Project V8 RX-7: Part 11 – Finishing the Driveline


Our local driveshaft shop was able to shorten the driveshaft we used with our LS1 swap from before by 3″ to accommodate the longer T-56 Magnum.  They also add the new Dyno-Shaft slip yoke and turned it around the following day.


The Strange Engineering chrome-moly yoke distinguishes the Pro Series Dyno-Shaft from the Sportsman which uses a forged steel yoke.


We’re still using the RX-7 rear differential so no changes were made to this end yet.


The controller housing slips onto the end of the tailshaft and simply clamps on.


Look carefully and you can see the optical speed sensor inside the controller housing.

We haven’t mentioned a peep about the rear differential up to this point because to be honest we weren’t sure if we’d have a chance to do it before we finished the engine swap.  For the time being, we’re going to stick with our Mazda differential.  Our ’93 RX-7 was originally a manual, which comes with a 4.10:1 final drive ratio—too high in our opinion for the gearing of the T-56.  Fortunately the automatic variant of the FD came with a 3.91:1 final drive, so we swapped our rear end out with one of those.  To finish it off we swapped the Torsen limited slip differential the FD’s come with to the clutch style found in the second generation turbo FC RX-7’s which are interchangeable and are supposed to handle more power.  Follow all that?

As equipped from Mazda the differential is mounted to the rear subframe on both sides in the back and up front by a large brace Mazda called a Powerplant Frame that extended to the transmission (sorry I didn’t take pics of that).  This large piece has to be removed with the engine swap so a new support for the front of the transmission is needed.  Enter Samberg Rod & Custom yet again!  (Like we said, Justin does it all!)  He makes a mount to support the stock differential as well as a super cool subframe to mount an 8.8” Ford IRS differential—the de facto differential for handling more power and an even lower final drive ratio.  We’re not going there yet though…


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