated both of them. My driveway is quite steep and the stupid thing would clang and bang. It won't stay engaged unless your spinning both wheels. My current truck has a limited slip and it gets me up the driveway better. Also, there are 2 3/16 bolts I believe that will shear and destroy the whole diff if you happen to hit dry pavement with the wheels spinning. For my situation the LS works better. Different strokes for different folks.

^^^ Exactly. Tyler is clueless. The G80 is known to break even on stock or lightly modified trucks. As I mentioned (I guess he can't read), there are even a lot of guys who've broken them just trying to retrieve a bass boat out of the water. I had one in a '06 Z71 and I was scared to death it was going to go BANG in slippery conditions. It made a lot of noise and didn't feel confident. GM engineering is the worst in the marketplace hands down and really it has been for decades. It is shocking that the best trucks on the road are the lowest sellers and the junk trucks sell the best. Then again, that's what peer pressure does to people.

I wish manufacturers would take "the rear" more seriously. I have owned way too many limited slips that were more on the slip than limited side... Yea I know most people NEVER need it and they don't want to be chirping all the time during normal driving but one would think that those of us wanting it would, well... want it.

I wish there were more factory options for rears (especially on HD trucks). More E lockers, Air lockers, Any locker, more gearing ratios, optional HD Diff covers with cooling and larger resivours and most of all why not a split rear? They can electronically FORCE a car to stop or parallel park itself why not a 2 speed split rear? That would double the ratios available to the trannys... no need for 2 companies to codevelop a 10spd... just stick with a 6 to 8 speed with a split rear it all doubles. There HAS to be a reason they haven't done this. I doubt it costs more than leather nav and sunroofs... and what a difference it would make in performance... ultra low granny gears and super high mileage making highway over drive gears and all that stuff between we have been living with.

@WXman, how many G80's have you broken? I have done many boosted launches with mine and smoked the tires up through drive with my modified 6.5 diesel. I also tow a 22' gooseneck trailer with two antique tractors regularly throughout the summer months. Not a lick of trouble with the diff. To be honest, the engine scares me a whole lot more!

@ Clint I won't buy GM's any more because I can't live with a 3.42 axle. Don't want the expensive package to get the 3.73. Ford and Ram offer 3.73 and 3.92 on most trucks. Ram did have a 4.10, but I think they did away with it when the 8 speed came out. Can't get 6.2 on GM without buying a expensive trim package. Can't get the 8 speed on a 5.3. I got tired of that crap and switched brands.

@mark49... thanks. .people are so ignorant to the GM/Isuzu joint venture as well as the fact that GM owned Allison for all those years.

And to all those that call GMs 6.2/6.5/6.5 Turbos a failure, you're down right stupid. . You havent seen powerstrokes in HMMWV's since 86 have you? Worked on plenty in the Army for 8 years, the detroit 6.2s and 6.5s were more than capable motors. The only problem we ever had was with injection pumps (standyne) and that was only because we ran JP8 (jet fuel) with no lubrication they would over heat and restrict fuel.. solved that by adding 1qt of tranny fluid every fill up.. haters.... nothing but haters..

I have this rear combined with stabilitrac on my van and on a snowflake or slightest damp grass it will make the engine go limp when you need to blast through there, and if youre already stuck, when the g80 engages at a going nowhere speedo of about 15mph it goes BANG!!! and makes you get more stuck. sounds like its going to blow up and it scares my dog. id surely have to have some better tires and a diff that selectively locks. the ole wivestale about putting sandbags over the axle is a fallacy as ive had 500 lbs worth and all it did was limit my cargo space and waste 20 bucks. the friggin thing already weighs 6k lbs as it is :-O

I have this rear combined with stabilitrac on my van and on a snowflake or slightest damp grass it will make the engine go limp when you need to blast through there, and if youre already stuck, when the g80 engages at a going nowhere speedo of about 15mph it goes BANG!!! and makes you get more stuck. sounds like its going to blow up and it scares my dog. id surely have to have some better tires and a diff that selectively locks. the ole wivestale about putting sandbags over the axle is a fallacy as ive had 500 lbs worth and all it did was limit my cargo space and waste 20 bucks. the friggin thing already weighs 6k lbs as it is :-O

@Tom Smith

My 09 Silverado LS has a Eaton G80 box checked and I've never had to service it apart from lube replacement.

Over 100k miles. It is a no brainer unless you want something for competition or love impressing your friends doing burn-outs. I'm about 40 years older than that.

The comments to this entry are closed.