Project FD RX7 Restomod: Part 16 – Installing the Ronin Ford 8.8 IRS Mount Kit using DSS Axles

MotoIQ Project FD RX-7 With the car on jackstands out in a parking lot, we started to drop the rear subframe.

FD RX-7 stock subframe and Sikky Diff Support BraceWe unbolted the driveshaft, rear shocks, disconnected the brake lines, and were ready to drop the subframe.

FD RX-7 Dropping subframeWe put a jack under the differential itself, removed the six subframe bolts, and the entire assembly dropped out of the car.

FD RX-7 dropping subframeEverything was clear and slid right out from under the car.

FD RX-7 stock diff and subframe with Sikky front diff support braceRemoving the rear assembly was surprisingly easy.  I was able to do this by myself within an hour.  The next step was to strip the subframe by removing the axles, suspension arms, and differential.  This was a perfect time to replace all of the spherical pillow balls and bushings in the suspension.

FD RX-7 rear subframeThe stock subframe has a “U-shape” to it, which is not the most inherently rigid design.  In 1994, Mazda added additional braces that triangulate the corners of the subframe by connecting the rearmost part of the subframe up to the front corners.  Unfortunately, this still does not increase the rigidity of the subframe or chassis by boxing in the front of the subframe.

4 comments

  1. This is vastly superior to any other 8.8 conversion I have seen for this car. Now to convince Jeff to do this to Project V8 FD!

  2. Great write-up and an impressive kit.
    Although, it seems the support bridge could be easily revisioned to be at least half an inch lower so it wouldn’t necessitate beating up your pristine RX-7-s body.

  3. Damn, great progress. 🙂

    still loving the fact that this went from rest-mod to restless-mod.
    been following from the beginning.

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