The information in this 1947-48 Truck Cab booklet in the last section on windshield wiper checks and adjustments should be helpful in figuring out your situation.
From what you described, sounds like you will need to reposition your wiper arms to get everything back in line. Section 1 in the 1948-51 Shop Manual describes the how to part of wiper arm removal and installation.
Let us know if this is helpful please.
Dan
Last edited by Gdads51; 05/06/20231:02 PM.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
The vacuum motor mounts screws can be loosened to allow the motor to twist slightly to align the wipers if moving them on the splines (where the wiper arms mount to) doesn’t help. This would move one arm up and the other down.
Last edited by Phak1; 05/09/202311:31 AM.
Phil Moderator, The Engine Shop, Interiors and Project Journals
1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc Brakes Project Journals Stovebolt Gallery Forum
Would suggest you start by removing the wiper arms from the splines on the outside of the cab. (See the 2 screenshot pictures attached below for reference in the next steps.)
With that done, manually move the wiper motor arm to the 12 - 6 O'clock alignment position (arms disconnected from motor).
Next, position the L and R wiper arms so the short arm on each splined drive shaft on both sides is positioned at 6 O'clock (actuating arms still disconnected).
Once these 2 steps are done, your "short" actuating arm for drivers side should reach the lower pivot point on the motor arm and the "long" actuating arm for the passenger side should reach the upper pivot point on the motor arm.
If they do, attach the two activating arms and reinstall your wipers to the splined shafts in the 12 O'clock position and things should all connect and your alignment process should be successful.
If the activating arms don't reach from the motor pivots to the splined drive tabs, there is either damage to one or more of them or you possible have some incorrect parts involved.
Check back and let us know if this is helpful and you figured it out (or not) please.
Dan
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
When I went to an electric motor, the arms and blades flopped around. I studied the situation under the dash and after a while, concluded the one arm was too short. I got brave (or was it stupidity) and cut the arm and put in an adjustable piece with slotted holes.
It worked but I still wouldn't advise anyone to do this. Note I could still adjust the arm to the previous total length.
34 Years. Now with a '61 261, 848 head, Rochester Monojet carb, SM420 4-speed, 4.10 rear, dual reservoir MC, Bendix up front, 235/85R16 tires, 12-volt w/alternator, electric wipers and a modern radio in the glove box.