Driving with EPAS
Discussion
After a couple of false starts (MOT issues, lots of rain and a few hours of overtime at work) I have managed to get the Griff out of the garage for the year.
Nothing much new this year, other than redesigned plenums, redesigned cooling system, redesigned ancillary drive on the engine, a Corsa C height adjustable EPAS steering column, 7" lights and version 2 of my heater box & controller...
So far, so good. The EPAS works amazingly well - in fact too well when the speed sensitive assistance is turned off. I might have to hand back the medallion and chest wig since it's a bit girly now. I was worried that the system wouldn't cope with low speed, but it is lighter than ever the hydraulic system was, and significantly lighter than my Jaguar. Plus there's one less fluid to decorate the garage floor with now. Will get some pictures taken in due course, but they're not all that interesting unless you like wires. All in all, the EPAS mod would seem to me to be well worth doing. There's a couple of things I'd do differently, but there's time to change these when I redesign the next bit of the car...
It's a shame I won't make it to the Growl this year, but it would seem in the current climate, you have to take the work when it's there.
Nothing much new this year, other than redesigned plenums, redesigned cooling system, redesigned ancillary drive on the engine, a Corsa C height adjustable EPAS steering column, 7" lights and version 2 of my heater box & controller...
So far, so good. The EPAS works amazingly well - in fact too well when the speed sensitive assistance is turned off. I might have to hand back the medallion and chest wig since it's a bit girly now. I was worried that the system wouldn't cope with low speed, but it is lighter than ever the hydraulic system was, and significantly lighter than my Jaguar. Plus there's one less fluid to decorate the garage floor with now. Will get some pictures taken in due course, but they're not all that interesting unless you like wires. All in all, the EPAS mod would seem to me to be well worth doing. There's a couple of things I'd do differently, but there's time to change these when I redesign the next bit of the car...
It's a shame I won't make it to the Growl this year, but it would seem in the current climate, you have to take the work when it's there.
Yes, mine's the Corsa system. I have a standard Corsa C EPAS ECU that gets stimulated by a circuit I designed to convert the Griff speed sender signal to something similar to what a Corsa has, and adapts the assistance profile to something more suitable. It took a bit of work to get the assistance profile to something I was happy with.
Would this not do the job, to get the feel right.
http://www.ebay.co.uk/itm/Corsa-B-C-Electric-power...
http://www.ebay.co.uk/itm/Corsa-B-C-Electric-power...
most of the std controllers just use a "pot" to dial in a preset assist level. no speed relatedness.
the one dnb made uses the speedo to get a proper speed related assistance.
absolutely key to getting a decent level of assistance from the steering.....and together with a proper bracket, ought to sell well....
i'd be interested to compare it to a hydraulic setup for feel, I once fitted a corsa system to a cobra replica. with an ebay type controller. removed it after a few days as i hated the lack of sewnsitivity, even at the lowest setting, but that could just have been the controller i used.
the one dnb made uses the speedo to get a proper speed related assistance.
absolutely key to getting a decent level of assistance from the steering.....and together with a proper bracket, ought to sell well....
i'd be interested to compare it to a hydraulic setup for feel, I once fitted a corsa system to a cobra replica. with an ebay type controller. removed it after a few days as i hated the lack of sewnsitivity, even at the lowest setting, but that could just have been the controller i used.
Edited by SSPPGG on Wednesday 30th May 21:09
Hi DnB,
I'd be very interested to hear what you've done regarding control of the EPAS resistance. I know of a few people who have tried this on race cars and found the same result: too much assistance.
I have put a Corsa C column on my Tuscan race car, though it hasn't turned a wheel yet so I've not had a chance to try it myself. Speaking with the guys from DC electronics, they are aware of the problem, and have designed a complete replacement ECU for the column costing around £500, or an even more complicated one for £1000. They claim that there is much more to it than speed sensing when you get into the guts of the thing, and that to get a decent feel from the steering, you need to buy their kit. I would like to not have too much assistance on the racer for obvious reasons, and retain as much feel as possible so I'm a bit worried I may have to go down this route. Have you had a chance to look into the guts of the unit and confirm or deny this? I do remember speaking to another guy from Wales who makes a cheaper unit, who claims to solve the problem with his box for around £200, though I haven't any evidence to back this up or not.
