Yeah, I know. The word "Mustang" is missing in the above title. It's kind of silly because, after all, we can all see with our own eyes that the Ford Shelby GT500 is a Mustang. But Ford chose to leave "Mustang" out of the official model name of this car. My hands are tied.
But my floor jack and lug wrench are fully unbound. Let's get in there and see if we can see what it takes to turn a Mustang into a Shelby -- apart from stripes, badges and Cobra medallions, that is.
Like all late-model Mustangs, the front end of the GT500 is suspended by coil-over struts. Our GT500 has the optional SVT performance package, with includes, among other things, stiffer springs (20.5% up) that produce a lower ride height (11mm down) and "upgraded" front struts and rear shocks. "Upgraded" doesn't merely refer to red paint -- the valving within has been re-tuned to produce more damping force.
Like most front-engine rear-drive (FR) cars, the Mustang family uses the preferred "front-steer" arrangement, wherein the steering rack sits ahead of the front axle centerline. The 15.7:1 steering ratio used in the GT500 is the same found in all other 2011 Mustangs.
The GT500's L-shaped lower control arm (yellow) is made from welded steel and carries a single lower ball joint.
Here's another seemingly shared part: the front knuckle (yellow) is appears to be made of the same ferrous material found on other Mustangs, and the Brembo brake calipers mount to the same "ears" on the part. That makes sense because a Brembo brake upgrade is offered on the Mustang GT option sheet.
All Mustangs use lightweight tubular front stabilizer bars (yellow). According to Ford press materials, the Mustang V6 uses a front bar that's 34mm in diameter and the GT uses one that measures 34.6mm. It's hard to tell how significant this difference is because the wall thickness of a hollow bar is needed to quantify its actual torsional stiffness, but Ford doesn't provide that tidbit on the spec sheet.
The GT500 is listed as having the smaller of the two choices, the hollow 34mm bar. With the firmer springs and dampers that go along with it, this probably doesn't increase body roll so much as it reduces understeer. Bigger isn't always better.
On the other hand, it could be a typo on the spec sheet.
Meanwhile, the direct-acting stab link (white) is something you'll see on all Mustangs.
These four-piston Brembo brake calipers are standard on the GT500, and they squeeze one-piece 14-inch ventilated cast-iron rotors. As mentioned earlier, they're available as an option on the Mustang GT.
It would have been nice to have little scrapers like this (yellow) on the brake pads of our Ford Flex long-term car so we could have easily heard when the brake pads were getting too thin before it was too late for the rotors.
And speaking of rotors, this one is not held in place by a Torx-head or Phillips-head screw, it's held in place by a couple of push-on, screw-off washers (black). They go on sort of easy, but they're a royal pain to remove.
Moving to the rear, this profile view doesn't quite show us what's going on. We can see a spring, a shock, a stabilizer bar (black) and an aluminum-looking trailing arm (green), but we need to see more to figure out how the wheels are being held in position.
What at first looked like a silver trailing arm (yellow) is actually a trailing link. It has single-point mountings on either end, so we still can't see how the rear axle resists the torque reaction and stays in the correct orientation. Further up, we can see how the rear spring (green) simply perches atop the solid rear axle and nests in a cavity in the unibody. Meanwhile, that rear stabilizer bar mounting is looking a little weird, with the rubber bushing (black) located out near the hooked end of the bar.
A-ha! This single top link (white) connects the middle of the rear-end housing to the unibody. Together with a matched pair of the trailing links we saw before, we can see why Ford calls this a three-link solid rear axle.
But these three links can only control the fore-aft and torque movement of the rear axle. They can do nothing to resist lateral loads. For that there's a Panhard rod (yellow).
Before we look at that in more detail, let's talk about the rear-end housing and what's inside it. The 3.73 diff ratio found in a GT500 with the SVT performance package, like this one, is NOT intended to enhance performance over the 3.55 ratio found in a regular GT500.
It's like this: the standard GT500 wears P285/35R19 rear tires, while the SVT track package comes with taller P285/35R20 rear meats. Turns out the 3.73 ratio is primarily intended to offset the performance-robbing taller gearing created by the taller 20-inch tires, and the two setups end up at more or less the same place from the engine's point of view. In other words, a GT500 with the SVT performance pack will turn over about the same number of revs as a regular GT500 at a given gear and engine speed, despite the impressive-looking difference in final-drive ratios.
