EPAS (Electric Power Assist Steering)

[Bill Musarra]

Several of the members for various reasons are adding EPAS(Electric Power Assist Steering) to their cars. We have found out that the heavy steering at low speeds is a real drawback to enjoying our cars. Just cuting one out of a bone yard and transplanting it to the cars is not just a cut here bolt there kind of setup. They require sensors that tell engine rpm and car speed. I can be corrected here by those that know more than I do.For now I plan to use the pulse signal from the Stewart Warner speedo. It has a magnetic sensor that reads the bolts on the front hub(8 per rev). This may need to be manipulated for the correct sensor count.
I have just finished installing a Corsa C in my DRB. I have recieved much help from several forum members, Mick, Renato, and Keith Stafford to name just a few. I chose the Corsa C(2000-2006), but there are several others that can be used depending how you choose your electronics. The Corsa B, Toyota Yaris abs and non abs, along with the Saturn Vue - from 2002 to 2007, Chevrolet Equinox - from 2005 to 2007, Saturn Ion - from 2003 to 2006. All of these can use a false signal to fool the ECU. These can be supplied by Rally Wiz. I beleive some of our electronic gurus here on the forum are working on their own versions of the controllers. I'll leave it up to them to fill in this area as I know and understand the electornics, just not the implementation. If you want the whole story on the pin outs look here:Corsa C Electric Power steering (EPAS) - blog - Seventh Heaven - Locost - Haynes Roadster
I chose the Corsa C, with an adjustable height column. It not only has an adjustabble height feature but a variable height for the entire column. This allows me to mount the box much higher in the cabin. It also makes it easier to take the dash out for repairs or changes, I can drop the front of the column and the dash slides right out. It also allows for the angle of the steering wheel to be set for comfort. The central body of the unit remains fixed and I don't have to struggle with taking it out and back in.
Here it is mounted with the dash in.

Here is the side view with the dash out. You can recognize the standard raise and lower mechanism with its lock arm(about 2"of travel)

The front view sans dash. Still have to add some bracing to prevent torque travel.

Here it is with the front column droped.

This view shows adequate foot room from the high mount of the central unit. The old straight mount rod it replaces hit the tops of my shoes. You can also make out the rear bracing and temporary bolts. It is tack welded for now and will be reinforced with the entire unit removed.
I am hoping some of the others will post thier choices and how they setup their controllers.

Bill

 

[Keith Stafford]

Hi Bill

You've leapfrogged me,.... I have the Corsa column as you know. I took off the top plastic housing and collar, so need to get a new one made to hold the top ball race. I attach a rough PDF of the design of the collar and mounting bracket. I also made up a aluminium bracket, simply to check dimensions and act as a guide to the guys in the workshop.

My bracket will be bolted or welded to the cross member behind the dash as yours is and will bolt to the top cross bracket which is already welded to the column, I think you have taken a different approach, not a criticism, just clarifying the difference.

(I realise my CAD is rubbish, used CorelDraw which is not a CAD package and,.... help, I need some free CAD software).

Still looking into the pulse issue, will be in touch.

Keith

 

[James Harvey]

help, I need some free CAD software

DraftSight is free and pretty good. It can do autocad files too...

Free CAD software * for your DWG files: DraftSight - Dassault Systèmes

 

[Keith Stafford]

Ta James, downloading now. K

 

[Keith Stafford]

Bill, the one thing I would say is that the EPAS will need to be held fairly rigidly, as it will be transferring torque from the motor to the pinion of the rack, so it will want to twist, just make sure your brackets do not allow any torsional movement, as it will try to rotate about the centre line of the column. With the angle on the bottom link bar there may also be other rotational forces, some of the mechanical engineers will be more familiar with this. The column may also try to rotate laterally, if that makes sense?

Keith

 

[Bill Musarra]

I realize the forces at play. That is why i will add triangulated pieces to each right angle to hold those forces in line. If I have any problem with that I will add diagonals to the frame. That should fix it. What I am most interested in now, is the controllers. I have the basics of how it should work, just not the implementation of it. Has annyone made up a board yet?? or which wires are in play, or which wire recieves which signals. The locost link told me a lot but it still left me in the dark, so to speak. I know I need a pulsed source whichI have with the Stewart Warner speedo. Just don't know if it needs a multiplier or divider circuit and how to accomplish that. Things of that sort.

Bill

 

[David]

This is how it is on my chassis

 

[Robert May Eng.]

I am also in throws of fitting epas. I managed to get a couple of steering columns from a local breaker, unfortunately they came minus the keys. I was hoping to use the whole column including the switches. These are popular in the uk for the rally cars and the electronic side of this is already catered for .


I found these on ebay Corsa B C - Kit - Electric power steering controller box - With ECU plug - EPAS | eBay.

Bob

 

[Randy V]

Watching with keen interest...

It seems that I brought this subject up along with assisted brakes and there was very little interest..

( Note that I did take the liberty of making your subject line a little more complete in case someone was not searching but browsing the forum for content.)

 

[Bill Musarra]

Appreciate that. I think there are more of these out there than most would imagine. The hard part is the electronics. Keith and I are trying to coble something that might last. We are probing the aftermarket guys to see what their systems compose of and what causes them to fail, or tire out, and what happens when they do. Will keep all posted as we go. Would like some of the EE or electronic whiz guys to check in and give some advice or ideas. It's the working together that moves these sort of things along.

Bill

 

[Robert May Eng.]

