# Drive windshield wipers with stepping motor

#### Model-a

Joined Jun 16, 2009
18
My 57 Ford car has a vacuum wiper motor and very complicated cables to actuate the wiper blades. I would like to replace the cables and put a motor on each arm and have them run in sync. Also able to change speed and have an interval feature. I haven't measured what torque I would need yet, just asking if this is a reasonable approach.

#### crutschow

Joined Mar 14, 2008
31,501
It could work but it would need a fairly powerful motor if you are going to direct drive the wipers.
Also how will you sync the position of the two?
Perhaps a limit-switch at the rest positive as the starting point?

Edit: I saw one wiper motor measurement of 13 to 17 lb-ft of torque but that, of course, is to drive two wipers.

Last edited:

Joined Jul 18, 2013
26,644
Is there no way you can pick up a motorized one from a wrecker and modify the whole lot?

I had an old Ford back in the UK that had vacuum wipers, lots of fun, especially going up and down hill!!
Max.

#### shortbus

Joined Sep 30, 2009
9,804
Don't think it's a good idea myself. I have over the years built electric motor replacements for old cars. The last being for a '57 Buick century. If you take the original vacuum unit out and see how it works(linkage wise) It's pretty easy to come up with a way to mount a universal wiper motor.

One like this for a lever and arm type - http://www.carparts.com/details/A1_...gclid=CJLqzIWonNECFU42gQodmzgDgQ&gclsrc=aw.ds

Or one like this for a cable type - https://www.surpluscenter.com/Elect...DC-Wiper-Motors/12-VDC-WIPER-MOTOR-5-1767.axd

Back in the day, VW bug wiper motors are what I used, but they aren't available in junk yards any more.

#### crutschow

Joined Mar 14, 2008
31,501
I had an old Ford back in the UK that had vacuum wipers, lots of fun, especially going up and down hill!!
Also when you pulled out to pass and the wipers stopped when you stomped the accelerator.
Some cars actually had a vacuum boost using an added diaphragm in the fuel pump to at least keep the wipers moving, even if they slowed down upon acceleration.

#### Model-a

Joined Jun 16, 2009
18
All the wiper motors in the junkyard are just rotary with a bellcrank after the motor, so my dilemma is producing a back and forth motion 130 degrees sweep. The link shortbus sent has 165 degrees of motion, but maybe some other rear window wiper motor will have what I need.
My other reason for moving the wiper motor is I'm trying to make a clean firewall and this sticks out like a sore thumb.
I see other problems with the stepper motor
1. how to get them to park if I turn the key off while the wipers are on.
2. If the motor slips a phase due the increased load then they will be out of sync.
3. these blades meet in the middle so the motors need to turn in opposite directions, thus 2 controllers.
There is a vendor that sells a bolt on motor for ~$300 so I might have to bite the bullet and buy his. Thanks guys #### crutschow Joined Mar 14, 2008 31,501 how to get them to park if I turn the key off while the wipers are on. You add a limit switch connected +12V that closes when the wiper is off park and applies power to the motor (in parallel with the on/off switch). Thus when you turn off the power, the wiper keeps moving until it opens the limit switch (that's how regular wipers work). If the motor slips a phase due the increased load then they will be out of sync. True. Thus you need a motor powerful enough so that's unlikely to happen. Alternately you might be able to use a limit switch to reset the pulse count at the end of each sweep. Thus it would be out of sync for only one sweep. these blades meet in the middle so the motors need to turn in opposite directions, thus 2 controllers. I think you just need to reverse the phase connections on one of the motors. #### shortbus Joined Sep 30, 2009 9,804 There is a vendor that sells a bolt on motor for ~$300 so I might have to bite the bullet and buy his
Do you mean New Port Engineering? That's kind of how I have done mine. The mid fifties Ford cable wipers are a pain. If your going to hide the new ones under the dash, you might as well change to the gm and mopar arm and link type, much easier. I'm in the building stage of a 37 Ford truck rat rod my self. The wipers for it are from a Jeep CJ7 don't remember the year. But if you need to reuse the wiper transmissions(the part the arms go on) you'll need to take the cable drums off and make arms to fit. The transmissions, of the VW bug, were really nice for this. They were long and threaded full length. You just needed take the old ones out of the cowl and put them through the chrome trim and adjust the top and bottom nuts to fit. And shorten or lengthen the links to fit.

The link shortbus sent has 165 degrees of motion, but maybe some other rear window wiper motor will have what I need.
I haven't used them, but if you look at the one for the rear wiper, it looks like it has an internal arm and link system. To change the sweep you would just need to change the pivot positions on the arms. I'm not aware of any electric wipers that actually reverse the motors rotation to make the sweep. They all use a rotating arm and link, but the rear wipers it is internal. Unlike the old vacuum motors.

#### KeepItSimpleStupid

Joined Mar 4, 2014
5,088

#### Model-a

Joined Jun 16, 2009
18
Do you mean New Port Engineering?
Yes, I'll take a look at the junk yard next time I go there for the Jeep and VW stuff

#### shortbus

Joined Sep 30, 2009
9,804
Yes, I'll take a look at the junk yard next time I go there for the Jeep and VW stuff
If you keep the existing cable system, the 165 degree sweep can be changed by using a different size cable drum on the drive motor.

#### MrSoftware

Joined Oct 29, 2013
2,069
I suspect that you'll need a reduction gear to use a stepper to drive the wipers... or a very very powerful stepper. Also if any steps are missed then they will be out of sync. You could potentially solve that by using a rotary encoder or limit switches to keep track of the wiper positions, but that starts to get complicated.

#### Dr.killjoy

Joined Apr 28, 2013
1,196
. I'm in the building stage of a 37 Ford truck rat rod my self.
Model's don't count lol

#### shortbus

Joined Sep 30, 2009
9,804
Model's don't count lol
This has been an ongoing project for over 30 years. When I had the money, didn't have the time. Now that I have the time, don't have the money.

#### BR-549

Joined Sep 22, 2013
4,928