slavehand

Yes we have and it has caused some major opinions to come about, which BTW, have been some great points from both sides.

It's right here
'07 Cobra at NY Autoshow.

jsaylor

I appreciate your soncerns and would not argue if an IRS showed up under the next Cobra's rear myself. But, if it has a live-axle and performs as it should I wont fuss either.

That said, remember that it is not necessarily accurate to assume that the Cobra has to be more stiffly sprung than does a GT. In the past Cobras have, at times, actually provided a better ride than have their GT brethren even when both were equipped with live axles.

Stiffer spring rates are not the only way to improved handling. And, more often than not they simply constitute a "quick fix" or "cheapest route" scenario to flatter handling IMO.

Chassis guru Herb Adams always made the point that the last thing you should do to improve handling is to stiffen the spring rate, and that you should always use the softest spring you could get away with.

I think SVT has demonstrated that they subscribe to a philosophy that is every bit as refined as Mr. Adams' was considering that cars like the SVT Focus, Contour, Cobra's, (R's not included) and even F-150 have all handled superbly while offering a ride that is virtually never worse than their no hi-po brethren and sometimes better.

Also, do not forget that stiffly sprung IRS cars can do their fair share of bouncing around too, as demonstrated by the "track" versions of the 350Z. These cars are extremely unforgiving, ride harshly, and do indeed bounce around a bit in corners when on a rough surface.

Assuming the Cobra shows up with a live-axle rear, if it handles and rides better than that 350Z Track model (I expect that it will) I will have no complaints at all whatever underpins the rear.

V10

How come I don't hear anyone complaining about the IRS on the Vett falling apart or that it's impossible to launch a vette.

Is Ford unable to engineer a decent IRS so we have to be stuck with a live axle?

Soccer2789

Almost every car bounces around up and down in corners (even the 997 carrera s). What they dont all do is what some live axle setups tend to when encountering a bump mid corner, and that is wiggle around. There is nothing more scary to me than going around a corner at fast speeds, hitting a bump, then feeling the rear end wiggle underneath me :shock: ........Hopefully ford engineers can fix this.

Jason

hatsharpener

You aren't on the right boards then. Vettes are tricky to launch and they do break their half-shafts, especially when modified. They are designed for IRS though and do perform well at stock power levels. The 99+ Cobras do not perform well at stock power levels with the IRS.

RaGsHoCkEy88

its being unveiled over by me in the NY auto show. ill take some pix and give info even tho i know its a long way off

rhumb

Presumably, the next Cobra chassis was designed to accomodate a proper IRS from the start. That is quite in contrast with the SN95 Cobra's highly IRS, which was greatly compromised in order to fit into a chassis never designed to accomodate one. Thus, I would avoid too many references to that IRS's shortcomings in relation to discussions regarding the upcoming Cobra (The '04 Cobra's hopped like a bunny off the line so all IRS's then stink...).

As for spring rates, overly stiff ones, quite true. Rock hard spring rates are a fool's first recourse for "good" handling and can often lead to very inferior handling on all but the smoothest of test tracks.

None the less, a live axle does have a huge and vry real disadvantage in terms of unsprung inertial mass to control and thus require stiffer components -- springs, shocks and bushing -- in order to reign in all that flailing mass. This inevitably results in a commensurate deterioration in ride quality for a given level of handling capability and a significant degradation of actual handling capability on deteriorating road surfaces.

If one is only concerned with ride OR handling, a live axle system can be well tuned to deliver on either criteria. What they are much less able to do, relative to a GOOD IRS, is to widen the envelope and give BOTH good ride AND handling over a much wider range of driving and road conditions. And perhaps rather than discussing good ride, which can imply simply creating a cushy ride, is to think about suspension compliance and the ability to keep the wheels planted on the ground over road irregularities, i.e., the ability to put the power down and maintain high cornering and braking levels over more than creamy smooth streets or test tracks. What good, really, is a 1G test track monster that goes skittering off any real-world road at the first whiff of lumpy pavement?

Of course a badly tuned suspension of either configuration can hobble a cars ride and handling, and there are many examples of overly stiff IRS system that end up obviating whatever potential benefit IRSs might have. But presuming SVT's demonstrated well-thought-out suspension tunings, applied to either live or IRS, a good IRS will give them a much broader envelope to work with in terms of developing the most ideal tuning and the broadest ultimate ride and handling qualities and capabilities.

To reiterate, given equally well developed systems, a live axle design can be developed to handle quite well and ride reasonably well too, though with a greater compromise of one quality for the other. A good IRS will be able to give a better ride AND better handling over a much wider range of driving conditions.

While this broader ride/performance envelope may not matter much to this very drag-race oriented board, or not enough to justify the higher price and complexity, that IRS advantage is very real and not mere techno braggadocio.

This is why I feel the best overall design and performance solution for the top of the hill Cobra is an IRS with a live axle option for that smaller enthusiast sub-set focused more narrowly on simple straight line performance.

Mystic_Cobra

Can I second that?
I've been thinking all along, maybe Ford will do what they should and offer both.

