The pull of magnetic ride: how to transform an SUV

Hey there, time traveller!
This article was published 30/01/2015 (3932 days ago), so information in it may no longer be current.

The GMC Yukon began life as, essentially, a warmed-over Sierra, which was essentially a warmed-over Chevy Silverado, with an SUV body.

If you drove the Sierra in those days, you knew exactly how the Yukon would feel. Your hands would fall to the exact same spaces on the dash to manipulate the exact same controls and the Yukon’s ride and handling was also a near carbon copy of the truck.

In other words, if the truck kicked out over washboard, the Yukon would, too. If a bump sent a shiver through the body of the Sierra, the same shiver would appear in Yukon.

Much of that has changed over the years, and it’s perhaps most evident in the all-new 2015 Yukon.

Aside from all the other changes to Yukon, which now shares zero body parts with the truck, and uses an entirely different interior design as well, perhaps the most-interesting change has been the addition of the third generation of General Motors’ magnetic ride control.

We first saw magnetic ride control on Z06 versions of the Chevrolet Corvette, and it’s since migrated to Cadillac and now to the GMC Yukon Denali. (It is, by the way, also available on the Sierra Denali.)

Magnetic ride control essentially uses a fluid in the shock absorbers with iron particles that align in the presence of a magnetic field to stiffen the fluid. The greater the magnetic field, the stiffer the fluid. The same particles fall out of alignment when the magnetic field is removed, returning the fluid to its original viscosity.

By changing the viscosity of the fluid, the system changes how much the shock absorbers allow the wheels to move up and down. At crawling speeds, the wheels can move to their maximum articulation for the best traction, particularly on a bumpy trail. At higher speeds, keeping the wheels from finding the bottom of every little bump and every little valley of washboard road greatly helps stability.

Craig Couch, product manager for the Yukon and Yukon Denali for GM Canada, said the third generation of magnetic ride control has increased the number of sensors, doubled the number of magnetic coils and increased the frequency at which the system samples sensors and responds to sensor signals, allowing for much greater control over the shock fluid viscosity and much faster response times.

“The way it works, it’s actually a rheological fluid, and that’s shock fluid that has some iron in it, and then we wrap the shock with magnetic coils,” Couch said. “We can energize that magnet instantaneously on, off, or to any degree necessary to adjust for body pitch, roll or to adjust for potholes in the road.

“We use that technology on Corvette and some of our sports cars and to employ that on a sport-utility really improves the ride and handling of the higher centre-of-gravity vehicles.”

GM says the magnetic ride control system reads the road conditions every 1/1000th of a second and can trigger a change in shock fluid viscosity in as little as five milliseconds. To put that into perspective, take the amount of time it takes you to read aloud the word “milliseconds”, divide that by 1,000 and multiply by five. So essentially, it would happen before you got about halfway through forming the “m” in milliseconds.

Couch said that allows magnetic ride control to hold the wheel in suspension longer over a bump, which accomplishes two things: It transmits less of the bump to the body and therefore the interior and prevents the wheel from bottoming out, such as in a pothole, which reduces the amount of downward wheel movement and helps mitigate impact coming out of the pothole.

That’s exactly what we noted when driving the Yukon and Yukon Denali over rough sub-arctic highways and gravel roads between Whitehorse and Dawson City in the Yukon Territories.

First off, the magnetic ride control really reduced the “trucky” feel of the Yukon, to the point my driving partner and I both commented on how much smaller the vehicle feels on the road than what it is. It was actually a surprise to get out after an hour’s drive and realize once again we were driving one of the largest SUVs on the market.

Where the magnetic ride control really shone, however, was on rough gravel leading up to a local gold mine. We experienced both the Yukon SLT, without magnetic ride, and the Yukon Denali, with magnetic ride, and the difference was extreme. Without the magnetic ride control, we were very conscious not only of increased body shake on bumps and body roll in corners, washboard gravel provided a few unexpected sphincter moments when the rear end started to walk out.

Such was much more controlled and far less prevalent with the Denali. At one point, we were driving an SLT behind a Denali and, while both drivers are experienced, capable drivers, we just couldn’t keep up to the Denali without throwing caution to the wind.

The bump from SLT to Denali is about $13k, and it includes a jump to the 6.2-litre V-8, HID projector headlamps, an eight-inch customizable display inside the instrument cluster, an eight-inch display for the touch-screen radio and navigation and active noise control in addition to the magnetic ride control.

If you’re on the fence about springing for the top-line Denali, the magnetic ride control might be the clincher. Drive both an SLT and a Denali and find the meanest, roughest gravel road you can and compare how they respond.