Gearbox Internals

The gearboxs on all three versions are identical. The motor mounting plate has two sets of mounting holes. The shaft on the the 700 motor has been turned down to 1/8" so that the same size pinion gear can be used on both 550 and 700 versions.

I tried an HTI Speed 700 to see if it would fit the plate but whilst the mounting screw holes were in the right place the centre bore was too small to match the diameter of the protrusion on the front (it aligns the motot on the plate).  The is plenty of material around the hole and it could be opened up to match. There is plenty of material in the pinion gear gear as well so a gear could be made that fitted the typical 5mm shaft on most Speed 700s. 

The reduced shaft on the motor is obviously a weak point. The pinion is a press fit on a single D shaft.

The gearbox differs from the usual Harbor Freight ones in that both planetary gear carriers are removable. The stage nearest the motor has 1.9mm pins whilst the second stage has 2.9mm pins. Gears are well sized and appear to be the usual sintered metal.

The Gears are metric, Mod 0.7, Motor Pinion has 15 teeth. I am looking into the possibility of getting some gears made that would allow other Speed 700s with the usual 5mm shaft to be used with these gearboxes.

Gearbox ratio is 24:1  (Harbor Freight ones are usually 36:1).

I think the motors and gearboxes will work well in all 12 -15 lbers and in the drive of spinner 30lbers or 30lbers that protect the wheels.  They would probably not be suitable for heavier weight classes.