Project FD RX7 Restomod: Part 8 – Trans and Diff Mount

NanoProMT front diff bushing Sikky Manufacturing FD RX7We used some NanoProMT Marine Grease to lubricate the Sikky Manufacturing rear diff mount.

Sikky Manufacturing FD RX7 diff mount pressing pin inThen we pressed the urethane bushing into the Sikky diff mount.

FD RX7 stock Power Plant Frame PPF vs front transmission mount and rear differential mountWith the PPF removed, we can see there is a significant difference in mass and weight of the heavy stock PPF vs the new trans and differential braces.  This modification has reduced the weight of our car by over 20 pounds!

FD RX7 removed PPFNext, we removed the stock aluminum crossmember.

FD RX7 Banzai Transmission MountWe then bolted the Banzai trans bushing to the transmission and the crossmember to the chassis to give the transmission the new support it needed.

5 comments

  1. Good writeup guys! Is the FD PPF really that heavy? I only have experience with the NA/NB Miata PPF which is a very light aluminum piece. Maybe only 5-10lbs. Is the FD one steel instead?

  2. I’m completely unfamiliar with Mazda’s ppf, so apologies if this is a dumb question. The ppf looks like it provides a bit of longitudinal stiffness that isn’t replaced with the new parts. Is there a risk of increasing the stress at some of the subframe connection points as a result?

    Love the project regardless – thanks.

    1. No worries at all, thanks for the feedback. The purpose of the PPF is to turn the entire drivetrain from the engine to the differential into one solid unit. So the entire drivetrain hangs off of the two engine mounts and the two differential mounts. The new setup changes this to a more traditional layout where the transmission is supported by a (new) bushing and the front of the differential is supported by a (new) bushing. Each additional bushing triangulates the engine/trans and the diff to provide longitudinal support and stiffness.

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