Is it worth it to save less than $20 ? Click the link below

Corsa B C - Kit - Electric power steering controller box - With ECU plug - EPAS |

Bob

 

[David]

Yes. That fakes it so that the assistance is the same at all speeds. As fitted originally they have different levels of assistance depending on the speed.

 

[Robert May Eng.]

Yes. That fakes it so that the assistance is the same at all speeds. As fitted originally they have different levels of assistance depending on the speed.

We must need this one then.Its still reasonably priced. http://www.ebay.co.uk/itm/Corsa-B-C...arts_Vehicles_CarParts_SM&hash=item3cd204f323

Bob

 

[David]

Hmmm, that wasn't available last time I looked...
You're right though that would do it. I'm going to email the seller for details.

 

[David]

I am also in throws of fitting epas. I managed to get a couple of steering columns from a local breaker, unfortunately they came minus the keys.

I've got a 'B' ign lock *with* the key if you want it. No use to me and I CBA to ebay it so yours for free if you want. PM if interested.

 

[Robert May Eng.]

I might take you up on that offer David, a local car locksmith is going to have a go at them first so I will let you know. I tried vauxhall and its no go unless you have the log book for the car in your name with proof of ID. I was hoping to use all the stalks so I need to fathom out the wiring.

Bob

 

[Bill Musarra]

There are several of these controllers that are being offered through Ebay. Be careful as some are as cheap as the price. Check with the seller and ask some pertinant questions. Like is there a warrantee and for how long. That too may not be worrrth the paper it is written on. So be careful. There are some from the UK and Australia. They may be better for a more expensive price. The company Rally Wiz seems to be the one with the most research and multiple types of systems out there(read columns) that is in the ball park as far as price is concerned. I have asked several questions to them that I think are important. More on that later.
For those of you that may want a complete system there are companys like Unisteer: Electric Power Steering | Search By Product | Unisteer Performance
Some will also install their propriatary systems. Be prepared to pay handsomely for them though.
If you are interested in trying this type of setup try and get a column that is not very old or has low mileage on the column. The wear and tear on the system may be the weak link regardless of the system employed to make it work.

Bill

 

[Robert May Eng.]

There are several of these controllers that are being offered through Ebay. Be careful as some are as cheap as the price. Check with the seller and ask some pertinant questions. Like is there a warrantee and for how long. That too may not be worrrth the paper it is written on. So be careful. There are some from the UK and Australia. They may be better for a more expensive price. The company Rally Wiz seems to be the one with the most research and multiple types of systems out there(read columns) that is in the ball park as far as price is concerned. I have asked several questions to them that I think are important. More on that later.
For those of you that may want a complete system there are companys like Unisteer: Electric Power Steering | Search By Product | Unisteer Performance
Some will also install their propriatary systems. Be prepared to pay handsomely for them though.
If you are interested in trying this type of setup try and get a column that is not very old or has low mileage on the column. The wear and tear on the system may be the weak link regardless of the system employed to make it work.

Bill

Point taken on the cheap aftermarket controller Bill, I will do a bit more research. The Corsa steering column is a tough little lot and they dont seem to be problematic. But on that note I will be engineering the system to ease removal and maintenance, its all to easy to install stuff like this and bury it:laugh: .

Bob

 

[Keith Stafford]

Guys, we have a microprocessor based circuit under test. the issue here is not the cost, if it were I would not be spending £,000 building a car, the issue for me is twofold:-

A) I think (for me) there is a better solution. Personally, I'd prefer a totally automatic system, but with no ABS and a mechanical speedo, getting actual speed pulses is not an option without a bit of upheaval. I believe that the semi-automatic system I have developed is an improvement, as there is no rotary control knob to turn, even if you could find where to position the knob. The circuit is almost fit and forget.

B) Sometime you do stuff because you can, or perhaps to see if you can.

Anyway, I am and electronic product designer, over the past couple of days we pulled together a circuit. Which is not totally automatic. The circuit attached does the following:-

1) Once powered up (car started) the circuit waits 10 sec before enabling the EPAS, it holds the red/white “engine multi-timer” low (0V), then after 10 seconds it goes to 12V, enabling the EPAS.

2) When the multi timer output is set to enable the EPAS, the circuit starts to produce a default pulse count of 420 pluses per second, setting the EPAS to map 3, that is 45+mph for the Corsa.

3) A button press will put the circuit into a low pulse count of 70 pulses per sec for a period of 30 seconds. The 30 secs allows you to park/unpark. It will then automatically revert to the high speed pulse count for driving.

To summarise, the EPAS default assistance will be map 3, the least, as if you are dtiving at 45+ mph. If you want more to park/unpark press the (momentary button) and get 30 secs of map 1, high assistance. The circuit then automatically reverts to the lower assist, so you need do nothing more. The circuit will also work with a toggle switch (rather then momentary make/break), if you use a toggle switch it will stay in the lower or higher assistance states, and not revert until you switch back.

Now, I could 'improve' it further thus, after the 10 sec delay to enable the EPAS to initialise, the circuit will give say 30 secs of high assistance to allow you to maneouvre/unpark, then revert automatically to the low assist for driving.

For those interested I can post more pix. We are soak testing the cct over the next few weeks. Electronics failure is always a possibility, but with sufficient testing and field testing you can get to a point where you have tested all reasonable scenarios and iterated towards a working stable solution.

K

 

[James Harvey]

Hi Keith

This looks really interesting, well done! What processor are you using? I've got a corsa unit too and looking for a solution for this (although I'm a little way off fitting it yet!). I've been wondering if something suitable could be built from an Arduino unit. Guess you're taking a similar approach with the microprocessor. Looking forward to seeing how your testing goes...