Any way to adjust the "Park" setting (Wiper)?

[soule64]

For three days the wiper motor has been kicking my butt. I have searched online and checked service manuals, but no luck. I am using a '78 NOS switch with a rebuilt '78 wiper motor in a '76 SWB with a new Painless chasis harness. Everything works great except for the park function - the motor WILL park itself, but it stops 90 degrees short of where it should be, putting the wipers in the middle of the windshield. Since it still wants to travel down when re-applying power to the motor, changing the postion of the wiper arms on the output fittings won't help. I can't change the position of the cam(?) on the motor shaft without drilling the shaft hole (on the cam), but doing that would eliminate the beveled area which keeps the arm from slipping around the motor shaft. So, back to my question - is there any way to adjust the wiper motor "park" timing?
Also, can anyone tell me was the bolt in the picture is used for? I thought it might have something to do with parking the wipers, but turning it in either direction has no effect. It does change the RPMs of the motor slightly, so perhaps it is used to set the speed of the wipers?
I sure would appreciate any help if anyone has ever run into this before. Thanks.

[Slick17]

Man you got me on there. I would have to go out and look at mine. You should be able to adjust it somehow.

[STOCKISH]

The park setting on the newer stuff is part of the relay. Do our trucks have a seperate wiper relay? Wow, I cant beleive I dont know this????

[soule64]

I came up with a possible solution last night - I am thinking that if I drill the cam hole to accept the motor shaft, position the wipers to where I want them to be parked when the motor parks itself, tighten-up everything and then weld the nut that holds the cam to the motor output shaft to the cam itself. since the motor turns clockwise (when looking from the front to the rear), the drag of the wipers would cause the nut and cam to always tighten itself on the shaft, while still maintaining the ability to remove it if the motor ever fails. I don't like the idea of hacking and welding, so if anyone has any other insight or ideas, I sure would like to hear them,
Still trying to solve the mystery of the random bolt, too. Any ideas?

[87Bob]

According to the service manual. There is a procedure to check out the problem you are describing. It says the following:

Ignition switch "ON" Dash switch in "OFF" Leave wiring connected to wiper and connect a jumper wire across terminals 4 and 5.

If the wiper runs replace the wiper park switch assy.

If wiper Inop. wire from wiper terminal no. 5 to dash switch open or dash switch is problem.

That information comes from a 1982 Shop Service manual. I realize that your working on an earlier model but I would at least try that jumper across the terminal of 4 & 5 before I started tearing a motor apart. I find that many times rebuilds are not done the best if they are done by a mass market re builder.

If that doesn't fix it before I tore into that rebuilt I get one from a pick a part and try it it might save you a lot of grief.

[soule64]

Bob - I appreciate you looking that up for me - I have the 1973 service manual with the 1976 suppliment, but it really isn't much help for this problem. I found the same proceedure you mentioned online and it parks in the same spot every time. Like I said earlier, the motor will park itself, but it needs to rotate another 90 degrees to be in the full down position. If I attach the wipers as-is against the bottom of the windshield, they will rotate down another 3 or 4 inches (into the cowl) when I turn the wiper switch on. Did the newer manual say what the bolt (circled in the picture) is for? Thanks for your help. You are right - tearing up a new motor will be my last resort

[78 Chevyrado]

sounds like you hooked the linkage up 180* out. I did that when I put my motor on, and it would park almost all the way at the top of travel. If this is the problem, unhook the wiper linkage from the motor and turn the motor 180 and rehook up the linkage.