We conclude March’s theme by wondering if the engineering ideal of suspension that thinks for itself is any closer to reality now than it was thirty years ago.
Pity the unfortunate suspension engineer, saddled with the seemingly impossible task of reconciling the hugely complex operating range of the motor vehicle against the twin imperatives of providing a comfortable ride for passengers, while allowing sufficient body control to allow for accurate and consistent handling. Under such constraints, the successful melding of conflicting forces acting vertically in ride and horizontally in cornering and steering, can only result in unhappy compromise.
Physics will always win, no matter how clever our putative chassis guru might be. And some of them have been very clever indeed, although superiority in this sphere can often be as much a function of an intuitive proving engineer as any groundbreaking idealist. Take for instance, the ability to successfully marry tyre and suspension characteristics, often being a process tantamount to alchemy. According to Leonard Setright, who seemed to know about these things, what was good for handling was also good for ride, although in this respect I’ve never fully understood what he was on about.
But some things will always hold true – for instance a tired driver is a less alert one. Because despite what Alec Issigonis might have asserted, driver comfort was, is and remains a safety issue. Given there’s been better solutions to the conventional steel spring/damper suspension available for well over half a century, we really ought to have left it all behind years ago. But complications of cost and cowardice have allowed the motor giants to successfully soften up the motoring public to low expectations, a position now gleefully accepted without question. Harsh = sporty = good. QED.
With Citroen and BMC blazing a more virtuous trail decades ago, it’s clear that some form of computer controlled, hydraulically actuated suspension system was and remains, if not the holy grail, a decent stab towards it. Lotus began working on active suspension technology around 1980 during the ‘ground effects‘ era of grand prix racing, when the levels of downforce being generated were effectively doubling the car’s static weight at racing speeds and the required suspension stiffness rendered the cars virtually undrivable.
This led to work on ‘synthetic springs’, hydraulic arms powered by a pressure pump and actuated by computer controlled valves. There were no springs, more a series of links worked by what Lotus engineers described as muscles controlled by an electronic brain, responding to sensors and a series of control parameters. Basically, active ride allowed Lotus to decouple force from displacement and the results as reported by Car‘s Steve Cropley in October 1986 were, even allowing for his notable propensity towards hyperbole, pretty impressive.
Cropley observed that the test Lotus Excel; “…refuses to roll or dive, or lurch or pitch, whatever you do. The car felt, most eerily, to be in touch with the road… All you could conclude was that this was a car that didn’t have to obey the rules that other cars live by”. Car made it their cover story, proclaiming the Lotus’ active prototype as; “the greatest single advance in car engineering since the war.”
Having reached a stage in its development where car companies such as GM, Volvo and others were successfully running prototypes, why it failed to make the final hurdle to series production remains one of those automotive mysteries yet to be satisfactorily explained. Cost, complication, politics? Certainly, the results being reported in 1986 suggested its introduction was imminent.
In its absence, perhaps the nearest and best approximation is the excellent Tenneco kinetic system used by McLaren in their current road cars. Mercedes-Benz too, having experimented with air and a form of oleopneumatics themselves over the years currently expound upon what is cringingly referred to as ‘Magic Ride‘, which despite being undoubtedly clever, sounds like a decal you’d find residing beneath a side rubbing strip on a mid-80’s Mitsubishi Tredia.
Employing lasers to read the road ahead and telegraphing this data directly to the suspension’s electronic brain has certainly yielded notable gains in passenger comfort, but behind the microprocessors remains hardware that would not be unfamiliar to a 1950’s mechanic. But even active ride on the cheap is better than nothing at all and at least Daimler are making the effort, which is more than can be said for most.
But looking further ahead, what form of suspension design will the autonomous car of the future take? By decoupling the driver from the equation, surely such terms as ‘ultimate handling, steering feel and incisive turn in’ won’t butter too many parsnips. But I suspect ride comfort will. After all, while technology can envisage a world without rough edges, reality tends to rather annoyingly intrude. Because in our roseate binary future, road surfaces will continue to crumble beneath our wheels. Not everything’s going to get better.
Driven To Write 
Can we say that active suspension is akin to nuclear fusion as a means of generating power? More work has gone into it than the results can justify and a commercial application is always ten years away.
While our roads have got busier and more restricted the focus has been on handling more than ride meaning less brain power and fewer resources have gone into suspension with a focus on comfort. I expect autonomous driving should make comfort a bigger factor although that will be too late. I recommend the train and a bike instead of the absurd space pods that are being dreamed up.
Putting things in perspective, ride quality in many modern cars is very good indeed. How good does it have to be? If a Ford Focus or a Kia Ceed ride as well as a hydropneumatic Citroen on most roads then that’s 80-90% of the problem solved for most people.
Just a thought – ride comfort would improve dramatically if manufacturers ignored the motoring press. Nobody on the public road needs a car that can lap the Nurburgring in under 8 minutes. One of the cheapest solutions to improve ride is to fit tyres that do what tyres were originally intended to do i.e. absorb the roughness of the road. Why normal family cars need 40 aspect ratio tyres is anyone’s guess ( my guess is that marketing rules the car industry and have trained us to think low profile tyres and huge wheels are astheticly de rigueur).
