Chevrolet 10 Series 1970, Service Manual

Page: 213 / 671

REAR SUSPENSION AND DRIVE LINE 4-37
F ig . 6 9 — R emoving D riv e S crew Bearing
(18) unless n ecessa ry to rep la ce one o f the p arts. If
n ecessa ry to d isassem b le, mount assem bly in vis e .
Turn spring winding le v e r clockw ise and pull to
separate.
Inspection and Test
F ir s t clean a ll p arts except m otor in cleaning solvent,
then inspect and test as follow s:
Autom atic Switch. The switch is s e rv ic e d only as an
a ssem b ly. The switch should have clean, flat, fre e m ov­
ing points which c lo se squ arely under spring tension.
Poin ts should open when a fo rc e ranging from 14 to 24
ounces is applied against spring p ressu re in the point
a rea o f the m ovable contact.
D riv e screw . W hile holding the nut, rotate the screw
fro m one end to the other. It should rotate fr e e ly . When
the nut gets to eith er end o f the screw , the screw should
F ig . 70 — R emoving M o to r W irin g Lock N uts
F ig . 71 — Rem oving A u to m a tic S w itc h
continue to turn, but the nut should not jam o r run o ff the
ends.
E le c tric M otor. The closed type r e v e r s ib le fie ld m otor
(s e rv ic e d only as an a ssem b ly) req u ires no lubrication
and cannot be disassem bled fo r rep a ir. M otor s e r v ic e ­
a b ility can be determ ined by p erfo rm in g the follow in g
tests.
W ith the m otor housing connected to one battery te r m i­
nal, and eith er one o f the two m otor w ire s connected to
the other b attery term in a l, the m otor w ill run in one
d irection . W ith the other m otor w ire connected to the
b attery, m otor w ill run in the opposite d irection .
Connected to a 12 vo lt test circu it, the shift m otor, fre e
running (no load), should “ turn up” 10,000 rpm with a
maximum draw o f 8 am p eres.
CA UTIO N: Do not overheat the m otor while
making the follow in g tests:
P la c e m otor in v is e , then clamp a sm all wrench on the
rectangular d riv e on the arm ature shaft and grasp wrench
handle with one hand. Connect one m otor w ire to a battery
term in a l and connect m otor housing to the other battery
term in a l. The wrench should tend to turn with a torque
o f about 6 in. lbs. A llo w wrench to turn v e r y slow ly,
making sure that this pull o r torque is presen t the full
360 d e g re e s turn o f the wrench. If one section o f the
arm ature is d efective, the torque w ill disappear fo r a
sm a ll part o f the 360 d egrees.
Apply enough load to the m otor in test c irc u it to m o­
m en tarily stop arm ature rotation (s ta ll the m otor). The
cu rren t draw at sta ll should be a maximum o f 40
am peres.
M iscellaneou s P a rts . Inspect bearing (10), i f b a lls a re
rough o r chipped, rep lace with new bearin g and snap ring
a ssem b ly. Pack bearin g assem bly with ch assis lubricant.
Check torsion spring (17) fo r breaks o r w ear at le v e r
contact points.
O b serve condition o f fib e r contact bum per (24); if
broken o r e x c e s s iv e ly worn, pull out old bumper and
p re s s in new.
NOTE: A ll gaskets rem oved should be r e ­
placed by new gaskets to assure p ro p er sealing
o f the unit.
CHEVROLET TRUCK SERVICE MANUAL