By on December 17, 2013

2015 Mustang

I was there when Ford debuted its new-for-1999 Mustang Cobra with its “revolutionary” new independent rear suspension. The IRS was a first for the Ford Mustang, and it was a move that Ford’s brass believed would allow the “new edge” Cobra to compete with cars like the BMW M3 for supremacy in the budget super car market. I also remember the very first question that was asked: Will a Ford 9″ bolt in? It was the first question, right out of the box … and it seems like someone at Ford remembers. The new-for-2015 Mustang is going to hit dealers with a new independent rear suspension late next year, and it seems like Ford Racing will have a 9″ live axle option ready.

According to a Ford Racing employee at PRI, the live-axle version of the 2015 Ford Mustang is expected to debut at next year’s PRI show as part of a new “body in white” program intended to attract serious racers to the platform. The body in white 2015 Mustang will also serve to take some of the shine off of bitter rival Chevrolet’s current COPO Camaro and body in white Camaro programs.

Once the live-axle 2015 Mustang racers are out “in the wild”, the parts needed to convert street-going Mustangs from independent rear suspensions to the 9″ setup should become available through Ford Racing and participating dealers. Back in 1999, SVT engineer Eric Zinkosky said the “new independent rear suspension (was packaged) in not only the same space as the solid-axle design, but we had to use the same suspension mounting points. We virtually ‘reverse-engineered’ the IRS from the known suspension hardpoints, and we had to keep everything inside the same box.” Assuming similar thinking went into the upcoming Ford Racing 9″ suspension for the bodies in white, getting a solid axle to help get a high-horsepower Ecoboost Mustang’s power down should be a lot easier than many have feared.

 

About my source: While I have opted to not give his name, this information came to me from a Ford Racing employee on-hand at the 2013 PRI Show yesterday, 12DEC2013, when I asked if I could look under the hood of the (supposedly) 4 cyl. Ecoboost Mustang spinning on the big lazy Susan at the Ford Racing stand. He said no. I told another PRI old-timer the story about the 1999 Cobra IRS reveal, which the Ford Racing rep overheard. He laughed and said, “Yeah, that’s not ’til next year. We’ll probably announce it at the same time as the body in white program …” but he got called away before he could say “That’s off the record.” Take that how you will.

 

Originally published on Gas 2.

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78 Comments on “2015 Ford Mustang “Body in White” Coming w/ Ford 9″ Axle...”


  • avatar
    bumpy ii

    No surprise there. The “all new” Mustang is basically a heavy revision of the current brick, so the engineers just had to protect the body for the live axle option when designing the IRS. I would imagine the live-axle conversion would primarily involve a new rear subframe, and that Ford will kick out a V8-only “Drag Pack” special in a year or two.

    • 0 avatar
      raph

      If anybody thinks this SRA kit will be a bolt in they are going to be in for a shock. There is no way Ford was able to increase interior volume and lower the roof and rear deck while protecting the space for a live axle.

      They might have included some points for locating the kit but this is going to be a back half kit with an axle designed to work with the new body

      • 0 avatar
        bumpy ii

        And yet Ford somehow managed to put a live axle in the Fox body Mustangs, which could fit inside the current model.

        • 0 avatar
          raph

          You sat more upright in the fox car allowing for tidier dimensions. However the car was just tighter overall, even the SN95/New Edge cars are cramped compared to the current car.

          Another reason was the lack of suspension travel in the fox car that was improved with the New Edge car and again with the S-197.

          Ford could not have lowered the rear belt line, increased rear seat room and increased trunk space while providing room for a live axle which requires more space to package by dint of having the whole rear suspension and axle moving in an arc up and down as the car goes about its business.

          One of the big reasons you see an independent rear suspension in some front wheel drive cheap as hell econobox that would do just as well with a torsion beam or dead axle is packaging as an IRS will allow a gain in the areas I mentioned above.

          Ergo this is not going to be some bolt in affair you can do in a coupla hours in your driveway with a ratchet and a few sockets.

          My guess is this is going to be some sort of sub-frame that might use the locating points for the IRS sub-frame that most likely is being used in the 2015 car but will require the floor pan to be modified in some fashion unless to allow for the proper range of motion (well unless Ford is keen on bringing back the gasser look) which most likely also require dumping the rear seats unless custom pieces are made.

          • 0 avatar
            RobertRyan

            “My guess is this is going to be some sort of sub-frame that might use the locating points for the IRS sub-frame that most likely is being used in the 2015 car but will require the floor pan to be modified in some fashion”

            See the Photo of the Ford Falcon IRS you are pretty much on the money.

          • 0 avatar
            bumpy ii

            ??? Torsion beam rear suspension takes up less space than a lateral-link IRS, which is why it is so prevalent on smaller cars these days.

            I suppose we’ll have to wait and see what Ford actually did, but it’s far from impossible to build a car that can take either setup.

          • 0 avatar
            raph

            @ bumpy ii – you probably just thinking about the straight axle itself which would be more compact overall compared to an IRS but the entire unit has to have room to move up and down or pivot from side to side where an IRS only needs that degree of freedom at either end and if the car is RWD then the axles to a lesser extent.

            The chassis designers can then shrink the area required for the rear suspension to move in and free up space elsewhere or shrink the car as a whole.

  • avatar
    RobertRyan

    “The New Independent suspension” comes from the Australian Ford Falcon.

