Technical Power steering conversion

[MrSlowly]

Hello everyone.

This time, I'm inquiring about my sister's mk2 Punto. It's a 2001 (IIRC), 1.2 non PA model. Is it possible to do a power steering conversion? From what I've seen, there are columns or motors plus ECU for sale on ebay or even local breakers, so I assume it is actually possible. What I don't know is about the torque and position sensors.

Would it be a simple column swap or would the rack need to be changed as well?

Lastly, if anyone's already done it, I'd very much appreciate the input.

Many thanks in advance.

 

[Eklipze3k]

I was under the impression that all Mk2 onwards had PAS as standard, unless it's been removed from hers for some reason?

 

[PuntoHowTo]

I was under the impression that all Mk2 onwards had PAS as standard, unless it's been removed from hers for some reason?

I believe there were some in far flung places that had some very low end budget cars with pout power steering, very few and far between though.

 

[MrSlowly]

There's a great number of non PA steering mk2 models over here. When the mk2 was first introduced, PA steering was a (quite costly, at the time) optional extra.

Which, from your assumptions, leads me to assume that the column and ECU swap would probably be enough.

Again, if someone else has done it, please chime in.

 

[flisko]

There's a great number of non PA steering mk2 models over here. When the mk2 was first introduced, PA steering was a (quite costly, at the time) optional extra.

Which, from your assumptions, leads me to assume that the column and ECU swap would probably be enough.

Again, if someone else has done it, please chime in.

do you got wiring for it on your car?

 

[brinker]

You would also need to relocate the front strut tops - the bearings sit with less caster angle on the non-PAS versions, so the top bearing will need to be turned half a turn. And the steering rack itself is also different - though it'll probably work, it'll likely be terrible to drive with, because the gear ratio in rack is different, and the number of turns higher.

 

[MrSlowly]

do you got wiring for it on your car?

What's there to wire? From what I've seen, the Punto PA steering seems like an autonomous system with its own sensors and ECU. All that's needed is power and I think I can make do without the possible failure indication on the dash. Is there something more to it that I've missed?


Brinker,
The rack I can source pretty easily and it's not that expensive but this does make it an even more laborious job and I'm starting to doubt whether the rest will fit OK as well.
I did not know about the struts, which seems to be the worst part. Would that really be possible? And if so, would it also be safe?

 

[Eklipze3k]

Seems like it would be a lot less hassle just to swap it for one with PAS, tbh

 

[PuntoHowTo]

Seems like it would be a lot less hassle just to swap it for one with PAS, tbh

It most likely would be, retro fitting canbus kit can be a nightmare, if the ECUs in the car are not 100% compatible with what you’re trying to fit then it’s not really gonna work, and then you have to have the detailed wiring diagrams (not the ones you get in the Haynes manual) to follow.

 

[MrDerv]

It's not just a case of providing power to it unfortunately. It will need wiring to communicate with the canbus system of the car so that it can provide OBD diagnostic info, but also allow enabling of city mode from the dash button which will need fitting too.

Believe it or not, it would be far easier to swap a hydraulic PAS system than an electric one, just a shame they didn't offer it on the Mk2

 

[MrSlowly]

I must be getting something wrong, or the Punto PA steering is indeed much different to what I've seen so far.

The whole thing about electric PA steering is a motor that essentially senses the direction you're turning the wheel to and assists you mechanically, thus making the movement easier.

The Corsa, for example, works with a normal rack and pinion system, it's just a motor on the steering column. Is the punto really different?

Apart from that, why would it need to be wired to the car's ECU at all? Yes, OBD diagnostics is one reason, but in this case, I don't have need for that, nor the dash indicator in case there's a fault. Or the city function, for that matter, since, I assume it's just another simple switch and, if needed, can be installed on its own, considering the whole PA system so far (to me) seems compeltely autonomous, independent from the rest of the electronics in the car.

Also, isn't there just a potentiometer to adjust the motor's "involvement" in the steering? I mean, people use such electric steering racks in much older cars and it seems to work fine.

What am I missing here?

edit: now that I think about it, the logical assumption for a connection to the ECU would be the speed sensor, so as not to have such light steering at high speeds, which would be downright dangerous. I assume the assistance is dialed down or cut out completely after a certain speed. So, there must either be some kind of "hack" connection to the ECU in order to get the speed reading, ooooor... I wonder if this can be achieved with a manual disengagement switch. Kind of the opposite of the city function.

 

[MrDerv]

The Corsa, for example, works with a normal rack and pinion system, it's just a motor on the steering column. Is the punto really different?

Essentially it's the same. The steering rack is a rack and pinion, and the power assistance is an electric motor on the steering column.

