Quadra-Steer

[mcali17]

I have driven the 2003 GMC Sierra Denali with Quadrasteer. I snowplow, and I see where having this incredibly tight turning radius would be helpful.  The turning radius is reduced by 10 feet and trailering at highway and slow speeds is supposed to be much easier with this system, especially when backing up. The truck can even "crawl" sideways.

 

Quadrasteer is slowly going to be introduced into the GMC and Chevy Pickup Lines and most likely will find its way into the Denali, Yukon, Suburban and Tahoe lines as well.

 

What do you guys think about Quadrasteer. As I know the Sierra Denali's are not exactly selling like Hotcakes.

[nonstop]

no thanks, no way. Not with the generals track record on stupid things that can go wrong. This is just one more, or however many extra parts are involved that could go wrong.

 

I'll pass, give me the solid rear end.

[Tucson_02Silverado]

GM needs to narrow back the rear track and go four wheel independent suspension like on the H1.  The current rear hangs to low for even moderate/light trails that 2WS trucks have no problems with.  Otherwise great execution thus far, but I would wait for it to prove it's length of service.

 

I have actually had a chance to test drive the 03 crew cab SWB version and boy does it swing it nice and straight into some tight parking spaces at the mall without even one reverse and back in the space manuever.

[TxDoc]

Drove one...ordered one...will be here soon!

[Stepside Z]

If I had the extra money to spend I would go for it.

[MarkD]

The Denali trucks are priced out of the market, so they don't sell well.

 

I would LOVE to have the maneuverability.  That is hte one thing I would change about my truck. (and the reason I sold my '98 RAM 4-door).

[GnatGoSplat]

#### yeah!!!

 

I don't like the styling on the bed, I think the rear-end should have been narrowed or at least they could have made the rear wheel wells bulge out gently instead of sharply.  However, I'd take one in a heartbeat.

[sk]

Just clarification on a couple of points:

 

- mcali17 said "The truck can even "crawl" sideways."  That's true, but it can only do this above 40 to 45 mph, so it's not really "crawling".  This feature enhances trailer stability and reduces trailer sway at higher speeds.

 

- As far as it making it's way into the GM SUV's, it already has.  For 2003 it is available on the 3/4-ton Yukon XL/Suburban.

 

- Concerning the rear track:  The wheel wells need extra space for the turning of the rear tires.  GM could have either moved the wheels out (wider track) or moved the wheel wells closer together (same track as a truck w/o QS).  If they had moved the wheel wells closer together you wouldn't be able to get a 4'x8' sheet of <anything> in between the wheel wells in the bed (this dimension is currently 50" on the Silverado/Sierra).

 

For anyone who has driven a truck with this, QuadraSteer is amazing.  Of course the smaller turning radius is important, but where QS really shines is when you are towing with it engaged.  If anyone gets a chance to test it like this do it -- you won't be dissappointed.

 

TxDoc:

 

Did you know that Delphi actually has a screensaver out for Quadrasteer?  It's not that great, but you can check it out at: http://delphiauto.com/automotive/handling/...ng/quadrasteer/

 

 

Scott

[mcali17]

Just clarification on a couple of points:

 

- mcali17 said "The truck can even "crawl" sideways."  That's true, but it can only do this above 40 to 45 mph, so it's not really "crawling".  This feature enhances trailer stability and reduces trailer sway at higher speeds.

SK Not to trying to be a jerk or anything but the crawling feature is absolutely true!!! You can make the truck crawl sideways from a dead stop. At highway speeds the rear wheels turn with the front, to assist when making lane changes when trailering etc.. like you said.

 

However, from a stop, lets say you have a camper attached, you are parked along another truck and camper to  your left, but you want to pull past what is to your left and make a left turn to exit a campsite. With Quadrasteer, you crank your steering wheel right and put one foot on the brake and press the accelerator. The rear wheels will pivot to the right. You can then let off of the brake, and drive slowly to your right.  I guess I should have really called in "Crabbing" and not "crawling." I belive that is the term that GMC uses, my fault.

Once you are far enough away from the vehicle on you left, you can pull forward and make your left turn, without cliping the front of what is next to you with your camper or whatever.

 

So, it is even better than you thought.   :thumb:

[Shotgun]

I think it would be good for a pimping truck,but not for anything heavy duty hauling any kind of weight or load......Gun

[TxDoc]

A question and some info for thought.

 

I have never seen any published information saying that putting your foot on the brake....and the wheels turn in the same direction while sitting still.  Everything I have read and the truck I saw performed as described earlier and below:

 

"At low speeds the rear wheels turn in the opposite, or negative, direction of the front wheels up to a transition zone of around 40 to 45 mph where the rear wheels track neutrally. At speeds over 45 mph the rear wheels turn in concert, or positively, with the front"

 

I would be interested to read the source of the info about turning the same direction while stopped--thanks

 

 

 

Regarding towing-Denali is the reference:

 

"The rear axle's weight rating increases by 250 pounds to 4000 pounds and maximum GCWR (gross combined weight rating) climbs from 14000 to 16000 pounds. Trailering capacity has increased from 8700 pounds to 10000 pounds. The wider rear axle also provides more stability when towing."

 

and--"Trailer towing becomes much easier with Quadrasteer engaged. The Sierra Denali's pivot point shifts from the front to the rear wheels providing more maneuverability

 

We took the Sierra Denali out first-hand to test drive the Quadrasteer's towing and trailer-free capabilities.

