Just got this 1968 and starting to go through the "to do" list. After finally releasing the frozen wiper door, I'm at a loss as to why the wipers won't park or at least go down manually. Wiper switch appears dead, wiper door non-functional. (Appears all new vacuum hoses all replaced). I might be crazy but I see only 1 over ride pull down under the dash. I push it up and it seems to float back down alittle. I am familiar with the 3 functions of the under steering wheel over rides on later years...
Why can't I get the wiper arms to go down by hand? I don't want to force them...

 

The wiper motor is a wormgear setup, you can't push it from the output, in fact if you push too hard it'll strip the larger plastic gear

Here you can see the "worm" that is on the motor shaft itself


it runs against the outside of the large gear and when the motor spins it pulls the gear around, almost like threaded a bolt into a nut pulls the nut down


so when you are trying to push the wipers down it's trying to turn that gear and get the worm to spin... like trying to push a nut onto a screw and getting the screw to spin...

anyway, if you just want the wipers out of the way for now, pull the arms off the splines on the transmissions (little clip underneath) or you'll need to pull the motor and disconnect the wiper arms (or remove the grill part and you can get at them there)


HIH
M

 

Thanks. (yes I have the grill off)

 

be aware that the over ride just disconnects a ground to the system stopping the wipers, but the motor will still have power until it parks and releases the relay, even with the switch off. So you would have to disconnect the wires at the motor. My 68 had the **** for the over rides between the 2 pulldowns, and it was just attached with a nut. so yours might be hardwired if therres no ****. You could also disconnect the wiper door interlock switch which should cause the motor to stop like the over ride, using that as a makeshift stop. then unpug the motor

 

Ive disconnected the power lines to the 68-72 Wiper Door Limit Switch and also the wiper motor itself. I still cannot move the wiper arms just little to park them. I wonder if theres something inside the motor jamming the rotation... The wiper motor hub barely moves but Im not trying to force it. (does it travel CW or CC if you're sitting in the drivers seat?)

 

You can't turn those motors from the output shaft. You need to disconnect the wiper arms to drop them below the door and fix the motor at some point
M

 

Have you tried applying Vacuum to your car's vacuum system? The 1968 C3 has a completely vacuum operated headlight and wiper blade cover as well. The windshield washer system on a 1968 is a more challenging systems to work on. I am grateful for having bought a copy of the complete Vacuum diagram in color for the 1968 Corvette (Thanks to "Dr.Rebuild" at Corvettes@Carlisle). At the time I replaced the original Vacuum Hose set on my 1968. There were a lot of parts and maybe I should go back and start getting the parts ready.

There is a 12 volt dc motor in the Windshield Wiper System and it provides the mechanical forces needed by the back and forth action of a windshield wiper system. To test this system get the parts engaged by activating the wiper switch usually gets the cover up automatically using only the vacuum in the system. On my old C3 I have two pull down valves and a **** that turned. The One **** made the wiper cover rise, The second one made the headlights come out the **** would disconnect the power going to the windshield wipers allowing a new owner to change the wiper blades.

Once my car calms down after running for a short bit it has good vacuum in the canister the headlights or the windshield washer cover used to "launch" up into place. Don't force the vacuum operated systems by hand, use a good source of vacuum. It was looking to be a challenge to get to the wipers again on my early 1968 Corvette. After some inspection I found loose Rubber vacuum lines and so I replaced the lines and the check valve assembly just to be safe. Once again the vacuum systems operate quickly and smoothly. Even with a "worked on" 427 Big block with high compression I get 16-18 inches of vacuum in my system.

For the first 10 years after the Complete Vacuum Hose set was installed professionally the headlights would pop right open and the vacuum was there for weeks. That was a while back and Corvettes@Carlisle is next weekend and 103 miles away. I have learned and saved so much from the Corvettes @ Carlisle experience. If you know what you want they will even bring it out for you. I need to visit Dr.Rebuild and Al Knock, I need a replacement Convertible top. It will be another winter project I hope. I have the abilities to sand blast and powder coat here in my garage. I have needed a good excuse to paint the hardtop for my 1968. The car is Daytona Yellow with a black convertible or a black painted hard top. I have thought of painting it all to match, it certainly needs it. But my flying instructor told me so wisely that (Paint Don't Fly) how it ran was all he wanted to know.

I hope that you get your vacuum system sorted out easily! I am hard of hearing (To say the least) so I can't hear the vacuum leaks that many of you can hear. It makes life a bit more challenging. Those of you who can hear properly, I envy you. It is one of the most important senses I miss.

Best regards,
Chris