Off Road Button with Single Spd Transfer Case

Thomcat · March 8, 2020

Choice of certain options on an RST prohibit addition of the Z71 option that I had in my gen1 and Avalanches, i.e., the OEM 22"s require a single speed transfer case with a 3:23 replacing the stock 3:42 rear. On these vehicles the 4Lo dash shift button used with a two speed transfer case truck is replaced with an "Off Road" button. Manual doesn't go into much detail in operation so of course had to play with it.

Seem operation differs from the typical crawl engagement with a two speed transfer case. Selecting "Off Road" in "2WD" brings no action other than a message in the DIC to switch to "4Hi". Selecting Off Road in "4Hi" while moving at around 10 mph or less lights up a green off road icon next to the white drive wheel icon in the main cluster and with a lurch reprograms the tranny to simulate the exact engine and wheel speeds as a two speed transfer case in "4Lo" - essentially the tranny computer simulates exact 4Lo operation without the transfer case actually switching gears but, with a lower torque output. Pressing the "2WD" button restores the default touring mode.

redwngr · March 8, 2020

Is your truck Max Tow (NHT) equipped?

Thomcat · March 9, 2020

18 hours ago, redwngr said:

Is your truck Max Tow (NHT) equipped?

No, just

Z82 - TRAILERING PACKAGE

redwngr · March 9, 2020

3 hours ago, Thomcat said:

No, just

Z82 - TRAILERING PACKAGE

So must be 2.7L or have 22" wheels..?

downtheroadar · March 10, 2020

On 3/8/2020 at 11:21 AM, Thomcat said:

Choice of certain options on an RST prohibit addition of the Z71 option that I had in my gen1 and Avalanches, i.e., the OEM 22"s require a single speed transfer case with a 3:23 replacing the stock 3:42 rear. On these vehicles the 4Lo dash shift button used with a two speed transfer case truck is replaced with an "Off Road" button. Manual doesn't go into much detail in operation so of course had to play with it.

Seem operation differs from the typical crawl engagement with a two speed transfer case. Selecting "Off Road" in "2WD" brings no action other than a message in the DIC to switch to "4Hi". Selecting Off Road in "4Hi" while moving at around 10 mph or less lights up a green off road icon next to the white drive wheel icon in the main cluster and with a lurch reprograms the tranny to simulate the exact engine and wheel speeds as a two speed transfer case in "4Lo" - essentially the tranny computer simulates exact 4Lo operation without the transfer case actually switching gears but, with a lower torque output. Pressing the "2WD" button restores the default touring mode.

What options limited not getting Z71. I ordered and have a Z71 RST 2020 3.0. Was it the 22's ? I didn't get that but can't imagine tire circumference being different. Missing something here, maybe their order logic.

Thomcat · March 10, 2020

7 minutes ago, downtheroadar said:

What options limited not getting Z71. I ordered and have a Z71 RST 2020 3.0. Was it the 22's ? I didn't get that but can't imagine tire circumference being different. Missing something here, maybe their order logic.

The $3K OEM dealer installed factory 22" wheels option on 5.3l V8 knocks out choice of the Z71 package option, also changes the standard rear axle from 3:42 (used in the Z71) to 3:23.

I don't explain 'em, I just buy 'em!

OnTheReel · March 11, 2020

1 hour ago, Thomcat said:

The $3K OEM dealer installed factory 22" wheels option on 5.3l V8 knocks out choice of the Z71 package option, also changes the standard rear axle from 3:42 (used in the Z71) to 3:23.

I don't explain 'em, I just buy 'em!

3.42 axle ratio isn’t a part of the Z71 package. 3.42s only come on max trailering package (NHT) RSTs.

NHT is also not available with 22” wheels for what it’s worth.

Thomcat · March 11, 2020

All I know is I'm going by the Maroney stickers and the build & price on the website.

All my Z71s came stock with 3:42 rears.

Build an RST Z71 on the website and then add 22"s and it knocks out the Z71 option.The RST with trailering package does comes stock with 3:42 but add 22"s and the trailer brake controller and it changes the rear end to 3:23.

OnTheReel · March 11, 2020

Yes, your 2016 Z71 had 3.42s. It also had a 6 speed transmission. I had a 2016 without Z71. It also had 3.42s. Z71 has nothing to do with gearing. It’s the transmission, and whether or not the truck has NHT that determines axle ratio.

Anyway, your initial comment was about your RST. Save for the 2.7 (that you don’t have)...8 and 10 speed trucks from 2019 and up simply do not get 3.42s without NHT.

You can’t get Z71 and 3.42s. You can’t get Z71 and 22s. You can’t get NHT and 22s. You can’t get NHT and Z71.

Your truck has 3.23s because it doesn’t have NHT, not because it doesn’t have Z71.

Thomcat · March 11, 2020

7 hours ago, OnTheReel said:

Yes, your 2016 Z71 had 3.42s. It also had a 6 speed transmission. I had a 2016 without Z71. It also had 3.42s. Z71 has nothing to do with gearing. It’s the transmission, and whether or not the truck has NHT that determines axle ratio.

Anyway, your initial comment was about your RST. Save for the 2.7 (that you don’t have)...8 and 10 speed trucks from 2019 and up simply do not get 3.42s without NHT.

You can’t get Z71 and 3.42s. You can’t get Z71 and 22s. You can’t get NHT and 22s. You can’t get NHT and Z71.

Your truck has 3.23s because it doesn’t have NHT, not because it doesn’t have Z71.

Thanks for the clarification, went with the info I could gather & that info not listed on site. Anyway wanted the 22"s more than the Z71....In the 4 truucks I've owned with the package never used the 2 spd case exactly once to make sure it worked and no sense using smaller knobby Goodyears driving mostly on pavement.

Thomcat · March 11, 2020

12 hours ago, downtheroadar said:

What options limited not getting Z71. I ordered and have a Z71 RST 2020 3.0. Was it the 22's ? I didn't get that but can't imagine tire circumference being different. Missing something here, maybe their order logic.

Diameter is different, so circumference is different;

From website

TRIM: RST

Standard Features

Exterior

18" Bright Silver painted aluminum wheels
- RST models feature Black bowties
18" 265/65R18SL all-season, blackwall tires
17" 265/70R17SL all-season, blackwall spare tire
May require additional optional equipment
Spare tire carrier lock
- Helps keep spare tire secure
- Utilizes the same key as the door and ignition .......

And according to tire sizing chart:

https://tiresize.com/height-chart/

265/70R 17 diameter = 31"

265/65R 18 diameter = 31"

Optional 22" Bridgestones on my RST are 275/50R 22

275/50R 22 diameter = 32"

So essentially the 22's not only have a larger circumference over stock combo tires, but they give the RST a 1/2" lift on the stock suspension.

OnTheReel · March 11, 2020

Stock 20” tires (275-60R20) are the tallest at 33”. The 20” setup is available on Z71 and NHT trucks.

So since you can get a Z71 or NHT with 31.6” 18s, or 33” 20s...wheel/ tire height isn’t the reason those packages can’t have 22s. The 22s are 32.8”, nearly identical to the 20s.

Must be some other goofy GM logic going on. I kind of understand why they wouldn’t offer 22s on the Z71...definitely not a good off road wheel & tire combo. Heck, GM doesn’t even have an all terrain tire option in 275-50R22. But none of that should make a difference on NHT trucks.