by John Grady September, 2020. Revised August, 2023.
I had occasion past few
days to work on three F windshield wiper setups. These came with the
“do it yourself F kit“ I bought in San Diego.
I had sent some pictures
of work on a fourth one earlier this year, mentioning the need to be
sure to ground both the motor unit and the switch housing or you will
damage the motor on the bench. That was a 57 but these seem to be the
same functionally. The switch body completes the field circuit to
ground.
This is how it reverses to
park -- it swaps the field wires. Yellow and red are field, black is
the armature and green is armature via park switch. The yellow and
red have to be right way on the switch - see picture. That is
correct placement. Black is “run“ armature, green is park
and white is the switch ground.
All 4 of these wiper
motors had sticky park cam switch levers in the gear case cover due
to old grease. A stuck switch means no park. The cam must readily
self center with the light coil spring on it. In my case the plastic
park switches were always good, but it was where the cam goes through
cover plate to move switch that caused the sticking to one side.
After total disassembly of all that switch stuff twice on the first
two, I realized that 75W oil on both parts of the nylon cam the on
underside of removed cover plus working back and forth frees it right
up! Easy!
But on all 4 motors the
wires coming out have fabric sleeves that dry up and crumble off the
winding wires at the motor hole. That is a short circuit, either now
or in the future. So I disassembled the motor and replaced the wire
from the brush with new plastic coated wire, soldered it on to the
brush tab and covered the others in small shrink tube to about 1/4”
into the motor. To keep the wire identity I used colored shrink
tubes. By the 4th one it one took only an hour to do.
I left the wiper arms on
because it is a bear to get that screw out. Generally it is corroded
solid. Plus, it is complicated to get the arms reassembled correctly.
I did oil the joints.
Two wipers had a smashed
park switch housing due to careless handling. The switch sticks out
and is easy to break. I fixed them with epoxy but it is frustrating
to have to make that repair – better to protect it in storage.
I used 3/4 4/40 screws to reassemble, the switch mount plate slides
side to side to get the rivets out.
But if not broken, the
switch is rugged and 99% of the time it is OK and the problem is the
cam sticking.
On reassembly be sure the
cam pin drive is hanging down into the 180 degree open part of the U
on the big gear. You can position it about in middle of that 180.
Information on the wiper motor system is under the "Electrical and Instruments" section of the service manual.
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