In the end, the $200,000 SLS AMG is like any other car in that I can jack it up, put jack stands underneath, yank the wheels off and have a good look at the mechanicals. The trick is getting my hands on the keys for a couple of days. As you can see above I managed to do just that.
This particular car came out of the west coast Mercedes-Benz press fleet and it's made the rounds. It has over 15,000 hard miles on the clock. More than a few celebrity posteriors have sat upon these red leather seats. One would assume it's been to the Grammys, the Golden Globe Awards and the Oscars, and we're pretty certain Adam Carolla flogged it during the taping of his yet-to-be-seen response to Top Gear, a show that will air on Speed if it airs at all.
So is there anything left? Let's have a look.
As you might expect, aluminum dominates the underside of the SLS AMG. Here we see a double wishbone front suspension made almost entirely of the stuff.
Forged aluminum upper and lower A-shaped control arms locate the wheel in 3D space. A reclined aluminum-bodied coil-over shock provides the necessary support and control.
The engine sits so far back in this machine that a front-mount steering rack placement (yellow) isn't a challenge at all.
Steel makes its first significant contribution in the form of a front stabilizer bar (green) and its associated drop link.
The forged aluminum upper control arm bolts to aluminum brackets which are in turn bolted to a cast aluminum section of the aluminum space frame. All told, the car's entire aluminum space frame weighs just 241 kg, otherwise known to us as 532 pounds.
And yes, 15,000 miles of hard driving and serious profiling have left it all a bit dusty.
The massive 15.4-inch rotors are of the two-piece variety, even though dozens of parts are necessary. Ten sets of spacers, clips and bolts allow the 1.4-inch thick ventilated, slotted and drilled cast-iron rotor to "float' on its aluminum hub.
Monstrous rotors demand humungous calipers, and the folks at AMG have obliged. These six piston (yellow x2) calipers feature an open pad window with a bridge bolt (white) that can be removed when it's time to change pads. The ears of the pads themselves feature tiny mass damper weights to quell vibration.
The AMG's 563-horsepower 6.2-liter V8 (yes, I know it says 6.3 on the side of the car, but the displacement is actually 6.2 liters) ... what was I saying? Oh, yes -- the V8 engine sits so far back that the shock towers (green) tie into a frame crossmember that spans across the engine bay entirely in front of the pulleys and accessories on the front of the motor.
The rear suspension is also made up of double wishbones and coil-over aluminum-body shocks.
This forged aluminum lower wishbone truly is shaped like a wishbone. The lower end of the Sachs aluminum shock (yellow) necks down to clear the driveshaft.
Double wishbones alone can't keep the rear wheels pointed straight ahead. In the front there's a steering rack, which is only straight when you want it to be.
Here in back you need a fixed toe-link (yellow) instead. The relative lengths of the upper arm, the lower wishbone and this link create a tiny measured amount of bump-steer, typically a wee bit of roll understeer to prevent the ass-end from swapping ends with the front.
Of course you can easily achieve that whenever you want by standing on the gas and boiling the rear tires with the stability control switched off. Or so I hear.
Like the front, the rear forged aluminum arms bolt to aluminum brackets that bolt to the aluminum space frame.
Like the front, steel is the material of choice for the stabilizer bar (yellow) and its drop link. Also the coil spring. Anything that sees a lot of torsional cycling is best made of spring steel.
Massive brakes adorn the rear of the SLS, but here the ventilated, slotted and drilled discs are one-piece cast-iron units. The brake calipers are 4-piston fixed units, but here the bridge (yellow) is fixed. You have to remove these calipers to change pads. Like the front, the ears of the rear pads have mass dampers connected to them.
It's no surprise that the wheel and tire package is huge. Continental ContiSport Contact 5P asymmetrical summer tires, sized 265/35ZR19, ride on 19-by-9.5-inch forged aluminum 10-spoke AMG wheels. The assemblies weigh 48.5 pounds, light for their size. And that's just the front.
