Yep, but the car was still effective none the less, it had a similar power to weight ratio as its competitors and proved to be faster through the corners than its competition, IIRC the only downside was the weight of the car and true to Mustang form inadequate brakes.

 

Bob, using the GAC as a benchmark for performance isn’t an apples to apples comparison. The Mustang is allowed a LOT of mods. It’s a factory backed race car, to put it bluntly. The other manufacturers, such as Nissan and Porsche, aren’t allowed the numerous modifications like Ford. If you have a minute, go on Grand Am Cup’s website and look at the PDF for campaigning specific cars.

 

Max, I checked out the GAC website, the rules are fairly simple and wide open for everybody, Ford did take advantage of some things by offering a racecar to the public, but at its heart its still a mac strut/sra chassis with a rear suspension remarkably similar to what underpins ever Mustang currently (now if you start talking front suspension, the FR500C is a pretty significant departure from stock).

 

Bob, take a gander at section 8-2.
http://grand-am.com/assets/KONIRules.pdf

The Mustang has a lot of allowed "mods".

 

Rear suspension on a GAC Mustang. Other than coilover shocks and tubular control arms, looks like the lowly stock design to me...

 

Yea, the FR500 comes with expensive Multimatic coilover setup, specific PHB, control arms w/ Rod ends and a lot of money in suspension tuning. There was a lot of testing that went into the FR500C.

 

Now you've really confused me.

You're saying that a Vette with IRS goes real fast in a drag race, but if they put IRS on a Mustang, the Mustang would go even slower?

 

How about an easier one. A few more interior colors. Black, grey and tan are old....and red was nice, but how about blue or white?? A red vert always looks awesome with a white interior! More power is always nice....drop the 3.5 in the V6 model, and bump the 4.6 to 5.0 with at least 350hp. A 6 speed should be standard as should ABS. Seats are fine, but hard plastic door panels need padding as does the dash. My '04 Cobra at least had a padded dash and door panels. My '07 feels cheap in those areas. But as a hole, the Mustang is still a great buy!

 

with the exact same HP and weight..i will

but i cant considering they weigh less than me AND have more power

 

Dont get me wrong, im all for IRS except one thing...cost! i dont want the mustang to end up like a corvette and only be a "semi" rich mans car if you get what im saying.

 

The S197 platform was designed for an IRS rear. I don't think that an IRS rear will add significant cost to the MSRP.

 

That whole cost issue (an extra $5k according to HHT) was either nothing but a red herring thrown out to quell legitimate questions as to why a 21st century performance car was soldiering on with a 19th century suspension design or admitting to Ford's incredible design and manufacturing incompetence in that they couldn't bring a contemporary design to market at a competitive price, something every other manufacturer seems able to do for maybe $500-$1k, max, over what a live axle might cost. Heck, Ford itself did it with the '99 SVT Cobra, in a chassis never intended for an IRS, for about that amount, though that particular design was, of necessity, rather cobbled together and hardly representative of what can be done.

I favor the former rationale, and no, an IRS ought not to jack up the Stang's price to Vette levels (where do people get this ridiculous ideas anyway?)

 

While it is only a theory I think the reality of the '5k IRS controversy' is likely founded in a misunderstanding regarding two different statements and what was meant by each. At one point we heard a comment, IIRC, stating that IRS on the S197 Mustang would have cost 300 dollars more per car than a SRA, or close to it, for Ford to implement. The other, perhgaps more famously stated scenario sees the cost of implementing IRS as 5k per car over the standard SRA setup. My suspicion is that both are true...let me explain.

We know that initially the D2C platform was slated to employ IRS exclusively, and under that sweeping plan it is very easy to believe that the 300 dollar figure per unit applied given economies of scale, etc.. Eventually that plan was scrapped, but as we know there were still rumors of an exclusive IRS setup for the GT500. In light of the stated mission of the GT500 at that point, which was to basically pack M3 balance and poise into a 500hp missile, it isn't difficult to believe that the IRS unit under consideration for that car was a high tech, high spec piece far removed from the cobbled together, bolt in job that the 03/04 models made due with.

Such a unit would likely see massive changes made to the rear structure of the GT500 as a whole accompanied simple to accommodate such a unit. Then of course we would have had a very limited production, world class IRS setup nestled under all that bespoke chassis work. Take into consideration a plausible worst case production scenario of 10k units or so a year over a production run potentially as short as two years, making for 20k units total, and it isn't difficult to see where a 5k a year final price tag for the customer could come from here. And that is before we address the likelihood that so many changes to the Mustang's chassis might require a large portion of assembly to take place on a separate, bespoke production line.

