GT in need of IRS

TeamCaffeineGT · Mar 17, 2009

Gearbanger 101 said:
You need to check our very own classifieds more often.

04 Cobra IRS complete - StangNet Mustang Classifieds

04 Cobra IRS assmbly complete w/Exhaust - StangNet Mustang Classifieds

Thanks for the heads up and links. Looking to do a swap not a sale though.

Thanks,
TeamCaffeineGT

TeamCaffeineGT · Mar 17, 2009

blubullett said:
Look around for a cobra owner who will swap you straight across. Post on your local craigs list or local mustang club forums.

Thanks for the info. I did think about posting on craigslist. I wanted to see if I could dig up more info on the topic before commiting to it, but it seems too many are interested in debating the issue.

Thanks again,
TeamCaffeineGT

Gearbanger 101 · Mar 17, 2009

calboss281 said:
As I said before, the IRS only assists the driver, it doesn't make the car perform better. The ENGINE makes the car perform better, the ford racing bushings, springs, control arms, and sway bars....THOSE help the car perform better. The IRS just helps the driver maintain control and stability of power distribution during turns. The live axle does this as well, just not as efficiently. The live axle uses a limited slip to perform a similar action to the IRS (shifting power to outside wheel), but the IRS does it more effective because it doesn't need a clutch to transfer the power to one side.

The IRS advantage goes a little deeper than just that.

The main advantage of the IRS is the ability to keep a full contact patch with "both tires" on all road surfaces and grades. When the road surface is uneven or not completely linear, one wheel retains a full contact patch, while the other runs on the inner or outer edge on a solid axle car.

An IRS car however will be able to maintain full contact patch with both wheels, since each wheel is situated and controlled independently from the other.

An exaggerated demonstration....

Solid Axle

Independent Rear Suspension

Not only does the contact area of the tires remain constant, but the suspension center and as a result vehicle centerline remains more horizontal as well. This limits body roll and unwanted weigh shift. Thus improving handling over all capability.

TeamCaffeineGT · Mar 17, 2009

02nightmaregt said:
Dude if you want the IRS(much better ride quality anyways) than i say go for it!

Thanks for the support.

TeamCaffeineGT · Mar 17, 2009

Gearbanger 101 said:
The IRS advantage goes a little deeper than just that.

The main advantage of the IRS is the ability to keep a full contact patch with "both tires" on all road surfaces and grades. When the road surface is uneven or not completely linear, one wheel retains a full contact patch, while the other runs on the inner or outer edge on a solid axle car.

An IRS car however will be able to maintain full contact patch with both wheels, since each wheel is situated and controlled independently from the other.

An exaggerated demonstration....

Solid Axle

Independent Rear Suspension

Yuppers! Seems logical doesn't it? No wonder performance car makers outside of the US rarely use anything but IRS. Nice pictures.

calboss281 · Mar 17, 2009

Gearbanger 101 said:
The IRS advantage goes a little deeper than just that.

The main advantage of the IRS is the ability to keep a full contact patch with "both tires" on all road surfaces and grades.

Which is pretty much irrelevant unless your driving abilities push the car to the limit where this advantage is actually necessary. Like I said, I've seen GTs blow away vettes just by driving ability. Things always sound great in theory, but it's really all about practice.

All this talk about what "makes sense" and what "seems logical" is all just, to me, paying tribute to the idea that modding your car as opposed to yourself makes your car better. But whatever, if you guys want to just mod your cars out to the max ability without learning how to even master the car first...be my guest.

crazystang25 · Mar 17, 2009

blksq10psi said:
if it was me id work with the live axle there are good suspension parts out there to make it a respectable corner carver

i agree honestly no need to look any farther than maximum motorsports. best there is for a road course. just look at the maximum grip box. has all you will need to beat out any IRS platform.

calboss281 · Mar 17, 2009

crazystang25 said:
i agree honestly no need to look any farther than maximum motorsports. best there is for a road course. just look at the maximum grip box. has all you will need to beat out any IRS platform.

That's what I've got, and I couldn't agree with you more.

