Project FD RX7 Restomod: Part 15 – Building the Ford 8.8 Differential with a Detroit Truetrac LSD and WPC

Ford Explorer diff rear cover modified for Ronin RX7 swapThis really cleaned up the look of the differential and removed a lot of sharp edges, making the diff nice and easy to handle without cutting your hands.

Ford Explorer diff masking for paintThe next step was to mask the diff housings in preparation for paint.

Ford Explorer 8.8 diff base coat Duplicolor MetalcastWe sprayed a base layer of Dupli-Color Metalcast Anodized Automotive Paint.  This gives parts a transparent-colored metallic finish that has an anodized look to it.  We’ve seen some good results of engines and differentials painted with this product, so we gave it a try.

Ford Explorer 8.8 diff Duplicolor Metalcast blueAfter a few base coats of silver, we started layering the transparent blue onto the diff housing.

Ford Explorer 8.8 diff Duplicolor Metalcast BlueWe kept applying coats until we had the dark, rich blue finish that we wanted.  The process was very quick and easy.

14 comments

  1. Looks like a win-win upgrade (adding a clutch-type LSD, reducing the assembly’s weight, and improving durability). Really enjoying this project – thanks for sharing all the progress!

  2. It’s always great to hear Mario’s named mentioned from TSR. He’s an artist with a welder. I love all the work he has done for the Datsun community.

  3. Awesome to see the attention to detail on the ring and pinion gears! All that work will increase the fatigue life by magnitudes.

  4. Love it. I’m still waiting to see a brake rotor WPC treated to see how much longer the brake distances would be.

  5. Whats the difference in length, axle centre to driveshaft flange between the two diffs? Currently have an aftermarket clutch type diff in the OEM housing that I don’t really trust behind a T56 Magnum. It’d be a shame to bin/remake the carbon driveshaft shaft…….they look pretty close!

    1. The Ford Explorer 8.8″ diff flange (using the Ronin mount) is 0.425″ rearward/closer to the axle centerline than stock. It sounds like your best bet is to get a 0.425″ spacer to adapt your driveshaft to the Ford 8.8 diff flange.

  6. Perfect – thanks Billy. That’s better than trying to go the other way! Looking forward to your next instalment.

  7. While the out side of the assembly might be larger, it’s no guarantee of greater strength. A measurement of the gears and the bearings would be needed to make that claim. The fact the Ford unit is lighter is also a factor. Also the original mounting with the PPF is quite strong, as the lever arm of the PPF is much longer than the bushings located right at the companion flange.

    1. Size does not determine strength, but the 8.8″ Ford gear and aluminum diff housing are known quantities to handle over 1,000hp. The FD’s PPF and cast iron diff housing are also known quantities and known to be weak and unreliable in the 400-450whp range.

  8. Hi there can sombody tell me which model Eaton Detroit Truetrac LSD was used please?
    Eaton Part number please?
    Many thanks

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