In back you'll find 295/30ZR20 tires on 20-by-11-inch rims. These tip the scales at 57 pounds apiece. The forged wheels are not standard equipment, either. The option costs a mere $2,400, but who's counting in this price range?
cjw88 says:
07:07 PM, 03/14/11
Check out how the rear calipers have an air scoop into the bottom of the rotor on the first pic. of it.
blueguydotcom says:
07:15 PM, 03/14/11
I've seen a few of these around La Jolla/UTC area in San Diego. This car takes anonymous to FBI undercover car levels.
omairkhanzada says:
07:23 PM, 03/14/11
I would love to be your neighbor!
subytrojan says:
07:41 PM, 03/14/11
Fantastic as usual, Dan! We appreciate your efforts! :thumbsup:
slickersdrip says:
09:23 PM, 03/14/11
Wonderful and informative as always. Thanks for this!
Could you explain why the lug bolts appear not to be there through the rotors and why the people at AMG chose this design?
church123 says:
10:19 PM, 03/14/11
I was actually shocked to see this car up on jackstands. Given the price, power and performance I figured this car to have a full undertray design which, on cars like Ferraris, Lambos, etc. (or the new LFA) precludes easy jacking or jackstand points.
Anyways, it's a shame this engine had such a short run with Benz. I understand that turbos have advantages in this regulatory environment, but the 6.2 has to be one of MB's best engines of all time.
Any comment on wheel bolts instead of studs Dan? Obviously lots of Euro cars use them (especially the Germans) and I've always wondered too. I figured it has something to do with fact that all bolts (or studs) stretch when tightened, and using wheel bolts allows regular replacement to avoid fatigue vs. the difficulty of replacing wheel studs. But I've never been able to find definitive proof one way or the other. Interestingly, the Lexus LFA is the only Japanese car I've ever seen that uses wheel bolts.
lostboyz says:
04:25 AM, 03/15/11
I would've like it better if it was the viper. Damn you mercedes!
Excellent write up as usual Dan. Do your neighbors give you strange looks especially with a car like this up on jack stands?
noburgers says:
04:29 AM, 03/15/11
Wow that's a lot of aluminum! I'm surprised there were no wheel locks, or you had the key to get them off a pres car. You do a ton of these--and they are fun to read. Do you torque the bolts back to spec?
Typo:
"In back you'll find 295/35ZR20 tires on 20-by-11-inch rims."
Right above that in the photo the tire sidewall says 295/30 ZR 20
rod_stewart says:
04:55 AM, 03/15/11
Mr. Edmunds,
Excellent write up! You deserve more than a blog post for this!
Question--
When the SLS was Track Tested it was said, "Wheelspin with ESC off was virtually impossible, much to the chagrin of our editor in chief."
You say you can boil the rear tires......just curious.
-Rod
http://blogs.insideline.com/straightline/2010/03/il-track-tested-2011-mercedes-benz-sls-amg.html
carbuyers2 says:
05:18 AM, 03/15/11
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eclogite says:
05:44 AM, 03/15/11
+1 omairkhanzada.
I'd love to be Dan's neighbor, too, just for the learning experience of it.
As I've mentioned before, I really enjoy these technical articles, Dan. They're really interesting.
throwback says:
06:15 AM, 03/15/11
A nother nice Job dan. How difficult is it to replace the brake pads?
streetsidestig says:
07:11 AM, 03/15/11
Rubber brake lines? I expected them to be braided. Gotta leave something for the tuners, right?
baggs32 says:
09:25 AM, 03/15/11
Dan,
Great write-up as usual. Question. What is the advantage to having the front rotor float around the hub? To quell vibration maybe?
actualsize says:
09:48 AM, 03/15/11
@rodstewart: Straight line drag launches are one thing; the key word there is "virtually".
I'm talking about cornering, where it's far easier to spin the rear tires and lose the rear of the car (unintentional) or get it drifting (intentional) with the ESC off because the suspension and tires aren't loaded evenly. I lapped one of these at Laguna Seca and corner exits required a somewhat careful application of throttle--just like any other any 563-horsepower rear-wheel drive machine.
