Science experiment - can the IRS from the S550 be transplanted into a 13/14 GT500?

mobeydick

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And I'm telling you that the 3 years I spent working on training salesmen proved to me without a shadow of a doubt that 1 in 100 actually care. They will do and say whatever it takes to get you into a car and out of the building so they can sell another. Asking a car salesman why the IRS is better than the SRA is like asking a bat boy at a Braves game the best way to throw a slider. He doesn't know, and he doesn't care.



Have you never driven a car with an IRS and big horsepower before? There seem to be plenty of Supras, Vipers, Vettes, more making 4 digit horsepower numbers and miraculously they all survive, or are you concerned because you don't feel you'd be up to the task of controlling a car where the two rear wheels aren't directly linked by a barbaric piece of steel pipe?

Please stop harping on the set of broken axles by AM as a failure point. Replacement axles will be availalbe soon and for cheap. I bet you could do rear half shafts and subframe bushings for $750 by the time we're all said and done in the market. The 8.8 has had plenty of issues that needed fixing, it was no champion of reliability and perfection.

$200 for panhard bar and brace, $400 for upper and lower control arms, $300 for 31 spline axles, $200 for welding the axles tubes so they don't rotate, etc....
I've put over 2,000,000 miles on vehicles with SRA and have never had anything other the an axle seal issue. The 2 vehicles I've driven over an extended period of time that had IRS couldn't stay out of the shop needing bushings. BTW: most of those vehicles had IFS also guess what those needed bushings over 100,000 of use also! Simple fact is IRS is not a panacea, they have their own issues. Number one on that list is reliability and number two is cost of repair. Putting one in a Mustang for everyday use is insane. Putting on in a track car is a great idea! It should be an factory option!
 

FortLewisCobra

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That cost would be miniscule vs. the cost of repairing it every time you drove it hard!

You do realize there are possibly hundreds of 03-04 IRS cars making similar power to a 13 and don't snap their half shafts on a daily basis? I think the tech has improved since and you should be able to mount an IRS in a 13 without an instant explosion. Try wondering out of the GT500 section sometime.

A good comparison would be the 03 IRS. Aside from the drag racing crowd no one else wants the SLA. Riding in a friends relatively stock 01 GT it was pretty apparent how rough the straight axle really was compared to my car, especially the bunny hop motion on entry ramps if you hit a expansion joint that I never knew was there in mine. As for the wheel hop the quadrabind has it every bit as bad as an IRS car. Guys rip out the stock IRS and replace it with an SLA on aftermarket parts then comment how much less it hops, no shit sherlock. Mine only hops slightly if its cold in which case I take my foot off the gas, which would be the same situation if the SLA broke traction and started that wonderful end swapping maneuver...

Background: 03 Cobra, 500RWHP, stock IRS, 250 treadwear tires, FLSC and minimal hop.

Like the other 99.998% of the people who are members of this forum.

Funny you should mention this. The Open Track section of this forum has 2400 threads vs the Drag section's 400. So 86% of the folks on this forum care more about OT than Drag performance, according to my hyper accurate polling method. :p
 
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01SVTSnake

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How are those half-shafts holding up on the 15s so far!

All in all i'd say pretty good. All the cars that are out there, maybe 2 or 3 have broken halfshafts under extreme conditions. American Muscle broke a halfshaft running slicks, 5000rpm launches, Justin Burcham behind the wheel on an incredible track prep and cutting a 1.595 60' time. Putting 350+ ft/lb of torque into a very sticky tire and good prep from a stand still is an incredible amount of shock to any stationary item that is subject to sudden twisting forces such as that. Ford isn't going to invest the money and time into the halfshafts to hold 1200 ft/lb of torque from the factory. It is not necessary for them and it leaves room for Ford Racing and other aftermarket vendors to fill the gaps in. Of all the other cars out there they are holding just fine.

The weakest point will always give. The SRA would bend axles as well. Ive seen plenty of LCA mounts fail, and UCAs as well. The halfshafts are almost always the weakest point in any IRS, but there are always solutions.
 
