VUE awd - rwd

[Roundthirteen]

Ok my parents have a 2003 VUE AWD V6 and I was curious as to if their is a site that explains how it works. All I know is I hit some snow and peg it and I get some noise out of the back and the rear wheels spin. I don't know if there is a transfer case or if it is electric???? How does the system work? This is a new deal to me seeing my fiance's VUE is a FWD V6 and I have a S-series which is pretty cut and dry, even with my mountains of mods.

[MrHorspwer]

The AWD system in your early (pre-2008) Vue is a single gerotor AWD system. It operates based on rotational speed differences between the propellor shaft and the rear drive axles.

At the transmission output, there is a PTO (some may call it a transfer case) which applies power to both the prop shaft and the front drive axles. During normal driving conditions, the prop shaft receives power, but the rear axle is physically disengaged.

When front wheel slip occurs, the prop shaft begins spinning faster than the rear drive axles. This speed differential causes the gerotor pump to spin, creating fluid pressure. This fluid pressure is used to apply a clutch pack which will connect the properlly shaft to the rear differential, sending power to the rear drive axles.

[1saxman]

Excellent description! May I add that it is a totally automatic and completely mechanical system. No switches, levers, vacuum lines or electrical connections. In addition, it's a simplified version of GM's Versatrak and is in reality simply rear wheel drive assist to the front wheel drive, only activating when the front wheels slip and immediately disengaging when front and rear axle speeds synchronize. It's really a very elegant solution.

[MrHorspwer]

it's a simplified version of GM's Versatrak

To expound on this statement...

Versatrak is a twin gerotor type AWD system. Instead of using a single gerotor pump on the input to the rear differential, Versatrak uses two gerotors, one at each output to the drive axles. This allows control of each rear drive axle independtly of the other, acting much like a limited slip differential, though still only engaging when needed. This makes Versatrak more capable than the open differential design used in the Vue, at the expense of cost and complexity.

[1saxman]

The Buick Rendevous is the only vehicle I know that has the 'real' Versatrak, although I wouldn't doubt there are more. It's a nice system, as is the 'plain' version in the old VUE, although I liked the original calibration on my '03. My RDM was replaced under warranty for moisture damage/noise (moisture apparently got into the 'drum' when the unit was improperly stored prior to assembly) and I got the new calibration which allows more wheel spin before engaging. I'd be willing to bet it's nothing more than a stiffer spring in a ball check that could be put back the way it's supposed to be. The problem they encountered was abuse by the owners consisting of spinning the wheels on dry pavement and trying to 'drift' around corners. Yes, that'll break it. You can use your Jeep part-time 4WD on the highway and break that too. The designers just never contemplated deliberate abuse of a system that was designed to get the VUE moving on slippery/loose surfaces then disengage.

[MrHorspwer]

The Buick Rendevous is the only vehicle I know that has the 'real' Versatrak

The Rendevous, Aztek, and all of the minivans (Venture/Uplander, Montana/Montana SV6, Terraza, and Relay) received the Versatrak system.