A Wiper Motor 101

A white male in a green shirt sitting next to a tall rectangular robot made of green and black components with an aluminum frame. In front of him are a variety of components from several windshield wiper motor assemblies. Casings, gearboxes, and the like are strewn across the wooden table.

Need a powerful electric motor on the cheap? [Daniel Simu] and his friend [Werner] show us the ins and outs of using windshield wiper motors.

Through many examples and disassembled components, the duo walk us through some of the potential uses of wiper motors to power a project. Some of the nuggets we get are the linear relationship of torque to current (10-15A max) and speed to voltage (12-15V DC) on these units, and some of the ways the wiring in these motors is a little different than a simple two wire DC motor.

They also discuss some of their favorite ways to control the motors ranging from a light switch to an Arduino. They even mention how to turn one into a big servo thanks to a project on Hackaday.io and a few modifications of their own. [Simu] also discusses some of the drawbacks of wiper motors, the most evident being that these motors use nylon gears which are prone to stripping or failing in other ways when subjected to high torque conditions for too long.

If you recognize [Simu], it may be from his robotic acrobat built with wiper motors. Want to see some more wiper motor hacks? How about a 3D scanner or making sure your wipers always keep the beat?


22 thoughts on “A Wiper Motor 101

  1. Huh, looks like there’s a bit more to these than I thought. I’m still not clear after skimming the video what the actual possible inputs of these things are – it seemed like they had several pins which produced multiple speeds in one direction, but later they had two pins and the direction depended on polariyt? Maybe that’s only the rear motors.

    I would say though, if anyone sees this and thinks it’s a great motor for high power continuous operation, I would say that while I agree it should be able to run for the equivalent of a long rainy day, there is another option for low dollars-per-watt, even though it is going to overheat if you expect it to produce the same torque as these without the gearbox. See, while they’re normally used at thousands of rpm, the kind of brushed “AC” motor you find in things from angle grinders to traditional sewing machines are generally universal motors, which run as well or better on DC and also produce the most torque at 0rpm, just like the DC motors. One direction only, of course. Here’s an example of what you can do to drive them with DC, although actually a variac or even a beefy dimmer switch / triac is all you need for basic speed control. The variac runs down to a much lower speed before it stalls; you could easily have it slowly wave a flag or something. https://hackaday.com/2023/11/18/bigfoot-turns-classic-sewing-machine-into-a-leather-eating-monster/#comments

    Specifically for angle grinders, they’re begging to have a sprocket mounted instead of a disc and a mounting bracket screwed into the holes for the hand brace. Very plug and play.

    1. We use a lot of this kind of motors in my company. They come from Bosch, Valeo, Nidec… Those we use are 24V rated and come at different speed/torque ratings, from 45-60 RPM to 240-260 RPM.
      They are driven with a H-bridge (old designs with a L6203, now with SMD Mosfets and gate drivers), with or without PWM. The additional pins are for optional AB encoder or tacho signal. We also have some applications with a torque limiter (current limit…).

      A small note to those who would start using these: don’t forget you can brake motor with the correct H-bridge combination, and also if you choose to use PWM, choose where to connect your PWM line on your driver: slow decay and fast decay, depending on PWM to Enable pins or In1/In2.

  2. I’m going to imagine they originally had brass gears. But we are probably talking 1950s through 1970s for that kind of build quality. Unless there is a source for replacement brass gears we could put in the new gearbox’

    1. Brass gears, huh! Maybe for looks. But for the force that’s applied to gears & the torque with friction, brass would not do well for gear usage. Brass would crack & fail just like plastic & nylon. NYlon & plastic is built to fail whenever it meets metal in application. The industry made it this way so you have to buy new. Anything made with plastic should automatically be a manufacturer’s defect & us consumers should turn over the tool or parts & demand metal only when we purchase tools. No talk, just make them conform or refund with their junk back.

  3. That wiper motor he shows looks like one for a Volkswagen Audi Group (VAG) vehicle. Those wiper motors are usually made in Germany by Ferdinand Bilstein GmbH (Febi) and are pretty good quality yet affordable. Yeah, the nylon or delrin gears are a weak point, but if you ask around you can find glass-reinforced resin or epoxy replacement gears. A brief web search immediately produced this:

    VW Windshield Wiper Motor – Febi Bilstein 251955119 Fox, Golf, Jetta, Quantum, Scirocco, Vanagon – Qty-1 Price Each: $23.58 USD (New)


    GM/ACDelco makes some heavy duty wiper motors with all metal gears used on trucks, but they cost more. Don’t harvest used wiper motors unless you are sure they have metal gears. The latest high quality wiper motors use Brush-Less DC (BLDC) motors which are much more complex to drive, but more reliable. If you look at vintage vehicles you may be able to harvest wiper motors that run on pressurized air (manifold vacuum). Air driven wiper motors will probably need to be rebuilt, but rebuild kits with new rubber parts like gaskets et-cetera are available.

    1. “wiper motors that run on pressurized air (manifold vacuum).”

      My brother and I had a 1954 Chevrolet two ton truck with those things. Sometimes when shifting gear under load you’d get a sort of half-assed backfire and the wipers would make one really fast “swipe” of the windshield.

    2. If they’re made for vacuum, you need something like a brake booster pump; there’s cheap diaphragm pumps and things but it’s not quite as convenient as compressed air.

  4. Note, expect to need a power supply that can handle delivering a relatively large amount of current. Other good sources of electric motors from cars include window winders and electric aerial motors. But there are also the actuators for central locking mechanisms and even the motors for the fan hesters and engine cooling. Although starter motors can have their uses, note that they don’t usually like running for extend periods and can require modification due to the incorporated contactor.

  5. Nice! I love using automotive sourced motors.
    For greater torque, electric power assisted steering columns are pretty good and usually come with torque sensor and an angular position sensor, precise to a fraction of a degree. Older Toyota and GM columns have DC motors and some mid-size Renault/Nissans feature a three phase motor and easily hackable integrated control unit.
    For linear actuators, BMW memory seat adjust motors have a few cm of travel and have a displacement sensor for feedback. You get three per seat. The EPS steering rack in GM Epsilon platform cars (Opel Insignia, Astra, etc.) has 100mm of travel and 12kN of force with integrated CAN bus controller. These are all mass produced in their millions and available as scrap for peanuts.

      1. Just be aware the wormgear will also have the force applied in the other direction.
        Although the motor can run backwards, often the wormgear design is not suitable to have high loads on it in the reverse direction.

  6. Just to add – Tim Hunkin uses a lot of wiper motors in his designs for similar reasons (cheap, powerful, reliable, quiet), and I remember him saying that the late great Rex Garrod used them in a design (IIRC it was a fake shark) that ran underwater, discovering that you could happily run 12v motors at 24v if they were submerged in water to keep them cool.

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