  • avatar
    SCE to AUX

    Ah, purity.

    If only Porsche made air-cooled conversion kits for their water-cooled cars.

    • 0 avatar
      Vega

      In contrast to rear axles there is noise and pollution regulation for engines, so your idea will probably remain a pipe dream.

      In addition, air-cooled engines would be far less powerful, as Porsche never managed to cool a 4 valve head with air alone…

  • avatar
    bikegoesbaa

    Having moved away from Michigan to a place with terrain/corners I often forget that “drag racing” is something that people do until news like this reminds me.

    If it’s necessary to convert road-going cars, even modified ones, from IRS to a solid axle then that’s probably an indication that the IRS isn’t very good.

    Manufacturers the world over successfully use IRS in very high-power cars without running into issues with axle hop or reliability. Why should an IRS Mustang be any different?

    • 0 avatar
      bikegoesbaa

      Also is there any word on the kits to change from EFI to a carb, fit bias-ply tires, or allow for manual ignition timing via a small brass lever?

      Let’s keep our fingers crossed that they’ll bring back a hand-cranked starter with the midcycle refresh.

      • 0 avatar
        Drzhivago138

        Or a manual choke? I’d like to pretend I’m driving the old L-700 farm truck whenever I get behind the wheel of my new ‘Stang.

        • 0 avatar
          DenverMike

          There’s nothing particularly sophisticated about IRS, and impedes on all-out performance, if anything. Then people complain about pot holes, frost heaves and such, while any hi-performance sports car you choose, is no picnic on them either. But it’s easier to change a suspension than popular opinion or perception. And most Mustangs aren’t of the hi-performance variety anyways, so there you go.

          • 0 avatar
            Austinpowerless

            Impedes all out performance?!?!
            Quick, tell Ferrari, Porsche, Lamborghini, Aston Martin, Lotus, McLaren, every Formula one constructor for fifty years, etc.–Denvermike says your IRS impedes all-Out performance!

            The only “performance” or racing car helped by a live axle is a drag racing one, period.
            Given the tiny percentage of people who believe the world is straight, flat and a quarter mile-long, Ford made the right decision.

          • 0 avatar
            DenverMike

            Mustangs have the advantage of keeping the tires planted though out the rear suspension’s range of motion. Meaning under hard cornering, braking, accelerating, or any combination thereof, an IRS sports car has the super wide and low profile tires on the inner or outer sidewall, partially.

            Most sports cars and exotics you mentioned have transaxles and can’t make use of a solid axle. Not that they would anyways. All other sports cars abandoned live axles back when tires were as tall as they were wide, IRS had all the advantages. Now not so much.

            The only sports car with a similar layout, balance and power to weight as the Boss 302 Mustang is the BMW M3. It can’t keep up with the Mustang in the turns.

            http://www.youtube.com/watch?v=BxEhnugwzCc

          • 0 avatar
            Austinpowerless

            DenverMike… are you actually serious?!

          • 0 avatar
            RobertRyan

            @Austinpowerless,
            Unfortunately Yes.

          • 0 avatar
            DenverMike

            @Austinpowerless – Show me something, anything convincing, other than popular opinion and wives tales. Just because something is commonly believed, doesn’t automatically make it so. Most people believe the world is less than 10,000 years old.

          • 0 avatar
            Austinpowerless

            Well, I’m sorta still hoping you’re putting me on, but … if you’re genuinely not kidding you could check out, oh, just about any SAE paper or publication dealing with suspension from about the last 60 years.
            My personal recommendation would be Matschinsky’s “Road Vehicle Suspensions,” but I think the English version is out of print.
            Seriously, though: why does EVERY, and I mean every road racing car (where rules allow) use IRS? Fashion or fads are certainly not the reason; many millions of dollars are at stake. Hell, F1 teams/LeMans teams, Indy, etc., pay engineers millions to figure this stuff out; they couldn’t care less abut perception or attitudes–they follow the science, period.
            I’m afraid you’re with the young-Earther’s on this one.
            (edited to correct title)

          • 0 avatar
            DenverMike

            In the 60s, IRS was the hands down choice for touring and high performance. Tires were skinny and profiles were very tall so there was nothing to think about. Performance cars either had IRS or wished they did. That sentiment continued on, all the while only US muscle and pony cars kept the solid axles through the ’70s and ’80s while focusing mostly on straight line performance. You really had to go aftermarket to bring out the handling and cornering performance of live axle cars. There was nothing wrong with solid axles in and of themselves, except the way OEMs would set them up. Bushings were huge and mushy while dampers lacked any real tuning.

            In the past, it didn’t matter that you couldn’t keep IRS tires parallel to the road because super wide and extra low profile tires were decades away.

            The current Camaro, Charger and Challenger are based on IRS sedans so on these, solid axles weren’t meant to be. These cars, as well as the Mustang are really, mostly softly sprung, daily drivers with all-out performance models a minority. Some compromises have to be made when they share a chassis. So the last remaining live axle loses and has to go. On luxury cars, don’t even think about it!

            If only there was an all-out, dedicated, no compromise and non luxury race car for the street, there might be a dilemma. IRS or SLA? Decisions, decisions… Front engine, and RWD layout, of course. Oh wait, there’s the Caterham and it runs a solid live axle. Not the traditional SLA, more of a hybrid. It uses a de Dion axle with a fixed pumpkin and independent half shafts, but the wheels are solidly connected, left to right, none the less.

