This is my build of an IRS that I installed for Road Racing / Open Track.
MM Delrin Upper Control Arm Bushings
MM Delrin Lower Control Arm Bushings
MM Urethane Differential Bushings
MM Urethane Subframe Bushings
MM Adjustable Rear Swaybar Endlinks
MM Low Profile IRS Subframe Bolts
MM IRS HD Crossmember
Motive 3.73 Ring / Pinion
Motive Bearing Kit
Detroit Truetrac LSD 31 Spline
Ford 31 Spline Half Shafts
Ford Aluminum Diff/Carrier
Steeda IRS Brace
MM Cross-Axis Joints [installed later]
MM Solid Differential Bushings [installed later]
MM Adjustable Tie-rods [installed later]
I used the MM Specialty Tools for all the Bushing removal and some persuasion from the Hammer, also a Micrometer / Caliper. The original IRS Drivetrain components were shattered in pieces from a Drag Car, so I built the IRS with new parts except the Subframe / Spindles / Hubs / Control Arms. Pictures start with the showing of the IRS [whats left] Subframe and its Bushings then to disassembly, upgraded build, to install.
In defense of the IRS and my decision:
Q. The #91 MM Mustang is using an IRS [Independent Rear Suspension], what drove you to this decision, how has the effort been going so far?
A. We had a growing number of customers who called us and said that they were not happy with their IRS, and asked us if they should swap in the proven MM Torque Arm / Panhard Bar rear suspension. We couldn't give them a truthful answer until we had done our own testing to directly compare the Ford IRS to a well-sorted Torque Arm / Panhard Bar system. Our AI race car had won races, and set track records, so it was the perfect candidate for comparison. We swapped the rear end over to the IRS, with all of the parts we had developed over the previous year on a street-driven 2003 Cobra. We left the front of the car exactly as it was with the Torque Arm suspension. We maintained the exact same rear track width, and even swapped over the same brakes, rotors, calipers, and pads, from the Solid Axle. We then hit the track for testing. By the end of the first day of testing we were 3 seconds under the AI track record at Buttonwillow. With the IRS we had to learn what alignment and bumpsteer settings worked best. That's what testing told us. Without track testing, we really could not have given our customers an honest answer to their questions about the IRS. Even if our testing had shown the IRS to be grossly inferior to a Solid Axle, we at least would then be able to help our customers make an informed decision about modifying their car. As it turned out, the IRS is superior to a Solid Axle fitted with a Torque Arm and Panhard Bar, in most aspects.
NASA Pro Racing – Interview with Chuck Schwynoch, CEO
Maximum Motorsports, Inc.
By Andy Bowman