Pinion assembly with Scorpion motors
(stepped 8mm and 10mm shaft with circlip)
First, remove the shaft circlip from the groove of the motor shaft (see red arrow in right picture). Then remove any eventually
existing spring washers from the shaft.
Be careful, don't pull the motor housing, since it is only after the assembly of the pinion secured again.
Before you continue, wrap the motor with foil or tape to prevent metal chips from entering the interior and sticking to the
magnets.
The shaft can now be shortened by an angle grinder to a length of 17mm. Burr the cutting edge.
Form a little surface of about 4 to 5mm width for the grub screw at the appropriate position (see left drawing). The centre of
the surface should be about 13mm from the bearing shield.
Since the shaft is hardened, you should use to a small square diamond file or a Dremel rotary tool.
Depending on the type of motor push either a spacer washer 8x14x0.5 or 10x16x0.5 onto the shaft up to the bearing. Then
mount the pinion.
Care must be taken that the motor housing is pushed all the way to the bearing shield and the pinion to the spacer washer to
prevent axial play of the housing.
The pinions are generally provided with a 10mm countersink and fit also to motors with a 8mm shaft. Reason is to be able to
push the pinion as close as possible to the motor bearing shield only with the 0.5mm thick spacer washer between the
bearing and the pinion.
After tightening the grub screw (using some Loctite) the pinion will prevent the shaft from moving up.
Do not use the counter bearing for the Scorpion because it will generate unnecessary additional heat.
Adjustment of the gear play:
As described above the plate can now be tightened to the chassis (use Loctite). To adjust the gear play push the plate to the
back until it reaches the stop. Then pull the plate slightly to the front again, press it down, so that it is positioned at right
angles and tighten the attachment screws slightly and step-by-step.
You hear a low ticktack when turning the large gears of the intermediate shaft. Check if the ticktack can be heard at different
positions, because it may jam at certain positions due to a minimum strike of the pinion. The plastics of the gear has a large
heat expansion property which may lead to a diameter increase by some tenth especially in midsummer during extreme heat
and a power-oriented flight style. Therefore it may be necessary to adjust a slightly larger play in summer to have some
reserves. The gear does not break due to a too high torque but due to an increasing heat caused by a decreasing play during
the operation.
It is also important to grease this gear often with some tenacious multi-purpose grease to minimise friction.
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