[JBT]

First off, excuse me for not understanding this or being a nob. My truck, a 2016 Z71 4x4, is a street truck used to travel long distances, sometimes in really bad weather. Not an offroad truck. So what is the deal with front and rear lockers if I already have 4 wheel drive. When I am in 4 wheel high on dry pavement the wheels bind just as though I have a solid axle. Isn't this the same? Aren't my rear and front axles locking to create 4 wheel drive? Be easy on me because no one has really ever explained this to me. Are my front and rear axles becoming solid when I am in 4 wheel mode either hi or low? I'm not talking AWD, nor do I even have that. If they are still slipping, why do I feel them bind on dry payment? And what advantage are the front and rear locker switches of the ZR2 if I already have a 4x4? Thanks

 

[rawman]

I think AWD is kind of the same thing as auto mode on these trucks. Hope this helps explain:


Four-Wheel Drive Benefits, Tips & Uses ? GMC Life

 

[ocelot]

How Part-Time Four-Wheel Drive (4WD) Works | The Art of Manliness

Read all of that and it will answer your question as to why lockers are needed.

 

[JBT]

I think AWD is kind of the same thing as auto mode on these trucks. Hope this helps explain:


Four-Wheel Drive Benefits, Tips & Uses ? GMC Life

In my question I stated I don't have AWD. Nor have I ever had a truck with AWD. I'll watch the video. Thanks

 

[JBT]

Ok, so I'm getting there, Differentials.

 

[JBT]

Ok, so am I correct to say I have a locking rear differential in my Z71 and a LSD in the front? If so why does the ZR2 have button for for the rear differential. Why not just shift into 4 wheel drive and turn on the front locker? I'm getting there lol. I think

 

[JBT]

So, the binding I feel is not between the solid axle of the rear but between the front and rear axle when turning on dry pavement in 4x4 mode?

 

[JBT]

Ok, both, the rear wheels binding from the locker and the one front wheel and rear wheels binding also.
@ocelot , thanks, great article. Got it

So let me see, with a G 80 locker on a Z71 4x4, I basically have 3 wheel drive in 4x4 mode. Just the front wheel is shifting to the wheel that is spinning. It's not locking like on a ZR2. And, in 4 wheel drive low the truck is creating higher torque at lower speeds. Not allowing it to go as fast but giving it much more low end power. So, the switches on the ZR2 are creating a true 4x4 solid axle drive with no slip at all?

 

[KMW]

Ok, so am I correct to say I have a locking rear differential in my Z71 and a LSD in the front? If so why does the ZR2 have button for for the rear differential. Why not just shift into 4 wheel drive and turn on the front locker? I'm getting there lol. I think

Yes and no.

Yes, you have an "automatic locker" in the rear. When one rear tire spins 120 rpm faster than the other, centrifugal force engages the locker, engaging both rear wheels together.

No, you do not have a LSD in the front. You have an open differential. An open differential gives equal torque to each tire. If one wheel is on a slippery surface and only requires 20 lb ft of torque to turn, and the other is on dry pavement and requires, say, 75 lb ft of torque to turn, then the slippery one will spin at 20 lb ft and the tire with traction will not, because it's only getting 20 lb ft.

A ZR2 has a "manual selectable locker" in the front and rear axles. It runs as an open differential until you activate the switch, which electrically engages the locker. There are other types of selectable lockers as well, such as the ARB air activated locker, or the OX cable activated locker.

Automatic lockers are suitable for on road use, not so much for serious of road use. Selectable lockers are intended for off road use.

So, the binding I feel is not between the solid axle of the rear but between the front and rear axle when turning on dry pavement in 4x4 mode?

That is correct. When you turn, each wheel on your truck is traveling in a different size circle, and therefore must each travel at a different speed. The extreme is the inside rear wheel and the outside front wheel. The outside front wheel is traveling much further than the inside rear, so it has to turn faster. So when you put it in 4x4, you are locking the front and rear axles together in the transfer case, thus the binding.

Hope that all makes sense!

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[JBT]

OK, so do the lockers on the ZR2 have any slip at all, like the G80 locker on my truck, or do they just become a solid axle?

 

[JBT]

@KMW If you were on the highway in horrible road conditions, or bad roads and snow with a ZR2, is there any time you would engage the front locker? It seems to me it would be overkill. Is there a speed restriction to the front locker on a ZR2?

Hey, sorry for the stupid questions. I just really like these ZR2s and I'm trying to justify in my little mind why I need one to travel highways. Maybe just because it's fun? :grin2:

 

[KMW]

If you were on the highway in horrible road conditions, or bad roads and snow with a ZR2, is there any time you would engage the front locker?

I would say no. Not on a roadway. Front lockers should only be use in low speed low traction settings. On the road they will cause you to plow right off a corner when trying to turn with any kind of speed on slick surfaces, because the locker makes one of the wheels have to break traction and slip.

A rear locker engaged will also push you right of a corner on slick roads with speed. With both rears locked together, they only want to go straight. One of them must slip for the truck to turn.

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[JBT]

I would say no. Not on a roadway. Front lockers should only be use in low speed low traction settings. On the road they will cause you to plow right off a corner when trying to turn with any kind of speed on slick surfaces, because the locker makes one of the wheels have to break traction and slip.

A rear locker engaged will also push you right of a corner on slick roads with speed. With both rears locked together, they only want to go straight. One of them must slip for the truck to turn.

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Very good logical point. Thanks

 

[JBT]

I have driven out of some cities with a lot of snow and ice on to major highways with no problem at all, with wrecked cars around me. And I just drove my 2016 Z71 through an ice storm in North Carolina on highway 95 last year and love this this truck. I loved the Last 2007 Colorado Z71 I had too. I guess getting a ZR2 for me is a big waste of money. Thanks all. It does look like fun though. And thanks for the lesson in lockers.