? Info ? Who has a 3 wire wiper motor?

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67Dart273

67Dart273

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The 67 wipers started acting "weird" turned out after a morning's work to be the...........................

BULKHEAD CONNECTOR

But I have two other motors that I've obtained, at least one is labled a rebuilt. These LOOK like 3 speed / variable speed motors which I have in the 67

BUT THEY ARE THREE WIRE

An ohmeter check, against t he 74 shop manual which shows internal motor wiring, seems to indicate that they've been CHANGED by the rebuilder.

With the poor documentation on these over the years (no internal switch wiring, etc) it's hard to figure WTF?

It SEEMS LIKE these are now set up for two speed, but ??? Both motors do run but they are both missing "the green" wire shown in the books.

That last thing is, the 67 parts car SEEMS to have a 2 speed switch hooked to this motor, but that might not prove anything, as it may never have been hooked up. The switch "acts funny" (detents) so it's difficult to figure what this is.

Anyone else run into ?
 
I am guessing. Long ago I knew. Before they went to permanent magnets, a second field winding gave low speed. The motor armature and one field in series, for high speed. The second field energized gives low speed. Adding a ballast resistor or pot to second field, gives variable speed, or 3rd speed. Less field current, is more speed, with higher armature current, because reduced back EMF.

To complicate matters, reverse is necessary for park cam to do its job. That needs to he done by reversing the armature polarity with respect to field. To do that takes additional switch features. To do that, the armature, is switched to ground, and 12V applied to the node of the armature/field connection. So the armature polarity is reversed and the field is in shunt at same polarity. And of course there is the 4th wire, ground.

So there should be a armature wire, an armature with field wire junction, and a second field wire. The other end of fields go to ground internal. You should be able to find the armature by using ohm meter and see fluctuations with rotation due to brush action.
 
I found a diagram in the 72 manual of the internals, I guess I should post it. Here's my guess: I think what the rebuilders have done is essentially converted the 3 speed to a 2 speed. But I still haven't figured this all out. It appears that they have eliminated the green wire and permanently grounded the bottom of that field

This is out of the '72 manual which you can download
 

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In my first post the wiring is similar except I assumed the shunt field grounded, and the armature connection to ground would be brought out. Your schematic helps!

In the positive direction red and brown wires supply both fields and the armature. The speed is controlled by inserting ballast resistance is series with the shunt field red wire. Green provides the shunt field ground.

A potential problem exists in park. The armature is supplied via the blue wire, so the polarity is the same, however the brown series field must be connected to ground. This reverses the series field polarity. If this is not done (left unconnected), the motor may be damaged due to no field. The armature current would be very high. It is not clear if the shunt field is also reversed, or not connected at park. My assumption is not connected. It would be nice to know the switch contact relationships. I would think terminal "A" brown wire should have connection to switch ground in "OFF".

Series field is a good thing because the field current is the highest when starting, and the motor will have good torque. The danger in reverse is, if the brown wire looses connection to ground (switch not connected to ground) motor may smoke in park and no easy way to stop, because it may not move to open the park contact. It would be interrupted by ignition switch, but may go too long if driving.
 
Yup. I just don't understand what they "did." I might have to recheck but I believe an ohmeter check shows what would have been green is now permanently ground.

One of the two motors I have is noisy. I may later pull it apart and see if I can figure.

The switch "looks" like it should be 3 speed (2 resistors) but the detents are either not working right or it's only 2 speed. The detents are not definitive, and it's not variable.
 
[quote="Dart67";1970126426]Here is the Wiper Section from the 1967 Dart Service Manual.[/quote]

Thanks, I already have all that. The problem is not what or how to do, the problem is that these motors appear to be modified by a rebuilder, therefore the factory info is no longer valid.
 
67Dart273 said:
Thanks, I already have all that. The problem is not what or how to do, the problem is that these motors appear to be modified by a rebuilder, therefore the factory info is no longer valid.
Click to expand...

I did not know if you had the 67 manual info or not.

Just thought I would share the info I had.

Herb
 
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