Book 3

The other end of the shunt wire soldered either on top of the dip or around the pickup
wire tab. By all means, do make a better solder joint than the one here. Remember to use
a long enough piece of shunt wire, so that it will not stretch when the brush is wearing
short. The other method of bulleting the bearing. The plastic ring is cut away, as in photo
and the bearing soldered in the plate. Only a few quick spots of solder are necessary
Shunting the brush: the shunt wire is jammed between the brush slot and the spring . , .
between practice and race, but this is up to you. If you are going to
put away the car for a few days. I advise you to unhook the springs
★ ★ ★ ★
22 assembly
At long last, we are now ready to assemble the motor. Check
everything for absolute cleanliness, no metal dust on the magnets,
nothing in the com slots, etc. Take the armature and put on the
washers - don't forget the fibre washer on the com side - and care ­
fully put the arm in the case. Check that there is a slight clearance
between armature and magnets. Then put on the endbell and screw
it on tight. Spin the armature a couple of times to check that nothing
is binding. Now install brushes, shunts and springs.
Solder the lead wires on each side and connect the motor to a
power source. Have it spin a 'fast idle' (R P M about 15,000). Run the
motor like this for about 20 seconds and then put a drop of oil in
each bearing. Increase revs slightly and run the motor like this for
1-minute periods. Total running-in time is usually about 15 minutes.
WARNING: do not let the motor run free at anywhere near max
R P M 's. since burrs at the com segment edges can easily crack the
brushes.
24
Figure 26: The s p r in g s should
be b ent a s show n. B y the
w ay, m ake sure that the
s p rin g w ill never stick in
the slo t o n the b ru sh holder,
a s th is w ill le sse n b ru sh
p ressure and th u s perform ­
ance. The s p rin g end m ust
m ove freely here.