If you take a look at the connection to the PAS motor, you'll see there are 2 large terminals for power and ground, then a multi-pin for canbus communication.

Bear in mind that the OBD function is very much needed as it'll require calibration for the steering angle sensor to ensure it knows where it's dead centre.

Have a look under the steering cowl cover and see if there is any random unused plugs sitting there. If there is, chances are the wiring is already there for it. If there isn't, then you are going to have a battle on your hands.

Also bear in mind you'll need to swap out the steering rack as the pinion ratio will be different compared to the non-pas rack.

 

[dtzgr]

The power steering has a separate ECU. One of the inputs it uses (apart from turn direction, steering torque etc that it takes from the steering column's sensor(s)) is the vehicle's current speed, as it gradually disengages (=motor provides less assistance) as the speed of the vehicle increases. At ~60 km/h the system is virtually turned off (=no PAS needed at these speeds).

So it's not that simple.

 

[MrSlowly]

I'm leaning towards the manual disengagement switch option to be honest, it seems like the easiest way to go but I'll have to take a look at the car as well as the PAS options in person. Right now it's all kinda vague to me since the car's about 500km away!

Many thanks again.

 

[PuntoHowTo]

The motor, steering ecu and sensors are all intrinsically linked you can’t have one without the others. The steering ecu, not only needs to be connected to the rest of the cars electrical system for the speed sensor which is supplied to the steering ecu via the canbus system, it also needs to be connected to the body computer for diagnostics and calibration to work and fault monitoring.

If faults are detected the system is designed to cut the power steering to prevent damage to the system or the cars other electronics, warning lights come up on the dash etc.

The steering doesn’t simply cut out at higher speeds it tapers the amount of power assistance down as you speed up to make the steering feel and respond in a more normal way as it would on a conventional system with hydraulics.

Steering isn’t something you can botch and expect it to work properly or safely, people on the forum won’t help if a botch job is what you have in mind.

 

[Brendan W]

What about the hydraulic system. Would seem a more straightforward route.

 

[Ziggy122]

What about the hydraulic system. Would seem a more straightforward route.

Ur probably looking at a mk1 punto bits then.... which aint thay common....

But getting a 2nd pulley installed to drive the pump....

Eh... i think a donor car electronics swap would probably be the better option....

I think for a 2000 (18y/o) car.... i personally dont think its worth it....

Ziggy

 

[MrSlowly]

Perhaps it's not worth it from a logical standpoint but it is her first car, she wants to keep it and to be honest, there aren't any good alternatives at her budget so I'm trying my best to find a viable solution. When she first drove the car she found the steering fine but repeated parking attempts have made her already bad shoulders worse, hence me racking my brain for alternatives.

I'd also thought about hydraulic steering but with a twist. I'm pretty sure adding another pulley and belt would probably be near impossible -not to mention less that optimal-, so I was thinking about an electric powered hydraulic pump to drive the system. However, this would raise even more problems. One's the constant power that would be required for the pump but most importantly, actually finding a suitable rack, and I highly doubt the mk1 would fit. Therefore, this one's most likely a no-go.

The electric motor path seems more doable but, not having the car to examine makes it more difficult. Parts are not that much so we could get the rack, column and even another ECU from a donor car for pretty cheap, but problems might arise in that case as well, if there's a conflict with the donor's ECU, for example.

 

[MrDerv]

Perhaps it's not worth it from a logical standpoint but it is her first car, she wants to keep it and to be honest, there aren't any good alternatives at her budget so I'm trying my best to find a viable solution. When she first drove the car she found the steering fine but repeated parking attempts have made her already bad shoulders worse, hence me racking my brain for alternatives.

I'd also thought about hydraulic steering but with a twist. I'm pretty sure adding another pulley and belt would probably be near impossible -not to mention less that optimal-, so I was thinking about an electric powered hydraulic pump to drive the system. However, this would raise even more problems. One's the constant power that would be required for the pump but most importantly, actually finding a suitable rack, and I highly doubt the mk1 would fit. Therefore, this one's most likely a no-go.

The electric motor path seems more doable but, not having the car to examine makes it more difficult. Parts are not that much so we could get the rack, column and even another ECU from a donor car for pretty cheap, but problems might arise in that case as well, if there's a conflict with the donor's ECU, for example.

Balls, one other consideration we didn't take into account is the Alternator. There's a good chance the one on your Non-PAS car is rated lower amperage, compared to one with electric PAS.

You will also find that if you were to run an electric-hydraulic pump (like the ones found on Opel Vectra C), do draw a lot of current and will need an alternator upgrade to supply sufficient demand.

 

[Brendan W]

Now that you mention it I believe that the pre EPS cars were fitted with batteries in the high 20s and that later EPS cars were high 30s. Some here have fitted 50Ah iirc,