Originally Posted by Racermac73
3.8 FDR should be close to start
Yep. Though it depends on how large and flowing the track is. 3.8 FDR with healthy dose of endbell timing should be pretty good on the vast majority of carpet tracks around.
You'll never get down to this low of an FDR with the kit 48P 84T spur though, so you will probably want to pick up a 64P 96T spur. I really like the Core RC machined spurs. They've worked very well for me. Leespeed is another good choice, I hear.
For pinions, I like the CRC gold ones, but I'm using some other brand in my car right now.
to get 3.8 FDR with a 96 tooth spur in an xray t4(internal ratio is 1.9 38/20
), you'll want a 48 tooth pinion. 96/48 x 1.9 = 3.8