2011 Hyundai Sonata GLS: Suspension Walkaround
February 03, 2011
Truth be told, I've been sitting on the suspension photos of our 2011 Hyundai Sonata GLS for some time. You know, things get busy around the office, a Leaf shows up, there's a hot story or three, and if you're not careful six months go flying by.
No more. I'm blowing the cobwebs off these ancient stills and trotting them out for all to see.
Why am I telling you this? I dunno. I guess I wanted to let you know why the Sonata's suspension bits and pieces look so sparkly and clean in the following pictures.
To the surprise of no one, the front end of the Sonata is propped up by MacPherson struts.
As with nearly all front-drive cars with transverse engines, the Sonata's steering (green) acts behind the front axle centerline.
A direct-acting stabilizer bar is used, so named because the drop link (yellow) attaches directly to the strut housing.
The Sonata's hollow lower control arm is made from a pair of welded steel stampings and its longer leg stretches forward. Three easily accessed bolts make ball joint replacement a simple task.
Here's another shot of the forward leg of that lower control arm. You can see how it's shaped to provide tire clearance at full steering lock.
We've stuck our head under the dashboard for this shot and we're looking straight up. The white arrow is pointing out the face of the brake pedal, and the green arrow is pointing off-screen toward the steering wheel.
Between them is the electronic power steering unit (yellow), a so-called column mounted unit because it's located under the dash in the steering column. Column-mounted EPS works in lighter cars, but not in a heavier vehicle like the Ford F-150, which uses rack-mounted EPS.
Why? The power steering unit of course adds muscle to your steering input. If you add that power-assist torque within the column, upstream of the steering rack & pinion gears, those gears have to be strong enough to handle the extra load.
That's OK in lighter applications, but something like a 4x4 truck needs much more steering assist, and a suitably-powerful column-mounted EPS unit might apply too much load to the pinion gear. Therefore, in heavier applications you won't see the EPS unit here; instead it will reside on the rack itself, downstream of the pinion gear.
As expected, the Sonata's front brakes consist of single-piston sliding calipers and ventilated rotors. But the calipers themselves are a little unique because the sliding half is made from two pieces that are bolted together. To the right of the split line, the hydraulic side that houses the piston is made of aluminum. To the left, the fingers that wrap around and clasp the opposite pad are made of cast iron.
The rear half of our Sonata sits on a multilink setup that's a bit more interesting.
A single trailing arm (black) locates the wheel in the fore-aft direction. Farther aft, the upper link (yellow) and lower link (white) define the camber angle as the wheel moves up and down. Finally, the stubbier toe-link (green) holds the wheel and tire at the desired toe setting throughout its travel.
Here's another look from the front, with the trailing arm's forward mounting bushing in the foreground.
We have a better view of the lower link (white) which is made of aluminum, carries the spring and has an eccentric inner mount for camber adjustment. Above it are the upper link (yellow) and the toe link (green), also with an eccentric adjustment for toe-in on its inside end.
Even though it's dark in color, the rear upright (yellow) is in fact made of aluminum. The shock absorber bolts directly to it, so its motion ratio is a straight 1-to-1. Meanwhile, the stabilizer bar sits far inboard at something like a 0.45-to-1 motion ratio and the spring, slightly further outboard, appears to be sitting at 0.65-to-1.
In other words, the apparent spring rate at the wheel, the wheel rate, will be about 65% softer than the spring rate itself. If the spring's stiffness was 200 lb/in (I have no idea - this is just an example), then the wheel rate, the one that really matters, would be 130 lb/in. Motion ratios closer to 1-to-1 allow softer (and lighter) springs to get the same job done, but packaging constraints don't often make that practical.
The stabilizer bar drop link has this big bar code sticker on it, making it a bit hard to follow the link from the bar end to the place where it bolts into the aluminum lower link.
The lower link connects to the upright via a pillow ball for higher lateral stiffness than one could get with a rubber bushing. It looks cockeyed because the suspension is at full droop. Things square up better when the suspension settles to ride height.
The toe link passes through a gap in the trailing arm to connect directly to the upright. Of course the toe link is still shorter than the other links so it can induce a stabilizing dose of roll understeer as the outside tire loads up in corners.
Just like the front, the rear sliding caliper uses a two-piece design, with aluminum on the inside and cast iron outside.
Our Sonata GLS rides on aluminum alloy wheels, 6.5 inches wide, 16 inches in diameter and with a 43 mm offset, as you can plainly see here. Wrapped in P205/65R16 Kumho Solus KH25 all-season rubber, the mounted assemblies weigh 44.5 pounds apiece.
The sportier Sonata 2.0T looks much the same underneath, but nearly-invisible things like spring rates and internal damper settings in the struts and shocks will differ according to its slightly different mission. Similarly, the EPS calibration under the dash is also set to generate a bit less assist so the steering doesn't feel quite so light as this. Much more visible are the tires, which can range up to 245/45R18.
Dan Edmunds, Director of Vehicle Testing