Locking rear differential questions

Appleboy84 · January 28, 2019

Our 2013 2WD Silverado recently got stuck in the snow on our driveway. My dad (who owns the truck) got it stuck on his way home from work. He ended up parking it, going into the garage, and digging out the truck. While the truck is 2WD, I do believe it has the G80 diff. I would have gone out to check to see how he was trying to get out of the snow before shoveling it, and I would have checked to see if the diff was locking, but I was sleeping at the time (He has been working overnight shifts).

I do have a basic understanding how the G80 is supposed to work. I do have some questions about it.

1. What has been your experiences with this locking rear differential? Has it been beneficial in your low traction situations.

2. Does it help disabling traction control or StabilitTrak, or should those be left on?

3. Does the computers care whether the front wheels are turned or if you applied too much throttle? Granite, I know it is best to have the front wheels straight and use light throttle when trying to get unstuck. I’m just curious if the computer cares about these conditions.

4. Any other useful information?

P.S. my dad told me the past two times he started the truck at work in the negative temperatures, he’s gotten a “Service Trailer Brake System” message. He doesn’t get this message when he starts the truck in the garage. Has anyone else had this issue in colder temperatures?

Edited January 28, 2019 by Appleboy84
P.S.

DeePa · January 28, 2019

The g80 is mechanical so there aren’t any CPU inputs. Look up on YouTube for how it works.

Turn off trac control. It will limit wheel spin while trying to get unstuck. Stabilitrak being on shouldn’t hurt you, but disable to be safe it concerns you.

Service trailer brake is a common thing, but unrelated to your traction issues. Look it up on the forums.

Think about weight in the bed or snow tires or both.

Ive never had an issue with the g80. When you know you’re in a low traction situation, apply the throttle slowly to give the rear time to slip and then lock up both wheels.

US Dashworks · January 28, 2019

The G80 in these truck is a mysterious creature, i dont think even the gm engineers know how they work.... I was plowing with a G80 equipped truck one tire was on the ice, one was on pavement. Only the tire on the ice spun, the other side never locked in..... The G80 is a mechanical unit, it should have locked up.

Appleboy84 · January 28, 2019

1 minute ago, DeePa said:

The g80 is mechanical so there aren’t any CPU inputs. Look up on YouTube for how it works.

Turn off trac control. It will limit wheel spin while trying to get unstuck. Stabilitrak being on shouldn’t hurt you, but disable to be safe it concerns you.

Service trailer brake is a common thing, but unrelated to your traction issues. Look it up on the forums.

Think about weight in the bed or snow tires or both.

Ive never had an issue with the g80. When you know you’re in a low traction situation, apply the throttle slowly to give the rear time to slip and then lock up both wheels.

Thanks for your input. Never thought the G80 locked through mechanics and not through a computer. But then again, I only have a very basic understanding of the system. The truck at the time of getting stuck had at least 200 ibs of sand bags over the rear axle.

I’ve done a little bit of research on the TBC. It’s odd since it only happens when it is really cold outside on startup. Couldn’t really find much of issues related to cold weather (Could also be coincidental).

Appleboy84 · January 28, 2019

4 minutes ago, US Dashworks said:

The G80 in these truck is a mysterious creature, i dont think even the gm engineers know how they work.... I was plowing with a G80 equipped truck one tire was on the ice, one was on pavement. Only the tire on the ice spun, the other side never locked in..... The G80 is a mechanical unit, it should have locked up.

Interesting. I have heard the G80 can be weird at times. Still makes me wonder if our G80 locked this morning when the truck got stuck. I would ask my dad, but he probably wasn’t paying attention as he was in a hurry, and he doesn’t really know what a locking rear differential does.

kickass audio · January 28, 2019

I wonder if the g80 engagement may be caused from metal shavings getting caught up in the pawl that engages/disengages the locker. At high speed the pawl is defeated so you won't blow up the diff by gunning the engine and having the rear end lock up under high speed. From my experience I mainly get the locker to engage if I rev the engine up to around 1200 rpm and then you feel the back end lock up and hear that loud bang when it kicks in.

I wouldn't say the g80 is ever a replacement for 4 wheel drive. If you have quite a bit of weight in the bed then it will help a lot more than an empty bed with just relying on the g80. I haven't found a need to use 4 wheel drive since I replaced my tires with ko2's. I still get a tiny bit of wheel spin in the rear end but it isn't even as close to the spin and total loss of traction from the OEM tires. In 4 wheel drive I could not get the truck to break traction one bit.

I would recommend taking the back end up off the ground and spin one tire by hand and then once you get it going take the tire and immediately spin it back the other direction. It should get the other wheel to immediately stop and you will hear the clunk when the locker opens up and engages. If you don't get it to lock try spinning the wheel faster by hand and then stop it and turn it the opposite direction.

Mainer02 · February 9, 2019

Call the plow man he can pull the truck out of the snow and then plow the driveway . I have two trucks with g80's both 4x4's they work ok. Weight in the back bed over the rear axle should help but ice and snow can be a bitch .

Mikebtte · February 10, 2019

My G80 has worked great and helped me climb a few dirt hills and not get stuck. Not all trucks had a G80 (gov bomb) and you should check the RPO codes in the glove box to see if it was equipped. The G80 is great and mechanical. I have had them in older trucks that had no teeth left and did not work. Lots of metal in oil will usually give this away.

RPO code should be G80. One wheel will make a few revolution's and the G80 will engage.