2011 Chevrolet Volt: Suspension Walkaround
We've all been bombarded with myriad technical descriptions of the Volt's plug-in hybrid powertrain. Heck, I've burned a lot of calories on analyzing the Voltiness of the Volt myself.
In the process, precious little discussion has focused on the rest of it. Our own track testing reveals that while it's no barn-burner, the Volt does ride and handle admirably for a four-door family/commuter sedan/hatchback thingy.
But does this somewhat expensive and technically interesting
candidate for Car of the Year winner ride on a similarly advanced suspension? We pulled the wheels off to find out.
Up front, the Volt is pure MacPherson strut.
Mass reduction is always a priority when you add the weight of batteries to a car, but it is particularly nice to see mass reductions of the unsprung kind. And here we have it -- both the lower control arm (yellow) and the knuckle (green) are made of aluminum.
A reinforced plastic stabilizer link (green) trims a bit more weight. It mounts directly to the strut housing for a 1-to-1 stabilizer bar motion ratio, a setup that is usually termed a "direct-acting stabilizer bar" on product data sheets.
Meanwhile, we're not surprised to see the steering rack (yellow) acting behind the front axle centerline -- standard practice on front-drive cars.
To no one's surprise, the Volt's lower control arm (green) is of the L-shaped variety.
A closer look at the aluminum knuckle (or suspension upright, as I like to call it) reveals the pair of caliper mounting bolts (yellow) you'd need to remove when the time comes to change brake rotors. We can also see two of the three wheel bearing mounting bolts. The suspension of the Volt is, at the very least, straightforward and easy to service.
Single-piston sliding calipers (green) and ventilated cast-iron rotors handle the front braking chores. However, like all advanced hybrids and electric vehicles, most of the Volt's light braking needs are handled by reversing the current flow in electric drive motor and turning it into a generator, a process known as regenerative braking.
Because of regen braking mode, our long-term Prius went about 85,000 miles before needing its first set of new brake pads. While it is impossible to hang a specific number of miles on the Volt's front pad life, there's every reason to expect a similarly low wear rate here.
The Volt's rear suspension consists of a simple twist beam axle (yellow).
We've seen twist beam axles like this on plenty of inexpensive small cars. Technically, it's a semi-independent suspension instead of a fully independent one because one side influences the other. And while it may appear that there's no stabilizer bar, the twist beam itself is in reality one gigantic stabilizer bar with wheels on the ends, the roll stiffness of which is determined by the cross-sectional shape and stiffness of the beam that spans from one side to the other. We refer to this as an "integrated" stabilizer bar on our spec sheets.
It the Volt's case the beam is welded to cast-iron ends. The forward pivot bushings are angled so they're not parallel with the beam itself, a move that helps the bushings manage the conflicting need for high lateral stiffness during cornering and soft fore-aft compliance to absorb harsh road impacts.
The shock absorbers mount very close to the rear axle centerline for a near 1-to-1 motion ratio, though the same cannot be said for the springs, which sit closer to the forward pivot point.
A mechanical cable-operated parking brake lever (yellow) actuates the otherwise-hydraulic rear disc brake calipers.
Here's another view of the cable-operated parking brake lever (green) that shows where it resides behind the single-piston hydraulic chamber.
In addition to solid rear rotors, here we can see that the Volt has extended studs that make it easier to mount a wheel and spin the lugs on with less chance of cross-threading. These are common on recent GM models, and it's one of those simple details that we appreciate.
Actual lightweight forged aluminum wheels adorn the Volt, and they wear P215/55R17 Goodyear Assurance tires. Considering the size, the combination is pretty light -- 37.5 pounds -- which means the aluminum front suspension bits we saw earlier were not merely compensating for heavy wheels and tires.
Too bad they don't offer a lot of stick. Our track test of the Volt maxed out at 60.2 mph through the slalom cones and 0.77 g on the skidpad. Braking from 60 mph took 124 feet. None of this is bad, but it's nothing to write home about, either. That's simply what you're left with when you fit low rolling resistance tires to squeeze out as much efficiency as possible, the Volt's primary reason for existence.