I have a '49 Ford truck that is stock, 6 volt positive ground. It has stock vacuum wipers that naturally don't work. I've worked on them a few times and got them to work only to fail a short time later. I am sick of vacuum wipers. I want to install electric wipers and I see a few options. I can buy a "bolt in" replacement 6 volt wiper system from LMC for $300 including tax and shipping. I can buy a "bolt in" replacement 12 volt wiper system from a few other vendors along and found a step up power booster to boost 6 volt to 12 volt. Total for this about $175 including tax and shipping. I want to leave the truck stock 6 volt, positive ground. If I go with the 12 volt system I'd have to reverse the direction of the wiper motor because I want to maintain the positive ground. I called tech support for the 12 volt system and he was very helpful but didn't know anything about reversing the direction of the motor although he said there was a note in the file for the '51/52 Ford truck that said to pull off the end of the motor and reverse the contacts inside the motor. I would like to know if anyone did this successfully.
I've tried the '51/52 setup it didn't work. The '48-50 has a different dash configuration. I have a stock radio and it occupied the area where the '51/52 motor sets. I up a unit and tried to make it work but there isn't much room where you have to have the motor. I've cleaned a stock vacuum set up and got it working but it stopped about four hours into a rainy trip. While searching for more information a member on the Ford Barn said the motors used for starters, heater and wiper are the kind that won't reverse if polarity is switched. I know the starter in the truck doesn't.
You have to change the direction of the current through the armature or the field, so as they are connected in parallel, you need to get into it and swap the wires around. How hard or easy it is to do this depends on the physical layout of the motor. Hopefully it has a removable end plate over the commutator (brush) end, it makes it a bit easier.
If the wiper motor is not grounded to it's housing (completely isolated) you can simply connect the output wires of the 6-12v converter in the normal manner. You might have to isolate the converter as well as these are generally used in neg ground installations and the case may be common with the neg side.
I talked to the tech guy at Speedway and from what he can tell the motor case is grounded so that why I was wondering about reverse polarity would affect the operation of the motor. I posted on here to see if anyone here has messed around with a situation like this. The HAMB is the go to place to find answers to odd car questions.
If it's a permanent magnet motor and one "brush" is connected to ground you might be able to dig into it and swap the connections that go to the brushes. If it's a series wound motor then it will run in the same direction no matter the polarity (like a starter motor) and you'll need to get inside and swap the connections on the field windings.
Kind of what I'm thinking. From what I've been finding on discussion boards it seems most automotive motors run the same direction no matter the polarity.
The concern for running them backwards is mostly because the wiper blades are parking in the wrong position, correct? Reversing the park position is a simple matter of reversing the direction the wiper arms park in. Is there enough space to operate the wiper pivot under the dash from the other direction? If the wiper pivots normally are pointing down, and you run them off the top side, you reverse the park position of the wipers. You can also change the park position by adding an idler bracket between the linkage off the motor and the linkage to the wiper pivots with an idler pivot with equal length arms in direct opposite directions. My 49 Dodge truck has a modern wiper system. With modern systems, both wipers move in the same direction. On my truck, I wanted each wiper to stroke toward and away from each other at the same time. To do that, I had to change the direction (park location) of the left side wiper blade. I see no reason it couldn't be implemented for changing the direction (park position) of both wipers. Had the photo been taken any higher up, you still could not have seen the top attachment, the bottom of the windshield frame would be in the way. Pic; This thing at the top center of the picture is my wiper linkage idler. It changes the direction (park position) of the left side wiper. The center bolt holds a sealed bearing (and flat 2 piece bolted together bearing housing) from a hardware store (these bearings and housings are used on furnace blower motors). This one has a 1/2" diameter inside bearing race. You can see the grade 5, 1/2" diameter bolt head, and washer (has a washer and a lock nut on the back as well) that act as the pivot point. The bearing housing moves freely when the bolt is tight. The bar its mounted to is a 1" x 1/8" flat steel bar that has the top welded to the firewall (bolting would also work as long as the mount is solid). That bracket is a simple mounting point and is about 4' long. The back part of the bearing housing has two "arms" welded to it, 180 degrees apart. Each matching arm is about 1 1/2" long 3/4" x 1/8" flat steel bar (both were cut and drilled together, I don't believe the actual length has any effect, as long as both pivot points are the same distance from the center and the linkage doesn't bind). I used grade 5, 1/4" bolts (with washers and lock nuts) to hold the wiper linkage to the idler (were I to do it again, I would use a pair of factory style wiper linkage mounting points to connect to the linkage, the bolts have worked flawlessly, but the linkage is a bit noisy with the bolts). When the bolts are tight, the linkage moves freely on the arms. The bottom wiper linkage is from the wiper motor, the top (which is just out of sight, but you can see the linkage from it (going towards the left) is attached to the wiper linkage to the wiper pivots that are orientated in the original factory position. I did add an adjustable sleeve to dial in the wiper stroke on my linkage to the wiper post (the top linkage, it may also be a sources of some of my noisy wiper linkage). The wiper linkage in its original configuration, would have both been on the bottom of the idler. In this picture, the wipers are in the park position. With the linkage in this position, the wipers are at the other end of the wiper stroke. This truck is driven all year around. Those wipers have been functioning for 2 3/4 years and nearly 28,000 miles without failure. They have cleared the windshield of 3" of snow and rain hard enough you had to pull over to let it pass (the modern 3 speed wipers were not removing the rain fast enough to see clearly). May be another option rather then trying to reverse the wiper electronically.
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