You've seen the outside and heard various favorable driving impressions. Now it's time to take a look underneath our long-term 2010 Suzuki Kizashi GTS to see what's what.
Our front-wheel drive GTS edition (AWD is available!) wears 18" Dunlop tires and multi-spoke alloy wheels. For now, let's yank them off of there and set them aside.
As expected, the front end of the Kizashi rides on MacPherson struts (yellow) and the steering rack (white) sits behind the sidewinder engine and steers the front wheels from behind. The front stabilizer bar (green) acts directly on the strut housing for a motion ratio that's as near to 1:1 as makes no difference.
Pretty (and pretty light) aluminum front knuckles (yellow) are used, and the front brake calipers (black) are of the single-piston sliding variety.
Here's the L-shaped lower control arm and its single ball joint.
The stabilizer bar (yellow) loops over and behind the steering rack (white). But that steering rack looks a little odd. Let's zoom in.
Here you can see the pinion axis and pinion gear (yellow) of rack & pinion fame. They look normal enough, but that there's an electric stepper motor hovering between the pinion and the steering wheel. Yes folks, this is electronic power steering, otherwise known as EPS. The Suzuki manages to bring decent effort and feel to the party, which means that EPS isn't necessarily an automatic ticket to Suckville.
The EPS advantages that engineers should confine their efforts to are these: improved fuel economy due to the lack of a hydraulic power steering pump and a drive belt run by the engine; reduced noise due to the lack of a whining power steering pump, a slipping drive belt run by the engine and resonating hoses; improved reliability due to the lack of a leaky power steering pump, a broken drive belt run by the engine and cracked hoses; improved underhood packaging due to the lack of a bulky power steering pump, the pulley necessary to fit a drive belt run by the engine, and a pair of 4-foot hoses; reduced vehicle weight due to the lack of a power steering pump and its attendant mounting bracket, the pulley necessary to fit a drive belt run by the engine, and a pair of 4-foot hoses, their bracketry and the fluid contained therein.
But oftentimes these guys can't resist the temptation to do things with the assist curve that they could never do hydraulically, namely to offer very low parking effort with substantially higher effort at higher speeds, for stability. But, as it turns out, this feels weird. Very low effort is associated with luxo-boats and higher efforts say "sports car". But the two don't coexist well in the same car because the Jekyll and Hyde personality that results is off-putting and the transition is usually noticeable, not seamless.
Thankfully, Suzuki has not done too much of that here. They've largely confined their efforts to pocketing the tangible egghead benefits while playing it cool and opting for a feel that isn't too much of a departure from what we're used to. In my mind, the best EPS is the kind you can't readily identify without looking under the hood or doing a suspension walkaround.
Single-piston sliding calipers and ventilated one-piece rotors: familiar, but effective.
The rear half of the Kizashi sits on a multilink suspension that consists of a blade-shaped trailing arm (black) that does all of the fore-aft wheel locating duties, a main lower link (green) that carries the spring, a toe link (yellow), and an upper camber link (white). If this were a Ford we'd call this Control Blade rear suspension. But it's not, so we won't.
The various parts in this layout have clearly-defined and separate responsibilities, so there isn't a lot of inherent friction. Also, this layout provides a clear path for a rear axle, which makes an AWD version possible.
Here's another look at the rear from the front. There's the main trailing blade/arm (yellow), which necks down to be quite thin so it's laterally flexible. Both lower links (black and white) have eccentric cams at their inner pivots for easy adjustments (camber and toe, respectively). The curved upper link (green) is also visible from here.
Avert you eyes because the main lower link is a shiny aluminum extrusion. The coil spring acts on it midway along its length at a motion ratio that looks to be 0.6:1 or so.
The shock absorber (white) and stabilizer bar (yellow) both appear to have motion ratios of 1:1 because they act directly on the lightweight aluminum rear knuckle (orange).
But the stabilizer bar link (yellow) comes in at a crazy angle (when jacked up, at least) so the actual motion ratio at the bar is somewhat fluid and a bit less than 1:1.
