Porsche and the death of steering feel


Steering feel. Much discussed, little understood and yet the crux of many a roadtest. Oily, nuggety, intuitive or fidgety - however you like your steering there's a cliché to fit.

And now there's a new cause celebre - electric steering and the supposed death of our cherished feel'n'feedback. When even the new 911, and Boxster not long after, adopted EPAS a watershed passed.

A 997 and a twisty British backroad - perfect!
A 997 and a twisty British backroad - perfect!
So how better to accept an invitation to Silverstone for a bit of product and tech indoctrination than hopping into a 997, pointing it up the A413 and savouring what we'll be missing. It's a perfect road for the job too, sweeping, fast corners with good sightlines, occasionally crappy surfaces and some lazy undulations and gradient shifts for good measure.

Time to wheel out those clichés because, as ever, the 997's wheel offers the kind of texture, feel and feedback that we'll apparently not be getting again from a Porsche steering wheel. It's the gentle murmurs and shimmies that tease your palms as the 911's nose arcs through the twists and turns of a classic, flowing piece of British backroad that, for many of us, make the whole Porsche experience so enriching.

Sprenger (second left) and the Porsche team
Sprenger (second left) and the Porsche team
A little knowledge...
Figuring words like 'nuggety' and 'feelsome' won't cut much mustard with the Porsche boffins I arrive at Silverstone armed with a bit of inside intel from a friendly engineer, and readiness to demonstrate quite how dangerous a little knowledge can be. I've also courted PHers for some questions, Actus_Reus, Ian_UK1, RemarkLima and Fioran0 among those chipping in with questions for the boffins.

And after a couple of hours on the twisty little handling circuit at the Porsche Experience Centre in a succession of 991s and new Boxsters I corner Porsche's General Manager Chassis Development Suspension, Steering and Hydraulic Systems (snappy!) Florian Sprenger and ask him "why have you ruined the 911's steering?" OK, I put it a little more tactfully than that but, regardless, I'm not entirely surprised to discover he's prepared for this.

Proving a point, via the medium of 911s
Proving a point, via the medium of 911s
First the 'why' bit. This is fairly easy. First, it's cheaper and easier to install. There's no need for a hydraulic pump in the engine bay, fluid lines to the steering gear (a fair distance apart on a 911 of course) and it's essentially maintenance free. Once you've designed the steering hardware it can be installed in any number of different cars and simply tuned to suit each application, or even variant should you be so inclined - it's all software based so, relatively, easy and affordable. And let's not forget the improvements in CO2 and fuel consumption.

So the engineers like it. And so do the bean counters. But since when have we wanted them to dictate how our 911s drive?

This is just the start
But there's a bigger picture here. Start-stop is in its infancy but likely to expand into engine-off coasting and the need to be hybrid ready means you need power steering that works whether the engine is on or not. Put simply, EPAS is something we're all going to have to get used to, like it or not.

Having accepted that future Porsches are all going to have EPAS how are they going to make sure they still offer the feel and feedback we're used to?

Porsche EPAS system designed with ZF
Porsche EPAS system designed with ZF
According to my inside man the big issue with EPAS is the inherently greater friction in the system (there are more moving parts) and increased inertia. And as a result the higher frequency feedback to the palm of your hands is masked and you don't have that same intuitive sense of what the front wheels are up to. Worse than that, word has it that Porsche has decided to filter out that higher frequency 'information' with its EPAS system for a smoother feel.

And it's here I enter shaky ground - briefed with my questions I sound (a bit) like I know what I'm talking about. But much as one could learn how to ask 'which way is it to Starbucks?' in Mandarin in no time at all it's naff-all use if you don't understand the answer.

Porsche's steering uses 'bottom up' control
Porsche's steering uses 'bottom up' control
Sprenger's eyebrows flicker but he answers deliberately and in layman's terms. The added friction? He says a good hydraulic system would need 150-200 Newtons of force were one to simply pull the tie-rod. "Initially it was too high," he admits, "so we got the friction down to similar levels."

