I have a 72 spur and I need to find the largest pinion that would fit into a TC4. I tried a 39T and it didn't fit. Instead of buying a whole bunch and trying them, I thought someone could help me out. These are 48P. Thanks.
I think 31t or 32t is about the biggest you can go with 72t spur. like said above grab a 60t rrp spur gear. part number rrp1860, tower has them. no you will not be able to run smaller than 29-30t pinion with the 60t spur. hope this helps.