Hot motor pinion gearing

[DikkeGnoen]

I'm pretty new, but do understand a bit of teching, I'm used to 1/8 buggies.


I got myself a RTR Absima Khamba, but I've got the feeling it has a very low ratio (pretty high top speed). The motor gets hot quick, and since I've got heavier tires & rims I especially want to lower the pinion.


It has a 21T 550 motor combined with a 16T pinion and a 44T spur, thrown through the calculator it comes at 2.75 ratio. The minimum pinion I can install is a 12T without clearance & motor mount issues.


https://www.absima.shop/pp/modellaut...=19053&p=19053

Transmission: 2-speed (Hi 1/15.1 / Lo 1/37.1), Remote shifting

Gear Pitch: Module 0.8/32dp - Pinion 16T / Spur Gear 44T

Motor: 550 high-torque brushed motor 21T


I use a 7.4v







What are your thoughts, what would you recommend?


Thanks in advance!

[DrIsotope]

I would put in a lower turn motor, like a 3-slot 27T 550, or a 5-slot 15T 550. The 21T in a TRX-4 is pretty hot for a 2-speed, and the Abisma doesn't have nearly as much gear reduction. High speed in that thing must be zoomin.

[Ninomaniac]

A 12t pinion, why not... And/or what drIsotope said. You can slow it down that way for creepy crawling, and go 3s to make up for top speed. I don't think I know anyone that runs 2s anymore...

[Voodoobrew]

If there is no room for a larger spur, then there is not much to do to reduce the gearing.

Possibly modifying the motor mount to move the motor closer to the spur to get a smaller pinion.

Planetary gear reduction modules are an option, but I hear they might not last long.

Outrunner brushless motors have a lower speed and lots of torque. They would be my choice. But would also require a new esc.

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[tigris99]

Don't go lower turn motor, go higher turn (not sure why someone advised go lower turn, that's for speed, only.make matters worse).

Since your stuck with higher gears in the truck, pushing your turn count on the motor way up will help for a simple fix that's also cheap. Go the lowest pinion you can and increase the turn count for the motor to something in the high 20s at least if not into the 30s. You can also go the high turn motor in the 30s, 40s etc and run that 16t (or try a few different) pinion to have some speed in high gear.

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[Maxx_Action]

I think you'd be surprised at how much difference dropping the pinion by 4 teeth will make.

I would try that first. Then if you do change motors, go with Brood, or Holmes hobbies, someone who makes a quality motor.

[Voodoobrew]

If the pinion spur mesh is too tight or any other gears are too tight, or need grease. Or bearings need oil. That will all make the motor hot.

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