Mustang Miss » Ford Mustang Racing » IRS on Mustangs
IRS on Mustangs
Question:
- Hide quoted text — Show quoted text – Pull one out of the latest Thunderbirds (salvage yard/over the counter) and set it up underneath that stang ….. Just because you can do it doesn’t make it a good thing. There’s two main problems with using the T-bird IRS. Hot Rodding is not for the faint of heart. First, The T-bird uses a rear subframe for the IRS mounts. this would need to be installed or fabricated for the Mustang. Hot Rodding is not for the faint of heart.
This is has all been done before. There is a company that either offers a kit to install the T-bird IRS under an ‘79-93 Fox platform or does installations. It has been featured in Mustang Monthly or one of the other Mustang mags. IRS is a definite worthwhile Mustang addition, if you can afford the price. Robert Hall
Response:
Hot Rodding is not for the faint of heart. This is has all been done before. There is a company that either offers a kit to install the T-bird IRS under an ‘79-93 Fox platform or does installations. It has been featured in Mustang Monthly or one of the other Mustang mags.
There are (or were) a couple of kits out there, but none of them has been much of a success. The one that made the biggest splash was the JBA kit developed on their Dominator Mustang. JBA abandoned that project before taking it to the market because it was heavy, expensive, and they couldn’t get it to work very well because of the geometries used in the T-bird setup and the excessive weight needed to get the thing installed. There just was not enough bang for the buck. IRS is a definite worthwhile Mustang addition, if you can afford the price.
And if you can get one in. The T-bird unit just doesn’t make sense from a performance point of view. Unless you want to run it just for the sake of running it, you’re better off running a torque arm, or even a 3-link. — Robert King | Robert A. King | I drank WHAT?!? | | 1988 Mustang GT | | 215,000 miles & still racing! | | 280hp | | 1:28 lap at Texas World Speedway |
Response:
I first came across the idea of IRS on a mustang in the November 94 issue of Mustang Monthly when they did a profile on the EXP 500, a Shelby prototype which had been one of those lost and found cases. The guy who ended up with it had the resources to find out how the car was originally set up and managed to duplicate it. A new IRS was made by Martin Euler at classic and Muscle Mustang Restoration, Dept MM 3820 Bay City Rd. Apt 7 Midland, MI 48642 (517) 496-2394. The only other lead I have on IRS for mustang is available through Impact Engineering, Dept. MM 617 W. 1900 N., Farmington, UT 84025 (801) 451-5283. I got that reference from Mustang Monthly. If you can obtain a back issue of March 95, you’ll find it on page 12 under new bits, or you can contact MM directly 7157, Lakeland, Fl 33807. Good Luck!
Response:
Robert I said: That is all I’m doing and it should be obvious that it is not my responsibility to provide ALL the answers. I merely provided an idea which is not too far from the mark that the Ford engineers may be exploring at this moment. You said: Trust me, they’re not. First off, I did say "may be exploring". I like to reserve a little wiggle-room for being wrong. It happens.
Nothing wrong with that, but I’m just educating you. they’re definately NOT considering the T-bird IRS setup. Secondly, if they’re not reviewing the requirements at this time, when will they ?
I didn’t say they wern’t working on an IRS, they are (The one on Saleen’s World Challenge cars.) Several folks have said that Mustang IRS functionality will be available in 1999, and at least one respondent said 1998.
That might have been me. there’s a definate change it might make the Cobra in ‘98. If this delivery date is bunk, please say so and I would unconditionally agree with you…again and believe the engineers are not logging time to this project.
No, they’re working on it, Its just that its not the T-bird IRS. I agree with many of your points, and from your remarks it seems evident that if Ford is ever going to install an IRS on the Mustangs, that some significant changes will need to be designed into the unibody/subframe structures.
Well, the T-bird IRS does because it was designed to be used with the T-bird’s rear subframe structure – somthing the Mustang doesn’t have. I have yet to see GOOD photos of the Mustang IRS setup as installed in Saleen’s race cars, but it looks likely that it will require minimal changes to the unibody/tub. While the IRS on the T-Bird may be heavy (not anymore than other performance/luxury cars), it will not be easy to make this or -ANY- IRS much lighter without more expensive/lighter materials. The T-Bird IRS is rather simple in it’s design and structure.
