It’s safe to say that 1980s nostalgia is still going strong, and one piece of automotive tech popular towards the end of that decade is experiencing a renaissance. Four-wheel-steering may have made its debut on the 1985 Nissan Skyline, spread throughout the industry as a curiosity, and vanished, but now it’s back in everything from sports cars to pickup trucks. Porsches have had it for years, the Tesla Cybertruck famously has four-wheel-steering, as does the GMC Hummer EV, as will the Chevrolet Silverado EV. However, four-wheel-steering on pickup trucks is older than you’d expect. Arguably the best four-wheel-steering setup on a pickup truck went on sale 22 years ago, and while it worked incredibly well, it was a colossal sales failure. I’m talking about Quadrasteer, the holy grail of GM truck tech.
If you’ve never heard of Quadrasteer, you aren’t alone. See, General Motors has always been an innovative company, it just hasn’t always known what to do with its innovations. The electronic trip computer, pioneered by the 1978 Cadillac Seville, quickly spread throughout the industry. The cathode ray touchscreen in the 1986 Buick Riviera? Not so much. Quadrasteer, available from 2002 to 2005 on half-ton and three-quarter-ton Chevrolet and GMC pickup trucks and long-wheelbase full-size SUVs, falls firmly in the latter camp. Oh, and it’s not on an independent rear suspension setup, making it an outlier among four-wheel-steering systems on production pickup trucks.
In short, there’s an electric power steering rack built into the rear differential cover:
How did GM make the ends of a leaf-sprung solid axle rotate around z axes? The same way Jeep makes the current Wrangler’s solid front axle steer — by adding steering knuckles and ball joints.
As for how power gets sent to steer-able wheels, well, the axle shafts have constant velocity joints just like your front-wheel drive car does:
Here’s a nice diagram of the system (with a few bits removed for clarity):
As you’d expect from a steered axle, toe was controlled by tie rods, each connected to a knuckle at one end and the diff cover-mounted rack at the other (you can see the tie rods labeled in the yellow and gray image a few pictures up).
But instead of a splined input shaft hooked to an intermediate shaft that you turn with your steering wheel, this steering rack featured an electric motor with a planetary gearset to multiply torque, and a pinion gear to act on the rack. By varying the position of the motor, GM could vary the rear wheel steering entirely electronically. Yep, it’s steer-by-wire back there.
The steer-by-wire rear axle was controlled by a Delphi-engineered module tucked underneath the bed that took input from the steering angle sensor (which measures the angle the driver has the steering wheel pointed), the vehicle speed sensor (measures how fast the truck is going), an insanely expensive rear steering rack-mounted rear wheel position sensor (which is basically the rear steering angle sensor) with splines to connect to the motor, a dashboard-mounted mode switch, and a serial data line. It also accepted yaw sensor input on early examples, but that was phased out for 2004.
In the grand scheme of things, that Delphi module doesn’t use a ton of inputs, but that makes sense when you consider how Quadrasteer had fairly simple logic that went as follows:
- Below 45 mph, the rear wheels would turn in the opposite direction of the fronts.
- At 45 mph, the Quadrasteer system would be in a transitory, neutral state, and the truck would drive like normal. Coincidentally, this was also the failsafe mode for the system, fulfilled using a shorting relay.
- Above 45 mph, the rear wheels would turn in the same direction as the front wheels.
- In reverse or park, rear-wheel-steering is limited to 5 degrees.
Thanks to huge rear wheel wells and little encumbrance, the rear wheels on a Quadrasteer truck could turn up to 12 degrees — two degrees more than Tesla claims the Cybertruck will be able to do with a promised eventual software update, and nine degrees more than what the Cybertruck is currently capable of. Maximum steering angle only kicked in at or below seven mph, which sounds like a limitation but works perfectly in parking lots.
Oh, and that absolutely enormous maximum rear steering angle had huge parking lot benefits. With the rear wheels turned 12 degrees in the opposite direction to the front wheels, the turning circle of a half-ton pickup truck would shrink down to just 37.4 feet. That’s circle, not radius. General Motors loved to brag about how a GMT800 with Quadrasteer had the same turning circle as a Saturn S-series sedan because it was 1) Amazing, and 2) True.
