Q I just installed a new modified motor in my Tamiya car so I’d be able to beat my friend in a race. The place where I bought my motor told me I needed a new speed controller to go with the modified motor, so I got that, too. The car runs much faster than when it was stock, but I had to resolder the wires going to the motor brushes twice. The car worked well for a while, but the last two times I drove it, the wires came loose. Am I doing something wrong? [email] Ed Smith
A The 60/40 solder melts at 370 degrees, so you must be doing something to get the motor so smokin’ hot SB that it melts the solder that holds the brush shunts on the endbell. That heat is almost certainly the result of your overgearing the modified motor.
A 10-turn motor makes roughly three times more power and rpm than the standard dosed-endbell motor included with most Tamiya cars. The amperage requirements for a modified motor are considerable; when combined with an excessively low gear ratio (high gearing), there’s almost no way to avoid tremendous overheating and damage to the new speed control and motor. You didn’t specify the type of car you own, so I don’t know whether you can change spur gears, but I would start by installing the smallest usable pinion gear. If that doesn’t reduce motor temps enough and you don’t have an option to make further gear-ratio changes, you should also set the motor timing to zero to reduce rpm.
Copyright Air Age Publishing Nov 2003
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