2015 Silverado 1500 Z71....Open rear?????

Silverado4x4 · July 16, 2015

You kinda have to know how to use a locker, if your stuck and the rear is not locked DO NOT MASH THE GAS or it will not lock. Lightly apply gas till it senses wheel spin then it will lock as wheel speed has to be below 20mph for it to lock this is to prevent a slipping wheel going 25-50 mph from locking as it would explode the rear if it locked. I have had many G80 rears and they always locked doing it this way.

SouthernSilveradoGuy85 · July 17, 2015

What is the purpose of turning off traction control then?

Not to high jack the thread just thought it may be relevant to your question OP

Sent from my iPhone using Tapatalk

I haven't gotten into a situation where I needed to turn TC off. But, I found out that if you want or need to take off better from a stop then turning TC off helps a lot. I remember in my 98 I could hold the brake and give it enough throttle to make the rear come up but not spin like if I wanted to do a power brake burnout. I tried it in the '14 and the rear didn't move at all. I then turned TC off and tried it again and the rear came up just like my 98 did. I could be wrong, but I think TC just reduces power at first, at least when talking about from a standing stop. These trucks also have TQ management to help protect the trans, but with TC off I didn't really notice it. I just keep it on because I'm not going to drive like an idiot like I did in my 98 so no burnouts or donuts or racing.

TxTruckMan · July 17, 2015

No. Traction control will A) reduce throttle if both rears spin too much from a start and B) apply brakes if you start sliding or approach rollover conditions.

GsBowtie · July 17, 2015

Thanks for the additional replies it may be Ok i guess. I was in my grassy yard when it happened the second time. On an incline. I was being very light with the throttle because i was in 2wd. The right rear started spinning and the left did not spin or lock up from what i can tell. u Even stopped a few times thinking it wold lock. Nope. I will have to keep an eye on things and take it in if this becomes a trend.

I only have 1500 miles on it. Maybe not broken in fully yet?

redwngr · July 17, 2015

Not a 'break-in' issue. Sounds like the truck does not have the locker. (There is no limited slip available - only open or the locker)

The G80 locker is ordered independant of Z71, so your truck may not have it installed.

Check the RPO code list in the glove box for the G80 code.

Animated video of how the G80 works, including how it engages and why it wont engage at high speed.

Video of G80 diff with the rear cover removed:

GsBowtie · July 17, 2015

According to the window sticker it has the locker. I will check for the g80 code though. Thanks. If i confirm i have the locker then Do you all think it has an issue? Thanks

redwngr · July 17, 2015

As silverado4x4 posted ( and the videos explain why) the locker will only engage below 20 mph.

If it was turning one wheel and the rear end was turning slower than 20mph then it should have engaged (if installed).

GsBowtie · July 17, 2015

Ok thanks much

El_Diablo_John · July 17, 2015

The g80 differential needs a minimum of a 120rpm differential in wheel speed in order to engage. Once engaged it will remain locked in until load is released, even if speed exceeds 20mph. Once moving at 20mph, if slip is detected, the locker will not engage.

Some of us sales guys listen during training, lol.

BlackZ71Silverado · July 17, 2015

Not a 'break-in' issue. Sounds like the truck does not have the locker. (There is no limited slip available - only open or the locker)

The G80 locker is ordered independant of Z71, so your truck may not have it installed.

Check the RPO code list in the glove box for the G80 code.

Animated video of how the G80 works, including how it engages and why it wont engage at high speed.

Video of G80 diff with the rear cover removed:

The G80 locking rear diff. is part of the Z71 package so his truck has it. I don't think you can get the Z71 package without the G80.

GsBowtie · July 18, 2015

This was my understanding. I thought the z71 included the locking rear diff. Well if it's working as designed i think i sucks. Give me an old posi rear any day over this. Twuce now I've had one wheel spin in conditions a posi would not have. Oh well. I'll confirm what i have and go from there.

I don't want to beat my truck but i suppose i could turn trac control off and do a quick burnout and see if it leaves 2 patches. Unless it won't engage the locker that way?

robvas · July 18, 2015

I'm willing to be it is locking and you just don't see it. Take a video of the truck from the rear next time.

redwngr · July 19, 2015

This was my understanding. I thought the z71 included the locking rear diff. Well if it's working as designed i think i sucks. Give me an old posi rear any day over this. Twuce now I've had one wheel spin in conditions a posi would not have. Oh well. I'll confirm what i have and go from there.

I don't want to beat my truck but i suppose i could turn trac control off and do a quick burnout and see if it leaves 2 patches. Unless it won't engage the locker that way?

Start by checking for the G80 code on the glove box sticker.

G80 is NOT included with Z71

SouthernSilveradoGuy85 · July 19, 2015

Start by checking for the G80 code on the glove box sticker.

G80 is NOT included with Z71

I thought at least with the K2s that it was because when you build one on the Chevy site some of the packages will say something like "If not equipped with Z71, included locking differential". It harder to know for 100% sure since for some reason GM made Z71 as part of the trim for Chevy because you'll see LT, LT Z71, LTZ and LTZ Z71 as different trims. GMC might be the one where you can get Z71 without having the G80. Looks like with GMC you can get the All-Terrain which will come with the G80 while you can get just the off-road suspension package which is Z71 and that doesn't list the G80. So looks like to me if you have a '14-'15 Chevy Z71 then you have the G80 for sure while if you have a GMC with just the Z71 package that it's not certain.

Just what I can see anyways.

BlackZ71Silverado · July 19, 2015

Start by checking for the G80 code on the glove box sticker.

G80 is NOT included with Z71

Sure is according to GM....

It has been for as long as I can remember. I only buy Z71 option trucks and the locking rear has always been listed as part of the Z71 package on the window stickers. I guess it is possible that GM is wrong though, they only build the trucks so who knows???

Here's a little information from their webpage:

Adding the Z71 package gives you the auto. locking rear, here's a little example.....

LT Z71 includes all LT features, with the addition or substitution of:

Z71 Off-Road Suspension with Rancho[emoji768] monotube shocks

Hill Descent Control

All-terrain tires

Underbody transfer case shield on 4WD models

Automatic Locking Rear Differential

Z71 appearance package (Brushed metal Z71 door plate, unique gauge cluster, unique finish interior trim plates, unique lower front bumper and unique new chrome grille design)

Fog lamps

Front recovery hooks

Sent from my crappy iPhone 6

using Tapatalk