TracRite?

[Phil H.]

Hi. I just brought home my new '06 Boulder Grey H3 with Adventure and Lux packages.

As you all know, I have the E-Locker in the rear. Is there a TracRite helical gear posi up front? Also, when unlocked, is the rear a posi too, like the Jeep Rubicon or Dodge Power Wagon?

I would imagine there is a TracRite up front, as it would be needed to make the TCS work.

I performed a search for this and came up with some information, but I just wanted clarification, so sorry if this is a dead horse.

Thanks!

[HummerNewbie]

No answers for you but congrats and welcome.

[Phil H.]

Thanks! I'm sure I'm going to have a great time with the H3.

Hopefully someone can give me an answer . . .

[Beastmaster]

I believe that the Tracrite diff is the core of every current AAM diff now.

The rear is a 9 inch AAM electronic locker. The drawing that I see on it shows nothing that would indicate that it's a posi type diff. It's locked or unlocked from what I can tell.

The front looks to be a 7.5" AAM open diff. Stabilitrac doesn't require it to be a posi type diff or a torsen worm gear style.

[Phil H.]

The front's an AAM 7.25. While the Stabilitrak doesn't need it, I would think the traction control system would, as it could preload the diff with the computerized braking, just like we can preload a TrueTrac helical gear posi and get it to almost completely lock. I could be WAY off here, though, as I don't know how the TCS and Stabiltrak do their respective jobs.

Thanks!

[Beastmaster]

Here's an article on how Stabilitrak works.

http://www.acarplace.com/brands/gm/gadgets.html
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Stabilitrak

We appreciate the help of Stabilitrak, which mostly eliminated the squealing tires that can bring the attention of the law, while keeping the rear end of cars with powerful engines where they should be - in the rear. Indeed, the difference between Camaros with and without Stabilitrak was fairly extreme, with the electronic application of traction control and suspension travel making the difference between a composed, predictable, incredibly fast car and one which seemed to always want to make sudden, unexpected U-turns when the gas was stomped.


GM writes: "StabiliTrak 2.0, an improved version of the most advanced integrated stability control system in the world... includes side-slip rate control and active steering effort compensation. Introduced on three performance-oriented Cadillac models in the 1997 model year, StabiliTrak provides an important safety advance by helping the driver maintain control during emergency or evasive maneuvers. StabiliTrak works by comparing the driver’s intentions (indicated by steering wheel position) with how the vehicle is responding. Three key sensors keep the ABS and traction control computer informed: one reads steering wheel angle, another reports the vehicle’s lateral acceleration and the third measures yaw rate (rotational velocity about a vertical axis through the car’s center of gravity). Information is also gathered from vehicle speed.


"If the vehicle’s dynamic response does not agree with the direction the driver is steering, StabiliTrak goes to work by selectively applying the individual front brakes to help keep the car on the intended course. If the car is slipping wide of the desired path in a turn, applying the inside brake helps the vehicle turn tighter. In case of diminished traction at the rear causing the tail of the car to drift wide, activating the outside-front brake gently nudges the car back in line. StabiliTrak is automatic and requires no additional driver action. In most cases, the driver probably won’t even notice the helping hand from this technically sophisticated system....Unlike stability control systems from other manufacturers, Cadillac’s system maintains the driver’s ability to apply throttle in StabiliTrak maneuvers."
We generally found Stabilitrak to be, well, an incredibly useful system, in dry, wet, or snowy conditions.
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And GM's version:
http://www.gm.com/company/gmability/...abilitrak.html

[f5fstop]

Front is open, to prevent scuffing when in 4-wheel unlock driving, which the vehicle is in at all times until a lock button is pushed. The open differential allows the wheels to turn at different rates of speed while the axle continues to transmit the driving force.
Rear is not posi; relies on TCS and E-locker on certain models.
The stab and TCS work on the brakes (the description from Beastmaster is pretty good), only main difference is the algorithms internal to the controllers. If no brake switch input, and there is slippage at a wheel, the TCS takes over, if the yaw sensor detects a skid, stability control takes over, if there is a brake switch, ABS takes over, and so can stability control under some conditions. Engine may also decrease torque by retarding the timing or shutting off injectors.

[Phil H.]

Thanks!