            If there’s a lesson to be learned, thing aren’t always as they appear. Or aren’t anything like Top Gear says they are.

          • 0 avatar
            RobertRyan

            @Austinpowerless

            A GOOD IRS may be better than a good solid axle, in some, repeat some, circumstances. If it’s good, it may give better wheel control on bumpy corners, and may offer better traction in difficult conditions, this is where IRS shines especially off roading. Even a good IRS, though, is unlikely to give better outright dry road grip than a dD, because the IRS can’t maintain the wheel upright in a corner without sacrifices in the geometry that will give up performance elsewhere.

          • 0 avatar
            ismasl

            DenverMike, IRS CAN mantein the wheels upright in the corners, if you want so, but you dont want that, you can do better you can adjust camber, toe, caster…
            You can make camber to go negative as the vertical load increases in a corner.
            My point is suspension geometry is a lot more complicated than keeping the wheels upright in the corners.
            Rear solid axel might be fun, easy to mantein, simple and economic but it is not the best solution now a day on any aplication.

          • 0 avatar
            DenverMike

            @ismasl – You can compensate for the caster/camber/toe the outer tire (in relation to a turn) needs for optimal contact in a hard turn, as the car leans into the turn and the outer suspension compresses, but how much lean? And what happens as the inside tire/suspension lifts? OK, you compensate for that too, so it does get complicated, but now you have weird geometry when the car is riding static. Now picture the rear of the car and its added caster/camber/toe as it lifts or squats perpendicular to the road, under say, hard braking or full throttle… A whole different dynamic and you’re totally fighting a losing IRS battle for optimal contact with the road.

            It may be a shock for you to hear this here, but I’ve been embarrassing expensive and exotic sports cars in junky/trashed Fox body Mustangs, set up with KONI dampers, Energy bushing, etc, at auto-X events way back since the ’80s. I love the look on their face…

            There’s nothing magic about the Boss 302 Mustangs. They’ve just tuned the suspension (from the factory) close to the way we’ve been doing it for decades thanks to the aftermarket. You’re just used to seeing Mustang GTs with sloppy/goofy, stock dampers and bushings.

          • 0 avatar
            Austinpowerless

            I feel like I’ve slipped into the twilight zone here. IRS shines in “bumpy corners”?! Well, compared to a live axle, yeah, it does, but it shines on the world’s smoothest surfaces as well. F1 tracks are billiard-table smooth. Ditto (most) indy track,. and BTCC, DTC, etc.
            They don’t use live axles because you get more dry, smooth, flat road grip in a corner using a properly designed IRS. Period. end of.

            One way to convince yourself of this is to simply pick up any book by a mechanical engineer on suspension design. I gave you the name of my old text, but there are many hundreds of others. But really, it’s simpler than that: ask yourself, If live axles actually EVER gave more levels of dry grip, why, oh why does NO road racing constructor or team use them? It’s ludicrous. There isn’t a debate or a controversy here, the unspung weight of an SLA ALONE puts them out of the running for serious road racing potential. And, no , mike, the changes in tires have manifestly not changed the equation–in fact, it’s broadened the gap between sla and irs, but I digress.

            Note: I’m talking about “all out performance,” which was what the OP actually talked about. Now, it’s shifted to compromises, comfort, etc., but that wasn’t the original claim. The question was, “what gives the best performance.” The answer is IRS.

          • 0 avatar
            DenverMike

            @Austinpowerless – Once the IRS suspension is set for racing, its ability to handle bumps is negligible vs live axles. And that’s what we’re talking about here. Not Camry vs Secretary Edition Mustang.

            F1 tracks are smooth, but that’s not what we’re talking about either. They don’t have the fast risers and quick drop offs in combination with sharp turns that you encounter on normal tracks and real roads.

            Any race car without being front-engine will automatically have a transaxle. It’s a given. Same with any car. That rules out any possibility of a live axle on those. Front-engine race cars built off of street cars normally have IRS specific bodies because most consumers don’t buy them for racing exclusively.

            I’m not saying a live axle is a tremendous advantage over IRS, so it’s not really worth building a front-engine racer from scratch around the live axle. The axle you chose can’t be an afterthought. It depends on what tires you’re going to run and on which track. If it’s less than flat and is loaded with hard, sharp turns and quick elevation changes within them, I’m definitely going with the live axle. The best of both worlds is the de Dion axle. Think about why they chose to connect the wheel hubs, side to side, and not have them independent?

            The de Dion solves the unsprung weight riddle, but fine tuning the dampers can do almost an equal job for live axles. But IRS has do deal with more sprung weight that transfers from side to side, front to back. So there you go.

          • 0 avatar
            Austinpowerless

            What the heck are you talking about? Elevation changes mixed with sharp corners is precisely where irs has its greatest advantage. Tracks I include in my “smooth” survey would include, say, laguna Seca, Bathurst, or the ‘ring.–plenty of elevation changes.
            r.
            The reason you can’t name a road-racing car that uses an SLA despite your insistence on its imaginary advantages is because, well, they’re imaginary.
            The transaxle thing’s a canard, too. The original Panoz Sports racer was front-engined, and a no-compromise racecar. Did they use an SLA? of course not. Ditto your beloved mustang: in every road race series that allows it, they put in an IRS. Every single time. Without exception.
            Oh, and my Smart has a deDion; it’s not the best of anything, I can assure you of that. Why did they choose it? cost and packaging; if Daimler wanted handling performance [they didn\'t] they’d have gone IRS–as has every single road race car designed in the last fifty years (rules allowing, of course) for: smooth tracks, bumpy tracks, elevation changing tracks, flat tracks, and every other kind of track, save a drag strip (or Land-speed, obviously).
            I’ve given you a good textbook to refer to, so ‘m just going to put this down to one of two things: trolling or dunning-Kruger.

