QuadraSteer, what exactly is that? Any gearhead knows about QuadraTraq, it’s the 4×4 system used by Jeeps, but no one seems to know anything about QuadraSteer. Obviously, it has something to do with steering, but what’s the Quadra part? It can’t mean four-wheel steering?
We’ll, yes it does. Almost 15 years ago, General Motors offered an accessory on some of its trucks called QuadraSteer. And, yes, it allowed all four wheels to pivot while the truck was moving. Speedway Autogroup of Lansing, KS said to us that it was a pretty cool technology but it never caught on and General Motors discontinued it. Here’s the story.
QuadraSteer was a four-wheel steering system that General Motors offered as an accessory on some of their trucks in 2003. The system dramatically reduces turning radius and improves overall handling but really shined when parking. When vehicles with Quadrasteer back in and out of a parking place, they are assisted by the rear wheels, changing direction during forward motion.
The system can be set in a “towing” mode which allows the rear wheels to add more stability while pulling a trailer.
Three driving modes
Quadrasteer has three driving modes: negative, neutral and positive. Here’s how they work.
Negative – The Negative phase is used for low speed maneuvers up to 45 mph. This is where the rear wheels turn opposite to the front wheels. This phase is limited to a maximum of 12 degrees rotation at slow speeds and gradually cancels out to zero degrees at 45 mph.
Neutral – The Neutral phase is used when the driver selects front-wheel steering only, or at 45 mph in the 4-wheel steering mode.
Positive – The Positive phase begins after 45 mph and is used when the rear wheels turn in the same direction as the front wheels. This is limited to a maximum arc of 5 degrees and decreases with speed.
Four basic parts
The QuadraSteer systems sounds complex but it just has four main components.
Mode Selector Switch – The Mode Selector Switch has three positions: 2WS, 4WS and Tow. The Tow mode operates the same as the 4WS mode, except that the crossover from the negative to the positive steering phase occurs at 25 mph instead of 45 mph.
Rear Wheel Steering Control Module – The RWSCM is located above the spare tire under the truck body. It receives control signals from the powertrain control module (PCM) including speed information; steering wheel position from the handwheel position sensor; rear axle position from the rear position sensor; and vehicle directional movement from the yaw rate and lateral accelerometer sensor.
Handwheel Position Sensor – Handwheel Position Sensor is located at the base of the steering column and gives the control module exact information about steering wheel position.
Steerable Rear Axle is controlled by a rack and pinion and is driven by a three-phase electric steering gear motor. If the system fails, two powerful return springs built into the rack force the rear steering back to a neutral position.
Serviced like 4×4
Driving force in the front and rear is transmitted through quarter shafts connected to CV joints. Steering motion is conventional and is accomplished through upper and lower ball joints and tie rod ends. These do not have lubrication fittings. The rear axle has both a drain and a fill plug and both are accessible without removal of any Quadrasteer component. Synthetic lubricant is used with a capacity of approximately three liters.
General Motors discontinued the QuadraSteer option after just a few years of sales. The reason had nothing to do with its functioning and reliability. It was a very expensive option and resulted in few sales. The brass at GM simply decided to phase in out.
Earthgarage – Greener Car. Fatter Wallet.