TR23 Gearbox

The team decided we didn't want four-wheel drive at all times. The fix: a clutch that could send power to the front wheels only when needed.

That clutch had to mount to the gearbox and the case had to take its new normal loads. We also wanted to pull belt tensioner duty into the gearbox (instead of off-loading it to the frame), so a large shear-and-bending load got added to the case.

I kept the TR22 architecture and iterated on what changed:

• Added clutch mounting and reinforced the case for the new normal loads.
• Rebuilt the section that takes the tensioner reaction so the case carries both shear and bending without needing the frame as a backstop.
• Increased the count of clamping screws to handle the new shear and normal loads.
• Added a large NPT port with a sight glass so the team could check oil level without disassembly.

Most of the original architecture stayed — the redesign was driven by the new load cases, not a desire to start over.

Cleaner serviceability (sight glass), cleaner force routing (case takes tensioner load directly), and accommodation for the new clutch — all without giving up the proven TR22 design.

• Iterating beats redesigning. The biggest design wins this year came from preserving what worked in TR22 and surgically extending where loads changed.
• Adding small instrumentation features (the sight glass) earned outsized goodwill from the people who service the car at events. Worth the manufacturing complexity.