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Advantages/ Disadvantages of IRS..

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Old 09-02-2011, 06:57 PM   #1
Soldier GT
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Default Advantages/ Disadvantages of IRS..

Hey all.. Got alot of plans/hopes/dreams this winter for the stang and one of them is maybe installing a IRS. I was just wondering what you guys thought about it. Is it worth the money? Any input would be much appreciated!
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Old 09-02-2011, 09:19 PM   #2
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Awesome if you want to carve corners... You will have to do some upgrading to not tear **** up with your power if you put a sticky tire on it and launch hard.

Money shouldn't be to bad as you can usually find a trade for a Cobra guy wanting a SRA for drag racing. Take your time and find the right deal.
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Old 09-02-2011, 10:26 PM   #3
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Soldier one of my goals in life is to buy this car from you. Adding an IRS would decrease my offer price 98%.

Cmon my man!!!!!!
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Old 09-03-2011, 12:13 AM   #4
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Do the switch! The sra only advantage of the sra is its better to launch with. So unless you go to the track all the time why not switch? It rides much better and with a good set of springs and shocks/struts it'll handle like its on rails too.
No reason not to switch in my opinion.
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Old 09-03-2011, 09:17 AM   #5
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http://www.svtperformance.com/forums/member.php?u=9457

03 Cobra - Sonic Blue
KB 2.8H, 6spd, IRS "stock halfshafts"
9.82@139
1.47 60ft
6.32@111.26 1/8th

This is a member's signature over on SVTP. IRS's launch just fine and when setup correctly they have a much reduced chance of breakage.

Anyways, as we've talked about before, the swap is definitely worth it! Handling and ride STOCK are worlds better, and any modification to it the better the ride and handling gets(save for lowering springs, they make it handle better but harsher ride...COILOVERS FTW!). As with any suspension style, they can be upgraded. Bushings and springs(if you get an 03 cobra IRS with stock bilsteins) goes a LONG way. If youre ever up in PA or northern MD, give me a shout. I'll take you for a spin in my car. You'll see why I made the swap real quick.

I definitely would not say that I got 5th place at the MW auto-x on driver skill. Especially since it was the first time I ever did it.
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Originally Posted by PurpleIcedGT View Post
Saying there is a 1whp difference between the X and H and trying to justify it as a performance difference, is like walking 100 feet to your car and eating a cheeseburger while saying its fine because you just did "cardio".
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Old 09-03-2011, 10:06 AM   #6
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soldier, when you do this swap, go ahead and get all the little things bracing wise. like i have the mm flsfc, lower torque box braces, rear irs braces, diff brace, and the irs already had poly bushings and 373s withe h&r race springs. i have had zero wheel hop running 315 nt05 and a i/c vortech. i really like mine but i havent been able to drive the car much. like teej said, the ride and handling is much better plus polished tail pipes with the irs look awsome! good luck with which ever route you take!
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Old 09-03-2011, 11:45 AM   #7
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Quote:
Originally Posted by teej281 View Post
http://www.svtperformance.com/forums/member.php?u=9457

03 Cobra - Sonic Blue
KB 2.8H, 6spd, IRS "stock halfshafts"
9.82@139
1.47 60ft
6.32@111.26 1/8th

This is a member's signature over on SVTP. IRS's launch just fine and when setup correctly they have a much reduced chance of breakage.
. The sad thing is he is pulling the irs out this winter and going sra. The only disadvantage to an irs is it is expensive to completely build it.
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Old 09-03-2011, 11:48 AM   #8
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Yea, buying a brace or an actual supportive cover for the diff is a good idea as well. The cover is better as the brace in my mind is just a band-aid. Get some real support there and you'll be good.

And +1947475893490378458 to the polished tailpipes...sexy sexy!

Evan, yea. It sucks that he is swapping out the IRS for the SRA. I mean when there is nothing else you can do to your setup short of adding more power to go faster than go to an SRA, than I guess thats what you have to do! His car is going to go faster, but when you're deep into the 9's, anything faster is really an accomplishment.
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Quote:
Originally Posted by PurpleIcedGT View Post
Saying there is a 1whp difference between the X and H and trying to justify it as a performance difference, is like walking 100 feet to your car and eating a cheeseburger while saying its fine because you just did "cardio".

Last edited by teej281; 09-03-2011 at 12:04 PM.
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Old 09-03-2011, 12:44 PM   #9
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Depends on what you want out of it. Stock SRA vs stock IRS, the IRS will ride nicer for you. Ford's IRS isn't the best design for one. If you are thinking of performance handling, I'd go with a properly built 5 link from Steeda instead. After looking into it for myself, the 5 link will out perform the IRS swap.
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Old 09-03-2011, 01:06 PM   #10
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Tell that to the cobra r guys

Spirited street car, you cant beat an IRS. Modify the IRS with bushings and the ride and handling gets worlds better, as well as launching and being able to put the power down.
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Quote:
Originally Posted by PurpleIcedGT View Post
Saying there is a 1whp difference between the X and H and trying to justify it as a performance difference, is like walking 100 feet to your car and eating a cheeseburger while saying its fine because you just did "cardio".
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Old 09-03-2011, 01:25 PM   #11
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Don't do it solider. Thats a ton of money you can do something better with.
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Old 09-03-2011, 02:28 PM   #12
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Quote:
Originally Posted by uberstang1 View Post
Don't do it solider. Thats a ton of money you can do something better with.