Gearbanger 101 · Mar 17, 2009

calboss281 said:
Which is pretty much irrelevant unless your driving abilities push the car to the limit where this advantage is actually necessary. Like I said, I've seen GTs blow away vettes just by driving ability. Things always sound great in theory, but it's really all about practice.

All this talk about what "makes sense" and what "seems logical" is all just, to me, paying tribute to the idea that modding your car as opposed to yourself makes your car better. But whatever, if you guys want to just mod your cars out to the max ability without learning how to even master the car first...be my guest.

How exactly is having the most amount of medial and lateral traction available irrelevant in a handling situation?

Great, you've seen modified Mustangs beat stock Corvettes around the track. Does that mean the solid axle set up is the better of the two, or does that must mean a modified solid axle car can be made to outperform a factory stock IRS? I mean...I can show you plenty of clips where Modified IRS cars are walking all over modified stick axle cars too?

Sure, driving skill is always going to be the deciding factor in any case, but you still can't bring a knife to a gun fight. In the case of two equal drivers, the guy with the better equipment is always going to have the advantage. So why get uptight about the guy who wants to upgrade his stuff and improve his driving skill from the point at which he'll be most accustom to? Or are you of a different opinion that a car with stock suspension and a car with modified suspension have completely different handling characteristics?

I mean...it’s like drag racing or motorcycle riding. Just because you may have learned and got good on a slower, smaller car/bike doesn't mean you're not going to have to relearn it all when you upgrade. What difference does it make if he wants to upgrade first and then get good, as opposed to getting good and then upgrading. Your argument makes zero sense!

calboss281 · Mar 17, 2009

Gearbanger 101 said:
How exactly is having the most amount of medial and lateral traction available irrelevant in a handling situation?

By taking it out of context, I can see how confusion might arise. However, my point was that driving ability and skill is by far vastly more important and vital than modifying a car. This kid is talking about a HUGE project, not something that is completed over the weekend with your buddies and a bottle of whiskey.

I bring up the abilities of modified live axles with experienced drivers because of the simple fact that you CAN outperform the stock IRS, even modified ones, if you have the experience behind the wheel. The author of the thread made no mention as to how far he has modified his car, what he does with it (is it a daily driver? a race car? weekend racer?), or what type of racing he prefers (SCCA auto cross? Super Cross? SCCA Road Racing?). So I gave him the best advice one can give with such limited information:

Before you go and spend a lot of money trying to make your car faster, you should make yourself better at driving it. AND...while you're doing that...you should consider that you can still outperform other drivers with better cars by being a BETTER DRIVER.

Just because you may have learned and got good on a slower, smaller car/bike doesn't mean you're not going to have to relearn it all when you upgrade.

There is a major difference between knowing exactly how your car performs, and not knowing at all; prior to a modification. If I know exactly how my car handles a 75 degree upwards turn at 35mph, I will notice the difference after I modify the car...and will learn how to adjust my driving to that ability. Whereas if I have NO clue how the car performs in a 75 degree turn at 35mph, I will have to do it many many times to figure out the car's ability. It's a matter of doing something once versus doing something ten thousand times over and over again.

What difference does it make if he wants to upgrade first and then get good, as opposed to getting good and then upgrading. Your argument makes zero sense!

Trying to save people time and money makes no sense? Well...we ARE in America I guess. I'm not ARGUING anything, I'm just putting forth my two cents that the guy should consider a few things prior to making his final decision. He seems pretty set on getting it so I'm not going to argue that he's making a bad choice. It's his car he can do whatever he wants to it. But in my opinion, it's a waste of money.

scupking · Mar 17, 2009

I would stick with the solid axle and if I had a cobra I would be swapping in a sold axle. As others have said you can make a sold handle very well and you can go in a strait line without issues of the IRS.

Gearbanger 101 · Mar 17, 2009

scupking said:
I would stick with the solid axle and if I had a cobra I would be swapping in a sold axle. As others have said you can make a sold handle very well and you can go in a strait line without issues of the IRS.

Once you address the soft factory bushings of the IRS that causes the wheel hop, its every bit as tough (actually tougher) than the stock 28-spline solid rear axle set up of the GT. You'd have to bump up to a 31-spline solid axle set up if you actually want a noticeably tougher system.