In tow mode, the maximum rear steering angle shrunk and behavior was slightly altered, but the biggest effect Quadrasteer had on towing was stability. Back in the day, Car And Driver had the opportunity to put the system through an emergency lane change maneuver with a trailer hooked up and reported a surprising result.
While towing a 7000-pound camper trailer at 60 mph in two-wheel-steer mode, we were instructed by Lorraine Babiar, the Sierra assistant brand manager, to do something that was farthest from our minds at the moment: Make a lane-change maneuver. We obliged, and as expected, jerking the steering wheel hard to the left and then to the right sent the trailer wagging so violently that we were sure the next stop on the itinerary was the nearby ditch. Somehow we stayed on the road. Next we performed the same test with Quadrasteer in the four-wheel-steer tow mode, and the trailer obediently followed the truck without any dangerous oscillations. With the trailer unhitched, we didn’t detect any twitchy behavior, either. Very neat.
So, not only did Quadrasteer make a half-ton GM truck easier to maneuver in tight spaces, it also made it safer while towing. Talk about killing two birds with one stone. With Quadrasteer, General Motors had finally made the USDA Prime half-ton truck work just about everywhere, so can you guess what happened? Yep, nobody bought it.
Oh, but it’s easy to see why. In GM’s hubris, the inaugural 2002 year of Quadrasteer saw the option bundled into a $7,000 package. I repeat, $7,000 in 2002 money. If you walked onto a Daewoo lot at the end of a month in 2002, you probably could’ve rolled off the lot in an entire ex-demonstrator Lanos for $7,000. Is Quadrasteer cooler than a Daewoo Lanos? Nobody’s ever made that comparison before, but it all depends on whether or not you’ve seen “Pineapple Express”.
For 2003, GM’s accountants separated Quadrasteer as an option with Mr. Trailer reporting that the price of adding Quadrasteer stood at $4,995 in 2003. That wasn’t enough, so the bean counters went into price-slashing mode and dropped the cost of the option to just $1,995 in 2004. It was too late, though. Dealers who couldn’t shift expensive Quadrasteer-equipped ’03s likely didn’t have much of a reason to stock Quadrasteer-equipped ’04s, so this nifty technology became a case of “if you know, you know.” By the end of 2005, GM had pulled the plug, and four-wheel-steering on a pickup truck was dead until the latest wave of electric haulers.
Total production? About 20,000 trucks and SUVs with Quadrasteer. While that would be wildly successful if we were talking about a Lotus or a car made entirely of peanut butter, we’re talking about half-ton GM trucks and SUVs, the heartbeat of America, baby. Forget by-the-truckload, these trucks sold by the trainload, and 20,000 is a drop in the bucket.
General Motors can take as much credit for implementing it as blame for killing it. If Quadrasteer were cheaper, it could’ve caught on. American consumers are generally price-sensitive, and if they’ve done fine without newfangled technology for decades, they might just turn up their noses if said tech is too expensive. Still, we love that Quadrasteer exists, and we love that a dedicated cadre of enthusiasts is keeping the legend alive today, by maintaining and enjoying their Quadrasteer trucks.
Oh, and if you’re looking to quickly spot a GMC Sierra, Chevrolet Silverado, GMC Yukon XL, or Chevrolet Suburban with Quadrasteer in the wild, the easiest tell-tale is a set of flared rear fenders with clearance lights. Due to needing extra room for the rear wheels to turn, GM installed wider rear fenders on trucks (flares on SUVs) that added two inches to the width of a standard GM truck, pushing it over the legal threshold for vehicles without clearance lights. The more you know.
(Photo credits: GM, eBay sellers)
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If I remember correctly, these also came with composite material beds.
Correct, the bed sides are fiberglass.
