# Coupling a 12v motor to stock power steering pump



## Yukon_Shane (Jul 15, 2010)

A bit of a strange question but has anyone ever tried to couple a 12v motor to their stock power steering pump? 

My VW has a pretty nice little power steering pump on it and I'm just wondering if it might be easier to try and couple a 12v motor rather then using a whole new motor/pump assembly. Alternatively I could run a pulley off the motor of course but then the motor has to be moving before power assist works which seems like a pain.


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## Woodsmith (Jun 5, 2008)

You could do it with a PM motor, or just use a steering motor and pump complete from a forklift truck that might even suit your pack voltage. That could be quite a big motor and pump though, enough to run a hydraulic winch and back hoe! 

The only issue is how much energy it will be using when you don't need the assistance as it would be running all the time.

Easiest is going to be the whole electric power steering system from another vehicle, either electric hydraulic or all electric, as it will have a better control system.


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## Caps18 (Jun 8, 2008)

I decided against this for a few reasons. But, I can't comment on if that was the correct decision yet because I haven't driven the manual steering setup yet.

In the garage, I don't see any problems with the manual steering being able to move the tires when parked at least. And I'm glad that it is done and won't use up any battery power.

If I were designing a car from scratch for production, it would probably have a drive by wire system with an electric motor that would only operate and use power when turning.


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## Yukon_Shane (Jul 15, 2010)

Caps18 said:


> I decided against this for a few reasons. But, I can't comment on if that was the correct decision yet because I haven't driven the manual steering setup yet.
> 
> In the garage, I don't see any problems with the manual steering being able to move the tires when parked at least. And I'm glad that it is done and won't use up any battery power.
> 
> If I were designing a car from scratch for production, it would probably have a drive by wire system with an electric motor that would only operate and use power when turning.


My first conversion was a geo tracker that came stock with manual steering. It was no problem at all once the car was moving but I found parking in certain situations a real pain. My vw golf was engineered to include power assist so I can only assume it would be even worst then the tracker but it might be worth trying it out without the pump to see what it's like.


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## dcb (Dec 5, 2009)

could be brave and just replace the wheels and pedals with a joystick, and hope it never comes into question... (or leave 'em hooked up)

Modern cars use a torque sensor on the steering shaft IIRC.


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## EV-propulsion.com (Jun 1, 2009)

We have hooked up many oem power steering pumps to the front shaft of the motor. Generally we found that as soon as we powered the motor up to move the car, we had power assist - you would be surprised how little rpm is needed to get assist. 
I recommend trying it since you don't need to purchase much to get it working, just some fabrication materials.
I find that most electric power steering pumps use over 40 amps when not even steering - so having this run all the time is quite a drain. Some people try to turn it off at speed then, but that can be a safety issue and definitely adds unnecessary complication.
Mike
EV-propulsion llc


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## Yukon_Shane (Jul 15, 2010)

EV-propulsion.com said:


> We have hooked up many oem power steering pumps to the front shaft of the motor. Generally we found that as soon as we powered the motor up to move the car, we had power assist - you would be surprised how little rpm is needed to get assist.
> I recommend trying it since you don't need to purchase much to get it working, just some fabrication materials.
> I find that most electric power steering pumps use over 40 amps when not even steering - so having this run all the time is quite a drain. Some people try to turn it off at speed then, but that can be a safety issue and definitely adds unnecessary complication.
> Mike
> EV-propulsion llc


If that's the case I'll definately give this a try. Fabricating a bracket to hold the stock pump is easy enough but maintaining tension on the belt will take some thought. Maybe I can incorporate the stock belt tensioner somehow.

Thanks Mike


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## piotrsko (Dec 9, 2007)

If you run the belt around 5/8 to 3/4 of the diameter on the pump pulley it takes way less tension


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