Top down versus bottom up
And the inertia? "The mass of inertia is higher because you have this huge electric motor that you have to accelerate and decelerate," says Sprenger. "But with our controller, since we are controlling a direct force we are able to compensate; other systems are just tuned to fixed graphs and you always have this much assistance [whatever the circumstances] but we leave the amount of assistance open and control it through our rack force controller." He goes on to say many rival EPAS systems are 'top down', ie, the assistance is calculated through the input torque from the steering wheel. Porsche goes the other way - "bottom up" in Sprenger's words - and uses the wealth of data available through the CAN from steering angle, yaw rate and other information coming through the stability control sensors to vary the assistance and, therefore, 'weight' at the wheel. Developed with ZF, the hardware and basic principles - referred to jokingly as EPAS 2.0 - is something Porsche claims a head start in. ZF will sell it to other manufacturers but, of course, installation, suspension geometry and programming will vary from brand to brand. Fundamentally though it's still a technology in its relative infancy and there's still room for it to develop further.

"Try it on a racetrack" they said ... rude not to
"Try it on a racetrack" they said ... rude not to
More than a feeling
So there's the why and how. The final bit, the bit that matters to the likes of us, is that less definable 'feel' thing. And in Porsche's EPAS system it IS contrived.

Imagine you were to keep adding steering lock during a constant radius turn with a conventional HPAS or non-assisted system. The rack force increases with lateral G and slip angle but tails off as the tyre runs out of grip - that sickening lightening at the wheel that tells you you're understeering. On its own an EPAS system doesn't recognise this. It simply says 'steering angle x, speed y, assistance force z' and can't 'read' that loss of grip, unless you tell it to. Which Porsche says it does, through that 'bottom up' system and a contrived reduction in rack force to simulate - yes, simulate - the sense of feedback at the wheel.

Artificial or not, on-limit feel is still there
Artificial or not, on-limit feel is still there
And the filtering? The Porsche EPAS 'cleans' out anything above 15Hz, the 'acceptable' range for feedback apparently 11-15Hz. An HPAS system would feed back as much as double that, possibly that intuitive nth degree of 'feel' we all harp on about. To put this into context inputs at the wheel end are typically 0.5Hz, 1.0Hz for a high-speed correction.

Artificially enhanced
So 'feedback' is filtered out and 'feel' is artificially created. But does it matter? Sprenger and his colleagues say no. With a roll of the eyes they point to similar outcry at the introduction of power steering on the 964. "The steering should be in the background and it should be comfortable and let you focus on the main task," says Sprenger. "We found a way to transmit things like road texture, understeer and oversteer these are the critical things the driver wants to feel. What I would recommend is be open-minded, drive it on the track, just be honest - did you miss anything? Did the steering hold you back? I'm pretty confident you would say no."

And pushing a 991 hard around Silverstone's National circuit he's right. It doesn't hold you back. You can sense that limit. The steering is well weighted, instinctive and pin sharp.

997's steering still the last word in feel
997's steering still the last word in feel
So you can accept his argument and understand why it had to be done. But as the 997's front wheels track the cambers and surface changes of the A413 on the way home and the wheel gently writhes, wriggles and tugs at my hands it just feels more alive and natural. And it took me until now before I even thought to mention analogue versus digital. Over to you...

P.H. O'meter

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Comments (178) Join the discussion on the forum

  • MadMark911 30 Aug 2012

    Slippydiff said:
    MadMark911 said:
    I've owned a 987 Boxster S, a 997 Carerra C2S and my current toy is a 997 GT3 so I would like to think that I "get" Porsches and steering feel is a key part of the experience, the GT3 being arguably the "best of breed" for me.

    Well I went to the Porsche Experience Centre at Silverstone to drive a 991 for the first time and was quite disapointed! Yes the steering is accurate and direct, but I found (as was confirmed by instructor) that I wasn't turning in fast or hard enough when we were playing "slide the 911" on the Ice Hill / Kick Plate / Low Grip Surface; because I just couldn't "feel" the transition from "grip to slip". OK it was much better on a dry Handling Course and when just nibbling the limits of understeer / oversteer, but for me it didn't give me the confidence I wanted.

