2010 Honda Accord Crosstour: Suspension Walkaround
May 07, 2010
This time it's our 2010 Honda Accord Crosstour's turn to have its wheels removed so we can take a peek at its underpinnings.
I've commuted in this car, and I've taken it on a long trip to Prescott, Arizona and back. So far I've been left with the impression that this car is tuned more to my liking than the 2008 Accord sedan we once had in our long-term fleet. The Crosstour has very good straight stability on the open road, and the rear suspension is much better settled over bumps and in corners.
Let's see what's going on.
You can learn almost everything you need to know about the Crosstour's front suspension in this one shot.
It's a double wishbone setup, featuring an elongated front knuckle (green) that curves up to meet a high-mount upper arm (yellow). A coil-over front shock (orange) mounts to the lower arm and stretches up to the unibody. A generously-sized front stabilizer bar (white) curves in beneath the rear-mounted power steering rack.
The stab bar need to be somewhat large because it connects to the lower arm midway along its length at a motion ratio that looks to be about 0.45:1. The shock fork connects further outboard, giving the spring and damper a motion ratio in the neighborhood of 0.6:1.
Here's a better view of the coil-over's lower mounting fork (yellow) and how it splits in two on its way past the drive axle to the lower arm.
We also get a good look at the business end of the 2-piston (black) sliding brake calipers.
An L-shaped lower control arm is still a variety of wishbone, so the suspension's double wishbone designation still applies.
Here's the high-mount upper control arm.
As is customary with high-mount upper arms, the pivot axis is higher at the forward end to provide anti-dive under braking.
The thin yellow line indicates the somewhat reclined axis of the pinion gear. The yellow arrow shows a nut that has a spring and a long-wearing plastic (or similar) puck behind it. The spring and puck applies force to the rack's gear teeth, pressing it against the pinion to preload the rack. Such "rack preload" is carefully specified to produce enough friction to smooth out the steering, but no so much as to deaden the feel. The nut can be moved in and out to adjust it, but it's not intended to be monkeyed-with during the life of the car.
Meanwhile, the thin pipe (white) is proof that this is hydraulically-assisted power steering.
Here's another look at the 2-piston sliding brake caliper and its corresponding ventilated brake rotor.
Out back, the Accord Crosstour uses a multilink arrangement. Up top there's a one piece upper wishbone (white), and down below there are two separate lower links (green, orange) that are splayed apart to roughly approximate a lower wishbone. A toe link (yellow) sits forward of the axle centerline to keep the wheel pointed straight ahead.
Here's another view of the two lower links (green, orange) from below. The toe-link (black) is also clearly visible. And check out that crazy cast aluminum knuckle (white). That's a nice-looking piece.
Here's one more view of the lower links (green, orange) and the cast-aluminum knuckle. It's interesting to note that no spring is visible here. That's because the rear end of the Crosstour uses coil-over shocks, and the lower end of the shock mounts high on the knuckle (white) for a 1:1 motion ratio. The same can be said of the rear stabilizer bar link (yellow), which connects to the knuckle in nearly the same place.
That upper control arm bolts to a massive rubber-isolated rear subframe that mounts to the unibody in two places (green) on each side of the car. The subframe also carries the rear stabilizer bar which, if the markings on the pivot bushing are to be believed, is 15mm in diameter.
Here's a shot of the coil-over shock that keeps everything up off the ground. This setup is quite good for packaging down below, but the relative bulkiness of the coil spring does eat into the Crosstour's cargo compartment a bit.
Yes, the rear shock towers intrude into the Crosstour's hatch area, but it's not all bad news. In fact, it's probably a good thing on at least two fronts. 1) The sheet metal structure of the shock towers stiffens-up the unibody and gives it much more rigidity than it would have without them. They may be partly responsible for the way the Crosstour's body feels solid and unaffected by rough road impacts. 2) The shock towers support the rear seatbacks very effectively when they are latched in the upright position. The seats aren't going anywhere in a rear-end collision.
The rear end shoulders less of the Crosstour's braking burden, so single-piston sliding calipers and solid rotors do the job here. The hat shape of the rotor is evidence that a drum parking brake is in use.
Our Crosstour rides on 225/60R18 Michelin Latitude Tour tires. Mounted on their aluminum alloy rims, they weigh 54.5 pounds per corner.
But wait, there's more. Our Crosstour is a 4x4 model--that's Honda's term, not mine. I like to reserve that term for pickups with no center diff and a real low-range transfer case.
Instead, the Crosstour is more of an all-wheel drive machine because you never manually engage anything with a lever and the transfer case (shown here) has no low range. The t-case is more akin to a power take-off (PTO) that runs all the time.
Front/rear torque distribution all happens here, inside the forward half of the elongated rear differential housing (yellow). The main prop shaft turns all the time, but the rear wheels are only driven by it when the multi-plate clutch located within this housing is engaged.
Here's how it works. This housing also contains two hydraulic pumps; one driven by the incoming prop shaft at the speed of the front wheels, the other driven by the rear wheels and rear diff. If the front and rear wheel speeds are the same (no front slip), the pumps will spin at the same speed and develop the same pressure. With the pressure difference at zero, the multi-plate clutch pack won't engage.
But when the driven front wheels start to slip, the corresponding pump spins faster and develops more pressure than the rear one. The resulting pressure difference causes the clutch pack to engage and start sending power to the rear wheels until the pressures balance out again.
It's automatic. There are no wires, switches or levers. You're barely aware it's happening.
But the drag of the always-spinning components and the weight of the system (the 4x4 Crosstour weighs 183 pounds more than a 4x2) does take a bite out of everyday fuel economy. Our 4x4 Crosstour EX-L is rated at 17 city/25 highway/20 combined. A corresponding front-wheel drive one is rated at 18 city/27 highway/21 combined, for a bottom-line difference of 1 mpg or 5 percent.
Dan Edmunds, Director of Vehicle Testing @ 5,243 miles
P.S.: We've added a category for Suspension Walkarounds so you can find the other 29 I've put up. Look for the new link at the bottom of the "Vehicles" list that sits just to the right of the blog text.