          • 0 avatar
            DenverMike

            Laguna Seca is a great example of where a Boss 302 kicks A$$. It’s tough for IRS sports cars to deal with the Corkscrew as it unloads the suspension while turning and braking hard into it, then completely compresses the IRS while turning and accelerating hard out of it. Never mind commonsense, lap times confirm this. The Boss 302 is running with supercars because the track is so damn technical. No other reason.

            It should be obvious, contact patch is everything in racing. It’s your only connection to the track. Unless a tire is flat on the pavement, it has limited grip. It’s simply not possible to keep a super low-profile IRS tire flat on the road throughout its range of motion with combinations of hard cornering, braking or accelerating, including quick drop offs and inclines thrown into the mix.

            There’s not many road-racing cars that can take advantage of a SLA. So start by naming the front-engine, dedicated racers that can use a SLA, besides the Smart ForTwo? The lower the profile is (like 30 series street cars) the more SLAs have the advantage. On race cars, it depends on the profile of tires allowed in the racing series.

            But the thing is, SLA aren’t readily accepted by the public for street driven cars, especially luxury. A lot of that is perception and wives tales perpetuated through the generations. It’s easier for OEMs to change an axle than popular belief.

            So what specific Mustang race cars run IRS? You’re talking tube chassis’ that run tacked on body skins in the form of Mustangs, Camaros, Impalas or whatever.

            But let’s hear a quote from one of your text books. I’m sure it was written during the Eisenhower Administration when tires were as wide as they were tall.

    • 0 avatar
      old5.0

      Because the cars running in the top NMRA/NMCA classes, as well as others, are stock bodied/back-halved chassis utilizing 2000+ horsepower smallblocks and turning the quarter in the low 7’s @ somewhere in the neighborhood of 200 mph. Even the slower, stock suspension cars make north of 1000 horsepower and regularly run in the low 8’s and over 150 mph. Add in a sticky tire, and I’m not aware of anyone who’s engineered an IRS capable of withstanding that sort of load.

      • 0 avatar
        ellomdian

        I have a sneaking suspicion you could engineer an IRS for those specifications, especially with multiple progressive clutches. The problems is that it would be HIDEOUSLY expensive to maintain.

        The current (and for the last 40 years?) Drag Racing ideology is that, short of Top Fuel, tires make up the biggest portion of your consumables. The burnout and launch turn the tires into progressive clutches, and because that’s how we’ve done it for years, no one questions the practice. Every cal of heat generated at the contact point is lost energy that is not actually driving the vehicle forward. It is significantly easier (see cheaper) to get massive Torque out of an engine than it is to design a drivetrain that does not slip.

        Having said that, Drag Racing fans (and I am one of them) want to see cars neigh-destruct to create as much power as possible each run, even when most of it is lost during the launch due to traction loss. I think most of the interesting next-gen stuff is coming with e-racers, where you can computer control the output based on feedback from sensors with millisecond accuracy – Traction control is great for cars today, but you simply cannot modulate the output of most drag engines fast enough to see a real benefit.

        • 0 avatar
          old5.0

          Driveline slip is not an option. Add a slick tire to a clutch activated manual trans or a ‘brake equipped automatic and without a certain amount of traction loss the shock would fold the car in half, depending on power levels involved. “Dead hook” is a very real phenomenon, and the results range from annoyance to massive destruction.

          Certainly you could design an IRS to withstand the top levels of drag racing, but why would you? What are you gaining, besides unnecessary complexity and unsprung weight?

    • 0 avatar
      greaseyknight

      I don’t think this is any indication of an inherent problem with the IRS. Its my understanding that these body in white mustangs are purpose built for drag racing, they won’t even have a VIN number. The teams that would run these would rip out the IRS and weld in a 9″ as a matter of course, as a solid axle is the only option for serious drag machines.

      • 0 avatar
        bikegoesbaa

        I get the idea of a body in white with a solid axle for purpose built competition only cars with lunatic horsepower.

        I’m curious about the bit that says “the parts needed to convert street-going Mustangs from independent rear suspensions to the 9″ setup should become available through Ford Racing and participating dealers”.

        Are the limitations of IRS really a practical consideration for anything that is plateable/streetable?

        Would a street-driven modified Mustang with 6-700 hp require a swap to a solid rear axle? If so, why? There’s no shortage of modern cars with power in this ballpark that are able to successfully run IRS and keep the tires on the ground and the driveline un-exploded.

        I’m picturing buttheads with a 5.0 installing a K&N and rumbly exhaust and then “upgrading” to a live axle because the IRS won’t support their new mad powerz.

        • 0 avatar
          Chopsui

          I think the part about a conversion kit being available is pure speculation by the author. I wouldn’t at all be concerned about the IRS being able to handle 6-700hp. I’m sure in a few years, the next-gen GT500 will be making at least that much power.

        • 0 avatar
          old5.0

          In that case, I agree. The IRS, if Ford’s done it properly, shouldn’t pose any problems in a true street car.