I'm hoping to get the Tuscan running this summer so I shall be getting to this problem in the next few months. If you'd be so kind as to make your findings public, I would be most grateful, and may well have to get in touch to see which is the best route to take..
I'd be very interested to hear what you've done regarding control of the EPAS resistance. I know of a few people who have tried this on race cars and found the same result: too much assistance.
I have put a Corsa C column on my Tuscan race car, though it hasn't turned a wheel yet so I've not had a chance to try it myself. Speaking with the guys from DC electronics, they are aware of the problem, and have designed a complete replacement ECU for the column costing around £500, or an even more complicated one for £1000. They claim that there is much more to it than speed sensing when you get into the guts of the thing, and that to get a decent feel from the steering, you need to buy their kit. I would like to not have too much assistance on the racer for obvious reasons, and retain as much feel as possible so I'm a bit worried I may have to go down this route. Have you had a chance to look into the guts of the unit and confirm or deny this? I do remember speaking to another guy from Wales who makes a cheaper unit, who claims to solve the problem with his box for around £200, though I haven't any evidence to back this up or not.
I'm hoping to get the Tuscan running this summer so I shall be getting to this problem in the next few months. If you'd be so kind as to make your findings public, I would be most grateful, and may well have to get in touch to see which is the best route to take..
Would be really interested in the circuit you have used for the controller (I'm assuimng an AVR/PIC or something similar). I was looking at the output signal from the speedo sensor with a scope whilst trouble-shooting. My car uses the S11S sensor which has the trigger wheel type disc (with folded over teeth) between the prop and diff. Did a quick spreadsheet with T5 ratios, GKN diff ratio, no. of disc teeth and wheel circumference to calculate the relationship between speed, gear, engine RPM/pulses per minute from the sensor.
Did you fabricate the brackets for reinforcing the pedal box, etc. yourself?
Did you fabricate the brackets for reinforcing the pedal box, etc. yourself?
I had a bit (read "lot") of help from CliveF making up the brakets for the EPAS. I did the design & drawing work and he did the difficult bit of making sense of how to fold and weld the bits.
Without giving away too much (there might be a couple of £ in this...), there is much more to the Corsa system than providing it a speed signal. There is RPM to deal with too, and a variety of constant level signals. I used a small AVR uC for my circuit, and so far it does what I need. There are a couple of improvements for version 2, but that's next week's problem
450Nick - I have a prototype controller that can be controlled manually so that an assistance profile can be derived. Let me know when you want to test, and I'm sure I can arrange for you to borrow it - your profile says "South East" so you can't be that far from me. None of it is rocket science, so I wouldn't think £1k worth of kit is required - why replace the GM/Mitsubishi controller when it's CE marked, extremely thoroughly tested and appearing to be sufficiently capable?
Without giving away too much (there might be a couple of £ in this...), there is much more to the Corsa system than providing it a speed signal. There is RPM to deal with too, and a variety of constant level signals. I used a small AVR uC for my circuit, and so far it does what I need. There are a couple of improvements for version 2, but that's next week's problem
450Nick - I have a prototype controller that can be controlled manually so that an assistance profile can be derived. Let me know when you want to test, and I'm sure I can arrange for you to borrow it - your profile says "South East" so you can't be that far from me. None of it is rocket science, so I wouldn't think £1k worth of kit is required - why replace the GM/Mitsubishi controller when it's CE marked, extremely thoroughly tested and appearing to be sufficiently capable?
dnb
I'm very very impressed you must be an electronics wiz if you can program a microprocessor to interface the Griffith speed sensor, simulate the revs & adapt the assistance profile. I'm sure if you took your interface to market it would be a great success and I would be at the front of the queue, If not can I be your chief tester.
