Gearbox for Speed 300
02-02-2004, 09:58 PM
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Gearbox for Speed 300
Greetings,
I have grown tired of trying to repair the gearbox on my Potensky Cobra. My last fix was to replace the circuit board material with aluminum. That actually kept it from breaking, then the plastic teeth stripped.
Anybody know of a gearbox that will screw on the front of the Graupner Speed 300 without further modification? I already have a brass pinion installed on the motor. Brass is plenty hard enough to strip the plastic, by the way.
Regards.
I have grown tired of trying to repair the gearbox on my Potensky Cobra. My last fix was to replace the circuit board material with aluminum. That actually kept it from breaking, then the plastic teeth stripped.
Anybody know of a gearbox that will screw on the front of the Graupner Speed 300 without further modification? I already have a brass pinion installed on the motor. Brass is plenty hard enough to strip the plastic, by the way.
Regards.
02-02-2004, 11:54 PM
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RE: Gearbox for Speed 300
I don't think that a stronger exact replacement for the POT3B exists. I'd undertake a retrofit (that nose is only foam after all) and use an MJ 8043 (5:1) or MJ 8044 (4.5:1) BB gearbox. THAT would stand up to the strain.
Cheers, Phil
Cheers, Phil
02-03-2004, 08:16 AM
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RE: Gearbox for Speed 300
Ah yes, the old engineering trick where strengthing something in one area will cause something else to break. Gotta love it 
If I read your post correctly, you want a gearbox that bolts on to the motor, right? You're not terribly concerned with the gearbox being a perfect fit on the plane, because you can modify the plane.
The MPJet gearboxes Dr. Kiwi recommended are a perfect fit for the Speed 300 motor. You may need to pop that pinion off and use a different one.
As an alternative, take a look at the GWS EPS350C drives. They're a popular choice for replacing the glass-jaw Potensky gearboxes.
If I read your post correctly, you want a gearbox that bolts on to the motor, right? You're not terribly concerned with the gearbox being a perfect fit on the plane, because you can modify the plane.
The MPJet gearboxes Dr. Kiwi recommended are a perfect fit for the Speed 300 motor. You may need to pop that pinion off and use a different one.
As an alternative, take a look at the GWS EPS350C drives. They're a popular choice for replacing the glass-jaw Potensky gearboxes.