        • 0 avatar
          jz78817

          “I’m picturing buttheads with a 5.0 installing a K&N and rumbly exhaust and then “upgrading” to a live axle because the IRS won’t support their new mad powerz.”

          BFD. It’s their money to waste, let them do what they want with it and you can go about your smug way.

        • 0 avatar
          Drewlssix

          It’s not about strength or wheel hop. At least not entirely. At almost any hp level a good solid axle will beat a great IRS. A “great” IRS is only as good as a decent stick axle. I can all but promise that a 9″ ford in something like a new M3 would easily be good for a few tents. Even keeping stock gears wheels and tires.

          • 0 avatar
            krhodes1

            A few tenths where? In a straight line? Who cares? Straight line speed is not the point of an M3. It would certainly be far worse on a bumpy corner at speed.

            I like the current Mustang despite the archaic rear suspension, and I am quite excited to try the new one, especially in turbo four spec. But I don’t drive 1/4 mile at a time.

          • 0 avatar
            DenverMike

            In theory yes, but there’s really no indication that an M3 can handle a bumpy road any better than a Mustang. A solid axle may not be ideal for bad road surfaces, but neither is an M3. An M3 gives you a choppy ride like any other hi-performance sports car or pony car. An M3 is not gawd’s gift to corners by any means.

            But a solid axle shines by keeping the tires perpendicular to the road where as an IRS is riding on the edge of the tires when thrown hard into a turn and or hard braking/accelerating. No weird toe and camber angles for solid axles plus less wheel hop.I mean for spirited driving, IRS is perfectly fine.

            Extra wide and super low profile tires practically beg for a solid axle for optimal contact patch.

            And the unsprung weight disadvantage of solid axles can be reduced by tuned damping.

            Then solid axle setups are lighter than IRS with less parasitic drag with less sprung weight to transfer from side to side.

            Other than that, the solid axle had to go for a “world car”. That’s just the way it goes, but the rest is really based on wives tales more than reality.

    • 0 avatar
      jz78817

      “Having moved away from Michigan to a place with terrain/corners I often forget that “drag racing” is something that people do until news like this reminds me.”

      Hey, you know that thing you like?

      It sucks!

      • 0 avatar
        bikegoesbaa

        Say what? I don’t think drag racing sucks, I used to have all sorts of fun with it.

        The automotive scene is just so different where I live that I genuinely forget how big of a deal drags in the midwest, and that quarter mile times are considered to be *the* yardstick for performance by most enthusiasts.

        I hardly hear anybody talk that way since I left town. It’s not better here, just different.

        • 0 avatar
          raph

          And the east coast. Drag racing is huge for us flat landers.

          • 0 avatar
            krhodes1

            I guess if you live where there are no corners, you have to find some way to have fun. Doesn’t interest me in the slightest. Luckily Ford is trying to cater to all comers with the new car. v8 live axle 1/4 mile king, and road course ripper, all depending on the options you tick.

            Let’s cross our fingers that they get the interior right.

          • 0 avatar
            jz78817

            “I guess if you live where there are no corners, you have to find some way to have fun.”

            yes, and thankfully us poor benighted souls have you to grace us with what is right and proper.

            save it.

  • avatar
    Ron B.

    To Add to the Australian content,back in the 1980’s ,Racer Dick Johnson was using a 9″ center in the independent rear rear end of his Ford Sierra racer in the touring car series.(from wiki) Johnson and Bowe claimed eight of the nine rounds of the 1988 ATCC, with Johnson finishing the year as national champion. Following the ATCC, the team took one of their Sierra’s to Silverstone in England for the RAC Tourist Trophy. Proving that the Australian developed Sierra was the fastest Group A touring car in the world, Johnson easily qualified the car on pole in front of the Eggenberger Texaco Sierra’s and the Andy Rouse example, and went on to an early race lead. The car was eventually slowed by a lengthy stop to replace a failed water pump with victory going to Rouse. Upon returning to Australia, Johnson and Bowe teamed up to finish 2nd at the 1988 Enzed 500 at Sandown after qualifying on pole. They followed this with a second at Bathurst in the teams 3rd car (also driven by John Smith) after Johnson’s pole winning car retired following a puncture and spin on Conrod Straight at over 220 km/h (137 mph) which caused a major drive train vibration, while Bowe’s car was out soon after with engine trouble.
    At the end of 1988, Britain’s Robb Gravett of Trakstar persuaded Dick Johnson to supply his team with his Sierra RS500s, cars that had out-qualified the official Ford entered cars in the Tourist Trophy race in 1988. Gravett was immediately on the pace of the Andy Rouse prepared Sierras, and he won 4 races to finish the 1989 season 2nd in class and 4th overall.[2] In 1990, Robb Gravett won the championship with 9 race wins.
    Success continued for the Shell team in the 1989 Australian Touring Car Championship, with Dick winning his 5th championship and Bowe again finishing second. The team’s position at the top was beginning to be threatened by the appearance of more Sierra’s, including Peter Brock’s Mobil cars (sourced from Andy Rouse), which allowed Brock to finish 3rd in the championship before going on to claim pole position from Johnson at Bathurst. The Shell team had the last laugh though when Johnson and Bowe led every lap of the race and went on to win the team’s second Bathurst 1000.
    Why is Ford still thinking back in the 1950’s with a live rear axle? Is the ghost of old Henry haunting the engineering departments of Ford USA with his attitude of using existing (and profitable) technology rather than investing in better ideas?

