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Default Power Steering Options

Power steering uses power, and in an EV power is a pretty valuable thing so there will be some deciding to be done over whether PS is worth the sacrifice in range. There are several options for what to do with power steering in an EV, it will depend on your preferences for PS and range. It should be noted however that in some countries it is illegal to swap the OEM power steering setup for non standard manual one if the vehicle did not have non power steering as an option when new or even disable it.

Here are some PS options:
  • Convert to a Manual Steering Rack: If your vehicle was also available with manual steering then it is possible to convert your PS to manual steering by swapping the racks. This is probably the best option for range focussed individuals.
  • Loop the hydraulic lines: Another option is to throw out 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) after filling the rack/gearbox with the proper fluid for your particular system. But due to the difference in ratios between the manual and power steering racks and the resistance of the hydraulic fluid this will require much more effort than a normal manual rack.
  • Use an accessory motor: It is possible to use a secondary electric motor to drive the stock power steering pump. This will give you standard power steering but the obvious problem with that is the additional draw on the batteries, and attendant decrease in range.
  • Electric power steering: Some cars have electric power steering pumps that can be harvested for use in EV's. However, these are high power devices (typically 12-60amp) and they will impact range. Some late model small European and Japanese cars use electric assisted power steering. These systems use an electric servo motor either in the rack or on the steering column somewhere meaning they are not hydraulic. This is much more efficient than the hydraulic system but obviously less than a completely manual rack.


Contributors: green caveman, mattW, DVR, dimitri
Created by mattW, 12-14-2007 at 11:13 PM
Last edited by green caveman, 10-09-2009 at 03:50 PM
5 Comments , 17385 Views
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  #2  
Old 06-25-2012, 05:54 AM
SHtruck SHtruck is offline
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Default Re: Power Steering Options

If there's hydroboost assisted brakes, one could use same pump for power steering, as they are on pick-ups. And about the pump, how about running like there's suggested on A/C options, using dual shaft motor? Some heavy trucks have a dual circuit power steering, there's a small hydraulic pump at the rear of the transmission, it's purpose is to ease steering if vehicle is towed and engine is not running. That pump is turned via propshaft.
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Old 07-10-2012, 04:39 PM
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McRat McRat is offline
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Default Re: Power Steering Options

From 2005+ all GM products that I know of that use the 4-cyl Ecotec engine are equipped with an advanced, progressive electric P/S system. Cobalts are probably the best source. I was given one for free. There are lots of junk Cobalts, or buy new at the dealer.
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Old 07-20-2012, 10:59 AM
Beemer Beemer is offline
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Default Re: Power Steering Options

If the car you want to convert has a diesel model then take a good look at the specs.
They have no vacuum from the engine so brakes and steering are already done. This ought to save a fair bit of effort and money.

Then there is the lower RPM and higher torque of electric motors. Once again, a diesel clutch and 'box makes for a better combo for electric.
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Old 07-25-2012, 11:23 PM
TomA TomA is offline
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Default Re: Power Steering Options

Quote:
Originally Posted by McRat View Post
From 2005+ all GM products that I know of that use the 4-cyl Ecotec engine are equipped with an advanced, progressive electric P/S system. Cobalts are probably the best source. I was given one for free. There are lots of junk Cobalts, or buy new at the dealer.
McRat, have you tried to use the one you have without the steering control module, or with the steering control module but without the Cobalt ECM and PCM? I've been following this system for a while, but have been afraid of it because I assumed it wouldn't work without its steering module, and that the steering module wouldn't work without info from the ECM about vehicle speed, and maybe more.

Does it work without the Cobalt harness and computers?
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Old 07-26-2012, 09:01 AM
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Default Re: Power Steering Options

To be honest, it's sitting on the shelf awaiting a project to use it on. It was free. IIRC, it has only a few connectors. I'll find out what signal they use.

It's basically just an electric actuator, you just have to know what kind of power and signal it's looking for (PWM? 0-5v with 12v supply? Other?)

The on-board computers exchange info via CAN, and one of the computers (BCM? Body Control Module?) would pump the signal to it.

I know I had the pinout for it, I'll post it in this thread ASAIFI (as soon as I find it). My garage is McGyverville, too much weird stuff. I'll try and post a pic today.
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