Hydraulic steering vs electric?
Discussion
Not all down to EPAS or hydraulic. My GT86 EPAS has better steering feel than many hydraulic set ups found in performance cars. Someone mentioned BMW's late hydraulic steering : that gave so little feedback, it hardly matters if the epas removed what little there was.
Edited by nickfrog on Saturday 27th December 22:38
nickfrog said:
Not all done to EPAS or hydraulic. My GT86 EPAS has better steering feel than many hydraulic set ups found in performance cars. Someone mentioned BMW's late hydraulic steering : that gave so little feedback, it hardly matters if the epas removed what little there was.
Agreed on that-the GT86's system felt pretty nice to me when I drove one. Ironically for a shopping car, the EPAS in my old Micra 160SR was pretty good too!I know when I am pottering round town, ringing the last percentage point from the cars performance is very important to me, so for this reason I will only tolerate a car with considerable steering feel. It also helps when the car is stuck in traffic to be able to feel understeer when I am changing lanes at a brisk walking pace.
p1tse said:
I was reading about civic ep3 type r vs integra dc5 as an example, where the teg is hydraulic and ep3 owners talking about lack of feedback
The EP3 steering rack (and all 7th gen Civics) is a good lesson in how not to do EPAS, it's far and away the worst aspect of the car. EPAS can be done reasonably well, but hydraulic system still tend to offer the lowest internal friction and hence the best feedback. Electro-hydraulic systems are probably the best all round solution, i.e. hydraulic rack and electrically driven hydraulic pump.The hydraulic system on my old Fiesta ST used to boil on trackdays, spilling fluid out of the cap. Ford, in all their wisdom decided to bolt the reservoir directly to the engine, so the heat would pass straight through. It was a common problem and there were many aftermarket fixes for it, but odd that Ford didn't fix it themselves since the car was available for such a long time.
No issues with the electronic system on the Megane. In fact, I didn't realise it was electronic when I bought the car, you can feel everything that's going on.
No issues with the electronic system on the Megane. In fact, I didn't realise it was electronic when I bought the car, you can feel everything that's going on.
I can understand that from an economics perspective, if the general buying public isn't fussed about electric steering, then why offer anything else?
I thought there was an MPG / Emissions reasoning by not having a Hydraulic PAS pump driven off a belt? I could be making that up.
Regarding steering feel, I have to admit the two MK1 Focus ST 170's I had on demo had very good steering feel (Awful engine but that's a separate issue) where as a much later Focus ST had steering that felt it was from an arcade game. Very artificial feeling.
I can't argue with the accountants but from a personal perspective if I could keep to Hydraulic PAS (or even No PAS in many cases) I would.
I thought there was an MPG / Emissions reasoning by not having a Hydraulic PAS pump driven off a belt? I could be making that up.
Regarding steering feel, I have to admit the two MK1 Focus ST 170's I had on demo had very good steering feel (Awful engine but that's a separate issue) where as a much later Focus ST had steering that felt it was from an arcade game. Very artificial feeling.
I can't argue with the accountants but from a personal perspective if I could keep to Hydraulic PAS (or even No PAS in many cases) I would.
Fire99 said:
I thought there was an MPG / Emissions reasoning by not having a Hydraulic PAS pump driven off a belt? I could be making that up.
It's entirely possible that there's a very small benefit - but a hydraulic pas pump will be running light the vast majority of the time, and when it would be drawing power, the bigger alternator will also be requiring oomph. However, I think the CO2/economy test cycles just involve straight lines...Willy Nilly said:
I know when I am pottering round town, ringing the last percentage point from the cars performance is very important to me, so for this reason I will only tolerate a car with considerable steering feel. It also helps when the car is stuck in traffic to be able to feel understeer when I am changing lanes at a brisk walking pace.
See, to me, pottering around town and just following other traffic are moments when steering feel is most important to me in a road car. With the old unassisted Alfa, even just driving through town the steering is fidgeting and communicating as the front wheels find their way down the road. Reminds me that I am operating a driving machine, makes boring drives just a little bit more interesting. On the other hand, the BMWs I tried at the time, in traffic I might as well have been operating an iPhone.Steering and road feel and feedback are the keys to making a car interesting to drive for the 99% of it's life that it's going to spend not pressing on. On the other hand, if you want a car that's fast asleep most of the time and only wakes up when it's on a race track or empty roundabout, I've driven plenty of cars that seem to be good at that.