I've seen guys run 10's and even dip into the 9's on the stock IRS. So swapping it out for a car that anything but the most extreme track duty ride is kind of a waste of time and money IMO? Especially for a daily driver that’s going to do the majority of its driving on the street, with the odd trip to the drag strip. Especially if all you're going to do is run your car in the 11-13 second zone.

You'd have to do twice the amount of work to a solid axle set up to greatly surpass the handling characteristics of a stock IRS, where all you really need to do to the IRS to meet or beat the strait line characteristics of the stock solid axle set up is address the wheel hop issue.

trinity_gt · Mar 17, 2009

Clearly, all else being equal, an independently sprung suspension is preferable to a solid axle in just about all circumstances from a handling and ride refinement perspective, especially when the solid axle located by an antiquated 4-link setup like the Fox-derived Mustang.

I'm sure on a glass smooth racetrack a solid axle car could do well against IRS cars whose suspensions are so stiffly setup they might as well be solids. if the original poster seeks track time on smooth courses, he could probably get away with a Panhard bar and torque-arm setup to compete with a stick axle.

But those cars don't generally have to deal with sunken manhole covers, radial expansion joints on on- and off-ramps and the like that street-going cars see. The fact is that a solid axle rear is a terrible, if inexpensive compromise on the street that delivers pick-up truck durability and pick-up truck finesse and handling.

The S197 set-up, with a Panhard bar is much better since individual links aren't expected to take on multiple tasks, allowing the rear to do its job without introducing all sorts of toe angles and bumpsteering properties in the back of the car. I'm sure that aftermarket kits to transform the 79-04 4-link TwistoFlex™ setup into a Panhard setup will indeed make a worthy handler. However, it still isn't equal to a fully independent setup where each wheel acts independently of the other(s).

Engineers don't equip sports cars -- higher and lower on the foodchain than the Mustang -- with IRSs because they're cheap. They do so because they're simply much better all-around suspensions. If refinement, predictability and so on aren't top-rung requirements, they go cheap and select a stick axle, like Ford did with the S197.

TeamCaffeineGT · Mar 18, 2009

Gearbanger 101 said:
How exactly is having the most amount of medial and lateral traction available irrelevant in a handling situation?

Great, you've seen modified Mustangs beat stock Corvettes around the track. Does that mean the solid axle set up is the better of the two, or does that must mean a modified solid axle car can be made to outperform a factory stock IRS? I mean...I can show you plenty of clips where Modified IRS cars are walking all over modified stick axle cars too?

Sure, driving skill is always going to be the deciding factor in any case, but you still can't bring a knife to a gun fight. In the case of two equal drivers, the guy with the better equipment is always going to have the advantage. So why get uptight about the guy who wants to upgrade his stuff and improve his driving skill from the point at which he'll be most accustom to? Or are you of a different opinion that a car with stock suspension and a car with modified suspension have completely different handling characteristics?

I mean...it’s like drag racing or motorcycle riding. Just because you may have learned and got good on a slower, smaller car/bike doesn't mean you're not going to have to relearn it all when you upgrade. What difference does it make if he wants to upgrade first and then get good, as opposed to getting good and then upgrading. Your argument makes zero sense!

I agree 100%. Yes driving skill has to start somewhere, whether it is with a solid setup or IRS. Why not learn on the car that you will be driving?

TeamCaffeineGT · Mar 18, 2009

calboss281 wrote: "This kid is talking about a HUGE project, not something that is completed over the weekend with your buddies and a bottle of whiskey."

First of all you seam to be very libral with your driving skills advice. Which is fine. I appreciate the guidance and knowledge that you have shared. However, WE ARE NOT AT THE TRACK! We are in a 4.6L TECH FORUM. We are talking about TECH and Mechanical Know-How. Who are you to automatically assume someone elses mechanical knowledge and ability are the same as your own? I think it is a ver straight forward swap.

The fact of the matter is that the "kid and author of the thread" could perform an IRS swap in close to the same amount of time that it would take to replace all the stock bushings with poly units or replace the control arms, convert to a coil over setup, install a panhard bar, weld in some sub-frames and install a set of rear end gears on the stock solid piece. Especially if I ordered a new alumminum drive shaft for the project that was pre-measured to fit. The mods above would be similar to the ones you have on your car calboss281.