True, and the IRS itself isn’t that heavy. But the structure required to provide the attachment points for the IRS is the rear subframe.) So even if Saleen is working on developing an IRS unit, and most likely a unit to sustain the punishment from their 351 S/C powerplants, it will be a difficult chore to make it much lighter than the T-Bird.
True, but it doesn’t require the subframe that the T-bird IRS needs. Bob Bondurant uses these IRS units exclusively in his A/C Cobra replicar vehicles. And as you know, the powerplant in these cars are typically greater than 300HP. If you’re curious, I can scan the photo and mail it to you. In fact, the one thing that I like about this rear-end, is it’s simplicity.
Yes, but the rear structure of Bondurant’s chassis is *designed* to provide the pickup points for the IRS – the Mustang isn’t. The 8.8" carrier these suspensions use is plenty strong for anything short of a high-horsepower drag race with slicks (which IRS doesn’t work well with anyway.) I know you will, and it’s painful to me, but please correct me where I’m wrong.
Info on Ford’s IRS plans hasn’t been that easy to come by (certainly the mass-market car rags haven’t taken up the story yet, and only one Mustang rag has.) Most of what I know is from sources in Detroit, and other folks in the industry. I do have questions for you from another topic. Your signature suggests you’re racing autocross,
Well, I road-race (Autocrossing is slightly different.) rather than strip (foot-down-turn-left). Do you know of any people who race 69 or 70 Mustangs (specifically Mach I’s)?
Not personally. I see them from time to time on the track though. I know there are alot of guys doing the pre-69 Shelby (shelby-look-alike) racing. My interest is in understanding what suspension/handling modifications these guys are performing. Of course, the best feedback I can expect to receive would be from these people. what do you think ?
Griggs Racing (they advertize in most Mustang rags,) does early as well as late-model Mustang suspension mods. You might start with them, or your local chapter of SAAC (Shelby American Automotive Club.) — Robert King | Robert A. King | I drank WHAT?!? | | 1988 Mustang GT | | 215,000 miles & still racing! | | 280hp | | 1:28 lap at Texas World Speedway |
Response:
Just because you can do it doesn’t make it a good thing. There’s two main problems with using the T-bird IRS. Hot Rodding is not for the faint of heart.
I never said it was. The post I replied to implied that it would be a "slap it in and go" operation. It isn’t. And I agree, just because it can be done doesn’t make it "a good thing". Should that prevent me from encouraging other who ask the question ?
No, but by the same token, anyone considering this should be well informed. If I was going to do it, I would want all the opinions and facts I could get before I started seriously considering it. That is all I’m doing and it should be obvious that it is not my responsibility to provide ALL the answers. I merely provided an idea which is not too far from the mark that the Ford engineers may be exploring at this moment.
Trust me, they’re not. This endeavor would require research, planning, cash, tools, and a bright/creative individual.
It did. First, The T-bird uses a rear subframe for the IRS mounts. this would need to be installed or fabricated for the Mustang. The problem is, the sucker’s HEAVY. Not a problem with the T-bird, but are you sure you want to add a few hundred pounds to an already portly car? I have no problems with 8.8 or 9" rears and yes it would be heavier. The T-bird IRS though is light if you compare it to the Jag or vette and most likely, this same unit, or a derivation thereof, will be installed under a Mustang, if it happens at all.
Nope. The IRS destined for the Mustang is a derevation of the one Saleen is playing with on his World Challenge cars. It doesn’t have much in common with the T-bird IRS except perhaps the 8.8" center section. Second, have you ever set up the geometries on a rear suspension? Not trivial! JBA tried this a few years back on their Dominator and just couldn’t make it work well enough to pursue. Hot Rodding is not for the faint of heart. JBA will agree.
Yep, and they never could get the car to work right. | Robert A. King | I drank WHAT?!? | | 1988 Mustang GT | | 215,000 miles & still racing! | | 280hp | | 1:28 lap at Texas World Speedway |
Response:
Bob, All good points, I would like to add a piece to my earlier reply. While the IRS may be heavier due to custom subframe additions, and a slight incremental increase with the rear-end, I believe it would still be -well- under 200 lbs more than stock.
