The Explorer diff is notably larger in every dimension over the original FD RX-7 diff.
The rear diff cover also shows how much wider the Explorer 8.8” diff is over stock. The larger bearings will also help to hold significantly more power than stock
The stock cast Iron FD RX-7 diff weighed in at 85.8lbs.
By comparison, the much larger aluminum Ford Explorer 8.8” diff weighed 81.6lbs, which is 4.2lbs lighter than stock!
The stock RX-7 Power Plant Frame (PPF) weighed 19.8lbs.
The Support Bridge (X-brace) and hardware from the Ronin Ford Explorer 8.8” diff kit weighed 14.8lbs. This is another 5lb weight saving for the 8.8” swap.
In total, the aluminum Ford Explorer 8.8” diff was 4.2lbs lighter than stock, and the weld-in Support Bridge for the rear subframe that replaces the PPF saved another 5lbs. That is a 9.2lb weight savings from the rear of our FD RX-7 by upgrading to the Ford 8.8” diff.
Now that our differential is together, we turned our attention to welding the Ronin Support Bridge to our rear subframe and re-installing the rear-end back into the car. Stay tuned for the next installment!
11 comments
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!
It isn’t a clutch LSD. He literally describes it as a gear LSD.
Facepalm. Not good reading comprehension on my part. Thanks for clarifying.
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.
This thing will be a monster! I appreciate all the updates.
Awesome to see the attention to detail on the ring and pinion gears! All that work will increase the fatigue life by magnitudes.
Love it. I’m still waiting to see a brake rotor WPC treated to see how much longer the brake distances would be.
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!
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.
Perfect – thanks Billy. That’s better than trying to go the other way! Looking forward to your next instalment.
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.