We recently finished the install of the new Art Morrison Enterprises IRS in Mary's 73 Camaro.
Unlike their First Gen Camaro IRS, the second gen install requires a fair amount of cutting to get it in there. Second gen's have the rear seats pushed as close as possible to the rear axle, the frame rails are vertical just ahead of the axle which poses clearance issues to the toe links. The first thing to install is the 2x4 cross-member. I chose to raise the floor to the top of this cross-member which made room for the mufflers. I added frame rail sections inside the rear seat area on top of the frame rails to beef up the strength lost by cutting away the rails in the toe link area. The new rear floor follows the reinforcements.
FEATURES
Center diff from Strange, based on Dana 60 internals. Ratios from 3:55 & lower, OR use a stock fifth gen Camaro diff.
Axles are Drive Shaft Shop, good to 1400hp.
Fifth gen outer axle carriers machined to take ZR1 HD hub/bearing units this gives you a GM bolt pattern, the Camaro has a slightly different wheel stud spacing. The Corvette hub has a larger center register than a Fifth Gen Camaro.
Stock fifth gen brakes work depending on wheel size or Willwood & Baer have 14" 6 piston brakes for it that should clear 18" wheels.
Adjustable toe-steer in turns.
INSTALLATION:
1. Mock up the IRS in the car with the frame brackets bolted on.
2. Center the wheel in the wheel arch, check for square.
3. Tack the frame brackets to the frame, (reinforcing plates should be welded on first).
4. Remove IRS then fully weld brackets.
A 2" x 4" cross-member must be installed by cutting through both frame rails, it extends pinch weld to pinch weld. There is a raised area in the floor pan that the cross-member sits half in and half into the rear seat area, so the floor pan has to be cut from the crossmember rearward. I also had to cut out the trunk floor from just above the fuel tank anchor points running 10" forward. Also the corners of the trunk drop-down needed to be cut back on an angle to allow access for welding on the frame rail reinforcement plates and cradle mounts.
New IRS
NOTE I quit Photobucket when they started charging too much so many photos are not available. I'm uploading new pics here but I don't have all of them, but Mary does.
Tie rod just clears what's left of the frame rail, only about 3/4" left, which I plated over on 3 sides with 10 ga cold rolled steel.
Note frame rail reinforcements left and right Floor is raised about 2" & slopes upward sooner. I should have cut out the tunnel straight across and made a whole new one.
I wasted a lot of time cutting out the old seat belt holes and patching them, the lower edge was not flat where it meets the new floor pans so lots of work there.
Left and right sides are the remains of the factory floor pan contour. The front cradle mounts are about an inch below the new floor, allowing installation from below by one person. The rear mounts have fairly good access by cutting off the trunk floor corners and using a Ricks gas tank with trimmed corners similar to the DSE tanks. This gives you a space to reach up and install the nuts.
unbelievably cool. Interested what your thoughts are on how it drives compared to the solid axle. I wanna see a 2nd gen with a tiny bit of negative camber on the rear!
It's way better right out of the box! Sure footed is the best description I can give of it. The car isn't upset as easily and the street manners are outstanding!
Mary has done two local autocrosses and one in San Diego where she won the new SCCA Tour CAM (Classic American Muscle) class.
Brian Hobaugh SCCA National Tour June 2014
First Hemi 'Cuda Convertible Ever Built
Short clips: Goodguys Pleasanton autocross and pit videos
Art Morrison IRS, 73 Camaro
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