Suspension Irs Swap From 03 Cobra


New Member
May 28, 2013
I have a friend who has a big power terminator and needs a SRA now. He is wiling to swap me over his IRS for free. Is there anything i need to be able to do this, or is it just bolt out and bolt in? Id really like to do it as 1. its free 2. it would make the car ride and handle better. I don't have HUGE power goals with the car but would like to create a mustang that can handle very well. Any replies are greatly appreciated.
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It will bolt in. No cutting or welding. I have never done one myself, but I have seen them put in Foxbodies. That is an awesome opportunity you have there. However, you might want to spend some money while you are at. For one, see if you can get some Cobra front brakes. Since the IRS setup will come with Cobra rear brakes, putting Cobra front brakes in will really help your braking system stay in balance. There are also a few trouble bushing and parts in that rear setup. I'm not sure exactly which ones they are, because I'm not too familiar with the setup. However, I'm sure you can talk to the Cobra guys to see which parts cause trouble. Since your friend has already been putting a lot of power through the rear end, it is a good opportunity to inspect it while it's out of the car and pre emptively replace those parts and or bushings that might cause you trouble down the road.

The IRS doesn't necessarily handle any better than the solid rear axle. However it allows you to make a car that handles very well without sacrificing as much ride comfort.

I wouldn't call it "bolt in". There is drilling involved. You also have to fabricate some kind of reinforcement plates for the upper subframe mounts where they bolt to the trunk floor. This is to reinforce the frame rail. You also have to drill/cut out the pinion snubbers. All in all, it's not too difficult though.
Well what the heck. Drilling and fabricating isn't bolt in! Have any details on what exactly is involved?

Scroll down about midway. You'll see what I did. Final install pictures are on Page 48. The way I did it is not the only solution. Some people weld nuts onto a piece of steel stock and then slide that into the frame rail so they don't have to drill through the trunk floor. The goal is to prevent collapsing the frame rail when you tighten the bolts down for the upper subframe mounts.
You have to drill 4 holes in the trunk for the reinforcement like said above. And you'll have to run two hard brake line from the rear brake line to the frame rail so the cobra soft lines hook up to
Also you either have swap the pinion flange on the differential with the SRA or swap out the driveshaft flange.

The Delrin bushings take out all the flex. Which causes the problems with the IRS. for all your IRS needs. Bruce over on svt is a great guy with great customer service he has detailed instructions on replacing the bushings.

I've got the full Delrin bushing kit with swaybar end links, tie rods, With Eibach upgraded swaybar. Coil over bilstiens. I'm working on getting some Kenny brown control arms, there not cheap.

I love my IRS handles great, rides smooth. And the 03-04 came with 31 spline and 3.55 gears.