That said, the 3.55/3.73 ratios offered on the GT500 are indeed more performance-oriented than the 3.31 gears offered on the Mustang GT and V6.
A Panhard rod (white) connects to the unibody on one end and the axle housing on the other end. You want it to be as long as possible so its "swing radius" is long enough to minimize the amount the axle moves left-to-right as it moves up and down.
Meanwhile, the rear-stabilizer bar mounting strategy is a bit unusual. Bass-ackwards, I would say because the links (green) are the pivots and the bushings (yellow) affix the ends of the bar. Hey, it still works. It's actually an effective way to put a rear bar on a solid live-axle car.
Once again, the GT500 uses one of the bars fitted to regular Mustangs, but in this case it's the larger 24mm bar from the GT. Together with the smaller bar on the front, this combination, on paper, at least, will produce the least amount of understeer. But that doesn't necessarily make the GT500 more tail-happy because the GT500 is the only variant in the Mustang stable that has wider rear tires than it has at the front. Taken as a whole, it all fits together.
Let's move back to the Panhard rod for a bit. The fixed end is this protruding bracket (green, no blue) that's welded firmly to the unibody itself. The upper piece (white) is a bolt-on stiffener that spans across the car to help stiffen the bracket near the point where the lateral loads will be applied by the panhard bar (yellow) itself. After all, the approximate loading will work out to whatever the rear tires can generate on a skidpad times the weight of the rear half of the car.
The other end of the Panhard rod (green) mounts to this bracket on the left end of the rear axle housing. It's a busy place, as evidenced brackets for the shock, that stabilizer bar end bushing (yellow), the trailing link (white) and even a rust-colored mass-damper.
About those trailing links: Despite what you may have assumed earlier, they're not made of aluminum. As you can see here (yellow), they're made of two pieces of stamped steel that are welded together. Let's hope the choice of silver as a paint color wasn't intentionally made to make the casual observer believe these are lightweight aluminum bits.
The SVT performance package includes rear springs that are 9.5% stiffer while they lower the rear of the car 8mm relative to a regular GT500. A urethane bump stop sits atop the axle next to each coil spring. When the suspension bottoms, it will impact a nearby reinforced part of the body structure and cushion the blow.
Red is the "in" color for GT500 rear shocks. These SVT performance pack units have higher damping levels that are tuned to work with the stiffer springs, lower ride height, stickier tires and other bits and pieces that come with this GT500 option.
No Brembos back here. The GT500 uses single-piston sliding calipers and ventilated cast-iron rear rotors, just like other Mustangs. Not that there's anything wrong with that.
These sticky tires are a big part of the SVT performance package, literally and figuratively. Size-wise, they're huge compared to other Mustang tires. How does P265/40R19 front and P285/35R20 rear grab you?
GT500 tires come mounted on lightweight forged aluminum rims, so their mounted weight, at 62.5 pounds apiece front and rear, is respectable for rubber this size.
You'll never have to (or be able to) rotate these babies left to right because the tread pattern is directional. In case you were wondering, the right half is the outer surface and the big directional water channels reside on the inner surface. Don't recognize the pattern? It's new. These are Goodyear Eagle F1 SuperCar G: 2 tires.
Goodyear chose to put that awkward space between the colon and the "2" in the official model name of this tire. My hands are tied.
So what makes a GT500 so different from a Mustang? Well, there certainly are differences in the wheel wells, but nothing too revolutionary. No, the most significant GT500 difference is under the hood in the form of a 550-horsepower supercharged V8 engine.
1krider1 says:
09:33 PM, 08/30/10
Solid Rear Axle= FAIL
Anyone who buys a car with a solid rear axle in 2010 is an idiot.
slickersdrip says:
09:35 PM, 08/30/10
As always, fantastic walkaround Dan. I really appreciate these. I feel much more knowledgeable after each one. One of my favorite features of the site.
It's funny that Ford dropped the Mustang moniker... reminds me of my dearly departed Neon SRT-4. Dodge really did just call it the Dodge SRT-4. People wanted to refer to it as a Neon... it was, but according to the marketing department it wasn't. I referred to it as a Neon. Made it even funnier when it would destroy Porsches, Mustangs and Corvettes.
intothewest says:
09:42 PM, 08/30/10
Very well-written article.
