1999 Cobra IRS Install


The following pictures are from the installation of a 1999 Cobra Independent Rear Suspension innto my 1998 Mustang Cobra. The IRS replaces the Live or Solid axle. I was able to find someone with a 1999 IRS that wanted a solid axle. The Solid axle is better at handling high horsepower applications but doesn't handle as well in street configuration. The IRS can be set up to handle very well and maintain streetable. I used this page from Joe Lynch's site as a reference for my install

The following is an overview of the process I used.

1. Here is a picture of the old solid rear with the old exhaust. Also pictured is the car without the rear in it. You can see the hardline on the passenger side that had a t-fitting. I removed these lines and put a t-fitting down in the tunnel. I then ran two you lines to the soft brake lines on each side.

Replica Watches Rolex Replica Watches

Old Rear with old Exhaust Old Rear (side view) Old Rear (back view)
Shot of Driver's side without solid rear Passenger side


2. I removed the rear from the 99 Cobra and rested it on a dolly. The dolly allowed me to move the rear around under the car and position it easily.

IRS (back view) IRS (front view)
Close up drivers side Close up passenger side


3. I then aligned the rear IRS brackets with the existing bolt holes in the rear frame. These bolt holes are in the frame from the brace for the quad shocks. You then can the lower the car onto the rear and put the remaining front and rear bolts in. Next I torqued down the upper shock bolts. The 99 Cobra uses two more bolts that go into the bracket from the bottom into the frame. These holes and nuts don't exist in the 98 and I will eventually have the rear brackets tack welded to the frame.

Drivers side Installed Drivers side rear bracket


5. The next step was to fabricate the hard brake lines and connect them to the soft lines. I then bolted down the soft brake line brackets to the frame. I reconnected the emergency brake cables and bolted down the cable bracket. I then bled the brakes and checked for leaks in my new hard brake lines.

6. I installed the IRS specific driveshaft next, by slipping the front yolk into the transmission and bolting the back of the shaft to the rear with the old 4 bolts. I was sure to use loctite on these bolts.

7. Here are pictures of the IRS specific exhaust. It is necessary to swap exhausts when doing the swap. This exhaust has a set of Flowmaster mufflers welded into into the stock locations.

IRS specific exhaust


8. Lastly, Put the rear wheels back on and lower the car down and get the car aligned.

Impressions: I really like this modification. This has really improved the ride and feel of this car. I no longer have noises from my Global West Rear Lower control arms. The rear suspension now has a solid feel without the noise. Also the car no longer hops to the side when hitting a bump while taking a turn. The ride is also smoother over bumps. I think on a smooth racetrack my solid rear would handle as well if not better than my new IRS rear. In the real world though the IRS handles much better. I would highly recommend this modification.

Back