- OMG - This is hilarious. You wouldn't get much better out of the pretentious wine drinkers of the world. 'Electric steering ruined my car', 'I just don't get the feel with electric steering'. Please, please say that in a nasal voice for full effect. I dare you, you'll cringe.
1) simple hydraulic - engine driven pump either pressurises linear rods or drives a glorified worm and peg/recirculating ball setup.
2) complex hydraulic - engine driven pump again, but this time add in varying assistance dependent on speed or self-centring. Dirass, Diraiv, AdWest - names from the past.
3) simple electric - motor on the steering column provides direct assistance
4) elector hydraulic - similar to 1 and 2 but the pump is powered by an electric motor.
Now I've driven, and owned, plenty of bad cars in my life. I've also sat behind the wheel of some good ones. Mine have either had no power steering or conventional hydraulic power steering. Those connoisseurs who can't bear electric steering clearly haven't driven a 700 series Volvo, and old school BMW or even a Nissan Bluebird. All have hydraulic power steering, are uncannily light and devoid of anything. Honestly I could drive the Bluebird with one finger over rough surfaces. The steering was so light it resembled a vintage arcade machine - I even used to steer the thing by accident on occasion. My mid-nineties Mazda isn't much better.
Moving on I've also had, and own now, cars without power steering. Some were terrible - parking becomes a full on upper body workout and the fetishized feel quickly wears one to distraction. Shaky steering wheel, plus carpal tunnel (in my case) isn't fun. However much of that is down to the pursuit of sportiness. Old stuff with a massive steering wheel and a slow box isn't bad. But try a late nineties Fiesta with quick-ish unpowered rack and pinion steering and the small airbag wheel. You'll hate it. I used to have to drive one, but chose the power steering equipped upgraded model when I had my own Fiesta. Loads better.
Power steering isn't evil! Racing cars have it. Formula 1 cars have it. It's there because, in most cases, it improves steering feel. Non-powered racks are shaky, fall victim to road surface changes, transmit every shock and bump. As a driver taking part in a long race, you wouldn't want all that.
Which moves on to the second point. Steering feel, such as it is, comes from an instinctive knowledge of where the wheels are and what they are doing. That doesn't necessarily mean the steering has to be heavy. Much of it comes from the design of the steering mechanism itself; for example recirculating ball steering as found on the Vauxhall Omega is something to behold. Feels like using a remote control. Add in suspension setups, steering geometry, application of the Ackerman principle, castor and camber angles, tyre width, wheel alignment, tyre inflation. It goes on. That's about half the list of variables.
Tie the two together and you should hopefully realise that steering has many complications. Of course 'feel' can be dictated by how much power assistance there is, but that's been variable since the beginning. It's fairly simple to add more assistance to a conventional hydraulic system, see the Nissan Bluebird example above.
Possibly manufacturers in those heady days pre GM electric steering column, shied away from adding too much power? Poor old Bluebird could do the single finger spin at parking speeds. Honestly, I could turn it lock to lock when stationary. But at 80 mph that lightness got rather intimidating. Thus other cars came with less assistance to add a sense of security at speed.
In conclusion, therefore, the method of providing power assistance isn't of much relevance. Can you honestly tell the difference between a hydraulic rack pressurised by an electric motor and one with a belt off the crank pulley? I thought not. If you were blindfolded and sat in front of steering simulators, could you work it out? No. Same as the wine critics doing blind tasting. They can have a go, but it's hardly exacting.
In my opinion a decent electric setup, as found in my parents' car, is better than a naff hydraulic one, as found in pretty much every car I've ever owned. It does more! Extra assistance when parking, improved 'feel' at speed.
So please, just because some nerd in Regatta trousers once decried electric steering as being Satanic, don't feel he was right. Some understanding of what's actually going on when the wheel is turned helps. I know there are bad electric systems. But there are also terrible hydraulic, and woeful unassisted setups too.
MagneticMeerkat said:
Power steering isn't evil! Racing cars have it. Formula 1 cars have it. It's there because, in most cases, it improves steering feel. Non-powered racks are shaky, fall victim to road surface changes, transmit every shock and bump. As a driver taking part in a long race, you wouldn't want all that.