It's amazing that Ford has managed to still push the solid-rear axle to where it is today....whether it's matching M3 performance on a track in stock form, or keeping-up with race-prepped 911s and BMW M3s (Grand Am racing).
bc1960 says:
10:53 PM, 08/30/10
Haven't Shelby GTs always been labeled as such, rather than Mustangs, even after Ford took over production from Shelby American? I seem to recall the 1960s versions were badged "S H E L B Y" across the decklid instead of "M U S T A N G". They're referred to generically as Shelby Mustangs, but it hasn't been the car's offical name, and still isn't.
kyolml says:
10:59 PM, 08/30/10
I am not sure what do you mean why the "three links" won't hold the axle? Is it the top link on top on the center housing is universal ball joint so it don't hold lateral direction? If top link fix on left-right direction, then it won't need the panhard rod? Or the link won't be strong enough so they added the panhard rod?
theripepunani says:
11:08 PM, 08/30/10
@1krider1: Yet, magically the Mustang GT competes against the BMW M3 not only in a straight line, but in lateral acceleration as well.
I love BMW and I especially love the M3, but even I have to give Ford a tremendous amount of respect for making such a well performing car while pushing technology that we consider antiquated and obsolete. It's odd why they do it, but the fact that they do and manage to keep up with some of the best deserves some respect.
angry_mushroom says:
11:33 PM, 08/30/10
@1krider1:
Call me an idiot because I want one. Remember this car keeps up with BMWs and the such with the suspension setup from the 60s...
The GT500 is an epic car of rarity that will be long remembered.
hybris says:
11:35 PM, 08/30/10
Its not out of date technology if it performs just as well as the newer tech at a fraction of the price.
angry_mushroom says:
12:02 AM, 08/31/10
Call me an idiot cause this is a car I want. Too bad it's a limited run.
kyolml says:
12:22 AM, 08/31/10
Now think about it, beside why need the center link on the diff housing won't hold it without panhard rod, how is the alignment adjusted? Don't fail to mention it on me, Dan, please
05stangdriver says:
01:05 AM, 08/31/10
@1krider1
Have you driven this car? Have you driven ANY 2005+ Mustang?
I thought not. In any event, the advantages that an independent rear suspension provide over a solid rear axle will only be evident on a racetrack, not in everyday driving. I respect your opinion that a solid rear axle may not be as effective in certain situations as an i.r.s., but to say that "Anyone who buys a car with a solid rear axle in 2010 is an idiot" is a bit juvenile, and doesn't make you look very informed. How about you cite some facts to support your namecalling?
Words to live by: "The fewer declarative statements a man makes, the less apt he is to look foolish in retrospect."
scottyscooter says:
03:34 AM, 08/31/10
I don't understand the purpose of the Panhard rod. Isn't it performing the exact same function as the stabilizer bar?
actualsize says:
04:13 AM, 08/31/10
@kyolml If the panhard rod -- also called a track bar by the NASCAR boys -- wasn't there, you or I could push the axle (if jacked-up like this) or the car body (if sitting on the ground) side to side a couple of inches. I've actually been on a racetrack following another car when its panhard rod failed. The whole axle shifted several inches to the left, with one tire sticking halfway out of the body and the other sucked way in, and they spun off. That short center link has very little to say in the matter. It has bushings on each end that work radially, in the direction of the link. They're not intended to do much axially, the direction of the bolt that goes through them. The Panhard rod/track bar takes the side loads. The other three links handle fore-aft and accel/brake torque.
Alignment adjustment? There is no alignment adjustment with a solid rear axle. Camber and toe are fixed.
half_ton says:
07:01 AM, 08/31/10
I have seen 1krider1 and others criticize Ford's use of a live axel much like some have criticized GM for the continued use of pushrods in their engines, however both companies are sucessfully using older technology to make their cars competitive.
The results speak for themselves so why complain?
EXCELLENT WORK LIKE ALWAYS DAN!
jcfast1 says:
07:10 AM, 08/31/10
YOU FORGOT THE UPPER TRAILING ARM! This is one of the most important parts of the Mustang rear suspension. It controls the pinion angle and helps reduce vibration and axle hop. If you're going do one of these "suspension" articles DO IT RIGHT!
ed124c says:
07:17 AM, 08/31/10
Can we start calling you Professor Dan? Or at least Dr. Dan?
