I'm Thad.

RGP007 Drivetrain

Drivetrain, assembled

Barren Installation

Spotting The Problems

Building on successes and learning from failures of RGP006’s drivetrain, 007’s proved to be a wonderful system with little issues. - The tabs holding the front of the engine to the frame broke. These tabs were pocketed, had a stress riser, and were either un-analyzed, or improperly analyzed, and broke right at the weld’s HAZ. - The roller tensioner kept disintegrating. Even the aluminum one showed major signs of wear, and abuse on the bearings. - Servicing the caliper proved difficult. - Aluminum jacking bar/truss was difficult to manufacture, and often broke.

Do Something About It

The changes made to fix things were to:

  • Integrate the engine mount into the differential mount. This provided better load paths.
  • Opted to use a shim tensioning system rather than roller system.
  • Moved the caliper to the bottom of the car, revealing the bleeder valve to technicians
  • Mounted the jacking bar/truss exclusively to the differential mount, rather than to the chassis as well (and shifted to simalarly sized sheetmetal throughout)
  • In addition to the usual FEA analysis to ensure everything was kosher.

The Design

Banana for Scale

We acquired a CNC mill, so we decided to put it to the test, and machine some sprockets. It turned out… actually well!

CNC'd Sprocket

How’d it go?

This system faced only one issue: The shims for tensioning popped out. I foresaw this as a possibility, and made sure to design in ‘ears’ for safety wire to be installed such that the shim is retained even under severe vibration and compressive loads. Installing said safety wire eliminated the problem.

Didn’t see any issues beyond that. And we didn’t really have enough time to tune things, so I can’t quite say how it all turned out from a performance standpoint.

Download the Complete Design Document