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.
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:
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.
1 - 20 of 21 Posts
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.
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.
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.
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.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.
Does it work without the Cobalt harness and computers?
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.
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.
Listing the options is great - including conversion to manual steering - but given that some readers have very little automotive experience, perhaps it would be good to explain the consequences of losing the power assist.
Most people driving today have never driven a car with manual steering, and may not understand that without power assist the steering will be very difficult to turn, unless a much "slower" (more gear reduction) rack or box is used... and having to spin the wheel much further for the same radius of turn would be considered unacceptable by most people. Even the fact that a vehicle with more weight on the front axle takes more effort to steer may not be obvious to many; this is particularly unfortunate given the stacks of battery placed up front in some conversions.
The effort difference is indirectly mentioned in the hose-looping section, but it probably wouldn't be clear to an automotive novice.
Most people driving today have never driven a car with manual steering, and may not understand that without power assist the steering will be very difficult to turn, unless a much "slower" (more gear reduction) rack or box is used... and having to spin the wheel much further for the same radius of turn would be considered unacceptable by most people. Even the fact that a vehicle with more weight on the front axle takes more effort to steer may not be obvious to many; this is particularly unfortunate given the stacks of battery placed up front in some conversions.
The effort difference is indirectly mentioned in the hose-looping section, but it probably wouldn't be clear to an automotive novice.
Steering boost does not come from engine vacuum, whether gas or diesel. Diesel or not is irrelevant to power steering (although it's certainly relevant to brakes), so the diesel version of the car may have exactly the same power steering as the gas version.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 does bring up another possible improvement for this wiki entry: explain that traditional hydraulic power steering uses a pump driven by the engine, and expected to be turning at a reasonable speed all of the time... unlike the drive motor of an electric car.
Does this car use an electric steering rack or an electric assist in the steering column? There are a number of companies that make aftermarket electric assist systems that either are mounted on the column under the dash, or on the steering shaft between the end of the column and the steering rack. They are rather pricey, but another option to add to the list. Here is one example, but there are others.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?
I am using a manual rack in my conversion, but if I find that the steering is too difficult I plan to add one of these systems.
Can't the motor shaft from the electric motor power the power steering pump using a pulley?This does bring up another possible improvement for this wiki entry: explain that traditional hydraulic power steering uses a pump driven by the engine, and expected to be turning at a reasonable speed all of the time... unlike the drive motor of an electric car.
Yes, but the motor only turns when the car moves, and the speed of the motor is proportional to the speed that the car is moving, so the steering pump wouldn't turn fast enough to be useful at low speed, and wouldn't do anything at all when stopped.Can't the motor shaft from the electric motor power the power steering pump using a pulley?
What if you kept your foot gently on the accelerator, with the other foot on the brake pedal and try to steer and park at the same time? So in that case, the motor would still be moving. I've heard some people talk about that, so I thought that might work, or am I mistaken?Yes, but the motor only turns when the car moves, and the speed of the motor is proportional to the speed that the car is moving, so the steering pump wouldn't turn fast enough to be useful at low speed, and wouldn't do anything at all when stopped.
No, unless you have an automatic transmission with a torque converter to slip, the motor is only moving if the car is moving, and the speed of the motor is directly proportional to the speed of the car.What if you kept your foot gently on the accelerator, with the other foot on the brake pedal and try to steer and park at the same time? So in that case, the motor would still be moving. I've heard some people talk about that, so I thought that might work, or am I mistaken?
If you're using an electric motor with an automatic transmission including a torque converter your setup is hopelessly nonsensical, and I don't have any suggestions.
Do you have any good accessory motor recommendations then? Is there a particular rpm, voltage, hp, amp rating to look for when buying a motor? Should it be on the 12V circuit, the high voltage circuit, or can it be powered by either?No, unless you have an automatic transmission with a torque converter to slip, the motor is only moving if the car is moving, and the speed of the motor is directly proportional to the speed of the car.
If you're using an electric motor with an automatic transmission including a torque converter your setup is hopelessly nonsensical, and I don't have any suggestions.
If you were trying to run several accessories as if they were still connected to a running engine, you would need to add up their power demands, and pick a speed that's just fast enough for all of them. It makes no sense to me to convert high voltage to 12 volts then use 12 volts to run this motor (although you can do it) - just use the high voltage.Do you have any good accessory motor recommendations then? Is there a particular rpm, voltage, hp, amp rating to look for when buying a motor? Should it be on the 12V circuit, the high voltage circuit, or can it be powered by either?
