Windshield wipers are fun, unless you don't have any, on a truck you intend to drive year around.
Most of the Dodge trucks of this era came factory equipped with electric powered wipers as an option. I suspect few trucks were built with the vacuum wipers and the electric conversions were pretty easy, even back then. The early year trucks were all 6 volts, but the later trucks (around 55-56) were 12 volts. The step up to 12 volts was pretty simple. These days you can buy new modern 12 volt electric wiper motors the come with switches and all the advantages of modern wipers. The only thing required was to still have the factory dual wiper posts sticking up through the cowl, just forward of the windshield and the linkage that connects the posts to the wiper motor. Those dual wiper posts were centered on each windshield section on each side of the truck. My truck came to me with holes where the wiper posts used to be and none of the linkage, it didn't even have the electric motor bracket.
Research followed, lots and lots of research. No one makes replacement wiper posts. No one wants to sell just used wiper posts, you have to buy the used wiper posts, the used wiper linkage under the dash, and the used wiper arms that only fit the Dodge wiper posts. Those pieces range from between $400 and $600. Of course, I need all of that because there is none of it on my truck, but really? That kind of money for 70+ year old stuff and that doesn't even include the motor or switch, which is another $350 add on? There has to be another option, and its sitting right there on my Donor Dakota. For $750+ I can spend some of my time messing around making something I already have work. I've done this before, a few times!
To understand the situation, you first have to understand the differences between how modern wipers work compared to how the old wipers worked. The old wipers were originally independent of each other, in fact for many years many vehicles only had a driver side wiper. At some point, a passenger side wiper became an option, eventually the passenger side became standard equipment (for the Dodge trucks the passenger wiper was standard starting in 1948). Up until about the mid 60s, most dual wipers would travel across the windshield in a mirror sweep, the wipers would either be going towards each other, or they were going away from each other. (I can see you moving your hands right now, LOL!) Usually this left a triangle area at the center of the windshield that was not cleared. Moving the posts around and positioning the blades to overlap at the center made some improvements, but that was the standard wiper operation, the blades either going towards each other, or the blades going away from each other.
In the mid-late 60s, that design started to change. Someone figured out that if they set up both wipers to move in the same direction at the same time, they could mount them closer to each other and eliminate or drastically reduce the size of that uncleared triangle at the center of the windshield. It also made the wiper motor and linkage easier because things only had to turn in one direction. The next step was to make one wiper travel farther across the windshield then the other. Then they could better cover most of the windshield. They could accomplish that by making one of the arms on the wiper post longer then the other.
The problem with using a modern wiper system on an old split glass windshield was both wipers have to have the same amount of movement across the glass (the sweep of the wiper), because neither wiper can cross over the center. One way to solve that would be to mount one wiper post at the center of the windshield area, and mount the other wiper on the farthest side of the other glass, but most people like the posts to be the same distance from the center of the glass, having one at the center and one at the far end just doesn't look right.
The arm on the wiper posts on a Dakota are different lengths, the passenger side has a sweep of 120 degrees and the driver side has a sweep of 90 degrees. The most sweep I can have on the 49 is 90 degrees. That means I will have to use two driver side wiper posts on the 49. It also means that if I use the Dakota motor & linkage, with corrected length, some how I'm going to have to change the direction of one of the wipers because I want both to be in the same position on the glass when they are parked. To accomplish that, I'm going to have to put an idler arm between the two wiper posts to change the direction of one wiper sweep. What can possibly go wrong?.
The 1st part of the adventure is to adapt the Dakota wiper posts to mount into the cowl, and the existing holes. First off, the Dakota wiper post mounts with 3 screws, and the 49 posts mounted with 2 screws, and unfortunately, none of those screw holes line up with each other. to add to that, the 49 mounting holes have threads in them, which means the housing for the 49 posts was outside of the truck, but the Dakota housings are threaded, so that means the mounting screws passed through what ever the Dakota wiper post were mounted to and screwed into the posts, the posts sat inside of the mounting metal. The 2nd challenge is the Dakota posts are pretty long, and have a larger diameter then the post holes on the 49. One would assume that the 49 posts must have been sealed under the posts, the Dakota posts were mounted under the vent cowl and were in an area that drained water away. Somehow the Dakota wiper posts are going to have to be sealed on the 49, or I'm going to have wet feet every time it rains. The wiper posts were installed before the windshield was installed. Unfortunately I don't have pictures of the wiper post bracket. The 1st thing I did was open up the hole so the Dakota post could fit through the cowl with as tight of a fit as I could. I also drilled the threads out of the two mounting holes on each side. Then I determined about how far out of the cowl I thought the post should stick, and marked the post. With the posts on the bench, I knew how much space I had to make a mounting bracket that would mount to the Dakota mounting holes and could use the existing holes in the cowl to mount the bracket to. If I remember correctly, that dual mounting bracket was about 1/4" in height. I made a cardboard pattern of the enlarged post hole and the enlarged mounting holes so it would fit flush under the cowl. Then I made a cardboard pattern of the Dakota post mounting pattern with the center hole. The Dakota pattern was larger then the 49 pattern. Since it was all under the dash, I could off set the Dakota pattern enough that I could insert the mounting screws and mount the pattern to the Dakota post. With the two cardboard patterns made. it was just a matter of transferring the two patterns to steel, then welding on the appropriate mounting nuts, and spacing the two pieces to the proper height to position the post at the correct height. The process was to mount the post to the bracket, then add a gasket and hold the post in place and insert the screws from outside into the bracket. it worked really well, too bad you guys can't see it...
That was the easy part! It took 2 times of mounting the motor just to get it where it could function, but I'm getting ahead of myself again. There is just one other little thing... The 49 has a cowl vent. I really would like to have that function as well. The linkage to open and close it will occupy the same space as the wiper linkage, if I can free the cowl vent linkage up enough to work... No sense making this easy!
Pic 1, You've seen this one before, but its the best view I have of the holes where the wiper posts should be. Also notice the location of the cowl vent in relation to the wiper posts.
Pic 2, You've seen this one before too. This pic shows what the cowl vent looks like from inside of the cab (its the big rusty looking piece in the center just under the windshield "V") If you look at the vent door itself you can see the two mounting hinges on either side of the door. The vent pivots open from that point. In this pic the vent is closed, when its open, it would barely be visible from this angle.
Pic 3, There is a lot in this pic to see. At the top center is the passenger side wiper post as viewed from inside of the truck. To its right is the end of the wiper motor with one of its 3 mounting bolts. The black bar attached to the wiper post is the Dakota wiper linkage for the right side. The more rusty looking rod below it is the original Dakota wiper motor linkage. In the original truck, both of these linkage rods would have connected to the wiper post on the driver side, but now both of these connect to the idler arm pivot you will see later. The bolt with all the washers is the right side cowl vent door hinge. The rusty part In this pic) is actually the bottom of the cowl itself. The white curved bar attached at the bolt is the mounting bracket that is attached to the vent door (it is the white painted piece under the cowl). the little module on the shelf is for the overhead consul temp and directional monitor (that still won't give me an outside temp).
Pic 4, You've seen this one before too. This is the only pic I have that shows just the wiper post on the outside. The passenger side post is the easiest to see (which happens to be the same post you got to see the back side of earlier.