To see a total buffoon needlessly burning a couple of pairs of rear tires off of one of these to overstate the hell out of his point, watch Jeremy Clarkson in one of the most recent Top Gear episodes. If Chris really wanted to put his hat on backwards, start yelling "yee-ha" and proceed to lay stripes down our test track he could have done it.
actualsize says:
10:02 AM, 03/15/11
@baggs32: Yep. Fixed calipers don't move, so it's advantageous to let the rotor float a bit instead. There's also an unsprung weight savings. And having the the rotor at arms length from the hub keeps the wheel bearing a bit cooler.
hopster says:
11:17 AM, 03/15/11
Thanks for the write up Dan!
Looks like a fairly standard sports car setup. I think the most interesting thing is just how far back that big motor is tucked in!
csubowtie says:
01:52 PM, 03/15/11
Pretty cool stuff! I can see where a lot of money goes. For example, the brackets the rear A-arms bolt into appear to be machined aluminum. Very expensive compared to a stamped steel part, to save a few ounces. Which just illustrates why it costs soo much to make such small gains once you reach a certain level.
I also thought the floating rotor was to compensate for the difference in thermal expansion of the rotor versus the hat. Using the lightweight aluminum hat saves unsprung weight and provides a thermal barrier between the rotor and the bearings, but the floating bit is there because the cast iron rotor will heat up faster and expand radially, where-as the aluminum hat doesn't expand as much.
flwind says:
03:31 PM, 03/15/11
A $200k car on $10 jack stands!..That's awesome!!!
I wonder what whoever owns this ride would think about that...
kevinlch says:
05:34 PM, 03/15/11
Great car! Thanks!
v8vader says:
09:01 PM, 03/15/11
hey, blueguydotcom, we're neighbors! why haven't i been lucky enough to spot one of these?
charlesb says:
12:02 AM, 03/21/11
Good article.
smokincrater says:
10:16 AM, 03/21/11
Love these walkarounds.
It's interesting how the lower mounts have extra space between one side of the mounting tabs and the suspension arm / bushing. What could that be for? Part of some ride or nvh control?
nwng says:
11:42 AM, 03/21/11
I humbly suggest that you put a piece of 12"x12" plywood under each jack stand as a flat platform. It boggles my mind that you would use $10 jackstands bought from walmart to support any type of vehicle, let alone a $200k MB. And you're under the car taking pictures of the suspension.
cleaver says:
07:42 PM, 03/22/11
I think it's kinda funny people are tripping out over putting the car on jackstands.
If you took it in to be serviced, do you think it would just levitate?
rasguetano says:
09:27 AM, 03/23/11
Its nice to know Mercedes-Benz and Detroit have something in common, nice to look at and the interiors somwhat too but under the hood pretty prosaic even at 200K. My lowly Boxster engine is the same way, no art there either.
nwng says:
12:14 PM, 03/23/11
I don't know if your mechanic uses jackstands, but mine's always on a hydraulic lift.
flwind says:
10:03 AM, 03/24/11
"I think it's kinda funny people are tripping out over putting the car on jackstands.
If you took it in to be serviced, do you think it would just levitate?"
That might be what your shade tree mechanic uses to wrench on your 1992 Hyundai Elantra.
A $200k vehicle on the other hand, probably needs to go on a lift.
cleaver says:
03:44 PM, 03/24/11
Regardless of whether a car is on a lift or on jackstands, the jacking points are built to bear the weight of the car. I don't think the car cares as long as it is jacked properly.
A hack with a lift can do more damage to a car than someone with jackstands who knows what they are doing.
agobela says:
12:09 PM, 03/27/11
Dan
Nice articles I like them. You are writing quitre often that the front positioned steering rack is preferred vs. "rear" positioned. What is the advantage of the front fitted one?
Thanks
Greetings from Hungary
Béla
arfdog3 says:
11:57 AM, 04/ 3/11
Great technical writeup. It's clear that Edmunds has real engineers in there lurking somewhere... and that's why I read this magazine. Spring steel and necking? Ah it's good to be an engineer.