I installed the Corsa B EPAS with the DC Electronics modified Corsa B ECU and separate road speed sensor so mine is speed sensitive. Parking was instantly a pleasure and its great for everyday use but for the enthusiastic drive I was hoping it would get even heaver than it does.
DC electronics explained the only way to make the system even heaver at speed is to dump the Corsa ECU and buy their programmable ECU for £700. I don't want heaver steering that much and that's why I'm very intested in your solution.
If you want to read about my installation goto
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Best wishes with version 2
Steve Sprint
I'm very very impressed you must be an electronics wiz if you can program a microprocessor to interface the Griffith speed sensor, simulate the revs & adapt the assistance profile. I'm sure if you took your interface to market it would be a great success and I would be at the front of the queue, If not can I be your chief tester.
I installed the Corsa B EPAS with the DC Electronics modified Corsa B ECU and separate road speed sensor so mine is speed sensitive. Parking was instantly a pleasure and its great for everyday use but for the enthusiastic drive I was hoping it would get even heaver than it does.
DC electronics explained the only way to make the system even heaver at speed is to dump the Corsa ECU and buy their programmable ECU for £700. I don't want heaver steering that much and that's why I'm very intested in your solution.
If you want to read about my installation goto
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Best wishes with version 2
Steve Sprint
With a manual rack the harder you turn into a bend the heavier the steering gets and that's the feeling you loose with PAS. Basically PAS increases the amount of assistance as the load increases so you don't feel how hard you are turning in. On the extreme, a manual rack on the track with R888's makes the steering so much heavier its hard to catch the rear end and negotiate the slalom at zolder.
Carsy
With the above in mind, the interface control box you have found on ebay is still a bargin at £30 as it makes the Corsa system plug & play and you could leave it on the heaviest setting which is actually not heavy enough. I realise its not ideal but neither is the Corsa ECU. It would certainly make parking a pleasure and give you a lighter feel that you will eventually get use to. For track days you can easily revert back to manual by pull the fuse which I've tried and was fine.
Please be assured the Corsa EPAS is not dangerous, vague or twitchy, its just very light. I'm personally struggerling to get use to it as I've had manual racks with V8's for 24 years which shows it is a personal choice based partly on what we are use to.
I am disappointed the Corsa's heavy setting is not heavy enough and that its not easy to make it heaver, thats why I'm particularly interested in dnb clever microprocessor interface.
Carsy
With the above in mind, the interface control box you have found on ebay is still a bargin at £30 as it makes the Corsa system plug & play and you could leave it on the heaviest setting which is actually not heavy enough. I realise its not ideal but neither is the Corsa ECU. It would certainly make parking a pleasure and give you a lighter feel that you will eventually get use to. For track days you can easily revert back to manual by pull the fuse which I've tried and was fine.
Please be assured the Corsa EPAS is not dangerous, vague or twitchy, its just very light. I'm personally struggerling to get use to it as I've had manual racks with V8's for 24 years which shows it is a personal choice based partly on what we are use to.
I am disappointed the Corsa's heavy setting is not heavy enough and that its not easy to make it heaver, thats why I'm particularly interested in dnb clever microprocessor interface.
stevesprint said:
With a manual rack the harder you turn into a bend the heavier the steering gets and that's the feeling you loose with PAS. Basically PAS increases the amount of assistance as the load increases so you don't feel how hard you are turning in. On the extreme, a manual rack on the track with R888's makes the steering so much heavier its hard to catch the rear end and negotiate the slalom at zolder.
Carsy
With the above in mind, the interface control box you have found on ebay is still a bargin at £30 as it makes the Corsa system plug & play and you could leave it on the heaviest setting which is actually not heavy enough. I realise its not ideal but neither is the Corsa ECU. It would certainly make parking a pleasure and give you a lighter feel that you will eventually get use to. For track days you can easily revert back to manual by pull the fuse which I've tried and was fine.
