Help with gearing

[nick f]

Ok, I have a new TA04S geared right now with a stock silver can 540, 25/83 (0.6 module). I have a Tamiya RZ motor 23 turn to put in it. The box on the motor calls my car out specifically for a 45/112 combo (0.4 module). Can that be right? It seems way overgeared to me?

Well

25/83 = 0.301 ratio
45/112 = 0.4017 ratio

Internal gear boxes and pulleys remain the same for a ratio of around 2.2

If I use the 25t pinion on the RZ motor am I over geared or under geared? I'm used to the 2 less teeth rule for pinions.

Please help this on road stuff is new to me. I dont want to burn the motor out due to improper gearing.

Thanks
Nick F
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[rccardude04]

If it gets hot, gear it shorter. If it's not getting hot and could use more speed, gear it taller.
-Eric

[highroller]

I haven't run any of the updated Tamiya kits, but past experience is that the motors they called mod aren't as fast as some standard stock 27 turn motors. The other aspect if you are using the stock metric gears (spur/pinion) it may restrict your choice in gearing ranges.
Even with the same vehicle/motor combo there can be a variation in gearing by as much as 3 teeth. You'll know when you it the right gearing when car accelerates smoothly and quickly, sustains that speed and motor is relatively warm (165-180 degrees) for a 4-5minute run or longer. If car doesn't exhibit a crisp acceleration, or seems to hesitate mid way, then suddenly gain a slight speed increase, motor starts to get hot or you notice a sharp decrease in speed after 1-2 minutes runnng then motor is overgeared. I've found that even the manufacturers' suggested gearing ratios can be off by as much as 5 teeth depending on what motor is used for. Generally for bashing the gearing is conservative about 3 teeth lower, due to fact that motor is run much longer, while race motors are run for 4-8 minutes.