This close-up of the blade-shaped trailing arm shows how it bolts to the aluminum knuckle (black) and allows us to see how the stiffening folds and rolled edges cease for a few inches to allow some deliberate lateral flexibility.
The blade's combination of lateral flexibility and an iron grip on longitudinal wheel location allows these lower links to sit parallel and concentrate 100% on lateral wheel location.
The lightly-loaded upper link doesn't have to deal with longitudinal wheel location and it's far from the contact patch where the cornering forces are happening, so it can be curvy and blade-thin. And even though you don't adjust camber up here, it's usually called the camber link because it's main job in this particular type of multilink suspension is to hold the top of the wheel at the desired camber angle and not much else.
The Kizashi's rear bump stop is a collapsible urethane sleeve on top of the shock absorber.
Rear wheel braking duties are handled by single-piston sliding calipers and solid rear discs.
Which brings us back to wheels and tires. P235/45R18 tires and 18x8-inch alloy wheels may look good, but at 54 pounds the combination is not necessarily light. Bigger is not always better.
Dan Edmunds, Director of Vehicle Testing @ Who-knows---I-took-these-pictures-last-week miles.
bankerdanny says:
04:21 PM, 04/20/10
The wheel design is a contributor to weight too. All those spokes add weight without any functional benefit in terms of strength I suspect.
carguy622 says:
04:23 PM, 04/20/10
They had a Kizashi hanging sideways at the NY Auto Show. It was a fun view that I don't usually get on a car.
Of course Ford also had the Mustang 5.0 suspended in such a manner, so the Kizashi was a little overshadowed.
chriso59 says:
05:33 PM, 04/20/10
I'm surprised that there's so much aluminum being used in a car at this price point!
auto4fun says:
05:55 PM, 04/20/10
Thanks Dan (as always)! I'm with chriso59 in being surprised at the amount of aluminum being used at this price point! Now if they'd just get some lighter weight 17" wheels we'd be good.
actualsize says:
06:12 PM, 04/20/10
Lighter (theoretically, anyway) 17" alloy wheels come on the cheaper SE model. But product planners and dealer droids are convinced we all want humungous wagon wheels when we opt for decent equipment inside. Frankly, I'm tired of big wheels for the sake of big wheels. There's a point where you are just adding weight (and unsprung weight at that, the bad cholesterol of automotive mass) without adding any kind of tangible performance. I'd rather have 50-series tires and 17" wheels on this car. Probably handle and ride better on the bumpy sorts of roads we get around here anyway.
auto4fun says:
10:16 PM, 04/20/10
I'm definitely with you in your frustration of having bigger wheels for the sake of being big. There was a short article in the latest Car and Driver testing the effect of wheel size on performance. They took a VW Golf 2.5 and tested it with the stock 15" steelies and aftermarket rims of the same design sized 16" - 19". I found the effects pretty interesting, with noticeable differences between the different sizes.
I think the sweet spot is the 17" - 18" wheel on most cars, with 17" being best for most cars; I don't see the point of ever having a wheel bigger than 18" unless it's a supercar that can't fit the brake rotors in 18 inchers. Not only will you usually get better performance from a smaller, lighter wheel, there is a huge price difference. Case in point: Dunlop Direzza Z1 Star Spec: 245/45ZR17 = $142 vs. 245/40ZR18 = $186 - that's a 31% price premium! The Star Specs also aren't available in anything bigger than 18" :)
zoomzoomn says:
06:07 AM, 04/21/10
I find the front lower control arm interesting with the rear inboard corner fixed by a pivot joint instead of a horizontal bushing secured by a stud as in the front. This could be one aspect that enhances it's steering feel and handling prowess(?).
throwback says:
06:10 AM, 04/21/10
I never cease to be amazed at how packed everything is on FWD cars. As someone who grew up driving and wrenching on RWD cars, I yearn for their simplicity. Also, can we get back to reasonable sized wheels and tires? P235/45R18 tires on 18x8-inch alloy wheels is way too much tire for this car. I'm sure a set of 205/55-16s with Summer tires would handle as well and ride much better.