Nope – the sucker’s pretty heavy. The Mustang unibody’s just not set up to take rear suuspension loads anywhere but the torque boxes and rear shock towers. Getting the pickup points installed for the IRS is going to take a LOT of fabrication. A company called C.W.I provides such suspension kits and they may be able to answer/address specific customer needs. These kits, however are more expensive than the T-Bird over the counter but, they are robust and can handle serious loads.
And ANY kind of IRS you put in there better be able to take quite a beating. In addition, the Serious Mustang Draggers, cut-out and replace the subframes all the time, typically with heavier 9" rears. Evidently, they are having success with finding the correct geometries.
Dragracing geomtries are MUCH simpler than road racing or even street geometries. (Ask anyone whose tried to road-race with Southside bars.) Lastly, I confess to not answering the question directly and I’ll concede that this endeavor is something that has me extremely curious. Out there somewhere, is a nut-bar who strapped on his balls and actually did it. I want to hear from that person regardless of their success..
Well, you’re getting that information second-hand. I’ve actually looked into this modification and talked with chassis fabricators and folks who’ve actually tried it (including JBA.) To a man, they said don’t waste your time, a live axle with a torque arm can be set up to run nearly as fast as an IRS cheaper, lighter, and easier to tune. — Robert King | Robert A. King | I drank WHAT?!? | | 1988 Mustang GT | | 215,000 miles & still racing! | | 280hp | | 1:28 lap at Texas World Speedway |
Response:
Bob, All good points, I would like to add a piece to my earlier reply. While the IRS may be heavier due to custom subframe additions, and a slight incremental increase with the rear-end, I believe it would still be -well- under 200 lbs more than stock. A company called C.W.I provides such suspension kits and they may be able to answer/address specific customer needs. These kits, however are more expensive than the T-Bird over the counter but, they are robust and can handle serious loads. In addition, the Serious Mustang Draggers, cut-out and replace the subframes all the time, typically with heavier 9" rears. Evidently, they are having success with finding the correct geometries. Lastly, I confess to not answering the question directly and I’ll concede that this endeavor is something that has me extremely curious. Out there somewhere, is a nut-bar who strapped on his balls and actually did it. I want to hear from that person regardless of their success.. Caio, -D
Disclaimer: The opinions expressed herein are my own and in no way reflects the same of my employer. All recommendations and advice must be verified to be accurate by the recipient before implementation.
Response:
Robert I said: That is all I’m doing and it should be obvious that it is not my responsibility to provide ALL the answers. I merely provided an idea which is not too far from the mark that the Ford engineers may be exploring at this moment. You said: Trust me, they’re not.
First off, I did say "may be exploring". I like to reserve a little wiggle-room for being wrong. It happens. Secondly, if they’re not reviewing the requirements at this time, when will they ? Several folks have said that Mustang IRS functionality will be available in 1999, and at least one respondent said 1998. If this delivery date is bunk, please say so and I would unconditionally agree with you…again and believe the engineers are not logging time to this project. I agree with many of your points, and from your remarks it seems evident that if Ford is ever going to install an IRS on the Mustangs, that some significant changes will need to be designed into the unibody/subframe structures. I may be wrong, but I would think the engineers would be thinking quite a bit about this issue -IF- delivery is indeed 1999. While the IRS on the T-Bird may be heavy (not anymore than other performance/luxury cars), it will not be easy to make this or -ANY- IRS much lighter without more expensive/lighter materials. The T-Bird IRS is rather simple in it’s design and structure. So even if Saleen is working on developing an IRS unit, and most likely a unit to sustain the punishment from their 351 S/C powerplants, it will be a difficult chore to make it much lighter than the T-Bird. Bob Bondurant uses these IRS units exclusively in his A/C Cobra replicar vehicles. And as you know, the powerplant in these cars are typically greater than 300HP. If you’re curious, I can scan the photo and mail it to you. In fact, the one thing that I like about this rear-end, is it’s simplicity. I know you will, and it’s painful to me, but please correct me where I’m wrong. I do have questions for you from another topic. Your signature suggests you’re racing autocross, rather than strip (foot-down-turn-left). Do you know of any people who race 69 or 70 Mustangs (specifically Mach I’s)? I know there are alot of guys doing the pre-69 Shelby (shelby-look-alike) racing. My interest is in understanding what suspension/handling modifications these guys are performing. Of course, the best feedback I can expect to receive would be from these people. what do you think ? Disclaimer: The opinions expressed herein are my own and in no way reflects the same of my employer. All recommendations and advice must be verified to be accurate by the recipient before implementation.
