12V wiper conversion - 1954 Pontiac
The original 1954 Pontiac had a vacuum powered windshield wiper motor. They work quite well except whenever you accelerate. For example if you stop at a traffic light and its raining. Once the light turns green and you press on the gas, you lose your vacuum and the wipers slow down to a crawl. It's very annoying. One solution is to add a vacuum cannister to hold vacuum for a little while or replace with an electric wiper. I chose to replace with an electric wiper from a 1976 Camaro.
76 Camaro wiper motor cleaned, painted and mounted on firewall
You can find these wiper motors in pretty much every 60s GM product.
There are two types of wipers: ones that sweep in the same direction and ones that sweep in the opposite directions:
The Pontiac uses the wipers that sweep in opposite direction which is the more difficult of the two to incorporate mechanically. I found a 62 International pickup's wiper mechanics that would work. I expected that the passenger and driver wiper arms would be 180 degrees opposite to each other and was puzzled as to why they weren't. The 180 deg separation is required in order to get the wipers moving in opposite directions.
Interior view of wiper motor
62 International pickup's wiper arm pivot - motor side view
Cleaned up and painted and in rest position - under dash view
The reason for the wiper arms not to be 180 degrees apart is so that if you can have long wipers that overlap in the center of the windshield. The wipers "take turns" leaving the center of the windshield.
The Camaro's wiper motor required a slotted screw hole so out came the hand file and voila a slot was made. IMPORTANT: make sure that the wiper motor is in the rest position before determining the angle of the slot. I ran the motor and shut it off in the rest position. The above picture shows the rest position. Note the nifty little access door for the center wiper bolt.
Interior view of modified wiper arm
The original wipers were cable driven and the vacuum motor did not turn 360 deg. The mechanism pivoted back and forth. I disassembled the wiper mechanism that goes through the dash and added a pivot arm. It's connected to the motor pivot arm with a small rod end. You need to use a rod end to allow some 3D movement as the wiper pivot arm and the motor center mechanism are not on the same plane.
This is a male rod-end, I used the female versions
Determing the length of the pivot arm was difficult. Originally, I thought that if the motor rotated through 360 deg, then the effective rotation would be 180 deg. The ratio of the radius from the center of the motor to the motor arm versus the length of the pivot arm would determine the desired wiper movement of 135 deg. Unfortunately, it didn't work and my pivot arm was too long. The result was that I ended up cutting the motor arm too short and had to weld on a longer bolt to compensate.
After figuring out that the mathematics didn't work, I drilled a series of holes 1/4" apart until one set worked. It was substantially shorter than I expected. Here's the results:
Here's the wiper at rest with no windshield in place
Here's the wiper at the other end of travel
Without a windshield the wiper leaned into the open space and fives the impression of a different angle than the pictures show. I ended up with 135 deg of travel with the wipers stopping at the rest position. In the up position the angle is closer to the door pillar than shown.
Tool used to remove and tighten wiper shaft retainer
To remove the wiper shaft retainer from the body, I ground down a piece of pipe that I had laying around with two knotches to match the slots in the retainer. It is well worth making this tool as it doesn't scratch or damage the retainer as using a screwdriver would. To remove the wiper shaft, you must unscrew the slotted head screw on top of the knurled knob. The end of the screw has been punched so that it wouldn't accidently unscrew. This means that it can be difficult to remove. The knurled knob is pressed on and can be difficult to remove. Gently pry with a screwdriver all around, use WD40 to help and even some heat if it is stuck.
I removed the spring inside the two piece bottom and JB welded the pieces together. I had to use a few washers to reduce the play. Strangely, there was quite a difference in play from passenger side to driver's side.
Shortening the Wiper Arms
Now that the roof is chopped 3 inches, the wiper arms have to be chopped shorter too! Here's some info on the wiper arms.
Here's a picture showing all the pieces of a wiper arm.
Shorten wiper arm top side - notice the internal hex cap screws instead of rivets
Shorten wiper arm bottom side - note the removed piece in the upper left corner