Which moves on to the second point. Steering feel, such as it is, comes from an instinctive knowledge of where the wheels are and what they are doing. That doesn't necessarily mean the steering has to be heavy. Much of it comes from the design of the steering mechanism itself; for example recirculating ball steering as found on the Vauxhall Omega is something to behold. Feels like using a remote control. Add in suspension setups, steering geometry, application of the Ackerman principle, castor and camber angles, tyre width, wheel alignment, tyre inflation. It goes on. That's about half the list of variables.
You're not really on the same page. Steering weight is not the same as steering feel. It's possible to have light steering with lots of feedback, just as much as it's possible to have heavy steering with numb feedback. Which moves on to the second point. Steering feel, such as it is, comes from an instinctive knowledge of where the wheels are and what they are doing. That doesn't necessarily mean the steering has to be heavy. Much of it comes from the design of the steering mechanism itself; for example recirculating ball steering as found on the Vauxhall Omega is something to behold. Feels like using a remote control. Add in suspension setups, steering geometry, application of the Ackerman principle, castor and camber angles, tyre width, wheel alignment, tyre inflation. It goes on. That's about half the list of variables.
MagneticMeerkat said:
In conclusion, therefore, the method of providing power assistance isn't of much relevance. Can you honestly tell the difference between a hydraulic rack pressurised by an electric motor and one with a belt off the crank pulley? I thought not. If you were blindfolded and sat in front of steering simulators, could you work it out? No. Same as the wine critics doing blind tasting. They can have a go, but it's hardly exacting.
There is no discernible difference between HPAS and EHPAS, and anyone claiming they can tell the difference probably is chatting s
te. But the difference between any form of HPAS and full blown EPAS is very real. The problem mostly stems from the torque sensors on the steering column reading tyre feedback exactly the same as steering wheel inputs, and boosting against them accordingly, effectively filtering out any force feedback to the driver.So you're wrong basically.
MagneticMeerkat said:
In conclusion, therefore, the method of providing power assistance isn't of much relevance.
That was a long post just to make a pointless and incorrect conclusion.The feel isn't so much about the amount of assistance provided as the internal friction within the steering system. With an EPAS system (at least the one on the Civic), when it's providing little or no assistance (i.e. higher speeds) you are effectively turning the assist motor via the worm and wheel, and via the torque sensor which is effectively a spring. This can give enough friction to destroy any feedback and make the steering feel imprecise.
BigBo said:
Not in the slightest to me anyway - What I see above is a tried and tested system that worked perfectly and better IMO for the best part of 30years or more, and what I don't see are ECU's, another loom of wires, Relays and potentiometer's/sensors, water ingress causes problems that never existed in the older system and then there is the added draw on the alternator+battery which becomes all to apparent in cold weather,
And what about the myriad of problems you can get with hydraulic? Leaks from any one of the seals, failed hoses, pump failure, corrosion ect... Epas is much more reliable- part of the reason its more common now. Draw on the battery is absolutely zero issue. Unless you also wouldn't use an aux socket in the car for the same reason? Regarding 'feel' I think there are bad Epas and bad hpas and vice versa. Ultimately there probably isn't an Epas which would better than the very best hpas (lotus esprit ect) at the moment anyway.
The Epas on my cliosport is certainly very good. I wouldn't guess it was electric if I didn't know.
MagneticMeerkat said:
.
In conclusion, therefore, the method of providing power assistance isn't of much relevance. Can you honestly tell the difference between a hydraulic rack pressurised by an electric
I couldn't agree with your conclusion more. It's only one parameter. There isn't anything inherently wrong with an epas that will prevent an otherwise well set up steering system from giving feedback of the quantity and quality of the feedback supplied by hydraulic systems in my experience. Otherwise how does one explain the fact that the steering feedback of the GT86 is so close to say, the feedback of a 987 hydraulic system ? Narrower tyres on the Toyota may help a little, but not to the extent that it compensates for the assumed shortcomings of epas.In conclusion, therefore, the method of providing power assistance isn't of much relevance. Can you honestly tell the difference between a hydraulic rack pressurised by an electric
MagneticMeerkat said:
Moving on I've also had, and own now, cars without power steering. Some were terrible - parking becomes a full on upper body workout and the fetishized feel quickly wears one to distraction. Shaky steering wheel, plus carpal tunnel (in my case) isn't fun. However much of that is down to the pursuit of sportiness. Old stuff with a massive steering wheel and a slow box isn't bad. But try a late nineties Fiesta with quick-ish unpowered rack and pinion steering and the small airbag wheel. You'll hate it. I used to have to drive one, but chose the power steering equipped upgraded model when I had my own Fiesta. Loads better.