Pretty much. IRS will increase comfort and handling with the ride. It weighs more than a SRA and to properly setup an IRS to handle hard launches it takes a lot of money.
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Old 09-03-2011, 03:42 PM   #13
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Yeah but if he's not going to be drag racing every weekend who cares if its not super strong. If its going to be driven mostly on the street then why not do the swap? Superior ride quality and handling.
I pretty much never drag race so what possible reason would i have to keep the SRA. That could be the same for soldier.
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Old 09-03-2011, 03:57 PM   #14
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But why drop 800$+ in an IRS for a car that you are using as your weekend toy? If it was free to do the swap? sure why not. Its more of a cost vs reward situation for me. The reward is not even close to worth the cost. And for it to be properly setup so you can do both? You are looking at around 1400$ or so.
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Old 09-03-2011, 04:04 PM   #15
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That's almost like saying why spend $2000 for a supercharger. Its to make the car more fun to drive. I know i have way more fun driving my car with the IRS just because it handles so well. For people who drag race all the time then yeah its a dumb swap but for street/auto-x ill take an IRS any day.
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Old 09-03-2011, 04:40 PM   #16
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Quote:
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Pretty much. IRS will increase comfort and handling with the ride. It weighs more than a SRA and to properly setup an IRS to handle hard launches it takes a lot of money.
Not only will it handle better because its a better design for it, but it will also handle and respond better because the car would then have something known as BALANCE! It adds weight, this is VERY true! But where does it add weight one would ask? Right where the car needs weight added. At the rear of the vehicle. Adding the weight to the back might make the car heavier, but it helps balance it out and put it closer to 50/50 distribution.

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But why drop 800$+ in an IRS for a car that you are using as your weekend toy? If it was free to do the swap? sure why not. Its more of a cost vs reward situation for me. The reward is not even close to worth the cost. And for it to be properly setup so you can do both? You are looking at around 1400$ or so.
So me buying my IRS outright at $400 and not having to give my SRA in return is really $800? You find the right guy who realizes that both parties are benefiting from the swap equally, you find yourself an even trade or minimal cash to put in, and its totally worth it.

Even if it takes $400 cash and your SRA for the swap, bushing kit is right around $650 and if you wait, you can usually find a sale around christmas time or tax return season you can find good deals too. And if you do the install yourself(plenty of online write-ups and directions and advice can be found on Fulltiltboogieracing.com...which is the only source I would buy the bushings from anyways) youre looking at just over a grand for a properly setup IRS. Throw a cover in there and youre looking at $1200. Build an SRA properly with 31 spline axles and differential($500ish for 03 cobra diff and moser 31's), new shocks($200 for a good set of shocks), upper and lower control arms(another $300 for UPR or something) or a torque arm and phb setup($978 from MM) and you have about the same or a lot more wrapped up in building your SRA than you would doing bushings and a cover on the IRS. Might be a little stronger, but to me I couldnt justify spending that kind of money on a suspension design that was also used since 1979 either...and rides like it too.

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That's almost like saying why spend $2000 for a supercharger. Its to make the car more fun to drive. I know i have way more fun driving my car with the IRS just because it handles so well. For people who drag race all the time then yeah its a dumb swap but for street/auto-x ill take an IRS any day.
This is an extreme example, but I do agree. Its hard to comprehend what the rear suspension of a stick axle car feels like in comparison to an IRS without driving it yourself. Going from stick axle to IRS, there was worlds more confidence in cornering because the suspension is not able to move side to side like it is with an SRA without a PHB. That alone made a difference. To have the car feel stable in a corner was awesome! Then add on the fact that it improved the ride of the car worlds it made it much more comfortable to ride in compared to the SRA. I much rather ride in the car now with the IRS than when I had the SRA with a lot softer springs and less valved shocks.

Both examples properly built, they might handle the same on smooth surfaces, but the second you throw in a bump or uneven surface, bye bye SRA. For launching, use of slicks reduces breakage over street tires or drag radials because sidewall helps absorb shock, allowing one to launch somewhat like an automatic that is a smooth engagement on the drivetrain.

For a street car, no other choice to me other than the IRS.
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Saying there is a 1whp difference between the X and H and trying to justify it as a performance difference, is like walking 100 feet to your car and eating a cheeseburger while saying its fine because you just did "cardio".
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Old 09-03-2011, 05:01 PM   #17
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Very valid points Teej. Don't get me wrong. I think an IRS is great, but for me, its just not worth the cost difference. But that doesn't mean its not worth the cost for someone else to do it.
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Old 09-03-2011, 06:25 PM   #18
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There really is very little to no cost difference. I got mine for a straight up trade. Only thing is, I had to drive a cuple hundred miles to pick it up. If youre into drag racing and drag race on a regular basis, then solid axle all the way, but if you want a nice smooth ride irs all the way.
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Old 09-03-2011, 06:36 PM   #19
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The guy that tj posted about has a stock irs except for diff bushings and a brace iirc he told me one time but I have slept since then. So it doesn't take a lot of money to make it handle high rpm launches. Just dome bias ply tires. I my self will never get rid of my irs for an 8.8 sraand I do mostly street racing and drag racing.
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Old 09-03-2011, 09:37 PM   #20
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FWIW ill be throwing one in my car as soon as i can find one!!!

mostly street and open track days, with the occasional trip to LVD
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Old 09-03-2011, 09:37 PM
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