mechanical speed control problem

[tuna.Rc]

I built a 6 gear buggy out spare parts , going by the manual.
Everything works as it should.
The green part gets really hot and something in that area smokes.
It's slow at first then picks up speed.
It won't take off quick and it gets stuck easily.for example, it'll get stuck in grass , the wheels won't even spin,I don't think the motor will even turn the spur gear.

I'm running a 10 turn motor, stock spur gear and pinion. Not sure what teeth count .

I built another 6 gear buggy by the book and it works fine, same gearing and mechanical speed control set up, just a different motor..This buggy is actually pretty fast and at first it'll spin the tires on take off if u get on it. The motor gets hot but nothing smokes, no wires heat up.

This is my first try at mechanical speed controls.

Any tips ?

[Asso_man!]

Wow a 10 turn on a mechanical speedo? No wonder it smokes! I would only run a stock motor on a mechanical speedo, or maybe a 19 turn but everything above will cause heat, smoke, melting or in the worst case a fire. You should look for a proper ESC.

[DMAT]

I think Assoman called it. You can continue to run a mechanical speed control if you want but your almost stuck running a stock motor only.

[Kyoshojoe]

yup, Be careful using an msc, they have no failsafe and if you glitch out, the car will go out of control. MSC's use resistors to lower voltage to motor so a low turn motor will pull more current through the resisitor which causes more heat. Brushed motors have a hard time dumping the heat because the coils are on the rotor and only have air to wick heat away. also the brushes have lots of resistance against the comm which causes heat. There is also a cascade effect with heat, as the resistor and motor heat up the resistance goes up and causes more heat.