American Bosch wiper motor repairs

I have 4 motors. I decided to convert these to self parking.
Reason is I was interested in adding a intermittent circuit and they all work only on self parking wiper motors.
These are single speed. Dual speed adds another electrical commutator brush.
Describes how wiper motors work.
http://triumph.daveola.com/NOTES/Windshield Wiper Motors.pdf
The shafts were tight due to rust internally built up. Tight enough some I could not turn by hand.
I tried soaking in oil but was so slow, so turned up the heat and very quickly the rust came off and they spin freely now. Probably oil got to 300 to 400 degrees. I used a 0-20w full synth oil.
Took about 30 minutes to clean out the internal rust.

When these went into hot oil, air bubbled out the end of the shafts. Then picking up with pliers and spinning the shafts, lots of rusty froth came out the ends. kept soaking and spinning the shafts till I saw no more rusty froth, then let them soak. I cooled down and reheated twice. Now when cool they spin smoothly and easily.
Those have a steel shaft and a brass housing, supposedly a rubber ring at the top keeps out water.

Second picture shows the parking feature I am adding. I will put a cam on the nylon gear to push open the relay contacts.
The cam idea I have is tap a #4-40 hole into the plastic gear. then put a 4-40 machine screw with a thin plastic bushing cut from a plastic tube. So when the gear comes around it will push open the contacts shutting off the motor ( creates the self parking). To align when it shuts off, you have to position the gear to where it moves the crank to the furthest it can go, and that is where the cam needs to be

The contact arms I obtained from an old manual dishwasher Frigidaire timer.

I am sure few people would do this. But if you have tight shafts in your wiper motors, you can dissolve out the rust with hot synthetic oil.

The picture of the wiper motor housing shows one with contact points added and one as was OEM.

So these shafts are now sitting in clean 0w-20 oil. I think this particular hot engine oil must be reacting chemically with rust dissolving it away. I am surprised how well this worked out.

Came up with a working cam design.
A single insulated screw, motor momentum moves gear past the points open and the points close and it keeps running.

For the cam simply,

Cut off the heads from two #4-40 1/2 length machine screws.
Cut a slot in the screw end
Drill and tap two #4-40 holes in the plastic gear, aligned so points open when arm has moved all the way over.

Screw them into plastic gear
Stretch a piece of tube vinyl around both machine screws. That came from repair rack tips I had used on the dishwasher rack. Another thing to use would be a couple layers of heat shrink tubing.

Works well. One change, I think I should reverse the motor spin direction. The plastic gear turns clockwise, which if one of my point arms came loose, it would be jam and be ruined.
Turn the gear counterclockwise, then the point arms can not jam.

I think to do this, all I need is to reverse the brush polarity.

I have 2 motors done now, and they self park. I had to lengthen the cam to 0.58 inches or inertia would bump it past the park - off position. I set this up for 120* sweeps since they were set that way already on my boat.

And I reversed the motor rotation to work with my point arms.
Simply ground off existing rivets, reversed brushes plate 180*
drilled and tapped where rivets were and run in a 4-40 bolt to which I cut off the head and secure brush plate with nuts and washers.

Anco sells new heads for shafts, so conceivably you could remove a worn head and fit a #4207 or #4209 onto your old shaft.

Finished third motor, one left to do.

Here I demonstrate how it auto parks.

Nice to see that some people can still fix things instead of replacing them. Good job.

Greetings,
Mr. 717. Yup. What Mr. b said above. Well done. I hope you put a dab of thread locker on those securing nuts.

Clever!

RT Firefly said:

Greetings,
Mr. 717. Yup. What Mr. b said above. Well done. I hope you put a dab of thread locker on those securing nuts.

Click to expand...

I cranked on the nuts holding the points sufficient to hold them. It is really very tight. One worry I had is don't tighten the wire on too tight or the point arm would twist and no longer park the motor.

The longer arm on the right is secured in place by a square head bolt and square nylon insulating bushing fit into the square hole of the gear housing. I looked but could not find such a nice locking type nylon bushing or square head machine screw for the other point.

And I needed to be able to twist it anyway to set the point gap, so it turned out to be best solution anyway.

Great job. You may have a marine wiper motor repair business starting up.

Nice engineering job. Couple questions/thoughts. Where did the rust come from initially? And how can it be stopped from 're rusting'? Were the shafts Chromed? Trying to recall if mine were. It's been years since I had to get into mine. Bronze bushings sometime gall up and get sticky. Wonder if a better bearing would prolong the life? Or was this caused by Oring failure? Is the Oring easily replaceable?

cappy208 said:

Nice engineering job. Couple questions/thoughts. Where did the rust come from initially? And how can it be stopped from 're rusting'? Were the shafts Chromed? Trying to recall if mine were. It's been years since I had to get into mine. Bronze bushings sometime gall up and get sticky. Wonder if a better bearing would prolong the life? Or was this caused by Oring failure? Is the Oring easily replaceable?

Click to expand...

The rust must come about due to the oring wearing or age shrinking-hardening and the rain slowly working it's way into the space between shaft and brass sleeve. A brass sleeve bearing is a very good bearing as long as grease or oil remains to lube the sleeve and shaft.

My shafts are a type of hardened steel, not chromed. They fit into a brass sleeve (has the mounting nut) and an o-ring at the top of the shaft keeps out the water. A separate brass sleeve is pressed onto the shaft at the top which makes a tight fit to the top of the bronze sleeve (one that has the mounting nut), which aids to keep out the water. On top of this is the drum, which holds the wiper arm. The shaft is riveted onto the drum. You could grind off the top shaft rivet and remove the old drum and replace with a new drum and of course renew the oring and cleanup re-grease the shaft and it would be like new. There is plenty of length if the old drum is removed to accommodate one of those ANCO drums that use set screws. Probably also worth drilling a hole or grinding a flat so the new drum is more secure to the old shaft.

When I regreased the gear case and motor bearings, I used a water resistant marine grease. If you use a standard grease, water will actually mix with the new grease.