operators says:
07:27 AM, 04/21/10
i dunno if its taboo to link to "competitor" websites here but here is the article auto4fun was talking about:
http://www.caranddriver.com/features/10q1/effects_of_upsized_wheels_and_tires_tested-tech_dept
thanks for mentioning it :) cool stuff!
ptcdawg says:
07:33 AM, 04/21/10
Bigger wheels are out of hand....C&D recently had a test of a Golf GTI, they tested wheels starting at 15" to 19"...acceleration was SLOWER every time they went up in size....handling was marginally better to a point. Noise was HIGHER with the larger size and fuel economy was LOWER when they went up in size. Not to mention the outrageous cost of tires as they get larger. Frankly, I don't get the fascination with DUBS.
exnevadan says:
10:02 AM, 04/21/10
"that's as near to (fill in the blank) as makes no difference" - will use that in my next technical/engineering report for a paying client, thanks for the inspiration.
is the muffler's mid-ship location a function of the AWD package as well? trunk space? gas tank volume?
actualsize says:
10:58 AM, 04/21/10
That's no muffler, it's a resonator. There are two actual mufflers further back in the usual location, after the exhaust splits in two. You can see one of them in some of the other shots.
exnevadan says:
11:33 AM, 04/21/10
that's what I get for thinking I know something (I now see the left side muffler in several photos)
I still know that the car looks good in photos (yet to see one on the road)
bc1960 says:
01:54 PM, 04/21/10
The tires weigh 26 lb so neglecting the weight of valves, weights, and air the wheels weigh approximately 28 lb. That's heavy, but OEM wheels tend to be overengineered and inexpensively cast--fewer spokes does not necessarily make them much lighter because they make the spokes beefier. Aftermarket 18-inchers cast with a similar number of spokes seem to weigh in the 24-26 lb range, but lightweight alternatives can weigh under 18 lb. 17-inchers seem to save 3-4 lb over similarly designed 18s.
xorbe says:
03:27 PM, 04/21/10
(216 pounds of tires and wheels?!!)
This blog entry was AWESOME. Pure win here.
joefrompa says:
03:52 PM, 04/21/10
Really loved this. Thanks. I'm impressed by the amount of aluminum in use, but otherwise seems like a very nice and functional setup.
For the wheel discussion: A car this size should have ~22-23 pound tires and ~22 pound wheels. You can figure out the dimensions. And those are stock sizes and cast wheels....nothing special.
I've recently been wondering why automakers don't use rotors and brake pads with a much smaller contact patch much closer to the inside edge of the wheel, with "veins" connecting the contact path to the rotor hub for strength, rigidity, and heat dissipation.
By having the contact patch further out, you'd be able to apply more braking pressure using less surface area, mass, and pad....because the point of inertia receiving resistance would be further out.
Anywho....
actualsize says:
07:14 AM, 04/22/10
@joefrompa: This car is sold with 16-, 17-, and 18-inch wheels in the USA. For all I know there's a 15-inch fitment elsewhere in the world. Unless they plan on developing and certifying more than one brake system (unnecessary unless a sporty version with lot more horsepower is in the lineup), the rotors and calipers will be sized to fit within the confines of the smallest of the fitted wheels.
e90_m3 says:
08:52 AM, 04/22/10
"[The] rotors and calipers will be sized to fit within the confines of the smallest of the fitted wheels."
That is another reason I find this large wheel trend amusing. So many family cars out there sporting near-dub wheels, only to emphasize the tiny little brake disks behind. It gets worse if the brake calipers are painted bright red or yellow.
Perhaps they can make fake slotted rotor discs and glue it behind the wheels? (I've seen this!)
kitaikki says:
07:53 AM, 04/23/11
Hi Dan, on the second rear suspension photo, there appears to be a link from the top middle of the picture to the middle of the picture, connected to the subframe mounting point (it's also visible in the first rear suspension photo) Is that to keep the rear subframe from moving around too much? Thanks.