Wait a minute-- you were also a race car driver? Geez-- when is the autobiography coming out?
jcfast1 says:
07:20 AM, 08/31/10
OH YOU DID MENTION IT, I'M GOING TO GO SIT DOWN NOW. Whoops.
strangelove says:
07:27 AM, 08/31/10
1krider1: anyone who buys cars because of specs and stats is an idiot. The proof is in the pudding: the Mustang GT and GT500 both perform beautifully, and how they achieve that performance doesn't matter. only the end product does.
why don't you go be a "genius" and get a Camaro, Challenger or 370Z just because the spec sheet says "IRS", and you can tell yourself how brilliant you are while staring at this "idiots" Mustang GT headlights (on a track or strip).
dukeisduke says:
07:27 AM, 08/31/10
A lot of interesting details on this setup, especially the novel way they attach the rear sway bar, and the mass damper on the rear axle. As for those push on nuts holding the rotors in place, they're a one-use thing, used to hold the rotors while the calipers are installed on the assembly line. My F-150 had them on both the front rotors and the rear drums. Usually the only way to get them off (when you're working on the brakes) is to twist with a screwdriver until they break, then throw them away. I thread on a couple of lug nuts to hold the rotor while I'm putting the caliper back on. The one thing I would change about the front end it to use bolt-on ball joints, to make them easier for the average guy to replace.
A live axle can work great as long as it's well controlled, by adding enough trailing links, and a Panhard rod or Watts linkage.
alukashe says:
07:35 AM, 08/31/10
I personally think the solid axle is the worst for regular daily driving. Most road racing racetracks I've been on are fairly smooth and the live axle isn't that huge of a deal. However you can't beat a solid axle if you live your life 1/4 mile at a time... lol
s197gt says:
07:44 AM, 08/31/10
dan,
great walk around. i have a few questions for you!
i have lowered my 2006 gt with steeda ultralite springs (1" fr/1.25" rr) and replaced my dampers with tokico d-specs. i also upgraded the stock panhard bar and brace to a stiffer adjustable unit from steeda. i've been holding off on the three links and i'd like your opinion if they would be worthwhile, even if just theoretically. but first:
in the mustang world we call that rear silver-painted trailing link a "lower control arm" (lca). (the gt500's silver version is an upgrade from the gt's stamped steel and softer bushings.) you at first called it a trailing arm but then said you actually found it to be a trailing link. can you explain the technical difference?
that was a great pic you got of the third upper link, oddly enough i've never seen an actual pic of it on a car. most refer to it as the upper control arm (uca).
would you expect to see much of a performance improvement in handling by upgrading these three links?
put in context, especially after lowering the car (and affecting the pinion angle) accepted wisdom is to upgrade the three links to aftermarket pieces: adjustable uca with stiffer busings and adjustability to fix the thrown off pinion angle and usually a fixed tubular lca with stiffer bushings.
i think for the drag strip stiffer bushings would certainly help but i have yet to upgrade my links for the road course as i'm not convinced they will give me much "bang for the buck" in terms of better "feel" for spirited driving and the occasional road course.
(i am aware of the nvh concerns with stiffer bushings or even rod-ends.)
i have upgraded the panhard bar and brace to an adjustable unit with stiffer bushings. (again, after lowering the rear axle is known to shift a little.) like you said, it handles the lateral loads, it made sense to me to upgrade that component.
here's another random question, any idea why lowering the car would reduce wheel hop during hard acceleration? my wheel hop is gone after lowering the front 1" and the rear 1.25".
any insight or opinion you could provide would appreciated!
lanceboyle says:
08:14 AM, 08/31/10
Would you people stop calling it a solid axle! It's not solid! It's a hollow tube with drive axles turning in it and it's called a live axle. A solid axle is what you would see at the front of a semi, or an MG TC or a lawn tractor.