The IRS swap isn't rocket science. The same SN95 unibody design is under the Cobra and the GT. The mounting points for the IRS already exist on the GT. The main complexity is with the driveline which is longer on the GT due to travel needed with the solid axle and differences in the T56 and T45/3650 transmissions.

PLUS THERE WOULD BE VERY LITTLE COST WITH A SWAP! The mods listed above would run close to 1k or more.

'03GTinFLA · Mar 18, 2009

Wow. I gave up reading all that stuff above but to the OP, I just did the IRS swap and love it. I posted on a couple boards, found a dude local to me that wanted to swap. Took it to the shop his car was in and had it done in a day. Cost about $300 for labor and the swap was straight up, no cash involved. My car is my DD, with occasional strip/street fun and hopefully some road racing. The IRS is much better than my solid axle. The car drives much better and I can't wait to polish the Bassani cobra pipes. The other guy got my Mac catback . LOVED the sound, hated the occasional clunk and look of them. I got the better end of that deal. Oh and the stock Cobra springs are progressive so you can cut coils on them instead of buying new lowering springs. For example, I had Steeda sport springs but because of the swap I now had rear stock cobra springs in the rear. Too much rake for me. So I could have cut them with no issues, as many cobra owners have, but I bought H&R's race springs all around. Now that I've done the swap, there are some plans on building it up over time, but that's ok. I love working on my car. I love planning what I"m going to do next. All that stuff is fun. I don't have a final destination of exactly how I want my car, but I have had a blast over the past 5 years modding the hell out of it. Wasted money, not to me. Worth every dime and no I don't know how to drive my car on the ragged edge but who cares. So do your research, take what everyone says -myself included- with a grain of salt, and make your own decision. Good luck whatever you decide to do.

crazystang25 · Mar 18, 2009

no matter which route you decide to take i would highly suggest maximum motorsports for the rest of your suspension needs, especially since you want to do road courses. one day i might get another new edge stang for cruisin and do an IRS swap for kicks and giggles.

TeamCaffeineGT · Mar 18, 2009

'03GTinFLA wrote:

"Wasted money, not to me. Worth every dime and no I don't know how to drive my car on the ragged edge but who cares. So do your research, take what everyone says -myself included- with a grain of salt, and make your own decision. Good luck whatever you decide to do."

Thanks man. You drove the point home. $300 bucks for and IRS...how could it not be worth it? Especially when most of the guys on here tell me to stick with the solid unit and upgrade it. Thier upgrades cost more than 500 bucks at minimum! I appreciate the info.

TeamCaffeineGT · Mar 18, 2009

crazystang25 said:
no matter which route you decide to take i would highly suggest maximum motorsports for the rest of your suspension needs, especially since you want to do road courses. one day i might get another new edge stang for cruisin and do an IRS swap for kicks and giggles.

I was looking at maximum motorsports webpage today. They have a lot of nice products. A cruising stang with an IRS would be very nice. From what I understand the IRS has very nice ride quality. It always irritates me when I feel the solid axle skip and wag a bit over highway bridges and divided pavement sections, I wonder how much better the IRS feels in everyday driving.

Dark_Horse · Mar 18, 2009

TeamCaffeineGT said:
Hey all,
I was thinking the other day about converting my 01' GT from the solid 8.8 to a IRS setup. I enjoy curvey roads more than the straight shot. I was reading several different threads about the swap and I know I would need to alter the drive shaft to accomidate the new rear axle. I am going to run a side exhaust so a cobra cat back would not be needed. What other items would I need to plan for in this swap?

Thanks,
TeamCaffeineGT

P.S. I reside in Springfield, MO for any potential Cobra IRS to live axle swap seekers.

Hey TeamCaffene, whereabouts in springfield are you from? You may have seen my black bullitt around town?

Anyways to your OP, it's really up to you on this. If you like the way an independent rear handles, go for it. If you find a good deal or a donor car willing to swap with you, mite as well do it. Buying one off a wrecked cobra will probably cost you an arm and two legs

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