# Power steering motor



## gary k (Aug 19, 2008)

It is more common to either drive the pump from the tailshaft of the drive motor, or replace the pump with an electric power steering pump from an EV parts supplier (or find a Toyota MR2 electric power steering pump). The EV parts pumps are about $700 so not cheap but a clean solution.

Sorry - no recommendations on what motor to use for driving the stock pump.


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## PatricioIN (Jun 13, 2008)

I have heard of people using a small motor from a treadmill, but not seen one implemented. I found an electric ps pump from an MR2 at a local import parts yard for about $100 as I recall. Works great as that is exactly what it was designed for.


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## TX_Dj (Jul 25, 2008)

+1 on the MR2 pump.

I've seen one in action, and it works great. There are two types, so be mindful. The older type (if memory serves) is harder to adapt, but the newer (again, darn memory) is easier.

If you do go the route of a secondary motor, I would suggest coming up with a way to run the pump only when you need it (to save power).

May be possible to rig a tensioner system on a tailshaft driven system to only spin the pump when a cable is pulled or something too.

On your saturn, it would probably be tough to switch to a proper manual steering setup, but it will make all the difference in the world.

On my S-10, before even stripping anything out of it, I did the old "double-back" of the PS hydraulic lines to the steering box, and it still took both hands and a lot of force to turn the tires. After stripping it all down to a bare front clip (only the frame weight on the front end) it still took considerable force with one hand to turn the tires. Swapped in a manual box and low-friction ball joints as part of my conversion process, and now with the same lack of weight on the front end, the wheels can easily be turned with one finger.


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## Woodsmith (Jun 5, 2008)

There are also electric power steering columns that don't have any hydraulics. Some of the European small hatchback cars have them.
Maybe you could modify one to fit your needs.


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## kimpaw (Feb 8, 2009)

I just started researching putting an electric PS motor in a 99 saturn sl2 conversion that I bought. From what I see it looks like a toyota pump would be a good choice. In my mind I picture turning it on with a left foot s/w when the car is not moving. Question, What will the steering be like with the pump in line but turned off? Will the fluid be able to bypass the pump? Kimpaw


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## gary k (Aug 19, 2008)

yes, it will bypass fine. we did this with the last conversion and put a toggle switch on the dash. it can be switched on and off at anytime and works well both ways.


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## PatricioIN (Jun 13, 2008)

I had an on/off switch on my mr2 pump on the dash for whenever i wanted to turn it off.. mostly if sitting still for a long time while car was "on", etc.. or if I knew I needed EVERY LAST DROP OF ELECTRONS to get where I was going. But honestly, I left it on most of the time. The amount of amps the 12v pump pulls off your overall pack is minimal. When I did turn the pump off, it was a HUGE difference in the amount of effort it took to turn the wheel. That's why I just left it on 90% of the time. However, you can still turn the wheel... just be prepared it won't be as easy as normal (turns, etc... can make it dangerous if you're not used to it.)


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## Woodsmith (Jun 5, 2008)

I think with the MR2 pump there are two versions. The older one draws around 50A in use and around 30A at rest while the later one draws only about 35A in use 7A at rest. Not sure where the cut off date is so maybe worth checking out an MR2 forum.

I am pretty sure the one in my 1991 Rev1 is the power hungry former version whre as a spare Ihave in my workshop is an unknown quantity.


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## PatricioIN (Jun 13, 2008)

Woodsmith said:


> I think with the MR2 pump there are two versions. The older one draws around 50A in use and around 30A at rest while the later one draws only about 35A in use 7A at rest. Not sure where the cut off date is so maybe worth checking out an MR2 forum.
> 
> I am pretty sure the one in my 1991 Rev1 is the power hungry former version whre as a spare Ihave in my workshop is an unknown quantity.


Keep in mind that is at 12v.. Mine was from a 2000 MR2 and on my 120v pack, I noticed only a 1amp increase on my ammeter when running (idle) I don't recall what it was if you just turned the wheels at a stop... I've since sold that EV


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## DIYguy (Sep 18, 2008)

If you want to go with an MR2 pump, you want to buy one from a 2000 to 2005 MR2 Spyder. I have a part number somewhere if u need it.

Here is a link on how to wire it. http://www.diyelectriccar.com/forums/showthread.php?t=46812&highlight=*mr2+pump* IF you buy one, try to get them to cut the wires and not unplug it so u get the other half of the plug. (save u buying one...or soldering/clugey connections)

As for power, most find it doesn't drive enough to worry about when not parking. If you want, you can investigate the speed sensor input (in thread above) some vehicles may be able to take advantage of this.

As for other motors...as mentioned Treadmill motors is one choice. Some have discussed driving the motor with a PWM control. I recently saw that one of the many functions of the Evision guage has this. (plus a lot more... but it's expensive, unless u need most of the functions it offers.)


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## PatricioIN (Jun 13, 2008)

yeah, I tried using the VSS (speed sensor) on my zx2 to control the PS pump, but the signals apparently weren't compatible as it didn't have any effect on the pump.


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