2010 Chevrolet Traverse: Suspension Walkaround
July 07, 2010
You never got to see the Lambda-platform underpinnings of the 2008 Buick Enclave we used to have in the fleet because, at that point, I hadn't yet begun my suspension walkaround series.
No problem. Our 2010 Chevrolet Traverse gives us another chance because it also rides on the same Lambda platform, as do the GMC Acadia and discontinued Saturn Outlook. And prototype examples of a yet-to-be-released Cadillac Lambda SUV are almost certainly running around behind the fences of GM's various proving grounds.
All of this means the Lambda platform is still very relevant. Let's have a look.
The Lambda platform is a front-drive architecture with a transverse-mounted engine and transmission. So it's no surprise that our 2010 Chevy Traverse rides on MacPherson strut front suspension.
Like almost every front-drive chassis out there, the Traverse's rack and pinion steering (green) does its work from behind the front axle centerline. Further out, the front wheel bearing rides within an aluminum front knuckle (yellow).
Here's another view of the same components.
The front stabilizer bar connects directly to the strut housing via this slender link. It connects to a point high up on the strut so there's no interference as the strut sweeps left and right during steering maneuvers.
Those two bulges in the brake caliper (green) make it easy to tell these are 2-piston sliding (aka floating) brake calipers. And check out how taut the brake hose is when the suspension is at full droop and full left lock. That's an admittedly uncommon circumstance, but it still looks like they've used no more material than is absolutely necessary.
Here you can clearly see that the lower control arm is made of two pieces of stamped steel that are welded together.
Here's another look at the dual-piston brake calipers and their ventilated rotors.
Multilink suspension is used in the rear. Here we see an upper link (yellow), a toe link (green), and a lower arm (orange). But this doesn't look like enough links to keep the wheel pointed properly. What's missing?
Before we find out, have a quick glance at the rear brake hose which, like the front, is no longer than it needs to be.
And here's your missing link. The lower aluminum arm (orange) that looked like an A-arm in the last picture is really an H-arm. But the stray leg of the H in the foreground does not connect to the knuckle. No, it connects to a slender vertical link (white) that connects to the knuckle at the top.
GM calls this a "linked H-arm", and since that seems descriptive enough, we'll roll with it.
Here's what's going on: The background leg of the H connects to the knuckle at a single point, like an A-arm would. So far so good. Since the free end is not connected to the knuckle, the toe-link (green) can apply torque to the knuckle to add dynamic toe-in without binding any of the bushings. The vertical link that's connected to the free end of the H absorbs the torque reaction cause by braking and, in AWD models, acceleration.
This angle shows this last point a bit more clearly.
The rear leg of the H-arm (white) connects directly to the knuckle. The front leg of the H (green) connects to the vertical link, and this allows the shorter toe link (yellow) to pull the front part of the knuckle inwards as the body rolls for a stabilizing dose of toe-in without causing any binding the neighboring bushings; the top of the link simply shifts left and right slightly to absorb this motion. But the link's vertical rigidity absolutely keeps the knuckle from rotating during accel and braking.
Meanwhile, the upper arm (yellow) is far enough above the tire's contact patch that it doesn't have to exert much effort to hold the top of the knuckle at the proper camber angle. That's why it can have this curious shape cut from a flat piece of steel.
This overhead view shows how the upper camber link and the vertical link share a common pivot axis and mounting bolt.
The aluminum H-arm carries the coil spring and bump stop about 60% of the way out from its inner pivot point. The shock absorber mounting bolt, just visible in the background, connects to the other leg of the H at more or less the same 0.60:1 motion ratio.
Don't worry too much about the bent appearance of the spring. This straightens out somewhat when the car is sitting on the ground and the suspension is compressed to the neutral position. Things get pretty parallel when the suspension compresses further with additional load.
Single-piston sliding brake calipers and ventilated rotors take care of rear braking.
Our Traverse is a 2WD model, so of course its rear hubs don't have any drive axles poking through the center.
Our Chevy Traverse rides on these optional P255/55R20 tires. Sure they look "better" than the 18s, but the ride is nowhere near as smooth and compliant as our departed long-term Buick Enclave, which rode on 18" rims and higher-section tires. OK, some of that has to do with the Buick ride tuning philosophy, but we can't ignore the fact that these tires have less sidewall and they weigh a full 71 pounds when mounted on their heavier "dub" rims. Maybe we should re-insert the letter "m" into that nickname.
Dan Edmunds, Director of Vehicle Testing