Originally Posted by
storytyme
I was fairly comfortable with my FDR where it was but I had a crash which loosened the motor and when I hit the gas I stripped a spur gear. So since I was going to get a new spur gear I was going to mix up the FDR and experiment with a different size. I am running a 17.5 express duo 2 in a TC5R and I run on carpet with 96 foot straightaway.
Thanks andrewdoherty for the good advice on the number of teeth. That is something that I did not know and it helps me out. Thanks for everyone's replies.
If you have a 17.5R, most likely your FDR is around 4.5 to 5.5 depending on your application and track size. In order to get to these ranges, you will need a smaller spur to start. For 48pitch, I suggest maybe 78 teeth or less.
As for 87/30 vs 76/41, the fitting is the same. However, the loading on the motor is completely different. In this case, the 76/41 requires more work to turn compared to 87/30, given they have the same FDR, so the motor is hotter for 76/41.