To me it seems like two different price tags for two different scenarios. Just my thoughts on the issue.

 

Naw, I was commenting on the fact that the Vette has 130 more HP and is about 200 pounds lighter than the Mustang and has more rubber to put power down so its IRS isn't really a detriment to the acceleration of the car even if it has traction problems due to the IRS.

Now take a 300hp Mustang and add another 100 pounds of IRS equipment that adds a bit (I suspect not much, but its there) of extra power absorbtion and yeah the Mustang would be slower.

I'm sure that would illicit far more groans than the the lack of chassis dynamics an SRA car exhibits, Imagine the brand new 2005 Mustang with 300hp and an IRS that would have only been marginally faster (if at all) than the car it replaced. Or worse, Ford using marginal materials to meet the SRA chassis price so it could trumpet having the most affordable 300hp car fitted with an IRS.

Then again, maybe price wasn't the whole issue. the F3/F4 GM cars came with a crapola rear axle due to weight, cost and the regulatory issues it would have caused.

and Max, thanks for the link to the GAC Koni rules, I don't know why I didn't see it, every time I hit the link to the Koni page I didn't see anything specific.

One thing I did find interesting where the cam rules for both the LSx and Windsor engines. I would have thought given the superiority of the LSX engine architecture compared to the Ford, the GM engine would have been restricted to a smaller cam, but the opposite is true.

I wouldn't have imagined the GT40 heads with porting would have been able to outpower the GM heads.

 

One change I would like to see is to give us some real gages for once. For the love of God, I dont know why they put gages in that are nothing more than an idiot lights. I can maybe understand it in a Fusion or something but this is a Mustang and Mustang drivers want to know whats going on.

 

I agree with about half to 3/4s of JSaylor's assessment. It does seem that the initial plans for the D2C platform was to have it IRS throughout, and in that case, $300 over an live axle design does sound about right. And I do think the initial intention of the S197 was to offer BMW 3 series chassis dynamics, poise and refinement, coupled with American V8 punch at working man's price.

But it seems the rather tortured development process, apparently starting with the excellent but expensive and heavy DEW chassis eventually failed and sucked up a large amount of development time, dimes and resources in the process. Elements of the DEW were pared and pruned away, like the front control arm suspension for various reasons of cost, weight and fitting in the bigger, cheaper Mod motors rather than the AJ engine. At the end of this tortuous process, little was left of the DEW chassis or, apparently, the development budget and with time bearing down for an ostensible 40th anniversary launch (already behind schedule) and pressure from the marketers for a sub $20K entry price, out too went the IRS and any pretense of being a genuine 3 series killer. So in the breach, the party line was to aim the Mustang a bit more narrowly and less boldly or broadly as simply a good, cheap muscle car with decent if ordinary chassis dynamics. The benefits of the relatively agrarian SRA were of course touted up -- what'd you expect them to say, "we tanked the development process and budget so this is the best you're going to get" -- but hope was that the GT500 at least would be a world class performance car.

But that too apparently succumbed to a combination of depleted development budgets, greatly increased per unit costs for what would now be a second rear suspension design produced in quantities that did not deliver much economies of scale benefits and probably greater sway from the suites and marketeers over the engineers after all the delays and snafus. So then too did the GT500 devolve from world class to a muscle car blunderbuss of a performance car. Nix the aluminum block and thus add 50-75 lbs of dead-weight on the nose (good bye agility) and lock up the nascent IRS in some shed behind the developemnt center.

But hey, since there was no real direct competition beyond perhaps the 90's design GTO, why bother and why hold the price line. Indeed, why not charge more for less, as compared to the SVT Cobra, and recoup some of those squandered development costs. Besides, there was already a huge base of Stang enthusiasts inured to mediocre handling after three decades of the early 70's era Fox platform who thus had long since relegated themselves to cheap, flashy, straight-line speed anyway, almost to a point where skittish handling became a badge of honor or something. The '05 would pull respectable enough handling numbers, at least on a smooth test tracks anyway, to brush back the IRS handling effetes while the andiron-simple, cheap and rugged live axle was all the drag racers needed or wanted anyways, world class handling be damned.

