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Discussion Starter #1
Has anyone ever swapped in an 8.8 or 9" in place of the bird IRS? I need details if it is possible othe than a complete custom setup. I know the Cobra IRS is an almost bolt in setup. I have a 94 bird and want to swap in a strong rear axle. Is it possible? I have a 9" that I can install using 8.8" brackets.
 

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1994 Cougar XR7 DOHC/5-Speed
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what kind of power do you have? is it a devoted drag car? do you have alot of money?
its not even close to a direct swap, the only cars i can think of are completely back halfed and usually tubbed. the mustang irs isnt a direct bolt up either, mounting points are totally different.
 

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It can, and has been done, however I can almost guarantee that you don't need it. We already have an 8.8" diff (at least in the V8s and SCs), and there are a number of people who have made low 10s passes on the stock IRS. The only ones that have problems are the people running a manual trans with ridiculous power levels, and launching on slicks. Other than that, the IRS will handle quite a bit of power before it becomes a limitation.
 

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how bout this novelty instead of saying that it cant be done, or its not worth doing, how bout explaining what needs to be done to do it.
 

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Discussion Starter #5
I am installing a 460/toploader in my 94LX shell and don't want to have to deal with busted half shafts. Are there any half shaft manufacturers that build shafts to handle 500hp? This is the level I am looking at which is not hard at all with a BBF. The Cobra IRS can be swapped fairly easily. It's a common swap for guys building high HP Cobras, which is not hard at all in the 03-up cars.

Does anyone know of a website showing some details of the 'bird IRS setup? I can crawl under it and look, but pics of installs/removals can sometimes help the brain cells to work harder.
 

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You don't need to swap in the entire cobra IRS. When the half-shafts fail, they break off at the hub, so swapping to 31 spline cobra hubs, and running a set of raxles should get you what you need.
 

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Circle track fab

how bout this novelty instead of saying that it cant be done, or its not worth doing, how bout explaining what needs to be done to do it.
Hello

I would contact a circle track fabricator. They should give you an idea what will be involved.

I know you will have to in stall lower trailing arms.
Upper control arms or A Watts link.
You will need upper spring pockets & shock mounts.
Of coarse the 9in. rear end. You will have to redo the rear brakes. (lines too)
(back spacing of wheels will need to be changed)
You will need to remove the gas tank. Most race cars will have a fuel cell in trunk anyway.
Redo the exhaust. You will need room for movement of the drive shaft.
More work to-get the angles correct.(control arms)

Paul
 

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I am installing a 460/toploader in my 94LX shell and.....
You must work for a tire company and get employee discounts on rear tires!

As a sidenote I think you will want to look into some extra bracing to stiffen the car as well.....something like "subframe connector" type stuff. I've twisted two of my own cars (not MN12) in the past by not having them when I really should've. :eek:

Good luck with the project....can't wait to see this.
 

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1994 Cougar XR7 DOHC/5-Speed
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The Cobra IRS can be swapped fairly easily. It's a common swap for guys building high HP Cobras, which is not hard at all in the 03-up cars.
because they are in cars that originally came with solid axles, the mn12 never EVER had a solid axle in its lifespan from the factory. the mustang irs is built to work with existing mounting points for all mustang chassis.
 
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