IRS install & Frame reinforcement

I chose to include the IRS option with my car. Three items entered into the decision

1) I was trying to be period correct –  the original car also carried an independent rear suspension
2) I did not plan to race the car, but was interested in the best ride and handling possible
3) Re-sale value with an IRS is higher

As stated earlier, I also chose to have the car provided in an “Un-assembled” condition. This adds a few complexities to the IRS.
1) Handling – it isn’t the lightest piece in the build. I found my floor jack would serve as a make-shift tranny jack, by adding a sheet of plywood to the saddle.
2) Fitting the frame: When the IRS is welded, there is a certain amount of weld draw. When factory assembled, they have to deal with the issues this creates. When it is delivered un-assembled, one of the items included is “mis-matched” holes. A little ingenuity works these out.

I strongly suggest you take documenting photographs before you dis-assemble anything. They may come in handy. With my pictures taken, I broke the suspension down and tackled the finishing process.
A) I cleaned up the center section and painted it.
B) the axle shafts were not painted – to accomplish this, I had to dis-assemble the half-shaft boots, paint, then reassemble
C) The upper and lower arms, and the rear housing bracket fit my blast cabinet. They were blasted and painted.
D) The frame was blasted and cleaned outdoors, it was too large for the cabinet.

On re-assembly, I noted these items:
1) The rear housing bracket did not fit the differential tightly. The fit was improved by adding 1/32″ thick washers inside the bracket. When torqued down, the bracket was then tightly clamped to the differential.
2) There are articles on the internet about the use of a differential brace. Under hard acceleration and cornering, some aluminum differential covers have failed. I have the opinion this is caused by a combination of the failure of the forward mounting bolts/bushings and the design of the Mustang rear differential hanger. The rear bracket on the Mustang is rubber mounted and can induce some twist into the components. I don’t think this is an issue on the Hurricane mounting. Hope I’m right.
3) At the time of my build, instructions for assembling and mounting the IRS had not been published. I have since been given this advance copy of the new manual pages: IRS Assembly


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Posted 06/26/2007 by Paul Proefrock in category "Build Details", "Drivetrain", "Mod's