I don’t think the article mentioned this so I’ll go ahead and throw this automotive minutia out there. If memory serves, Quadrasteer was released on the GMC Sierra C3, which was marketed as their top of the line full zoot, big baller model. It only lasted a couple of years and was quickly rechristened the Denali, which we all know today.
I never knew the suburbans had quadrasteer as an option. I think I’ve only ever seen 1 Sierra Denali with the option. The wider pickup bed is an easy tell.
I’m certain I saw a rear-steer pickup or two earlier than this. Early-mid 70s? They were fleet trucks, for a lumber company. Or was it the Forest Service? I assume they were modified by a third party outfitter. I remember first not believing what I was seeing, then wondering how it worked. About the same time I saw my first pickup with the gizmos for running on railroad tracks.
Years ago, a co-worker bought a 1500 Sierra Denali with the quadrasteer option. He let me drive it and when in regular steer mode I could not make a u-turn in a parking lot without backing up. With quadrasteer activated, I was able to make the same u-turn with plenty of room to spare. I found it most impressive and have always been fond of the Q-steer GM trucks. If memory serves me correct, in a Suburban or Yukon XL it was only available on the 8 lug 2500 series. I don’t believe it was available as an option on the Tahoe or regular Yukon.
After my dad’s 2500 was lost to a freak snowstorm accident, we went searching for another crew cab. We found a deal on the quadrasteer crew cab that we wound up with. It was awesome to park a truck like it were a Corolla!!! (In terms of maneuverability, not size of course) I remember we replaced the front steering gear box at one point, and somehow the steering wheel had gotten spun around, causing an issue with the aforementioned steering position sensor. When we went to test drive it after we put it all back together, the truck immediately went full crab walk with the rear steer locked opposite the steering wheel. (When it sensed an issue like that it would lockout and go back to straight). The other awesome benefit of those quadrasteer trucks is they were all 1500HD, which meant they got 6.0l motors instead of the 5.3, but retained the lighter frame of the 1500, making for something that was great at towing for our needs. If rust hadn’t started to get to it, we’d likely still have it today.
They did get the 6.0, but there was a 1500HD quadrasteer; about as rare as the QS Suburban.
In the later years, 2003-05 you could get the Silverado with the 5.3 and Quadrasteer. It was a $1195 option.
Mazda did this in the 626, and it was on the cover of C&D. We had a guy at work that had one, who would crank the wheel all the way in one direction and the rear would tilt out. One always did a double take.
I always thought it was funny that these vehicles were the “first” GM product to have both steer by wire and electric power steering
For more perspective on the $7000 price tag… In 2002, you could walk into your Chevy dealer and order a half-ton Silverado RCSB, in Work Truck trim, with a 4.3 V-6 and a 5-speed stick. It would have had an MSRP of $17,168, and you might have negotiated 5-10% off. So yeah, $7000 seems like an expensive package.
One of my favorite custom builds of all time is on a rear steer chassis with a 6.0L. Its a custom built crew cab ’71 or so Chevy truck, 2wd. The guy narrowed the axle some, but kept the rear steer. He never complained it rubbed the frame, so I’m guessing his tire size meant he never saw the possible interference that narrowing could have created.
Back when gas hit $4.00 in 2007, new and used Sierra Denali’s and C3’s with the 6.0l were dirt cheap. I had my heart set on an 02 Denali with the Quadrasteer. At that point, used was still commanding a $3000 for the Quadrasteer option.
I followed one the Quadrasteers in a rain storm one day as I was close to buying, and it is 100% as advertised. What broke me was difference in width between the front and rear axles. The gap was the entire width of the tire. That got me thinking about how it would handle in the snow here in the Midwest, and that made me no longer want one.
Ended up finding an 01 Sierra C3 with low miles, and bought it. No regrets on the decision, and we still have it 16 years later. It’s very comfortable, and goes like hell. Whenever we take it out, people ask what the C3 on the tailgate means.
Was the track difference only a quadrasteer thing?
Yep. On the Quadrasteer the front wheel track was 3.5″ narrower then the rear wheel track. The first time you see the wheel track in rain or snow, it’s hard for your mind to come back from that when you see it!