    • 0 avatar
      old5.0

      The car is coming with IRS. Ford is offering the live axle kit for those who want it. What’s the big deal? I personally don’t care about the IRS one way or another, but it was clearly a move to appease the Europeans that Ford hopes will embrace this new car. The fact is that most of complaining about the lack of IRS over the past 25 years or so has come from people who wouldn’t buy a Mustang anyway. The bulk of Mustangs purchased by enthusiasts since the 1980’s have ended up on dragstrips, where the IRS is not an ideal solution.

      • 0 avatar
        RobertRyan

        @Old5.0
        This is the Ford Falcon IRS Control Blade suspension put on the 2002 Falcons.
        http://www.goauto.com.au/mellor/mellor.nsf/0/C9AE8D10D112A6A3CA256C790018CA06/$file/2002.11.25_sus2_Ford_FalconXR6Turbo.jpg?OpenElement

        • 0 avatar
          DevilsRotary86

          I am in the pro-IRS camp. The work that Ford has done with this IRS is nothing short of impressive. I would of course reserve judgement until we can actually try one for real, but the new IRS seems to be a leap forward.

          • 0 avatar
            old5.0

            The IRS should be better, and it certainly wouldn’t keep me from buying one. But how bad was the old beam axle, really? The Boss 302 seemed to do okay with a tree trunk under the back.

            I’ve always equated the Mustang’s axle with the 911’s rear-engine layout. An inherently flawed design that was refined until it actually worked pretty well. Clearly you’d expect an IRS Mustang (or a mid-engined 911) would be a better car, but I don’t think the old way was as bad as some people make it out to be.

            Don’t get me wrong, I’m not against independent rear in the new one at all. Ford’s global intentions for the car almost make it mandatory. But in the past, as I stated, I’ve always felt that the IRS was the answer to a question asked only by people who wouldn’t own a Mustang anyway.

          • 0 avatar
            jz78817

            on a good track the live axle isn’t a hindrance. When the surface turns bumpy (especially in the corners) you can feel that unsprung mass clomping around back there. Plus, while it’s pretty good out of the box, there isn’t much if any room to make it better.

            (Mustang GT owner)

        • 0 avatar
          raph

          Not supposed to be the control blade rear suspension. Supposed to be conceptually similar to what underpins the Exploder and the Fusion.

      • 0 avatar
        3Deuce27

        I’m a pro IRS guy for good reason. I have owned two Mustangs, a personal street driven one, an SVO(live axle), and a road race car, a 2000 Cobra ‘R\'(IRS).

        A reasonably compliant and effective live axle configuration can be accomplished as the SVO and recent Mustangs have proved, but they leave a lot on the table that IRS deals with effectively.

        Even in drag racing, a live axle has to be properly set-up in order to go straight and not break. The better controlled IRS, only has to be setup for limited travel so it doesn’t get into adverse camber situations due to squat and torque issues, resulting in a reduced contact area. And, this set-up varies from side to side due to chassis torque in a drag race vehicle.

        The only reasons to pull and IRS and replace it with a live axle, is to save the valuable IRS(as regards the 2003-4 SVT Cobra) unit, and put in place a cheaper live axle arrangement. And with the 9″ Ford removable pumpkin, too give you an easy gear ratio change and parts change at the track should ratios need to be adjusted or if anything goes kaput. That conversion, is something I have seen numerous times on 2003-4 SVT’s here in the NW for those reasons. Never, was it, an IRS durability issue. Things break, better to break a cheaper and more readily available live axle parts, then rare, specialized IRS parts.

        A long time friend and AHRA/NHRA record holder in years past, Steve Barker, always said he preferred the IRS of his race Vette’s over the live axle Camaro’s and Chevelle’s, in the quarter mile regime. And Steve knows suspension set-up and engines. He is also my GM back door guy for GM parts, because GM still appreciates what he did for GM racing, back in the day and his savvy, intuitive engineering abilities.

        Want to see a GM ‘Mystery Motor’ or a factory racing inline five cylinder, dual turbocharged Ecotec, visit Steve’s Red Barn on Friday nights. Bring something special for the burn out show, along with libations and something to eat and share.

        Don’t bring any tude’ or prejudices, Steve will eviscerate your afflictions regarding cars and your supposed automotive technical expertise or fantasies. Steve can tell you more about Fords and MOPAR products then Ford and MOPAR fan boys as he knew what it took to beat them and always respected whatever Ford or Chrysler built.

        Always a good and informative time with a lot of GM and Steve’s racing history on display, and if Steve takes a liking to you, you will get a tour of GM’s and Steve’s special racing/engineering engines from over five decades of GM racing.

        Funny story about Steve and I from many years ago that I just recently told him. Back in the day when I only knew Steve by sight and his deserved reputation, mind you he was a nearby neighbor, but a few years a head of me in school, we were not friends or even acquainted. Steve was a big deal then, and that has followed him through the years. I knew him, he didn’t know I existed, except, maybe, for my rides.

        I had left Doug’s Speed Shop on Old River Road and was headed home in my hot and radical 57′ VW convertible towards Old Pioneer when I saw Steve in one of his Vette’s sitting at the intersection waiting to see whether I was going straight or turning. I didn’t signal my right turn as I wanted Steve to be sitting where he was when I made the turn. I came up to the intersection at a speed that anyone would have safely thought that I was going straight, but I didn’t, and I did one of my infamous, cornering broad slides, high up on two wheels, door handle to door handle turns, right along side Steve’s precious Corvette and his incredulous and panicked face, . After, I was surprise he didn’t run me down, probably had something to do with the beauty in the other seat or he really had to be somewhere, soonest.