But why use one accessory motor, instead of each accessory system having a suitable motor of its own? You want hydraulic fluid pumped to run the steering - why not just use an electric power steering pump? Many cars came with electrohydraulic power steering (EHPS, one of the "electric power steering" systems listed in the first post), and some still do; you can salvage a pump from one of these vehicles to power your steering rack. EHPAS pumps are usually 12 volt powered, because they come from cars with engines, not EVs.
Ok, so a donor vehicle with an electric power steering pump will just stay connected to the 12v battery and I won't have to mess with it in any way?If you were trying to run several accessories as if they were still connected to a running engine, you would need to add up their power demands, and pick a speed that's just fast enough for all of them. It makes no sense to me to convert high voltage to 12 volts then use 12 volts to run this motor (although you can do it) - just use the high voltage.
But why use one accessory motor, instead of each accessory system having a suitable motor of its own? You want hydraulic fluid pumped to run the steering - why not just use an electric power steering pump? Many cars came with electrohydraulic power steering (EHPS, one of the "electric power steering" systems listed in the first post), and some still do; you can salvage a pump from one of these vehicles to power your steering rack. EHPAS pumps are usually 12 volt powered, because they come from cars with engines, not EVs.
YesOk, so a donor vehicle with an electric power steering pump will just stay connected to the 12v battery and I won't have to mess with it in any way?
... although some of those pumps expect CAN (computer network) messages so you need to be careful that those continue to work - they shouldn't depend on the engine.I am putting a Tesla motor into a Porsche Boxster. I have a question regarding the PS pump set up. I have a Volvo S40 C70 C30 V50 ELECTRIC POWER STEERING PUMP. This was actually made by Ford and is used on smaller cars such as the Focus. I connected the #8 power cables to a 12V battery and the single 18AWG grey control wire to a switch and then to the 12V+ side of the battery. I have not connected the other two control wires. When I turn the switch on, there is a 3 sec delay and the pump starts for 1/2 second and then stops. I leave the switch on and 3 sec later the pump does the same thing. All the forum threads I have read say the grey wire is the non-CAN wire that will keep the pump running at about 70%. They also say to keep a 12V #8AWG power supply to the pump to keep the built in capacitors fully charged. I have connected the other two wires individually to the switch but they do not do anything. I think my pump is looking for a CAN signal to keep running. Any ideas or suggestions?
I found this in my search maybe it will be helpful
Volvo Electric power steering conversion (Full write up) | Ford Mustang Forums (corral.net)
Volvo Electric power steering conversion (Full write up) | Ford Mustang Forums (corral.net)
Part of that discussion:I found this in my search maybe it will be helpful
Volvo Electric power steering conversion (Full write up) | Ford Mustang Forums (corral.net)
A number of guys who do HPDE or autocross on the FB groups have stated they have begun to move away from the volvo electric pumps. In this application the pump is operating in failsafe mode, and the main complaint is that it cannot keep up during quick steering movements.
[/QUOTE]Ive been told just hook up a potentiometer and you can manual tune the voltage and adjust power assist that way.[/QUOTE]The pump in failsafe mode runs at about 70%. If/when the CAN BUS code is broken we will be able to adjust the duty cycle making HPDE and auto-x shortfalls a thing of the past.
[/QUOTE]Not quite so simple. It's CANbus controlled, so you would need to use a microcontroller to send a signal to the unit. You could use a Arduino or such. The issue is cracking the canbus "code" which would be easy if someone who was motivated had a working Volvo that one of these pumps was used on to filter out the code a bit. You could easily wire up a VSS variable reluctor signal to the Arduino and have it output the desired signal to the pump based on input from the VSS.
The issue is deciphering and writing the code. There have been folks working on it, but unsure if they ever figured it out.[/QUOTE]
I have a Mazda 3 (which has a Ford assist system from the C1 platform, shared with the Volvo V40 II and successor to the C platform used by the S40 II), and aside from any EV conversion I would like to tune the assist level. After looking into how it is controlled I realized that a CAN-based controller system would be needed, and didn't pursue it.
Operation without CAN communication of at least one generation of these pumps is feasible, but limited in pressure and therefore in steering boost.
1 - 20 of 21 Posts
- This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
DIY Electric Car Forums
A forum community dedicated to DIY electric car owners and enthusiasts. Come join the discussion about electric vehicle conversions, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more!
Full Forum Listing
Top Contributors this Month
View All
remy_martian
125 Replies
Functional Artist
39 Replies
428RC
22 Replies
Recommended Communities
