Prestolite wiper park function question

Ok, it's fixed !! Many, many thanks to Bill D.

There were two problems within the wiper motor that was causing the wonky parking issues and Bill's thorough text and pictures were of IMMENSE HELP. Problem one was that the cam pin on the plastic park switch cam was on the wrong ( wide) side of the metal flip tabs on the main gear plate. I'm sure this was what was causing the erratic park position of the wiper blades. When I corrected this the wipers were then "parking" at the top of their sweep. But... they were now always parking in the same spot.

This was corrected by removing and clocking the metal plate with the flip tabs 180 degrees rotation. This plate is on the top of the main gear and is held in place with a single nut and lockwasher. I also made sure that the plastic cam tab of the parking switch was positioned in the correct, narrow side spacing, between the actuating tabs on the metal plate.

It's now parking perfectly every time.

Edited by george w - Jan/22/2021 at 4:33am

george w wrote: Ok, it's fixed !! Many, many thanks to Bill D. There were two problems within the wiper motor that was causing the wonky parking issues and Bill's thorough text and pictures were of IMMENSE HELP. Problem one was that the cam pin on the plastic park switch cam was on the wrong ( wide) side of the metal flip tabs on the main gear plate. I'm sure this was what was causing the erratic park position of the wiper blades. When I corrected this the wiper were then "parking" at the top of their sweep. But... they were now always parking in the same spot. This was corrected by removing and clocking the metal plate with the flip tabs 180 degrees rotation. This plate is on the top of the main gear and is held in place with a single nut and lockwasher. I also made sure that the plastic cam tab of the parking switch was positioned in the correct, narrow side spacing, between the actuating tabs on the metal plate. It's now parking perfectly every time.

I've screwed this up myself with the vertical parking!

It was a big plus that I was able, with Bill's help, to solve my problem without having to remove the wiper motor from the car or to have to send it back to the rebuilder. It's unfortunate that the TSM provided no useful information other than the wiring diagram between the switch and the motor. It's a huge help when troubleshooting if one knows the principle of how a part works. For example the TSM is very useful in explaining how the automatic transmission works and shifts through the gears and how the air conditioning system operates, but I guess small, outsourced assemblies like the wiper motor, are pretty much ignored.
Fortunately we have some real experts here on the Forum that can fill in these gaps of knowledge. Thanks to all who also helped with tips regarding the wiper switch and it's grounding requirements.

Just as a side comment, the difference between the slowest setting and the fastest setting on these Prestolite electric wipers is nowhere near as great as that provided with the vacuum wiper system. For all practical purposes this "variable" electric system is roughly comparable to a standard two speed electric system of the era.

Edited by george w - Jan/22/2021 at 4:39am

Some AMC dealers did replace the upper control arm bushings. I have the K-M tools we used (and it's in the TSM)  It's where I learned to do the bushings without removing the control arm, leaving the upper ball joint in the steering knuckle. We replaced bushings.

We repaired alternators to a point - bearings and brushes - again, I have the K-M tools we used. 

Those were a royal pain - one reason we kept a lot of good spare stuff around in the 70s as after they stopped selling cars, we still did the upkeep on them so almost all customers for a while were "Rambler owners". You learned tricks as many of our customers were older and they'd scrap the car before they'd pay 50 bucks for a repair.