Help - my motor is burning up!!...

[Libertine]

I recently got myself a TA04-R and have equipped it with Reedy 3300 cells, a Novak Super Rooster ESC, and an 11T Tamiya Super Modified Motor.

I've experimented with several different gearing ratios, but have opted for the standard set up recommended by Tamiya for my particular motor (a 39T pinion and 128T spur, if memory serves me correctly).

However, my motor is still getting unbelievably hot - so hot in fact, that this morning it melted the solder joints and disconnected itself from the ESC! [!]

I know that I'm using the right gear ratio for my motor, so how come it's getting so hot? Surely this can't all be down to my driving style?..

Does anyone have any ideas? [?]

[mr_pushrod]

Gearing is very dependant on where you run it, Tamiya don't know where you are driving so you should use their recommendation as a starting point. I would guess that you are seriously overgeared in which case you need a smaller pinion or larger spur. It is also worth looking at heatsinks to draw heat away from the motor.

[Libertine]

Thanks. I run it mainly in a car park, which isn't huge, so there's a lot of stopping and starting (mainly wheelspinning), which I suppose wouldn't help.

The TA04-R comes with the optional heatsink (which the motor bolts on to), and I think this is the only one I can get on there, due to the fact that it is surrounded with other bits and pieces. I've got air vents cut into my 'everyday' subaru body too, to maximise airflow. Other than that, I suppose I could get one of those fancy fans that are doing the rounds.

I will drop the gear ratio as much as I can with the gears I've got, but I'm wondering if I've got one of my belt tensioners done up too tight? The wheels seem to spin quite freely, but I'll double check just in case..

If it is the gear ratio, it will have to be dropped an awful lot in order to get the motor to run cool enough. It really does get red hot!

[BiggusDitchus]

To me I would say that pinion is far too big, especially if only running on small car park. I would also check that the car is free running back the motor pinion away from the spur gear and see if it will roll freely if not there is an issue there too.

[terry.sc]

The recommended gearing with the motor is a starting point for racing on a national standard racetrack, where the car will never stop and rarely slow down over the length of the race. using an 11 turn motor in a small car park I would recommend starting with a 34 tooth pinion, the smallest pinion you can fit on the car. I would also recommend reducing the timing advance on the motor to try and give you more low end torque. The best solution would be to replace the motor with something more suitable for running in a car park, something around 17-19 turns.

As you are running in a car park which isn't the cleanest of surfaces I would recommend you ditch the TA04 gears and replace them with 48dp gears. The 0.4 module gears are designed for racing and are fine on a clean surface but the smallest bit of dirt in the gears will destroy them. The TA04 will fit standard 48dp spurs made by all the major manufacturers so they are easier to get hold of when you damage them but they will take a lot more abuse.

If the motor has got so hot the wires have unsoldered themselves I expect that the motor will need rebuilding as the brushes will have overheated and need replacing. I would also expect the commutator will be damaged and need skimming to bring it back to life. This work will also means it runs more efficiently and so should run a little cooler, although I still think the motor is way too much though.

[Libertine]

I do sometimes run it in a very large car park, so I'd like to keep the 11T motor in it (anything else just won't seem as much fun now).

I am going through gears quite regularly, so losing the 0.4 pitch ones does sound like a good idea. The belt drive was a generally bad idea for where I run it, but I got it so cheap I couldn't say no. I doubt it'll ever see a race track, to be honest.

The car rolls freely when the motor is disengaged. I just thought that slackening off the belt tensioner a little bit might help things - I did have it probably a little tighter than it needed to be.

For now, I'll drop a few pinion sizes and take things from there.

Would a brushless set up work better? Would I still suffer the same problems with this gearing set up? (it's a nice mixture of speed and acceleration this way).

Thanks for your help.[]

[Libertine]

Oh, and I'll look into rebuilding the motor. I've got brushes myself, but I'll have to take it to a model shop to have the commutator skimmed.

Cheers!