Same thing when you look at a GMT-400 3/4 ton 4×4. The front track on those is 3″ wider then the back. 😉
Comparing the turning radius to a Saturn S-series is hilarious since the Saturn S-series have a horrible turning radius for such a small vehicle.
A Saturn S-series will have to three or more point a turn that larger vehicles take with ease, even without four wheel steering.
If you were around and able to watch a TV or read a magazine when it came out, you definitely knew about Quadrasteer. There was a huge marketing push for it. I am willing to bet I saw more ads for it than I ever saw individual trucks with it in real life though. You could always easily spot it since the rear fenders bulged out a bit to accommodate it. That’s how you knew you found the rich truck guy, checked all of the boxes for extras.
I wonder how many people went to a GM dealer wanting to check out the Quadrasteer trucks, say the price and said, “Hell, no!”… only to drive away in a new Chevy or GMC sans Quadrasteer.
There’s a bright red, completely mint, low-mileage Suburban that shows up occasionally on very nice days in the parking lot of the building I work in. The guy who owns it is also has a low-mileage 1996 Impala SS and one of the nicest restored 1959 Impalas I’ve ever seen.
I’ve talked to the owner on several occasions and one of the best things about his truck is that it is still completely functional, even if it had to sit in the shop for for a few weeks on at least one occasion. As noted elsewhere in the comments, parts availability for this system is not great.
I remember test driving a used (2006 timing) Silverado with this. It was pretty cool to test it out and the difference was really obvious. Even I knew at the time though that it was a risky proposition as far as durability.
Yeah, Quadrasteer is cool 😀
GM had said the last price of $2000 was below cost.
In the uppermost ad, the asterisk/disclaimer at lower right notes that ‘Lamborghini’ and their model names are registered trademarks, etc. Is this because the full ad references a Lamborghini? I can’t find any connection in a quick search. What’s going on there?
They may have compared the turning radius to a Saturn at some point, but the comparison I remember best in early aughts print mag ads was to a Diablo.
You may have just answered my above question. Unfortunately, there apparently was a tune called Diablo, so the search is complicated. Random rabbit-hole hell 😉
These were awesome, and I’d love one if certain parts were not unobtainable.
Back when these were new, a neighbor had one, and it was incredible to watch how easily he could park his trailer in the tight spot open for it. He was the worst neighbor I’ve ever had, but his truck was awesome.
I remember when Quadrasteer came out, and feeling perplexed over it not catching on. Trapping it behind an expensive option package paywall, like it was a paint color other than grayscale, explains that
I would do inappropriate things for a 2500 LBZ-Swapped Quadrasteer Suburban. Ultimate dad car.
One of my best friends will help you do those things. His desire for a an LBZ Suburban approaches discomfort for the rest of us.
If you drive to Iowa you only need to do $22k worth of things to make this dream a reality: https://www.facebook.com/marketplace/item/1390118818346837/
I have read that there is one weakness to this system. The rear wheel position sensor is no longer made, and finding a used one is a crap shoot. Once it dies, you obviously only have two wheel steering, but one place I read says that not only will you lose 4WS, you can lose 4WD. That may not be true, as I’ve not seen it anywhere else.
You still maintain 4WD no matter what. The transfer case was full-time AWD with no low range, like the Olds Bravada or higher trim GMC Envoy. The transfer case would automatically to a maximum of 70% rear and 30% front.
There is a company that makes them now. I forget the name but I have an 03 and looked in to the sensor replacement when I got it.
I have seen two in the wild- both had been de-activated due to the cost of parts sadly
My dad had this on one of his older trucks. I’m willing to bet he rubbed shoulders with some of the engineers that helped design it. It was extremely cool. He and I are both extremely sad to see that it didn’t catch on.
The Quadrasteer trucks remind me of the Sierra C3, which predated the Quadrasteer by one year. C3, of course, became Denali in 2002, and while Quadrasteer was a sales flop, Denali has been a success. Both show the hit-and-miss nature of GM’s innovations, be they engineering or marketing.