But what now of '10? Different world -- genuine competition now faces the Stang with fully 21st century chassis. Gas is now approaching twice the price as when the '05 was being birthed so simple big-motor, gas-swilling, carbon belching brute speed as a sole performance criteria holds a narrowing market appeal. The '10, if it doesn't pick up its performance game beyond a simple stoplight sprint risks being perceived as an archaic and out of step anachronism. Even Hyundai is offering an affordable 300hp RWD performance coupe with IRS.

But Ford's hands may be tied now. The S197 is approaching the fall of its life cycle in a suddenly full competitve market -- sales numbers will never approach those of '05, and Ford is bleeding money and selling off divisions at fire sale prices to keep the lights on and water running. So it would be hard to justify dusting off even the nearly developed IRS sitting in that back shed for just a couple year run, especially with a clean sheet design on the '14-'15 horizon. Instead, I suspect Ford will tart up the styling a bit, offer a 5.0 as a swan song variant of the Mod motors and try to undercut the GM and Chrysler ponies - and ignore Hyundai.

Might work well enough to bide the Mustang's time until the new foal springs from the barn in a couple of years, or at least we can hope so.

 

I'm not getting the continued comments of the hundreds of pound the IRS will add???

If the car is developed for IRS the weight increase would be minimal. The SN 95 cobras had all kinds of brackets and housings and bars and supports to somehow attach an IRS to a car that wasn't built for it.

However, on a car designed for IRS none of that nuisance is necessary. I built Subaru's for 7 years. Granted the top performer I built was the B4 Legacy with about 265 hp and equivelant torque. But the rear diff. bolted directly to the Unibody with bushings in between. They featured a double wishbone style control arms. Old style below had twin rods instead of control arms.

New style has gone back to tie rod/end links as well. Sorry for the misinformation:


So isn' this the difference:

Diff bolted to body Instead of floating ( added vehicle stability)
Two CVJs instead of solid axles (additional weight)
Control arms are at the hub instead of floating inbetween the the floor pan and axle (typically cast aluminum vs stamped steal).
no pan hard bar (reduced weight)
No axle housing (reduced weight)
Typically coil over strut suspension instead of shock and coil separate. (two mounting point vs. 4)

Well this is over simplified, but other then the CVJs I really dont see where all this weight is coming from??? With the deletion of the PHB, Axle housing, etc It ought to be rather close

 

Yeah, I think many of the arguments against an IRS embody worst case scenarios rather than more typical implementations, much less ideal or state of the art. Of course, anyone could trot out some IRS atrocity to try to debase IRS systems in general -- often pointing to the (of necessity) compromised SVT Cobra design. But then, you could also point to the Vette and Viper designs as highly effective performance enhancements to those vehicles or perhaps even the Mazda RX-8 as an excellent and very affordable design.

On the other hand, the worst case scenario approach may be applied to live axles too, though I think in most of these discussions, people are using the Stang's SRA design as the reference point, one that lies far closer to the acme of live axle capability rather than the nadir.

My guess is that any Mustang IRS, current or future, would resemble the Aussie control blade architecture, a rather simple, rugged, lightweight and apparently effective design.

 

I too would bet the farm that a multi-link 'Control Blade' setup will be under the rear of the next all-new Mustang for reasons of space savings, cost effectiveness, and dynamic prowess. Technically there are superior designs if superior handling is the only goal, but out here in the real world Control Blade is a very simple, effective design that does almost nothing you don't want it to and which is very easy to 'get right'. Control Blade is to IRS what the Mac Strut is to IFS, and Ford invented both systems FWIW.

As for weight issues. A good IRS will likely weigh a little more than a good SRA, but little is the key word here particularly if the IRS is a Control Blade design. In a worst case scenario I can't imagine more than a 100lb difference and would be surprised it it were that much. If the interior, engine, transmission, brake, and suspension setups are suitably improved this go 'round then I think the current SRA design is more than good enough to hold off the competition until a GRWD based Mustang shows three or four years later...particularly since so many have missed the mark to some degree with their newest offerings.

That said, I'm glad we'll be getting IRS during the next complete overhaul.

 

If the IRS rear package was designed for inception to be lightweight, I doubt it would add much weight overall. On the Cobra, the IRS rear accounted for a 125 lb reduction in unsprung weight which is huge for the overall dynamics of the vehicle.

The problem with a lot of Mustang owners is they equate the Cobra IRS to a modern IRS system. The Cobra's IRS was an afterthought and not the best designed system. From everything I've read of the "swing blade" setup, it should be great in the S197 chassi.