Response:
Pull one out of the latest Thunderbirds (salvage yard/over the counter) and set it up underneath that stang ….. Just because you can do it doesn’t make it a good thing. There’s two main problems with using the T-bird IRS.
Hot Rodding is not for the faint of heart. And I agree, just because it can be done doesn’t make it "a good thing". Should that prevent me from encouraging other who ask the question ? That is all I’m doing and it should be obvious that it is not my responsibility to provide ALL the answers. I merely provided an idea which is not too far from the mark that the Ford engineers may be exploring at this moment. This endeavor would require research, planning, cash, tools, and a bright/creative individual. First, The T-bird uses a rear subframe for the IRS mounts. this would need to be installed or fabricated for the Mustang.
Hot Rodding is not for the faint of heart. The problem is, the sucker’s HEAVY. Not a problem with the T-bird, but are you sure you want to add a few hundred pounds to an already portly car?
I have no problems with 8.8 or 9" rears and yes it would be heavier. The T-bird IRS though is light if you compare it to the Jag or vette and most likely, this same unit, or a derivation thereof, will be installed under a Mustang, if it happens at all. Second, have you ever set up the geometries on a rear suspension? Not trivial! JBA tried this a few years back on their Dominator and just couldn’t make it work well enough to pursue.
Hot Rodding is not for the faint of heart. JBA will agree. — Robert King | Robert A. King | I drank WHAT?!? | | 1988 Mustang GT | | 215,000 miles & still racing! | | 280hp | | 1:28 lap at Texas World Speedway |
Disclaimer: The opinions expressed herein are my own and in no way reflects the same of my employer. All recommendations and advice must be verified to be accurate by the recipient before implementation.
Response:
Pull one out of the latest Thunderbirds (salvage yard/over the counter) and set it up underneath that stang …..
Just because you can do it doesn’t make it a good thing. There’s two main problems with using the T-bird IRS. First, The T-bird uses a rear subframe for the IRS mounts. this would need to be installed or fabricated for the Mustang. The problem is, the sucker’s HEAVY. Not a problem with the T-bird, but are you sure you want to add a few hundred pounds to an already portly car? Second, have you ever set up the geometries on a rear suspension? Not trivial! JBA tried this a few years back on their Dominator and just couldn’t make it work well enough to pursue. — Robert King | Robert A. King | I drank WHAT?!? | | 1988 Mustang GT | | 215,000 miles & still racing! | | 280hp | | 1:28 lap at Texas World Speedway |
Response:
Does anyone know when, better yet if ever ford will implement IRS on Mustangs? -Max V. 94 GT
Sometime in the year 2000 most likely…along with a $38,000 base sticker price. 
Brant
Response:
Where the hell are the Hot rodders ??? Pull one out of the latest Thunderbirds (salvage yard/over the counter) and set it up underneath that stang ….. -D Does anyone know when, better yet if ever ford will implement IRS on Mustangs? -Max V. 94 GT
Disclaimer: The opinions expressed herein are my own and in no way reflects the same of my employer. All recommendations and advice must be verified to be accurate by the recipient before implementation.
Response:
Does anyone know when, better yet if ever ford will implement IRS on
Look for it to show up on the ‘98 Cobra. — Robert King
Response:
Salleen is supposedly testing one that will be a production unit (in MM&FF a few months ago). When… I’m not sure, the bigger question is HOW MUCH? Patrick
Response:
Does anyone know when, better yet if ever ford will implement IRS on Mustangs? -Max V. 94 GT
The IRS will absolutely show up on all mustangs for model year 1999. Along with this, the GT will get cobra style twin piston front brake calipers and slightly bigger rotors. Every chart in Dearborn shows this to be the gospel word of what’s happening for SN95. There will also be a mild body reworking for 1999. ~gb "What’s the difference between a Corvette and a porcupine?" "With the porcupine, the pricks are on the outside…"
Response:
Does anyone know when, better yet if ever ford will implement IRS on Mustangs? -Max V. 94 GT