Crashly

Like many others, I have been experiencing spontaneous gearbox failures on my Spitfire. Average lifespan is about 5 flights. I run full throttle most of the time with the Lipo battery. I have come to the conclusion that the plastic motor housing is too tight a fit to allow expansion of the motor when hot and so stress cracks develop and eventually propagate till total failure or vibration occurs. This does not happen with the Supercub even though it has the same gearbox and motor but it has a smaller battery and therefore less heat. Have seen fixes based on strengthening the gearbox motor housing using the removable metal sleeve on the motor.ffice:office" /><O</O
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I thought I'd give it a try, then it occurred to me, "why not just leave the sleeve off all together and see what happens. So far after 10 flights all is good. My question is: What is that metal band for? <O</O
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soar-ne

You must be talking about a "Flux Ring". These come with some motors, not a expert but I think the motor is a little more effecient with it on. On the old Johnson motors we took them off all the time with no effect. In our use where we abuse them so much I doubt if it matters one way or the other.

Good Luck
Bob

Crashly

Thanks for your reply Bob. I havnt noticed any performance differences although when I turn the prop by hand that clunky feel as the windings pass from magnet to magnet is much weaker than when new. Might just be from pushing these motors to thier limit, heat etc.

Cheers,
Dan