It seems to work here due to careful tuning of springs, shocks and sway bars despite the unsprung weight of those massive rear tires. I am surprised at the the exclusive use of stamped steel for the A-arms and the rear links and the use of a panhard rod rather than a Watts linkage.
cello_one says:
08:14 AM, 08/31/10
Thanks as always Dan. The live rear axle argument will continue to live on for many years. But the new Mustangs do it VERY well! Even the V6 econo version is fun to take a long cruise in (it helped it was a rental, on Hwy 1 headed S to the cut over to Eugen, OR along the Pacific coast)...
raybanz says:
08:35 AM, 08/31/10
Dan wrote: "a GT500 with the SVT performance pack will turn over about the same number of revs as a regular GT500 at a given gear and engine speed".....
Shouldn't this be "at a given gear and VEHICLE speed"? Otherwise I am not sure what the point would be. Any two vehicles rev the same at a given engine speed.
compressor says:
08:38 AM, 08/31/10
@ 1krider1 - I guess we can look forward to being smart and buying one in 2011.
BTW - "alukashe" has it correct on live axle performance.
kosmo69 says:
09:09 AM, 08/31/10
at this price point and performance level slotted rotors s/b standard.
exnevadan says:
09:44 AM, 08/31/10
can't decide which is funnier - "green, no blue" or "rust-colored mass-damper"
of course the first is an homage to MP, but the Shelby is new, so was the second a nice way of saying "rusty/rusted"?
still haven't driven my b-i-l's 2010 convertible, but it sounds unbelievable
new22003 says:
10:20 AM, 08/31/10
You can tell by some of the comments about solid axles that people have no grasp of engineering and only regurgitate what they have read.
northsparrow says:
10:40 AM, 08/31/10
Perhaps tomorrow you can do a 'Suspension Walkaround' on a 2010 Explorer just
to prove to skeptics that Ford can make an independent rear suspension on a RWD
vehicle when they feel like it.
fordfrenzy says:
11:36 AM, 08/31/10
IT'S JUST AMAZING HOW FORD HAS MANAGE TO TAKE ONE OF THE OLDEST SUSPENSIONS SETUPS AND MAKE IT SO ADVANCED THAT IT RIVALS AN M3....AND MY BET IS THAT THEY DO IT ON PURPOSE BECAUSE LOOKING AT THAT ALL OF THOSE PARTS WOULD COST JUST AS MUCH OR IF NOT EQUAL TO AN INDEPENDENT SUSPENSION I THINK FORD JUST WANT TO PISS OFF THERE COMPETITION LMAO......GO FORD
gidger says:
12:52 PM, 08/31/10
The best Solid Rear Axle ever > par I.R.S. *coughcamarocough*
hemi_ownz_u says:
01:15 PM, 08/31/10
Anyone who trashes the Mustang because it has a live axle without having ever driven one is and idiot.
desmolicious says:
02:54 PM, 08/31/10
So, is this car a new arrival to the LT fleet?
norm_peterson says:
05:40 PM, 08/31/10
s197gt - I think the way the anti-squat varies with ride height is at least partly responsible. From some measurements of the various rear suspension pivot points on my '08 GT (non-GT500) it looks like over about the first inch and a half of rear suspension compression from static ride height you give away some anti-squat before the trend halts and then reverses. A slightly lowered car would gain anti-squat almost from the get-go, and I suspect that the trend is worth as much as the values themselves (which aren't particularly high as dragstrip launch preferences for A-S go). The rear suspension of the GT500 may differ slightly due to possible differences in rear suspension static ride height, but I'd expect the trend to be similar (if possibly over a smaller amount of rear suspension compression).
1krider1 - before you condemn a live axle suspension arrangement, understand that a well done stick axle trumps an indifferently done IRS in most respects other than bumpy road ride quality and bumpy cornering performance. In general, stick axles are more predictable than IRS, since you can't have unequal camber and toe changes, LR vs RR. Most people, when a car isn't quite as predictable, tend to drive it not quite as hard once it's given them a little unexpected warning. Just so you know, I have two stick axle cars with different arrangements, two with various IRS arrangements, and one with a twist beam.
Norm
lions208487 says:
07:28 PM, 08/31/10
Love the car, but I don't like all of the cast iron rust that will have to be fixed later on when this car becomes dated. Brembo brakes are nice, but even the Brembo package on a 370 Z goes with lighter materials that don't rust. For 55 or 60K, Ford could have gave ceramic an option.