 

The first Sierra Denali we drove came with a 30-foot, 7500 pound trailer attached for a GCWR of 14500 pounds.

 

GMC engineer Gene Rodden took us out to a closed course, marked with cones, to test out Quadrasteer's maneuverability. Attempting to tow in 2WS mode quickly demonstrated how challenging towing can be and the large amount of attentiveness required by the driver to clearances, the length of both vehicles and placement of the trailer axle. Needless to say the course was not optimized for 2WS trailer towing resulting in the senseless mutilation of multiple orange traffic cones.

 

Switching to 4WS TOW mode to run the same course again, Quadrasteer provided a clear improvement in maneuverability, measurably improving the driver's level of confidence and margin of error in moving the trailer around and meeting clearances in corners. The cones were also a lot happier.

 

An interesting demonstration of rear wheel movement was shown in response to increased throttle while holding the brake on. Quadrasteer is also sensitive to throttle response not steering alone. 4WS TOW angles ranged from 7 degrees, increasing to 12 with full lock for low speed maneuvers. Reversing the truck lowered the tolerances and reduced the steering angles available for maneuvering the truck. Not that it was a rally course, but rounding the cones at a decent clip seemed to make trailering easier than maneuvering at very low speeds.

 

We left the trailer course to make our way to Highway 52 outside San Diego.

 

Navigating surface streets with the trailer and heavy morning commuter traffic proved to be quite easy with Quadrasteer. When making right turns you could actually keep the Denali in the right lane of the street you had just turned onto. No more wide turns into the middle or left lanes. And when making U-turns the only word that came to mind is amazing. We made a U-turn onto a three lane road and were easily able to make the middle lane towing the 30-foot trailer!

 

On the freeway Quadrasteer shined again. Lane changes at 60 mph were seamless. The synchronized movement of the front and rear wheels at these speeds reduced the articulation angle between the Sierra and trailer. Reduced side forces acting on the trailer made the entire platform more stable.

 

If you didn't know you were towing a trailer and looked in the rearview mirror, you would think someone was tailgating.

 

Rodden remarked that during separate road testing on highways in high wind conditions in 4WS TOW mode the truck / trailer combo was also much more stable than in standard 2WS mode."

 

And, one other towing tidbit:

 

"the Quadrasteer  truck and requires a beefier 9.5" rear axle, as opposed to the 8.5" rear axle normally found on GM's conventionally steered trucks."  

"In durability testing GM claims to have found no unusual wear or tear on the QuadraSteer's rear joints even after towing heavy loads for extended periods."

 

 

Trailering safety:

"Towing performance is also significantly enhanced at higher speeds. To quote the Delphi official press release at length:

 

 

At high speeds, trailering stability is significantly enhanced. The positive rear steering reduces the articulation angle between the vehicle and trailer, which reduces the lateral forces applied to the rear of the vehicle by the trailer. This, in turn, reduces the yaw velocity gain and increases yaw damping of the vehicle and the trailer system. The net result is increased trailering stability, reduced trailer sway, and reduced driver corrective steering to external disturbances such as wind gusts, semi-truck passing, and road inputs.

As if that weren't enough, Delphi claims that Quadrasteer also aids trailering performance in medium- and low-speed situations as well. For instance, the company claims that "during low-speed, negative-phase towing maneuvers, the trailer follows the true vehicle path much more closely than with two-wheel steering." Makes sense to us. Also, when backing in a trailer, the negative phase improves steering input, making it easier to put the trailer into position.

 

We noted that the Delphi press materials did not specifically address the SUV rollover issue that has been so much in the news the last few years, so we contacted the manufacturer to follow up on this. It seemed to us, on first impression, that Quadrasteer could be a potential ally in the fight against sport-utility rollover. Although we found Delphi's response somewhat guarded, the company did prepare a special statement for this article, which follows:

 

Delphi's Quadrasteer Four-Wheel Steering System increases vehicle stability, especially during high-speed maneuvers such as passing another vehicle or changing lanes. By steering the rear wheels in the same direction as the front wheels, Quadrasteer reduces the degree of vehicle yaw, or rotational motion, required to accomplish a maneuver, thus stabilizing the vehicle. Although other factors contribute to rollover conditions, Quadrasteer may help reduce the potential for rollover by providing added stability while driving at normal highway speeds."

[Shotgun]

HMMMMMMMMMMM!

[blacksab2]

I cant find a good alignment shop as it is let alone have them do a 4 wheel steering truck!....hahaha

[mcali17]

A question and some info for thought.

 

I have never seen any published information saying that putting your foot on the brake....and the wheels turn in the same direction while sitting still.  Everything I have read and the truck I saw performed as described earlier and below:

 

"At low speeds the rear wheels turn in the opposite, or negative, direction of the front wheels up to a transition zone of around 40 to 45 mph where the rear wheels track neutrally. At speeds over 45 mph the rear wheels turn in concert, or positively, with the front"

 

I would be interested to read the source of the info about turning the same direction while stopped--thanks

Well, once source was the 30 min infomercial that GMC did last fall and through the winter on all there 2002 Vehicles. Did anyone else happen to see it? I also belive it is in the owners manual. And also, I actually did it with the truck and it works. But I will see if I can find you a link to an arcticle.

[Stepside Z]

I think I remember reading GM uses a DANA 60 rear axle for quadrasteer trucks. That is a hole lot better then what comes on regular 1500s.