I am running stock Tammy gearboxes and 480 motors.
I tried to install MPI 1:3 gear reductions, but they came with a 4mm shaft.
The closest pinions I could find were for 1/8" shaft.
I do not have the ability to accurately drill-out the pinions to fit .
I have ruined 4 pinions already.

I only need to shave between 1/2 and 1 second (at 25 feet) off my road speed times.
So, I figured dropping to a smaller pinion would give the the correct speed.<br type="_moz" />