        When I recently(2006-7) told him this story, he remembered, and he said, “you were that guy in the VW?” and at the time he thought “if I ever catch up to that guy I’m going to strangle him to within an inch of his life’.

        Steve is a big man, and at the time, I knew that if he ever caught up to me it wouldn’t be pretty, he was bigger, but I was a force to be reckoned with, with my athletes body and 21″ arms… COL! But today, its a big laugh as we aren’t too much of a physical threat to anyone, anymore, just don’t challenge us on a drag strip or me on road course, especially if your driving a manual box. Both of us are known for our fast, optimum manual shifts in the quarter mile. Something, I don’t recommend in road racing, if you want to go the distance and be a contender at the end.

      • 0 avatar
        Ron B.

        ..or was the live axle option to appeal to a tiny market segment who want to go drag racing?
        Surely you are not suggesting that a live axle is the be all and end all of speeding down a drag strip?
        Real life has a way of proving things wrong occasionally…

        • 0 avatar
          raph

          If the segment was “tiny” as most people who aren’t into drag racing like to believe do you think Ford would pursue the body in white program and develop a live axle kit for the car.

          As far as Mustang motorsports goes drag racing is huge, the bulk of the people who post on Mustang forums tend toward drag racing as do the people in various FB Mustang groups.

          Mustang drag racing is so big it supports its own sanctioning body( NMRA) and most of the aftermarket for these cars is geared toward that.

          The only group that I’d say is larger than the drag racing crowd are people who just want to use the car as a fashion accessory and could car less about how fast the car accelerates or how fast it goes around a turn so in that respect your probably right.

          • 0 avatar
            RobertRyan

            Oh so that is why we are getting posts saying how great solid axles are as Ford sells a lot of solid axle Fords to Drag Racers!!!! Wonder why that was happening . Logically the posts did not make sense, but if there is a NMRA sanctioning body must a be a strong market for Ford.

          • 0 avatar
            raph

            I also think its because its different and it works just like GMi guys and their push rods.

            As a Mustang guy I could care less, my only expectation with Ford and its newly IRS equipped Mustang is that when I get around to buying one it should be no less reliable than the stick axle in the current car nor should it perform differently at a drag strip,. In effect I expect the technology to be invisible as far as drag racing is concerned .

  • avatar
    NMGOM

    Great. Now if Ford can only figure out how to simply offer the solid axle as a co-equal purchase option for ordinary customers, who may not want IRS, then….Oh wait. I forget. That may be beyond the abilities of creative accounting….

    ————–

  • avatar
    carlisimo

    What does 9″ refer to? Why’s it called that?

    • 0 avatar
      highdesertcat

      The legendary 9″ Ford differential! Pretty much bullet proof for hot rodders and street rodders alike. The 9″ refers to the diameter of the ring gear.

      • 0 avatar
        raph

        Yep, the 9″ also features a carrier that is separate from the axle housing and the axles are located by pressed bearing retained by a plate at the end of the axle.

        The current Mustang axle is an 8.8 but utilizes a carrier that is integral to the housing and features pressed axle tubes and C-clips which retain the axle.

        Another nice feature of the 9″ is to have multiple gears set-up in individual carriers and the ability to swap them out without having to compensate for tolerance issues with the gears and carrier, just pull the axles, take out the old carrier and put in the new carrier with new ratio.

        The down side to the 9″ is the placement of the pinion gear in relation to the ring gear (although this was changed some years ago by a few 9″ specialist) but it absorbs about 4% more power IIRC to operate the axle.

        Ford’s 8.8 is loosely based on GM’s 12 bolt rear end.

        • 0 avatar
          NMGOM

          raph – – –

          Excellent. So, tell me, how does Ford’s new IRS compare to what you described?

          —————–

          • 0 avatar
            Scoutdude

            At this point it is too early to say to much specific about the new Mustang’s diff but it is almost certain that it is an intergal style design. It is most likely based on the tried and true 8.8″ diff as that is what Ford used in the last Mustang’s IRS as well as the IRS used in the last gen of Explorer/Mountaineer/Aviator, Expedition/Navigator, Lincoln Mark VIII and related T-bird/Cougar.

        • 0 avatar
          Scoutdude

          Note some of the greater friction in the 9″ is due to the 3rd pinion bearing which is also one of the reasons it is so strong.

        • 0 avatar
          Dan R

          I knew that.

  • avatar
    3Deuce27

    @ ‘Denvermike’

    You seem to keep repeating the same mantra… “solid axles are better at keeping the wheels perpendicular to the road surface’ Pray tell how?

    Why the need for swing axle IRS and fully articulated IRS if not to keep the wheel nearly perpendicular and to bias that to pre-load the inside contact area of the tire, something a solid axle can’t do effectively reducing its contact area in side loadings inducing slip angles. Modification or adjustments to roll couples through roll centers and roll stiffness, is easier with an IRS.

    “IRS sports car has the super wide and low profile tires on the inner or outer sidewall, partially.”

