Epas retrofits; What is the state of play?

[mobby666]

Hello all,
This is my second post to the group (my first was exactly the same, but I managed to lodge it in the wrong place, for which I am eternaly sorry).

I am asking how current is my question (Epas retrofits; What is the state of play?). Is it dead & burried, or nailed down. & who does what, where & with who (or should that be whom? I never know).

I have been asked by a friend to help him fix an MGF EPAS to his original 60s style Mini. To be honest I can't see too many problems, but I am known to have been wrong in the past....lol.

Any help or gentle nudges in the direction of current information (You know the sort of thing) will be greatly appreciated.

Many thanks in advance.

Mobby

 

[GregLocock]

As I said before, you'll need to tell the unit the steering wheel angle, vehicle sped and steering column torque, at the least. The steering column sensors may be built into the unit, or may not.



Cheers

Greg Locock


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[mobby666]

Hi Greg,

Speed is a given. However, above a certain speed the power assist needs to disappear (0n one of the MG sites they have designed an on/off switch for their epas systems...Gives a much tighter feel, if off at speed).

Wheel angle/steering wheel angle, column torque, rate of spin, is steering centered etc. I believe that some of this is the engineering equivalent of a blue trout!

Very little of the above type of information was ever gathered by the old hydraulic steering servos, nor do the now generally superseded, but OK for years vacuum servoed brakes.

Whilst I realise that is now possible with our vast array of sensors & sophisticated software to tell if the driver should fart, & how that might alter the 'eta'. I am bound to ask "exactly what info does the steering need"

PAS is ever really only of use at 'parking' speeds & was always turned down as speed increase. In my very humble experience I only noticed power assist at sub 6/7 mph speeds.

I would hope that the above taken in context should suggest that the chances of mating most epas systems to most other vehicles originally epas or not shouldn’t present too many problems……..This is the point that I usually duck…..Ho Hum.

 

[NormPeterson]

I wonder if switching the EPAS off completely is anything that you'd really want. A requirement of greater effort at the steering wheel to turn over the then-deactived motor isn't going to improve the tactile sensations coming up the steering column, and might just interfere with them. Same signal, with a bit more "noise" to get lost in.


Norm

 

[patprimmer]

A sudden change at a particular rpm or wheel speed could have some very undesirable effects on a rough slippery surface,especially if drifting it a bit and trying to catch it with some quick opposite lock.

Regards
Pat
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[mobby666]

Interesting points, but we are all so used to pas that we forget what driving was like back in the day. To answere Norm first, the system I'm looking at is cluched magneticaly so when the system is turned off no motor to deal with just the road (if you think about it 'no system in line' is the default 'limp home mode')

To reply to pat, I'm not quite sure if you are supporting the 'No epas' button or not? Again if you are moving at speed pas is mostly off anyway. In forest conditions I'd rather have the feel of the surface than the parking convenience of pas 'E' or otherwise

Cars never used to have pas on every single model from every manufacturer. It was for the top of the range only, those of us who worked for a living only saw cars with pas in the directors spaces...lol

I'll let you know how we get along.

 

[patprimmer]

I am against an off button, and I am especially against an automatic system that turns it off for you at a time you may not expect or keeps cycling on and off as you keep crossing the on off threshold in a turn.

For the record, on road cars, PS is faster than MS in most circumstances for most drivers and the ability to quickly get from lock to lock is more important than some extra feel.

A well designed ps system at a reasonable assist level has ample feel.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[GregLocock]

Early FIATs with EPAS had a 'girlie' switch, which was presumably intended for parking. One interesting outcome, I am told, is that lazy drivers left it switched on and were quite happy.

Commodore had a speed sensitive HPAS that switched effort assistance at around 50 or 60 kph, which was most amusing in slow corners.

I've read of several people who reckon that in a long race in sedans they were faster with PAS than not.

I suspect that rather than trying to game the controller your best bet is to plug it in and use it as it was intended. If push comes to shove you might want to fiddle with the road speed input, either manually (faking a higher speed to give less assistance) or electronically, perhaps installing a non linear curve of pulse rate vs roadspeed.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[mobby666]

Yes Greg, the altered mark/space curve is top of my play list.

As for other comments; I am only flitting between specialist sites for MGF owners, general EPAS modders sites & here. I'm trying to amass info to help a friend.

It may be that the best help I can give him would be to 'leave well enough alone'. Trouble is I love to tinker, I think I will have him sign a 'waiver' in case of catastrophic failure....lol.

Best regards to all.

Mobby