S2 wiper motor

#1
Used the car for the first time in ages over the bank holiday weekend, and took it to work Tuesday, that morning, used the wipers, it did half a sweep then packed up with the arms pointing skywards.

FFWD to today, and I have a play, taken motor and linkage out, cleaned the brushes and commutator regressed everything, sorted power, all good I think, put it all back, try wipers and success, it works. For 5 seconds, where the arm is now jammed up against the plunger for the vacuum delay. Odd I think, as its never done it before, and I've not touched that side. Now, it looks to me as if the motor is now turning clockwise, but before it looked as if it was turning anti clock, which when rotated manually that way, the arm pushes plunger in without catching. I've not changed the wires in the plug, so I have no idea why suddenly it seems to be running backwards, so, any ideas what I've buggered up motor wise? TIA
 

redrover

Well-Known Member
#2
It should turn anti-clockwise in normal operation. If you've had the brushes out, you may have put them back on the wrong way around? Or simply the wiring connections have been put on the wrong way.
I haven't taken one apart, but if the magnet was removable, it will run backwards if you put it in the wrong way around. This is a common issue on old Hornby and Triang model railway motors of the 50s/60s.
 
#3
The wiring can't be reversed as it's in a multiplug that only attaches one way.

I've taken motor back out, and connected direct to battery, it turns clockwise, so jams up on pushrod, reversing the connections, it runs the correct way, so I've taken the motor cover off, and turned it through 180° and it now runs the right way!

Just need to go and purchase several new fuses now, and hope it all works properly once back in the car.
 

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jp928

Well-Known Member
#4
On my cable drive wipers the delay rod has a small nylon cap on the end,which I think is so it slides on the plate. Try a little lubrication on the plate, or maybe look for the nylon cap.
 

redrover

Well-Known Member
#5
...so I've taken the motor cover off, and turned it through 180° and it now runs the right way!
That would make sense. Presumably the motor cover have the connections to the armature in it? If so, the connections were probably reversed internally.
 
#6
That would make sense. Presumably the motor cover have the connections to the armature in it? If so, the connections were probably reversed internally.
Theres no connections attached to the cover, just the 2 magnets, so I'm guessing they're polarity sensitive. Removing everything and wiring it up back to front saw the motor run correct way, as the cover was the only part with bits in that would affect it running, turned it 180 degrees, and bingo!
 
#7
On my cable drive wipers the delay rod has a small nylon cap on the end,which I think is so it slides on the plate. Try a little lubrication on the plate, or maybe look for the nylon cap.
There was a plastic end piece at one point, long gone now, however, even if it was attached, the part that pushes the rod in comes up and hits the rod in the middle running back to front, so the end piece would make no difference. When it runs the correct way, the large flat on the rod comes into contact in an inwards and down direction, pushing the plunger in nice and square.
 
#8
Without the plastic end piece on the delay unit's vacuum plunger rod, there is a dead short when the actuating plate touches the rod and the wiper switch is set to intermittent. That makes the wipers stop in an unexpected position and blows the wiper fuse. So the plastic cap is important for insulation as well as lowering friction between the rod and the actuating plate. Its length is critical for correct intermittent operation. I replaced the missing nylon cap on my car with a piece cut from an old nylon throttle linkage.
 
#10
The missing nylon cap has been replaced with some snug fitting tubing, which seems to be doing the job. The point I was making, with the motor running backwards so to speak, it would make no difference if the cap was there or not, the arm as it rotates back to front hits the intermittent rod along its length and stops dead, rather than coming into contact with the end, and pushing the rod in to create the vacuum.
 

redrover

Well-Known Member
#11
Without the plastic end piece on the delay unit's vacuum plunger rod, there is a dead short when the actuating plate touches the rod and the wiper switch is set to intermittent.
Possibly worth adding that a strip on insulation tape on the actuating rod helps. It seems to self-lubricate when sliding along the depressed rod as well as minimising the risk of shorting if the end cap is slightly damaged (as mine is).
 
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