Robert

The question is: Can Ford make a business case for designing a Cobra that offers both IRS and live axle options? Doing so means a different set of additional engineering parameters for two variations of essentially the same vehicle.

Ain't gonna happen, IMHO. Ford will settle on one or the other rather than incur the costs of engineering two variations of a single edition.

rhumb

That really is THE question, and one with lots of variables, especially in terms of market perception. Cars have done that before with success, some earlier Toyota Celicas/Supras come to mind with the lower end Celicas getting the live axle and the higher end Supra an IRS.

While the dyed-in-the-wook current Mustang entuhusiasts, who tend to be very drag-race centered, at least on this board, probably see little sense in an IRS given that it gives little if any advantage at the stoplight/strip. But presumably Ford is trying to appeal to a much broader enthusiast market and establish the Stang as a world class performance car, not just a big motored, straight line drag queen. Sure, a good live axle can be made to work well enough, but well enough may well fall short of the higher aspirations and expectations at the $40K+ playing field where you going against superlative chassis such as the M3, Vette, Boxter, etc.

And Ford still seems to have a bit of a habit of going on the cheap, product-wise, if they think nobody will obviously notice, more of a marketing-oriented perspective than a car-guy, engineering-oriented one. Especially on such a halo car for Ford as their top of the line Mustang, essential their public platform for engineering ability and prowess, to stick a good-enough truck axle to truss up the **** end would not be impressive.

Sure, it'll keep the boys at the drag strip satisfied (though they don't need much in the way of suspensions anyways, just a big motor), along with the penny-pinchers (is that the audience you're trying to appeal to with the Cobra?), but to break out of preaching to the choir -- to appeal to a broader, more discerning enthusiast market -- Ford may well shoot themselves in the foot by scrimping here.

Even beyond the manifold technical advantages to a good IRS, perception and expectation is important when someone's shelling out 40K frogskins for their ride and to have a cost cutting compromise holding up the back end would be very corrosive to creating a warm and fuzzy feeling as one strokes out that big check. Let's hope Ford doesn't continue to be penny wise but pound foolish.

Joes66Pony

Part of the business case has already been made if what Mr Thai-Tang said about the chassis is true, that it was designed from the outset to accept IRS from the beginning. It wouldn't make sense to waste engineering resources on designing the chassis to accept IRS, but never use it.

And rhumb is correct. Ford has a habit of doing just "good enough". And judging by the reaction of many on these board and on Mustang enthusiast publications seems to be that the live axle is just good enough, so no need to change it.

Robert

Yeah, well, I agree with both of you above. The direct consequence of this "if it's good enough for mulletted midwestern males named Skeeter, it's good enough for Ford," attitude, is that it's directly hurting Ford in the pocketbook right now. Rhumb is absolutely right: penny wise and pound foolish. Ford's sales have been languishing the past few years - automobile manufacturing is actually their least profitable wing. And what's the upshot: Ford is now the number three automaker in the world, after a Japanese brand, when they used to be number two. Wake up and smell the coffee, Ford, it's a global marketplace now - stop being cheap and stop catering just to rednecks.

rhumb

Absolutely. Ford needs to start striving for overall product excellence, not adequacy. Look at the running gear on the upcoming Solstice/Sky for under (just) $20K.

Crowing that the Mustang's running gear meets the needs and expectations of drag racers is a case of aiming low and hitting a bull’s eye. Drag racing has got to be the motor sport that is absolutely the least demanding of a suspension, asking that it merely be cheap, hold straight, hold still and hold together, all of which would most adequately be fulfilled by a go-carts chassis. Ford needs to exceed expectations, not merely to not fall so far below them as to be completely unpalatable to the buyer.

Daimler/Chrysler seems to get this, evidenced by their Magnum/300 delivering Mercedes chassis dynamics, Hemi wallop all at an affordable price. So while Ford's market equivalent, the 500 - a perfectly adequate car, is on the short track to fleet and rental company sales, C/D can hardly make enough of the Magnum/300s. And then what do they do a year out? Give us the immensely impressive SRT versions.

Even GM seems to be waking from its design and engineering torpor, in no small part to Lutz's proddings (see what happens when you put a real car/product guy in charge rather than some marketeer or bean counter). The aforementioned Sky/Soltice are at initial review, very impressively designed, styled and engineered, all at a very affordable cost. The upcoming Z06 is a stunningly thorough engineering work, no mere adequacy here but rather, a car that fascinates in its design and engineering depth and details and will readily command its price. And not that the relatively affordable base Vette is a shabby design job to begin with. The newer Caddy's are starting to show genuine world-class design, engineering and capability, not relegating themselves as senior plush mobiles.

Anyways, the bottom line is that good enough is not good enough. Ford needs to surpass buyer expectations, not just struggle be good enough to stay on the radar screen.

While a case for a live axle can be made for the budget leader GT, that penurious posturing falls flat with Ford's production performance and engineering showpiece, the SVT Stang. Braying that the live axle meets the needs of the Mustang's drag racing sub-contingent is like saying they've developed an elephant gun that can slay a mouse.