Motor Mounts and the Power Plant Frame or PPF
The RX-8 does not utilize a traditional transmission mount,
instead it uses what is called a PPF. This is a steel back bone that
connects the rear of the transmission to the front of the differential. The
front mounting points of the PPF are four slotted holes that are
slipped over the four studs located on the rear of the transmission. When
changing the clutch, flywheel, engine or transmission these four (4) 21mm nuts
are usually loosened or removed.
When reinstalling the PPF after major work there is a specific adjustment
range of 55 -57mm that sets the engine, differential and driveshaft angles to ensure optimum performance. This procedure is discussed in the factory workshop manual section(s) 05-11-7 (manual) and 05-13-42 (automatic). If the technician
or owner was not aware of this factory alignment specification (pretty common), the nuts are likely to be reinstalled in the wrong position making the alignment incorrect. Alternatively, if these nuts were loosened and
adjusted to the factory recommend settings and the OE motor mounts were worn,
broken or sagging it will be out of the specified range.
After installing your new RX8Performance motor mounts take a quick look along the slots in the PPF and check for markings where the paint was scratched when the 21mm nuts were previously installed. If there is scratched paint in a different location than where the nuts are currently, it is likely out of adjustment. We suggest you take a few minutes to setup your PPF as Mazda had intended. By aligning the drivetrain components to the correct angles you will eliminate any preload on the new motor mounts and will reduce NVH throughout the drivetrain.
As always, if you have any questions during your installation don't hesitate to call or email us for technical support or advice!