    Clearly you don’t understand suspension design, Live/beam or IRS, and, vehicle dynamics under non static loads and how that effects suspension movement in relation to its loads and loading under applied forces. That’s ok, few people do, it is a very specialized environment, one engineers have been working on for many years and are still researching for improvements. The power of currently available computers, is advancing suspension design through finite element computational software.
    One would think suspension design is primarily a geometrical contrivance based on perceived needs with a nod to suspending loads and dampening impact forces, applied mechanically. It goes beyond that with transient responses affecting interactions of the various components coupled with inescapable dynamics of physics.

    If it were only an exercise establishing roll center, resistive contact areas and dampening regimes, and it would be if vehicles only ran on flat, straight surfaces and never turned. However, when that vehicle turns it creates dynamic forces that have to be managed effectively. These forces create elastic conditions that stretch the hard points, structures, and components, effectively changing the static designed geometry. The permutation of these forces are infinite.

    Modern IRS design uses fully ‘articulated’ mechanical elements, which keeps the tires contact area at near 100%. Old swing axle IRS designs didn’t do that, but even those designs were superior in ride and maintaining a great deal of the available contact area compared to a live/beam axle.

    Live and beam axles significantly ‘Jack\'(shift the ‘roll-center’) under lateral dynamic loads, greatly reducing contact at the limits and the increased unsprung weight of a live axle further degrades ride and handling. Applied longitudinal loads, significantly compound the situation.
    We used to think that a good road holding set-up for road racing had to be hard and stiff, effectively eliminating most of the movement of suspension components and negating compliance in an effort to reduce body roll and the messy dynamics that engenders. . We know better today. Watch the range of motion with a modern F1 car suspension.
    Reg; “the BMW M3. It can’t keep up with the Mustang in the turns.”

    Anecdotal and unsupported comment. Your provided video only shows a lap time, not speed in a corner.

    In a betting situation, in a contest of cornering speeds, serious money would pick the M3 over the stock Boss 302, foolish money would pick the Boss 302. unless it is a ‘Laguna Seca, Boss 302R, or 302S, which is a Ford Motorsport and Watson sorted race car.

    The stock M3 and base Boss 302, are cars set-up for anybody, regardless of driving skills, who can afford to buy one. One quickly understands the difference of the two vehicles when driven on the street and tracked. The M3 has a compliant ride with linear transitions that are easily nuanced. The Boss rides much rougher and though its handling is capable and effective, it requires much more physical input and doesn’t respond to deft adjustments. And the situation worsens for the Boss with less then ideal road/track surfaces.

    • 0 avatar
      DenverMike

      @3Deuce27 – The poor M3 can barely keep ahead of the Mustang GT and its sloppy bushings and dampers thru the turns. If you don’t believe me, ask MotorTrend. And they’ve never been fans of the Mustang. They’re total M3 fanboys too.

      youtube.com/watch?v=uOwSPccbzl4

      The GT has flaws that the Boss 302 corrects. Still, the aftermarket can do a much better job than Ford’s SVT.

      The Boss 302 lacks cockpit adjustable dampers, like the M3, when going from street to track, but that’s its only disadvantage. But when each are at their hardest setting, there’s not proof the M3 is any more of a picnic to control when the road gets rough and tore up.

      Here’s 3 cars negotiating a bad spot on the Burgerkingring’s Carousel. First is the GT500, the Camaro Z28, then the Merc SL:

      youtube.com/watch?v=n7_Ge2gWXmM

      youtube.com/watch?v=wyRHF1RNsU8

      youtube.com/watch?v=83Il6HEeI_c

      I’m not saying live axles are gawd’s gift, but neither is IRS. Each have their downsides and fine tuning helps. You can tune an IRS for hard turning in an otherwise static ride, but what about braking hard at the same time? Or turning hard with the rear suspension compressed (both left and right) from accelerating hard, landing a dip or reaching a sudden riser? You’re fighting a losing battle trying to keep a decent contact patch with IRS in all situations.

      While basically trying to emulate a solid axle’s contact patch, no matter what the road or track throws at you, why not go for the real thing?

    • 0 avatar
      RobertRyan

      @3deuce27,
      Ford has Drag racing Division that is only for solid axle Mustangs the NMRA. As long as that exists, Denvermike will rave about solid axle Mustangs.

  • avatar
    3Deuce27

    You all are welcome to Denvermike’s ‘The World is Flat’ alternate reality. And so it goes… for Mike, anyway

    • 0 avatar
      DenverMike

      It definitely goes against the grain, but you’ve provide nothing but wives tales. Suppose the M3 has World Class refinement. That doesn’t make the M3 faster around a track. Or less hard to control on busted up pavement. Show anything that proves your point of view. Even a Top Gear link. Anything? Top Gear has been remarkably silent about the M3 getting embarrassed at the track by a log axle’d pony car. Before the Boss 302, every 3rd of 4th episode trashed the Mustang and or humped the M3’s leg.

      • 0 avatar
        bikegoesbaa

        Since it’s apparently very well-established that solid axles are superior in terms of contact patch and weight transfer I expect it should be very easy for you to provide a link to an SAE or academic paper that supports this in more detail, right?

  • avatar

    I didn’t know where to tuck this little tidbit I just got but here is my news: “Job 1 for the 2015 Mustang is July 15th”. Meaning no April 50th anniversary. Perhaps that’s not really news though.

  • avatar
    3Deuce27

    OK! Franz.. Now just get us the early order date. Has to sometime before the July 15th intro.


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