Open Diff's

[shakazulu12]

Just curious why they went with open diff's on the hummer? It seems like they could have put a viscous coupling in there to improve AWD grip, and not sacrificed anything when locked in 4hi, and a mechanical distribution of power is much better than using the brakes to send power to the other wheel in my opinion.

Does the old NVG149 that they used in the Denali pickups/early SUV's bolt in or anything? Or has anyone put an LSD on the rear at all?

I know most of you are using 4 HI locked when you wheel, but on snow and ice its not always the best idea, or general on road driving.

Not really meant as a slam, just really curious as it would seem to maximize grip on all surfaces.

[vlxjim]

GM uses the ABS system to do the same thing.


TCS/TC2
The Single Wheel traction control system gives you traction when you need it most. The system detects a slipping wheel and applies brake pressure to slow it down, it then takes the energy that would have otherwise gone to the slipping wheel and transfers it to a wheel that's not slipping. With this system, you could have as many as three wheels on a slippery surface (virtually no traction) and still get enough torque out of the fourth wheel to move the truck up a 10% grade.

The H2's base TCS mode is great for normal hard surface traction needs, like on-road use, off-road rock crawling or ice and snow. But once you hit a variable surface like deep mud, sand or gravel the TC2 takes over. The TC2 works just like TCS but allows limited wheel spin to help gain even more traction.

So with three transfer case selections, two rear axle differential selections and two modes provided by the TCS mode switch, you actually have a total of seven driving mode selections in the H2, providing you with the ability to match the performance of the H2 with almost any driving condition.

[shakazulu12]

Oh yes, I'm aware of the functionality of the ABS based system. However its been my experience that nothing replaces a good old fashioned coupling, it seems to me that its kind of in-efficient to use an ABS based system with open diffs, because you are consuming engine power and torque by using the brakes to move power around. I have driven a Sierra Denali in all kinds of mud and bad situations, and it pulls grip out of nowhere it seems (uses a viscous coupling, not sure why this model does when most GM vehicles don't, not even the regular Denali SUV), where ABS based systems still feel a little hesitant to put power down, I have no experience with the H2 system yet, but it was just an observation.

Does anyone make an aftermarket LSD or something?

[Alan06SUT]

Originally Posted by shakazulu12

Oh yes, I'm aware of the functionality of the ABS based system. However its been my experience that nothing replaces a good old fashioned coupling, it seems to me that its kind of in-efficient to use an ABS based system with open diffs, because you are consuming engine power and torque by using the brakes to move power around. I have driven a Sierra Denali in all kinds of mud and bad situations, and it pulls grip out of nowhere it seems (uses a viscous coupling, not sure why this model does when most GM vehicles don't, not even the regular Denali SUV), where ABS based systems still feel a little hesitant to put power down, I have no experience with the H2 system yet, but it was just an observation.

Does anyone make an aftermarket LSD or something?

There is a rear locker in all H2's. They are not both "open Diffs". It is a push button E-locker. The front is open though. Basically we have 3 wheel drive. You can get a front e-locker though.