Originally Posted by Scottmisfits

I never noticed any significant temp difference for such a small gear change, but what I did notice was corner speed. The bigger the spur, the more rotating mass, the more corner speed. This is overcome somewhat by the weight of the pinion. But we are dealing with a 4lb car, a few grams will have an effect. But the same is true going to a smaller spur. Quicker acceleration, even with the same gear ratio.

This is just my findings, other people may have found something different.