    So unless the optional Sports PASM or later iterations of the 991 improve things, I can't see myself buying one! frown
    No disrespect to you Mark, I suspect that having owned the vehicles you've listed, you don't get Porsches or more accurately that their steering feel is a key part of the experience of driving them.

    If you'd driven/owned a 2.7 RS, a 964 RS, a 993 RS and a Mk1 996 GT3 (and some would say a 996 GT3 RS) then you'd know just what Porsche steering feel is, and how key it is to the whole 911 driving experience.

    As plenty other have highlighted, Porsche want to reduce production costs, if fitting a cheaper part enables them to do that that, they will. Seemingly they'll go to the end of the world to justify the fitment of such a part, even when it's removed a key part of the DNA that contributes to the 911 driving experience.

    Though I still own several of their cars, I feel nothing but disgust towards the company that used to prize their engineering integrity and customer loyalty above everything.
    No offence taken - I did say "I think", what I should have said was that I got more "modern" Porsches, but I agree with Manks. You're going back too far for me and whilst they might be the best reference points - they're not mine - they're yours!

    Manks said:
    More accurately what old Porsche steering feel is.


  • brianjohns 29 Aug 2012

    cmoose said:
    Maybe. Mazda have got enough problems of their own surviving for the very reasons I mentioned above without being distracted by a project that in realistic terms is entirely inconsequential.

    Don't want to be all doom and gloom. If I had the money, I'd be having a close look at the G60. In theory, it's everything I want in a sports car (except the cabin, which looks pretty ghastly) and I wouldn't have a problem not having the badge, so to speak.
    cmoose,
    Take a look here at the future of industrial design...
    http://vimeo.com/47522348#
    and
    http://blog.makezine.com/2012/05/14/jay-leno-scans...

    We aren't that many years away from being able to design (any type what-so-ever) large parts (be they metal or CFRP) with far greater accuracy and at much lower cost. If allowed by the powers that be, this tech will change manufacturing at some point. b


    Edited by brianjohns on Wednesday 29th August 00:20

  • brianjohns 29 Aug 2012


    This is one of the bests points of all:

    "I wouldn't have a problem not having the badge, so to speak."

    Me too for goodness sake. I am tired of badges and images to keep up. I got to think that there are some people out there for whom a badge is a bit silly after awhile. I would actually take some pride in knowing that others DID NOT know what brand of car I was driving. b

  • cmoose 29 Aug 2012

    Maybe. Mazda have got enough problems of their own surviving for the very reasons I mentioned above without being distracted by a project that in realistic terms is entirely inconsequential.

    Don't want to be all doom and gloom. If I had the money, I'd be having a close look at the G60. In theory, it's everything I want in a sports car (except the cabin, which looks pretty ghastly) and I wouldn't have a problem not having the badge, so to speak.

  • brianjohns 29 Aug 2012

    cmoose said:
    Adding gadgets is far from easy, ditto a "plush interior" that doesn't get annihilated for fit and finish in the press. Lotus got a kicking for the Evora's cabin and that was probably better than anything a company like Ginetta could aspire to.

    It would probably wipe out Ginetta's entire development budget just honing the overall wind noise to acceptable levels let alone anything else.

    The bottom line is that if it was easy, people would be doing it. You hardly need me to dish out the roll call of start ups that have had a crack and failed miserably. Even TVR has evaporated. And that's why it's a shame when Porsche moves its cars further away from the sports car core. The barriers to entry for new car makers are so very high, we kind of need Porsche to not forget its roots.
    I mostly agree with you. BUT, I will look at this with slightly more positivity..by that I mean Ginetta is only recently been doing this- the close to a road car- thing for a VERY little while. I think it is way too early to say that for instance Ginetta's collaboration on engines and gearbox's with Mazda cannot go further into interior and maybe some NVH technology if Ginetta get some traction. They seem to be headed that way; and fabrication costs are going down every year- just listen to Gordon Murray (and ask BMW who are learning how to make CFRP cars fairly inexpensively) about that. This task is hard but by no means impossible as technology improves..I think it is a matter of time before Gordan Murray type dreams- (well there really not only his to be fair) will start to make sense on a larger scale. b

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