I too have owned or driven similar models of cars available both with and without power steering, usually FWD ones. Without exception I preferred the ones with assistance, because the unassisted ones were slow, heavy and had a horrible springy feeling. I just didn't like them (and that included an unassisted 205GTi). So yes, of course, just like the FWD/RWD threads, it's what the car as a whole does that matters, not just one item in its specification.MagneticMeerkat said:
Power steering isn't evil! Racing cars have it. Formula 1 cars have it. It's there because, in most cases, it improves steering feel. Non-powered racks are shaky, fall victim to road surface changes, transmit every shock and bump. As a driver taking part in a long race, you wouldn't want all that.
I'm not a racing driver taking part in a long race. I'm an average driver getting bored cruising up the M4. I do want all that, to add a bit of involvement and interaction to an otherwise entirely mundane drive. And on road cars even the unassisted racks insulate a lot more than a slick shod racecar's with a turn lock to lock.
MagneticMeerkat said:
So please, just because some nerd in Regatta trousers once decried electric steering as being Satanic, don't feel he was right. Some understanding of what's actually going on when the wheel is turned helps. I know there are bad electric systems. But there are also terrible hydraulic, and woeful unassisted setups too.
Most of your post concentrates on the premise that it matters less what the power system is, it matters more how the end product (the car) feels. Any type can be good or bad or can have strengths and weaknesses. That, in your words, more or less, the type of system is largely irrelevant. This I would agree with. However, if this is the case then no understanding of what is actually going on when the wheel is turned is required. We will all like what we like and driving a car will give the answer. It's not always that simple though. The systems DO have strengths and weaknesses and drivers will pick up common threads within that, for example my preference to have assistance in FWD cars. It's anecdotal, just like the wine tasters.Edited by kiseca on Sunday 28th December 11:48
Mr2Mike said:
MagneticMeerkat said:
In conclusion, therefore, the method of providing power assistance isn't of much relevance.
That was a long post just to make a pointless and incorrect conclusion.The feel isn't so much about the amount of assistance provided as the internal friction within the steering system. With an EPAS system (at least the one on the Civic), when it's providing little or no assistance (i.e. higher speeds) you are effectively turning the assist motor via the worm and wheel, and via the torque sensor which is effectively a spring. This can give enough friction to destroy any feedback and make the steering feel imprecise.
Because your car only has a 12v battery, an electric machine powerful enough to move the steering road wheels when at zero speed (say 1kW) is a big, heavy and high inertia device that must be coupled to the steering rack bar via a large reduction ratio (in order to provide enough force). The rotational inertia of the motor is therefore referenced to the racks linear motion via the gear reduction ratio, and hence appears to be massive. So, high frequency vibrations, typically those that are a result of road surface, tyre tread / carcase shuffling etc, get damped and do not make it up to the handwheel. This results in a "lack of feel" to a skilled driver.
Because these are damped by the motors inertia, the system cannot even measure this high frequency component, no matter what torque sensor or control bandwidth is available.
Later systems in the last couple of years have moved to low inertia high torque brushless motors mounted directly on the rack, driving via a lower reduction ratio in an effort to increase the systems control bandwidth. These electric racks look like this:
In future, as the Tier1 suppliers like Valeo, Bosch, and Denso, revise and improve there steering system products i can't see any reason that we couldn't return to really excellent levels of feedback at all frequencies, especially when we move to a higher vehicle system voltage (42V etc)
However, the biggest "Killer" of steering feel over the last 15 years is NOT the steering system itself, but the vehicles tyres and chassis settings!
Tyres are now very wide, and very very stiff / low profile. Those lovely old skool changes in weighting as the tyre started to slip were more a result of the centre of pressure moving around the geometric steering centre point, as the tyre carcass deformed and the vehicle rolled. Modern cars have extreme lateral stiffness, and because they are heavy and powerful, must control the interaction between contact patch and steering geometery very closely (otherwise the large forces will just rip the wheel out of your grasp!
Cars which have classically good steering feel are the ones that are light, have relatively low lateral limits on taller, narrow tyres. As a result, these show the largest and most linear change in handwheel loadings verses tyre slip angle. And being light, have small lightweight suspension/steering components with low inertia, and hence do not damp out the higher frequency road surface vibrations etc
Edited by anonymous-user on Sunday 28th December 12:08
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