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Aftermarket power steering

27K views 40 replies 19 participants last post by  doorfx 
#1 ·
What do you all think about this product? I wonder if it's too soon for a really good aftermarket power steering unit or is this one the real deal? Maybe it is just the ticket?
I would bet if someone were able to get the dimensions it could be retrofitted into a ThunderCat!!!!

http://allterrainresearch.net/polaris-spor...power-steering/
 
#27 ·
Well! There's good news and bad news. The good news is that the ps unit will fit in the chassis. I did finish up the brackets, installed everything and hooked up the power to the control unit. But the bad news is that it still didn't work. I fugured we would just ride it with the ps unit in place until I can get the controls figured out. But when I took it out for a ride there is a dead spot in the steering that leaves several degrees of slop in the steering. I couldn't notice it without the resistance of the tires against the output side. Just sitting the handlebars rotate several degrees back and forth without any movement in the wheels. The movement is in the power steering unit. So we can't use the machine with the ps unit in place. I ordered a new steering column which I hope to put in this weekend so we can use the atv. I am keeping everything as is with the work I've done so I can re-install it if I can get the controls to work right. My initial enquiries have me beleiving that GM is not very inclined to share information about how this system works. I will continue tinkering as I can. So at this point we are going to enjoy the summer riding and I'll continue to look for a solution to the controls as I have some time. If anyone has any information about these systems that might be helpful or knows someone who does I would appreciate any input that would help solve the controls issue. There has to be a solution out there some where if I can just find it. But right now my attention has been diverted by good riding weather. If I make any progress, I will post it.
 
#28 ·
I'm an engineer that works with controls systems (i wouldn't call myself a CS engineer though). If you post up the info you have or PM it to me i'll take a look. There are a lot of other smart guys and engineers on here too that can probably help.
 
#29 ·
Dumb question, do you have three wires hooked up to that unit??? One is constant power, one is a ignition switched power and the third is a ground. Thats what the diagram for my 05 Cobalt shows anyway. The other problem I am seeing is that the power wire for constant battery power is protected by a 60 amp fuse on the cobalt, may draw to much power. Another thing my diagram is showing is a 4 wire connection with the vehicle data link connector, I also believe the electric ps units require a vehicle speed input and perhaps others, that may be what the dlc connection is for, missing these inputs could make the unit dead and useless.

More research has shown me that two of those 4 wires goes to the Body Control Module the other two to the DLC, I have a feeling the BCM is giving the ps unit vital info to work.

Actually this may help, please read.

Power Steering System Description and Operation
The electric power steering (EPS) system reduces the amount of effort needed to steer the vehicle. The system uses the body control module (BCM), power steering control module (PSCM), torque sensor, discrete battery voltage supply circuit, EPS motor, serial data bus, and the instrument panel cluster (IPC) message center to perform the system functions. The PSCM, torque sensor, not the EPS motor are serviced separately from each other or from the steering column. Any EPS components diagnosed to be malfunctioning requires replacement of the steering column assembly, also known as the EPS assembly.

Torque Sensor
The PSCM uses a torque sensor as it's main input for determining the amount of steering assist. The steering column has an input shaft, from the steering wheel to the torque sensor, and an output shaft, from the torque sensor to the steering shaft coupler. The input and output shafts are separated by a torsion bar, where the torque sensor is located. The sensor consists of a compensation coil, detecting coil and 3 detecting rings. These detecting rings have toothed edges that face each other. Detecting ring 1 is fixed to the output shaft, detecting rings 2 and 3 are fixed top the input shaft. The detecting coil is positioned around the toothed edges of detecting rings 1 and 2. As torque is applied to the steering column shaft the alignment of the teeth between detecting rings 1 and 2 changes, which causes the detecting coil signal voltage to change. The PSCM recognizes this change in signal voltage as steering column shaft torque. The compensation coil is used to compensate for changes in electrical circuit impedance due to circuit temperature changes from the electrical current and voltage levels as well as ambient temperatures for accurate torque detection.

EPS Motor
The EPS motor is a 12 volt brushed DC reversible motor with a 58 amp rating. The motor assists steering through a worm shaft and reduction gear located in the steering column housing.

Power Steering Control Module (PSCM)
The PSCM uses a combination of torque sensor inputs, vehicle speed, calculated system temperature and the steering calibration to determine the amount of steering assist. When the steering wheel is turned, the PSCM uses signal voltage from the torque sensor to detect the amount of torque being applied to the steering column shaft and the amount of current to command to the EPS motor. The PSCM receives serial data from the engine control module (ECM) to determine vehicle speed. At low speeds more assist is provided for easy turning during parking maneuvers. At high speeds, less assist is provided for improved road feel and directional stability. The PSCM nor the EPS motor are designed to handle 58 amps continuously. The PSCM will go into overload protection mode to avoid system thermal damage. In this mode the PSCM will limit the amount of current commanded to the EPS motor which reduces steering assist levels. The PSCM also chooses which steering calibration to use when the ignition is turned ON, based on the production map number stored in the BCM. The PSCM contains all 8 of the steering calibrations which are different in relation to the vehicles RPO's. The PSCM has the ability to detect malfunctions within the EPS system. Any malfunction detected will cause the IPC message center to display PWR STR (or Power Steering) warning message.
 
#30 ·
yikes. nice job boaty. Sounds like this project is not feasible. Far too much input required, however it is possible that you could fool the signal to the PSCM with a constant volatge. It's now looking for variable analog proportional values for the variable settings. it's also possible that you could bypass that PSCM but that would involve creating you own control system. The picutres you posted show the PCSM integral to the EPS so i think it's impractical.
 
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#31 ·
Fooling may not work, those cars use a sophisticated communication system for the modules to "talk" with one another. The speed signal is inputted into the pcm, it then tells the bcm which tells the pscm. By then it may be more than just a AC voltage the speed sensor produces.
 
#32 ·
I believe it could be fooled with a constant voltage (if you could find the voltage range) however I think the problem will then be finding a happy medium for steering assist as too much could be dangerous. Actually IMO this project although a great idea will have to chock up to FAIL as I would not be comfortable at this point putting my wife on a machine that could loose all steering ability at any point, because if it has play with the unit dead then it sounds to me that it is not equipped with any type of failsafe to where you could still steer in the event of unit failure. Chock this up to learning experience and scrap it is my vote!!
 
#36 ·
A small rack and pinion might work pretty good, but I'd wonder about the ratio being useable for a quad.

When I was looking for other PS units, I saw someone cut down a geo rack for use in a go kart.
 
#37 ·
I Just ordered a Vauxhall Corsa EPS unit ans a control box for it from the Uk. The EPS unit is used and the control is aftermarket unit with a knob that cn be used to adjust the sensitivity..

The whole thing including shipping cost just over $300 much cheaper than the $1200.00 for an after market one.
 
#38 ·
I have a cobalt EPS unit and have been interested in a swap with it as well. In the car it uses serial data inputs from the BCM and ECU to reduce the power assist at high speeds. I'm not sure if it will work without these inputs. It has however a defalt/limp mode that make kick in and be adequate for our application, without these signals.
 
#39 ·
Interesting info guys. - I was looking at a '12 1000LTE at bass-pro recently and the frame on it with the power steering module was no different than the frame on my '09 1k TRV.
 
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