The solid rear axle works on every current Mustang model all the way down to the 3.7 Liter, but an independent setup will not only further improve handling, but also eliminate the rough ride quality that most Mustang owners are custom to.
s197gt says:
07:39 PM, 08/31/10
thanks norm.
what do you think? upgrading the three links worth it for spirited driving and the occasional road course? if they are dealing mainly with fore/aft (acceleration) forces, how much affect would upgrading them have on the lateral side-to-side of cornering? noticeable or negligible?
they are three connections to the chassis, i don't want to downplay their importance. would they help with the live-axle's nemesis, the mid-corner bump/irregularity?
kyolml says:
07:46 PM, 08/31/10
@Dan the Actual,
Thanks for the explanation.
I have to look at the drifting Mustangs, maybe they changed the live axle to IRS, so the camper looks so negative.
Not sure why they keep the panhard rod, as using a A-arm on top of the center diff housing could be the same keeping thing from moving left-right (even the top link now will have circular moving to make the housing front or back when compressed). A watt's linkage is fine, but I still think A-arm on top will be truly get rid of the side way circular motion.
davisdvm says:
08:04 PM, 08/31/10
Hey, thanks very much for this excellent review of the legs on the GT500. I'm no engineer but i've been an enthusiast for years and I really appreciate understanding what's happening underneath. There were a lot of hours spent in the prep and photographing and it's appreciated. I'd like to suggest that a comparison of this relatively primitive setup with a more expensive performance car (the M3 or S4 would provide great contrast) be done in the future. I can't help but think there is some sophisticated stuff going on in the German hot rods and it would be great to understand where the money goes when you pay the big bucks. Thanks again.
omairkhanzada says:
10:13 PM, 08/31/10
1krider or whatever is a NOOB and should be disregarded... Apparently he is unaware of what ford has been able to do with a SRA.
norm_peterson says:
05:13 AM, 09/ 1/10
s197gt – the links themselves are certainly strong enough, and even the "plain GT" bushings are firm enough for spirited driving and most autocross and track day use. I think the GT500 control arm bushings are slightly firmer, though you probably have to get the entire arms.
Bushings seem to be most critical for drag racing and that sort of hard launching. By itself, cornering loads the LCAs/UCA only indirectly, so it'll be when you're accelerating off a corner or trail braking that you'd be doing much axial loading of the three longitudinal links. There is a little to be had with some sort of spherical pivots at both ends and somewhat less with poly in one end and a spherical at the other, at varying penalty in ride quality or NVH. Leave the poly/poly for the drag racers, and if you do decide to go with poly/spherical consider the poly bushing to be a "wear item".
It doesn't matter how a live axle is located, a one wheel bump anywhere will affect the grip of both rear tires, since the wheel that isn't hitting the bump is still forced to undergo a camber change. And there will be some amount of lateral force applied to the chassis.
kyolml – it is entirely possible to put negative camber into a live axle, just a lot of work and usually a lot of heat involved. Chances are that even off the showroom floor stick axle cars don't have precisely 0.00° camber.
A high mounted A-arm would put the rear roll center way up at the top of the axle instead of down around axle center height, and would probably force the LCAs to be skewed differently than they are (they are not quite parallel to car centerline). What you'd end up with would probably behave more like the converging 4-link of the Fox-body (more axle roll steer and not nearly as nice).
davisdvm – there already has been a direct track comparison of the M3 vs the 2011 5.0 Mustang. Long story short, the M3 is more composed with better damping control while the Mustang understeers less on turn-in and mid-corner and is stronger coming off the corners. Randy Pobst driving.
Norm
kyolml says:
07:12 PM, 09/ 1/10
@Norm
So you meant the link that is already on the top of the center diff housing is not going to cause axle roll? Is it too soft or the linkage is not fix so it won't cause the axle roll on the high mount?
