wtrdave

Hi,

I've just started doing electric cars, recently doing petrol but have stopped that now and concentrating 100% on electric. Now I've built up a car, got a 14t motor with a decent esc. And I'm running a 120t spur and 43t pinion. It goes great, very speedy, even going faster than my mates petrol rc car.. But the motor seems to overheat alot (the esc is fine and doesnt overheat), is there anything I can do to solve this problem?? Is my spur/pinion ratio right??

Thanks for any help,

Dave

InspGadgt

What car is it?

CarbonJoe

Without more details, we'd just be guessing.

First, what temperature is "overheating"? But, if you're convinced you're overheating the motor, you're most likely geared to high. Drop 5 teeth on the pinion and try again. If still too hot, drop some more teeth.

wtrdave

Sorry, its on a Tamiya TA04

I dont really get the whole pinion/spur thing with the ratio n that...

All I have is 120T and 83T spurs, and 43T, 42T and 23T pinions, I'm assuming I need to buy some more??

Also I cant put my finger on the motor after a few seconds of touching it, I hear if you cant touch it for less then 5 seconds its over heating... This is on a brushed motor by the way.

Thanks,
Dave

oeoeo327

iTrader: (75)

Given the limited amount of information we have, the recommendation of dropping a few teeth on the pinion gear would be the first course of action. Usually, too large of a pinion gear would be the first reason a motor overheats. Since your car has a 2.123 internal transmission ratio, and the gear ratio of your spur and pinion choice equals 2.79, your total gear ratio calculates to 5.92:1 (in other words, your pinion gear rotates 5.92 times for each time the tires make one full rotation).

You've also mentioned that you're using a 14 turn brushed motor; if we knew exactly which motor you have, we'd be able to help you make a more informed decision about gearing the car properly. However, 5.92 isn't too far off for a 14 turn motor in a 4WD touring chassis, provided that the motor doesn't have its endbell timing turned all the way up. If you've adjusted the timing, try a 40 tooth pinion and see if the motor runs cooler. If the motor still continues to overheat, drop a few more pinion teeth until you're comfortable with the motor temperature.

bertrandsv87

iTrader: (2)

5.92 fdr is more for 19t motors. A 14t motor should be geared closer to a 12t motor( 7.1 fdr) to start, and then geared higher if the motor stays too cold.

bertrandsv87

iTrader: (2)

With 120t spur you will probably need 35t to 41t for some gearing flexibility... Good luck....

wtrdave

Thanks for the help, as it all helps as I am very new to this.

Motor: LRP GT4 14x2

ESC: Nosram Magnum Power Reverse

Battery: 4300 mAh NiMh

I'd rather get the right ones as I dont have too much money to spend on pinions/spurs.

Thanks,
Dave

RsageD

My motor overheats too.

TF5 RTR, 5.5t ezrun. Spur at 78, Pinion at 24. FDR is 8.125.

The auto cutoff stops my car after a 6 min run.

By the way, What about timing? i have no clue about this. Its now set on default but a fellow racer at the track said to lower it.

Thanks in advance!

YZFAndy

What temperature do you consider to be overheating? It'll probably go to 120 before the enamel wire starts to give up. I know you say you can't touch it but even 60c is going to feel almost untouchable. If it smells like the magic smoke is trying to escape then keep putting smaller pinions on until satisfied. Other than that back the timing down.

Skynet

Yeah, overheating is when the cables go off from the motor, and that's damn hot!!
Normally you start with a high total gear ratio, eg. 7.5
Then you lower the gear ratio by adding one or two teeth to the pinion

RsageD

When u say lower as in more for pickup like my current FDR is 8.125. Right? Thanks Skynet

RsageD

What are the effects of dropping the timing besides that the motor will run cooler? Sorry, i dont understand the timing for brushless motor.

Are they like engines so they run smother and proper burning of fuel etc.?

Rick Hohwart

If you can touch the motor for a few seconds it is not overheated.

YZFAndy

By reducing timing you will have a less rpms but should have more torque and overall efficiency is increased. Overall power is reduced but sometimes you can back timing down and not see any lose. I would start at minimum timing and work your way up. Generally by increasing timing you find a point where the motor wont make any more power but heat start to rise suddenly.