Better Beaters - Building Cars and Daily Drivers

 Rebuilding the wiper motor on my Plymouth. Part Two.

The eventual success was punctuated by a bout of frustration! In other words, it was like most other old car repairs!

That picture above is the paddle shaft. It is connected to the linkage that moves the wiper arms. It will be reused and attached inside the new paddle that was supplied in the rebuild kit.

New and old. Note the direction of the "vee."

The kit provided a new replacement paddle, though the original could be reused with a new gasket. This is the top view of the paddle, the teardrop shaped gasket faces up and contacts the wiper park structure.

Mocked up before I set the rivet.
The shaft is 180 degrees out of phase.

This is the underside of the paddle as I mocked it up, before I set the supplied rivet. What I failed to notice was that the angle of the "vee" was pointing towards the underside of the panel. Refer to the previous photo and note that the "vee" is pointing up towards the top of the paddle.

I used a rivet setting tool that I borrowed from my Wife. I held it in one hand and used the free hand to take a photo. Then I used the free hand to wield the hammer.

There are six slab head screws that attach the motor top plate.
The two small screws attach the switch chamber cover.
Why not use regular screws?

This photo shows the dissembled switch chamber. Note that the cutaway of the paddle shaft points up.

Unfortunately I had attached the paddle shaft out of phase, and the cutout was facing down. There was no way to reassemble the timer properly, so I had to pull the top off, drill out the rivet, and rotate the shaft. This time I used a pop rivet, which worked perfectly. No pictures of that process. This was the frustrating part that I mentioned earlier.

Those three holes carry the vacuum that powers the paddle back and forth.

                     This photo is before I replaced the paddle, and shows the proper orientation.

These are the components that are used in the switching chamber. The only replacement part that was supplied was the tiny spring.

photo source: AACA forums
These are not from my car's motor.

This photo illustrates how the components are assembled. This was already old proven technology by the time my Plymouth rolled off the assembly line in 1946. This tech probably had it's origin in the Steam Age, but it is very clever and simple. The arm has reciprocating motion because the vacuum is switched from one side of the paddle to the other, as it reaches the end of it's movement.

photo source" AACA forums
The fiber "yoke" seems to be the only fragile component.

The "yoke" is an internal cam that trips the lever from one side to the other. The arm does not rotate 360 degrees, it only moves clockwise and counter clockwise in a 180 degree arc.

I was concerned that the "yoke" was fragile and would be hard to replace. My Wife told me that she could probably make a replacement with her GlowForge. 

The GlowForge is a computer controlled cutter, similar to a CNC machine, which uses a laser to cut thin wood, metal, paper, and plastic. It can cut complex shapes in a very small scale. The machine scanned the original part and made a file that was used to duplicate the item. Initially my Wife used 1/16th acrylic, but she also used an old Amazon gift card, as credit cards are pretty tough.

The original part is in the center. It is made out of phenolic plastic. While phenolic material is  available, my Wife used what she had on hand. The acrylic and the gift card. I ended up reassembling the switching mechanism using the gift card part.

You can see the outside shape of the part as it was cut out of the card.

I should have asked my Wife to scan the replacement top gasket to make a file to copy it. However

I had applied gasket sealer to the gasket before I assembled the top to the motor body. It would have been simple to replicate the gasket using the GlowForge. Maybe I'll find another gasket set at a swap meet in the future and do that.

There was also a small gasket supplied for the on/off switch. This gasket was used on the top of the switch lever, the actual sliding contact was metal to metal. I decided that the existing assembly looked fine, and I was more likely to damage the little plate by prying it off, so I left it as is.

Top view

Bottom view.
It looks fine despite metal to metal sliding contact.

There didn't seem to be any visible wear or scoring on the top plate.

I just assembled the parts and lubed them afterwards.

After assembling and checking everything I moved the paddle shaft back and forth, and it moved freely, though it felt a bit tight. I used engine assembly lube to lubricate the inner chamber and other parts. I hooked it up to my Mightyvac to test the motor, pumped away and it worked! It cycled (slowly!) from side to side and I could hear a faint click as it changed direction.

Now I have to trim the actuating cable, reattach the motor to the underside of the dash, and reattach the wiper arm linkage, and hook up the vacuum line.

I'll save that for part three.

There are lots of people making and posting "how to do it" videos on the internet. I have to give them a lot of credit. When I put together a post like this, I try to take photos that represent the general direction of the repair process. When a problem occurs, or the procedure gets a bit tricky, frustration sets in. Then I direct all of my attention to just getting the thing done! Once the thing is together, I'm not going to disassemble it and take more pictures! 

I thank those posters for their efforts, it makes all of our hobbyist lives much easier.