The Colorado ZR2 Bison has a high-tech suspension. This is how it works

Multimatic has been making suspension components since I was born – literally since 1984. And they’ve done a damn good job. Red Bull won four consecutive Formula 1 titles using Multimatic’s Dynamic Suspensions Spool Valve (DSSV) dampers. Five major racing series have since adopted them as standard. And today, DSSV dampers can be found in production cars from Maranello to ‘Merica – in this case, the Chevrolet Colorado ZR2 Bison.

Believe it or not, the Colorado ZR2 was the first off-road vehicle to use Multimatic’s DSSV shocks in 2017. Before that, they were reserved for sports cars. The Bison brings 12.2 inches of ground clearance and 35-inch off-road tires to the mix. Chevy engineers put everything into this ZR2 to make it the meanest, strongest, most capable truck in its class – DSSVs included.

The shock absorbers here basically work the same way they do in sports cars: a pair of spring-loaded control valves are pushed through a chamber filled with pressurized hydraulic fluid, while adjustable orifices control the rate of oil flow. However, to account for the massive hits that the ZR2’s suspension regularly takes in off-road use, Multimatic has made some tweaks.

The biggest change is the bump stop, which is exclusive to the Bison model. Instead of the traditional rubber bump stops that release as much force as they absorb, the Bison has special hydraulic bump stops that control the rebound – Multimatic has coined the term “Jounce Control”.

Simply put, these shocks absorb more and disperse less. Say you’re driving through the Mojave Desert at 40 miles per hour and you hit a giant rock. Instead of taking a violent smack on your butt and shaking the truck’s suspension, as can happen with some weaker shocks, the hydraulic bump stops absorb all of the pressure and redirect less of it back through the wheel on rebound.

When we say that an off-road vehicle “soaks up” bumps, we mean it almost literally.

Ford uses similar suspension technology on the Ranger Raptor, although it’s not as advanced. The ubiquitous Fox internal-bypass shocks feature adaptive damping in compression with a clever valving system that channels fluid more freely through the shocks. It’s closer to the setup found in the standard ZR2.

But Fox’s hydraulics are rebound-focused (at least on the Ranger; the F-150 Raptor R has new dual-live-valve shocks) and the shocks still have traditional rubber bumpers. Both of these result in less control than the Bison during high-speed desert driving, at least in theory.

Robert Teseo, vehicle dynamics engineer at Multimatic’s technical center, explains the basics well.

“We want something that can withstand all the aggressive conditions of off-road driving, so it can stay in control and withstand all the stresses that come with it,” he notes. “But we also don’t want to compromise on-road handling or comfort.”

To achieve this, Multimatic pursued four main objectives when manufacturing its DSSV dampers and hydraulic bump stops for off-road use:

• Minimize body movement
• Reduce the cycle path
• Reduce peak loads on tires and frames
• Increase energy dissipation

The first two principles are obvious when you take the truck out on a trail. The ZR2 Bison doesn’t have as much suspension travel as other off-road vehicles — some would describe it as “stiff” at lower speeds. But this truck was designed for fast off-roading, jumping over rocks and dirt like a jet ski on a still lake. It takes a really hard bump to upset the truck’s chassis.

This comfort extends to the road, too. The suspension soaks up broken asphalt as quickly as it does rocky roads, and is barely affected by speed bumps. The only detriment to ride quality (and cabin noise) comes from the huge tires – but that’s not unexpected for an off-road vehicle of this caliber.

However, the ZR2 Bison has more to offer than just the suspension.

Speaking of tires, they’re ridiculous. They’re about two inches taller than the already massive 33-inch tires on the regular ZR2, and 1.2 inches thicker. Chevy actually had to move the front axle forward a bit and shift the offset outward by nearly an inch to accommodate the new rubber. The tires raise the ride height from 10.7 inches to 12.2 inches and increase the truck’s overall width by 2.1 inches. They’re also wrapped around 17-inch beadlock rims designed specifically for the Bison.

The engine is the only area where I think the ZR2 Bison could use more. It’s the same turbocharged 2.7-liter four-cylinder found in all other versions of the Colorado, and here it makes 310 horsepower and 590 Nm of torque.

Is it underpowered? Not necessarily. The four-cylinder has more than enough power to pull the ZR2 out of a pit at a decent speed. On the highway, it shows some signs of trouble, but still has more power than some of the naturally aspirated six-cylinder engines in other trucks.

After a week of driving, I’d say Chevrolet has achieved its goal. With Multimatic’s clever “Jounce Control” technology and a wealth of off-road equipment unusual for this segment, the Colorado ZR2 Bison is by far the most capable midsize truck in the world. But don’t tell that to the good folks at Ford.