Originally Posted by Pit-racer
what type of track? Medium to large sized outdoor tracks you want a target FDR of around 3.5 and adjust gearing according to track from there. If all else fails, ask the fast guys with 17.5s what their FDR is and match it to that.
to achieve 3.52 FDR you need a 78t spur and a 54t pinion (all 64p of course).
your internal drive ratio is 2.4375
(spur/pinion) x Internal Drive Ratio
Originally Posted by wheruat
hey everyone. well i have a pretty stupid question but here it goes. ive had my pro4 for awhile but havent play'd with it in a while. been messing around with my Avid lately. the question is im going through the gear box's and making sure everything is koo but noticed that the gear box fills not really tight but kinda snug filling! is that the way it fills compared to a belt driven car. cause the belt is so dam smooth. Thx for the help in advance.
Put it all back together, if theres a motor in it then take the pinion off and do the same with the Avid, then roll it down a hallway. If the Pro4 rolls freely and further than the Avid then its fine. If the Avid rolls further, theres something wrong with the pro4 because shaft drive cars simply roll free-er and further than any belt drive car. At that point check your bearings and diff condition.