What i meant is replacing that link with 2 fixed point on the body and a ball joint on top, then it won't shift left-right. maybe i am wrong. but anyway the panhard rod probably is the cheapest way to go at this point.
actualsize says:
08:35 PM, 09/ 1/10
@raybanz: Yeah, I meant something along the lines of "a similar number of revs in a given gear at a given vehicle speed." Good catch. Too bad I didn't find it myself before I hit "send". :)
actualsize says:
08:43 PM, 09/ 1/10
@davisdvm: I did the 2009 M3 about a year ago. There's an Audi S5 in the archives, too. http://blogs.insideline.com/roadtests/2009/06/2009-bmw-m3-suspension-walkaround.html In all there's about 40 of these in the IL LT blog. Scroll to the bottom of the "Current Vehicle" list on the RH side of the LT blog page to find the link.
norm_peterson says:
06:11 AM, 09/ 2/10
kyolml
>
The existing upper longitudinal link is only intended to resist axle torque under either accelerating or braking (in conjunction with the LCAs). Otherwise, it's intended to be flexible so as to stay out of the way of the PHB doing its job. Compliant bushings is the OE method of accomplishing this, so strictly speaking there are small loads and stresses in the UCA from cornering because the bushings still do give the upper link some stiffness in the lateral direction. But this effect is small enough that for practical purposes it can be ignored.
>
The height at which a solid method of lateral location like that is placed is by definition the "roll center height", and that's exactly what I was getting at. Instead of being down around 12" or so above the ground where the current PHB lies, it'll be way up at 17" or so. There are other geometric consequences associated with a relocated "roll center" that need to be addressed or else the car will be rather clumsy to drive in certain situations. A PHB isn't necessarily the best theoretical solution, but it's simple and quite effective. Even in stock form, the car is "faster" than most drivers, so having a PHB isn't a particularly limiting feature, performancewise, for most folks.
Incidentally, in times way-back-when, Alfa-Romeo actually ran the arrangement that you have suggested, and Lotus ran a low-mounted A-arm to a pivot point under the diff and a pair of longitudinal uppers in at least one model.
Norm
s197gt says:
06:53 AM, 09/ 2/10
thanks again, norm!
csubowtie says:
10:34 AM, 09/ 3/10
I find many things about this walk around interesting... But as a qualifier, I do fully understand the use of a live axle. Drag racers (i.e. a big percentage of users of these cars) prefer the live axle, and it can be made to corner just as well as an IRS, and be cheaper. My beefs though include the cheesy use of aluminum colored paint to mislead someone into thinking the trailing links are cast aluminum instead of cheap steel. LAME. Also, it seems that Ford could have saved some unsprung weight, for example, mounting the bump stops on the body instead of the axle.
fryota says:
05:59 PM, 09/ 3/10
1krider1--
In the latest Motor Trend, a 2011 Mustang GT beat a 2011 M3 coupe on the Streets of Willow Springs road course. Not by much, but the Mustang won. It posted slightly better skidpad numbers than the M3, and outgunned it in a straight line (except 0-60, which was identical).
Maybe Mustang buyers aren't as dumb as you thought.
charlesb says:
06:14 PM, 09/ 4/10
I think 1krider1 kind of hit it on the head in the first post but, after BMW went back to McPherson struts on the 3-series I realized that most buyers don't buy based on the sophistication of the underpinnings. The automakers want profits and cheap parts that work well is the best way to make that happen.
chunky_azian says:
11:48 PM, 09/ 7/10
Almost everyone refers to handling as one specific number that a car must generate. It is a lot more complicated than that. Good "handling" refers to a car that does what the drivers wants and communicates (there's a reason why some people don't like Toyota's overly boosted steering) with the driver through a combination of steering feel and body roll. Being predictable and not do anything wild (gradual skid versus a snap oversteer) as the driver pushes the car beyond its limit is an important factor in building driver confidence.
If done right, a solid axle would have less unsprung weight than a modern multilink suspension. But I would like to see Ford De Dion setup instead of carrying those heavy gears in the suspension. How much more expensive are universal joints going to be? Also, a simple Panhard rod seems a little primitive. I was expecting something out of the ordinary, such as the Scott Russell link Nissan used a decade ago.
jman1743 says:
11:29 AM, 11/ 2/10
Just a quick note on the silver lca. This was done to differentiate the SVT lower arm from the base car arm in the assembly plant. Aside from the bushings, the arm is the same as the base car and needed to look different to avoid mixing them up during assembly.
The same condition is true for the rear stabar drop links, the V8 gets black links, the V6 gets white and the SVT got the blue ones. Get behind a V6 on the road and you will see those white drop links quite clearly. All in the name of error proofing the build.
Also, the careful observer will note the lower arm is acutally a single stamping, the folded over edges are just that, folded over and not extra pieces welded on after forming. It's a slick little piece of engineering.