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biminiLX

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All in all i'd say pretty good. All the cars that are out there, maybe 2 or 3 have broken halfshafts under extreme conditions. American Muscle broke a halfshaft running slicks, 5000rpm launches, Justin Burcham behind the wheel on an incredible track prep and cutting a 1.595 60' time. Putting 350+ ft/lb of torque into a very sticky tire and good prep from a stand still is an incredible amount of shock to any stationary item that is subject to sudden twisting forces such as that. Ford isn't going to invest the money and time into the halfshafts to hold 1200 ft/lb of torque from the factory. It is not necessary for them and it leaves room for Ford Racing and other aftermarket vendors to fill the gaps in. Of all the other cars out there they are holding just fine.

The weakest point will always give. The SRA would bend axles as well. Ive seen plenty of LCA mounts fail, and UCAs as well. The halfshafts are almost always the weakest point in any IRS, but there are always solutions.

Good points.
I'm very much a drag racer and we've all seen the Vipers, Vettes, Supras, etc. running VERY hard at the strip with IRS.
As with anything, money in the aftermarket should allow to build to goals, even extreme.
Will be interesting to see the aftermarket adapt to the IRS in the s550.
-J
 

Tob

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biminiLX

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Exactly.
The FRPP drag video cited those upgrades and the IRS subframe reinforcement, will be interesting to see how far that FRPP-reinforced stock IRS goes.
I still love the 9" centersection you showed, that 9" will open so many options.
If I could adapt the 9" centered, mega-halfshaft s550 IRS into my '14 GT500, I might be game.
My fully built 8.8" from a top chassis shop was awesome quiet for 2 days but went right back to whining like hell after only 2 passes on DRs :(
We shall see, but I plan on keeping this car for a long time and don't mind spending money on it.
-J
 

01SVTSnake

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Yeah thats tough. Be nice if they were around 900-1200$ for the pair. I'm sure vendors may have them for a better price (1,600-,1800 for the set) but thats some serious coin.

I see American Muscle has DSS 800hp for 599.99 each and the 1400hp for 799.99 each. Be nice to know what FRPP rates them to though for their money.
 

mavisky

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Pretty sure the MSRP on my mufflers from Ford Racing was like $670 or something, paid $490 for them from Autonation Ford up in Minnesota.

The $599 price from DSS sounds more in line with where these axles should be.

That being said it looks like Lingenfelter is selling their 1400hp axles for the Camaro at $925 each so the DSS 1400hp for $800 isn't a terrible deal.
 

StealthV8

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Cortex makes great stuff!
Pic of the S550 IRS going into the S197: https://www.instagram.com/p/BUQYLyeh-JJ/

Thanks...Pribilof for the link!...I checked it out and it looked like he flared out the rear fender a little bit. I tried calling Crick to get an update on the install, but I guess he hasn't gotten in his office yet!...But again Thank for the Picture and it looks like it's going to work out!...God Bless!
 

StealthV8

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Very cool man, you will LOVE the PBH built 6R.
I'm not impressed with this whiney 8.8 in my '14, it can't handle any track launches without howling on the way home. Maybe if they have a built IRS option I'd consider it down the road.
Please keep us updated on your project.
-J

Yes biminiLX, I will keep you all updated when I start my project using a 2013/14 shelby GT500! I am waiting on Crick from CorteX Racing to finish his 2015 IRS swap into the S197 chassis first and then I'll decide to move forward on the shelby GT500 project!

Meanwhile I currently have a 03 Ford Mustang GT/Cobra Project going...my plan is to swap a 13/14 5.8L Shelby GT500 S/C engine, swapping my 5-sp manual for a PBH 6R80 Auto trans with a custom Paddle Shift setup. I plan to swap out the SRA for a 03 IRS out of a Cobra re-built by Kenny Brown.

So that will give you a flavor of my current plans and also I too used to own a 85 Mercury Capri RS 5.0 back in the day! God Bless!
 

biminiLX

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Very nice. I just took apart my clean '93 Cobra for a Coyote/TR6060/'03 IRS swap.
My friends have questioned my sanity, but that one will never go to tracks, just ultimate Fox cruiser.
-J
 

Steve@TF

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the one thing i dislike about my car is the SRA. i miss the IRS from my terminator.
 

SCALECRAFT

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My 14 with a Cortex Watts link solved my issues with rear end instability on a track. As for the street. I use my Volvo or Nissan truck.

The IRS is cool, but I work with what I have.
 

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