4k4m3

An upcoming TC 1:10 electric race has a ratio limit of 4.5 for the 17.5T categ.
It's going to be a large long track with just a couple of slow down areas.
What combination of spur and pinion makes more sense? If I look at the extremes covered by my car chassis, taking into account my cars internal ratio, I could get closest to 4.5 with:
95-40 on one end or 110-46 on the other end.
How do I choose, or should I choose somewhere in the middle? Is there a rule?

DirkW

iTrader: (1)

The "only" difference will be the position of the motor, and therefore a slight change in weight distribution.

the rc guy

why ask the same question again. you have been given the answer. have you run (tested) and of the gear ratios you have listed? test then ask.dont mess around brushless system can heatup fast test temp after15 seconds of run time then 30 then 1 minute.seen a young racer burn up a brushless system in a gear test run he never checked temps on can or esc after running less than 2 minutes his car went up in flames total loss. and is 4:1 final drive ratio.betting it is.. so unless you tell the specific rc we will never know

GerryH

iTrader: (26)

As Dirk said, it doesn't matter how you to get to final drive ratio. It makes no difference on top speed or acceleration. 4.5FDR isn't very low especially for a big open track, so use whatever gets you the closest to it.

If there was no rule on FDR (final drive ratio), then you'd start with a spur that gives you ability to swap out pinions bigger or smaller. Then run tests at the track.

If you're running a new chassis, motor or completely new gear ratio, then take only a couple of laps and check motor temp.

But you should also test your motor temp after a race to make sure it's still in the safe zone. I'm sure there is some debate on safe max temp, but I always use 180f/82c as my rule of thumb. If I'm close or slightly over, I need to either add a fan, a better fan or reduce my gearing.