Please be assured the Corsa EPAS is not dangerous, vague or twitchy, its just very light. I'm personally struggerling to get use to it as I've had manual racks with V8's for 24 years which shows it is a personal choice based partly on what we are use to.
I am disappointed the Corsa's heavy setting is not heavy enough and that its not easy to make it heaver, thats why I'm particularly interested in dnb clever microprocessor interface.
Hello mate! Looking forward to hooking up next week for the Growl and trying your steering out! Glad you've found a topic to get you postingCarsy
With the above in mind, the interface control box you have found on ebay is still a bargin at £30 as it makes the Corsa system plug & play and you could leave it on the heaviest setting which is actually not heavy enough. I realise its not ideal but neither is the Corsa ECU. It would certainly make parking a pleasure and give you a lighter feel that you will eventually get use to. For track days you can easily revert back to manual by pull the fuse which I've tried and was fine.
Please be assured the Corsa EPAS is not dangerous, vague or twitchy, its just very light. I'm personally struggerling to get use to it as I've had manual racks with V8's for 24 years which shows it is a personal choice based partly on what we are use to.
I am disappointed the Corsa's heavy setting is not heavy enough and that its not easy to make it heaver, thats why I'm particularly interested in dnb clever microprocessor interface.
7 TVR
I'm looking forward to the drive to the Growl with yourself and Precat.
You must give my steering a proper hard test drive before you make a final decision on your PAS. Given the quality & level of your Giffith, I really don't think you will be happy with the lightness of the Corsa system especially as track days are your priority.
I'm looking forward to the drive to the Growl with yourself and Precat.
You must give my steering a proper hard test drive before you make a final decision on your PAS. Given the quality & level of your Giffith, I really don't think you will be happy with the lightness of the Corsa system especially as track days are your priority.
Further to my post above I've remembered there is a torsion bar in the EPAS unit that allows a few degrees of play when the unit is powered off. I therefore withdraw my suggestion to drive with the EPAS unit powered off even though I didn't notice this play on my short test drive. At least I've proved its safe to drive home in the unlikely event of the EPAS fuse blowing.
BJwoods
Here’s an article about Racing Green’s EPAS, http://www.thetvrshop.com/steering.pdf
BJwoods
Here’s an article about Racing Green’s EPAS, http://www.thetvrshop.com/steering.pdf
It is indeed safe to drive the Corsa EPAS without power. (For one thing, GM wouldn't have got type approval unless there were a "degraded mode" to get you home) I too have not noticed much play in the unpowered system, but I have not used it in this way to do anything but get me home when the prototype controller box decided to play up. I guess that from the way it appears to work you'd perceive it as tiny slow initial response (probably small enough to not notice unless you were looking for it) that got worse as load on the wheels increased rather than play in the true sense.
dnb said:
It is indeed safe to drive the Corsa EPAS without power. (For one thing, GM wouldn't have got type approval unless there were a "degraded mode" to get you home) I too have not noticed much play in the unpowered system, but I have not used it in this way to do anything but get me home when the prototype controller box decided to play up. I guess that from the way it appears to work you'd perceive it as tiny slow initial response (probably small enough to not notice unless you were looking for it) that got worse as load on the wheels increased rather than play in the true sense.
Well I have the Corsa EPAS on my Tasmin Racer, with the ebay controller, but find it way to sensitive, esp with a non PAS rack.I fitted a switch to the 12v to the ebay controller, that turns it off, and thus dis-enabling the EPAS, which is also useful for cranking.
So I race with it totally turned off, and being racing like this for 2 years, so it's not a problem to have it off.
I would like to have a system that works though, esp If I goto bigger rubber or do longer races, as I'm only 10 stone.
Other people though have complained the Corsa ECU can't cope with wide race rubber, and can overheat, and turn on/off at will, which can be dangerous.
I'm visiting the Isle of Wight this weekend, as my Mum lives there, and will be in Shanklin and Cows, so if your about would be nice to see what you have done.
Leigh
hi mate, I`ll make sure dave sees this.Gassing Station | Griffith | Top of Page | What's New | My Stuff