I often wonder about this in the context of Ireland where I come from and visit twice a year. You often see Audis with no-profile tyres. It is perplexing to imagine these drivers have access to silky smooth, high speed roads upon which they can make use of the suspension and tyre specs of their sportline cars. The roads in Ireland and narrow and badly surfaced, even the motorways which have coarser dressing than in mainland Europe. My father has a Focus estate with quite high profile tyres and even that car rides rather horrilbly. The same car in Germany is pleasant to drive in sharp contrast.
The truth of the matter is that most customers prefers form over function. Even here in Chile, with our very poorly surfaced secondary roads and gigantic potholes, it has become almost impossible to order a car without low to ultra low profile tires, even on off-road oriented SUV’s such as the Discovery 4 or the Jeep Grand Cherokee.
I suspect one of the qualities people find attractive about CUVs is the ride afforded by extra suspension travel and larger dead cat holes. Indeed, I suspect that one of the reasons Audis have historically ridden so firmly is their quest to eliminate dead cat holes from their wheel arches.
Where do semi-active magnetorheological damper systems fit into this history? GM seems particularly keen on this technology and by all reputes it works miracles on Corvettes and Cadillacs alike.
There´s a technology that is under-used. Citroen could have had a stab at something along those lines if they did not want to carry on with HP.
Magneto-rheological technology has been around for quite some time. Don´t Bose have a version? No-one seems very willing to take it up so it seldom gets from being more than fodder for car technology articles in magazines.
According to Wikipedia:
“These types of systems are available from OEMs for several vehicles, including the Acura MDX, Audi TT and R8, Buick Lucerne, Cadillac ATS, CTS-V, DTS, XLR, SRX, STS, Chevrolet Corvette, Camaro ZL1, Ferrari 458 Italia, 599GTB, F12 Berlinetta, Holden HSV E-Series and Lamborghini Huracán. These systems were produced by the Delphi Corporation and now by BWI Group under the proprietary name MagneRide.”
Mark’s point about tyres is very relevant. I viewed the 20″ wheels to be fitted across the range on the new Scenic with respect and horror. Respect that designers had at least ensured for once that their showcar promises were honoured. Horror that this will set a precedent. Walk down any London street and find a full set of alloys that haven’t been scuffed by errant curbs, unless they are driven by someone who parks in the middle of the road. I love the fat 70 profile Michelins on my old Citroen as much as I loathed the mean 40 Series tyres on my Audi. As Richard points out, deeper tyres don’t ensure a good ride, but they do make the suspension engineer’s job a bit easier.
Possibly we need to admit that, basically, we (the customers) don’t really care about ride comfort that much. Or seat shape. Or driving position. Or visibility. Unless any of these things end up giving us a bad back or causing us to crash, we don’t give a toss. We don’t notice. Watch people on their sofas, or work seats. Designers try to make these objects just right and we end up sprawled, lopsided, with one leg bent underneath us and an elbow over the backrest. We are, in essence, slobs. We can’t tell the difference. The designer’s or engineer’s time is wasted. People go “yeah, this Citroen rides really well – so what”. “Yeah, my Audi’s a bit harsh over the bumps, so what – keeps me awake”.
Sean: is it time for a refreshingly crisp Manzanilla? Or a soothing glass of Lustau’s excellent Don Nuno oloroso? Perhaps a nice Marsala is on order if need something a shade less dry?
A case can be made that customers do care about seating and usability but that designers or more likely cost-cutters of various types prevent the execution of good ideas. What the customer can’t often do is express these preferences. The forces of indifference are, in this case, stronger than the passive buyers’ preference. Comfort used to be attended to by people aware of the less quantifiable elements of car design. The coarser side of the motoring press and chsnges to firms’ internal taste-arbitrators meant comfort got neglected. I bet a properly modern but comfort-biased car (a Citroen, if the world was sane) would be a success. I am convinced customers would accept the comfort and re-assess it in the context of non-retro, quality, advanced design.
Spot on.
Richard. Just because I agree with everything you say, that doesn’t make you right. My case is that only a handful of us are connoisseurs in a particular field, and none of us are connoisseurs in all fields. You can teach people to concentrate on specifics, but there’s too much noise in the world to differentiate that broadly. Most people driving cars are thinking about something else and, really, they don’t notice, let alone savour, the experience. I totally agree that the obsession on faux sportiness for everyday vehicles is stupid – actually I find it demeaning that we fall for it. But I don’t believe most driver’s attitudes towards their cars is sensual. Sadly, what is more important is what they represent.
We (who like to think ourselves informed) might believe that we know what is best for them, but do we really? Are we like a head waiter recommending a Mouton-Rothschild to a diner when, really, they’d be happier with a bottle of their usual Shiraz.
Daniel: thank you!
Thx, but that was meant as a comment to Sean’s text, I have to admit. Had not read yours by the time of writing…
Another interesting design was the Bose Suspension System with linear electric motors. Impressive stuff
https://www.bose.co.uk/GB/en/automotive/innovations/suspension-system/the-challenge/