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Power Steering Conversion

30860 Views 23 Replies 16 Participants Last post by  martymcfly
I've got an '89 Ranger that's on it's last leg and I'm considering making the leap to EV...

I've seen lots of good info about motors, controllers, electric vacuum pumps, etc, but nothing on how to handle the power steering.

What are people doing for steering... changing the steering rack out to totally manual system (where do you find one for certain vehicles?), some type of electric pump?
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I too am wondering about this!
In fact, I have no idea how it is handled, whether or not it is part of the engine or some kind of an attachment that can be attached to the electric motor...
Mostly, I think it's necessary to get creative.

It would be possible to use a secondary electric motor to drive the stock power steering pump, but the obvious problem with that is the additional draw on the batteries, and attendant decrease in range.

Some have experimented with the electric power steering systems used in late model "hybrid" cars from automakers.

Switching to full manual steering would be my first choice, although some vehicles may never have been produced with manual steering, so finding a rack or steering gear box without the hydraulics could be difficult. Converting a PS vehicle to accept the manual steering gear from a different model/make is the most difficult (probably something I'd try :D )

Putting the PS pump on the tail shaft of a standard EV traction motor would leave you with no power assist when you need it most, times when the vehicle is standing still.

You could just build the EV without changing the steering at all, simply chuck as much of the PS equipment as possible, loop the input and output of the steering hydraulics together with a section of hose (do NOT cap those fittings off, you'll end up with locked steering, or the most difficult steering you could imagine) after filling the rack/gearbox with the proper fluid for your particular system. Of course, this assumes that you will be doing some body building to get your arms in shape for parallel parking!

Manual steering systems are usually of a lower ratio, meaning that less effort but more wheel twisting is necessary to turn the front wheels lock-to-lock. Power assisted steering gear is of a faster ratio, and will require more effort, although not as much as when the engine has died after you've removed all the extra bits.
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Ugh, I know what power steering with the pump removed feels like. I used to have a Lada 4x4 with oversized tyres. Just about broke my arms doing a 3 point turn. I actually strained my arm once driving that car! Hurt like hell!
I'd be very keen to know what other people have done to de-power their racks. I think just looping the pressure and return lines together would still result in considerable hydraulic resistance in the steering system. It would be like trying to turn a power steer car with the motor stalled. Real Armstrong steering. You would be forcing hydraulic fluid from one side of the assist cylinder up through the torque valving and back to the other side of the cylinder. I heard of one guy venting one of the cylinder lines up to a small reservoir and running the rack low on oil to reduce resistance. I've wondered about taking the seals out of the cylinder piston or some such thing to reduce the resistance or removing part of the valving to noble it so oil would still circulate to lubricate things.
Looping the lines together works fine, but as was previously mentioned, it is the different ratio that makes it extra hard to steer. You still want fluid in the steering box, and not air.

I changed my rack to a manual one, but if I was to use power steering, I would use mount a separate electric motor to power the stock pump. You could have it shut off above 40mph, or run it at variable speeds with a VFD, depending on drive speed. There would be many options to try to economize power.
Pehaps some sort of torque rod / switch arrangement on the steering column linkage that would control a (variable-speed?) small motor-driven hydraulic pump to supply the pressure for the power steering assist, but only when needed ? - no sense continously motoring a hydraulic pump when it is not actually needed to supply pressure to the steering rack cyinder(s).

I just don't think you can attribute all of the extra resistance in a depowered power steering system to the gearing. Surly some of it comes by forcing fluid around a now redundant hydraulic circuit that simply doesn't exist on a manual rack. It would be nice to get rid of that unwanted resistance.
What would happen if the steering was repowered with air? Use a 12v air compressor and tank to supply the air and let some of the PS fluid travel through the system to keep the PS unit lubricated. Also a pressure switch to cycle the compressor.

The air could not supply all the pressure needed to have a high end PS but it may give enough to make it easier to turn the wheel. Plus the air is compressable whereas the oil is not and the air at 75-100psi is not going to do the work of oil at 1500psi.

Just thinking out loud

I can't see how that would work. You don't want air in the steering box.
As far as I understand power steering is just like a normal steering system but it has a slightly different ratio and hydraulic sections that when pressure is applied, helps to push the wheels in either direction.
So isn't most of the backforce on a de-pressurised power steering system simply the fluid being forced through chambers by the driver? If so, why not just completely remove the fluid and vent the hydraulic chambers? Wouldn't that allow the steering system to move more freely?

I ask this because one day I'm sure I'll have another conversion project and chances are it will be a more modern car with power steering.
No, you really do just want to loop the lines together and keep it relatively full. This is not a new idea; people have been doing this for over 30 years for conversions on the cheap, or to save horsepower in racing applications. It won't be as easy to steer, but you already knew that. It is not the lubrication that makes it difficult, but the gearing.
My Hyundai Accent power rack is about 3 turns lock to lock. The manual Excell rack I have is about 3.75 turns lock to lock. So the de-powered power rack would require about 25% more effort than the manual rack due to the gearing alone. The rest of the resistance must come from the hydraulics. Surely the torque valve would be quite restrictive until some torque was applied to the steering input shaft then its restrictiveness would reduce as the input torque increased. On the Accent's power rack it looks like the bit containing the torque valving unbolts so I will be pulling that apart on my spare rack. It was real easy to turn the input shaft with all the hydraulics and everything else disconnected. I could make up a loop pipe and fill it up with power steering fluid and see what comparative resistance it has.
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Here is a link that goes over both ways with a steering rack. All of my experiences are with recirculating ball steering boxes.
You can try to use aftermarket unit , i my case i used flaming river unit with some minor modification and it is quite Arm frendly:D.Even my wife was able to steer the car in the garage.


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A lot of people use the electric power steering pump from a Toyota MR2.
That is what I am doing. I don't have it installed yet as I ran into some complications with connection the high pressure line to my steering rack, but once I do have it in I am going to put up a page on what I did and how it works... for starters it will run continuously but at some point I want to make it variable speed based on the speed of the vehicle (less steering torque is needed at high speed) and maybe even only turn on when the wheel is turned.
OK 1st Question ... I am looking at using 4 in hub motors ... and would like Power steering ... I am just lookin up about Electric Power Steering System at this site at the moment

This is looking like a good bet ...but HOW do you connect up the Steering to Hub Motors.

BTW : I am building a Kit Car in the next 12 to 24 months but I am going full EV .. I have build a Westfield and AC Cobra in the Past .. but now gone 100% Eco ... so the next kit will be 100%, so at the moment getting as much information as I can!
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Direct electric assist looks like the way of the future in power steering. It's not parasitic like a hydraulic system. The little OEM label is a worry though (as is the notion of adapting it to an existing steering system). I guess you could find out what cars they are fitted to and find a wrecked one. They are libel to be fitted to very late model and high end cars at this point in time. I think Honda NSX and Toyota Prius are two cars with electric assist (not Denso though).
the 89 ranger was available with manual steering recirculating ball and was almost 4 turns lock to lock, very easy with the 4cyl but a little harder when you drop in a 302. depending on the front axle weight it may be something to look into. try to get front and rear and overall weights before you pull the engine. then you will know how much you can add back up front and keep the same feel. if you motor will be bolted to the trans instead of direct drive, you should have enough setback to put more weight near the center of the truck. hope that helps. btw, you should be able to find a gear box pretty cheap
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