PH Blog: known unknowns


Dreams of being a car designer meant my maths lessons were doodled away with drawings rather than working out long division or quadratic equations. More fool me. I've since grown to have a fascination with engineering and the 'grown-up' end of vehicle design and could spend hours being politely baffled by the likes of Lotus's Matt Becker or Mike Cross at Jaguar. What fascinates me in particular is how seat of the pants 'feel' can be turned into something that can be ordered from a component supplier, calibrated and bolted into a car's drivetrain.

British firms still rule for ride quality
British firms still rule for ride quality
Hanging out with Mike Cross recently was a perfect opportunity to address some of these nagging questions that loom like Donald Rumsfeld's known unknowns. Like, why is it cars with passive dampers seem to feel more natural than those with multi-setting adaptive ones? Talk to the marketing guys like BMW's Ian Robertson and they'll tell you these gizmos can give you a car that can both nail perfect 'ring laps and waft like a Roller when you're around town. Which is why cars like the M5 and M6 have a million different settings for dampers, throttle and even steering weight. And yet, in my experience, I've rarely encountered an adaptive system for steering or damping I'd choose over a well-judged passive set-up. So, am I just a Luddite?

In terms of suspension, perhaps not. "A passive damper probably always responds in a way that's consistent," says Mike Cross, "and I think probably what you need to do with an adaptive damper is make it feel as if the car is a little more controlled but try and do it in a seamless way so that the driver is not aware of the system working. If it's obviously doing something, in a way, we've failed."

'Stiff' can still be 'comfy', as our Megane proves
'Stiff' can still be 'comfy', as our Megane proves
And yet the bloke who's just spent a few hundred quid on the optional adjustable dampers still wants to feel something when he pushes that 'sport' button, right? A polite smile in response says a lot. And takes me back to a comment from Richard Attwood on a Porsche launch. As we headed out onto the track my reflex was to hit the Sport button on the PASM. "Don't bother," he growled. "It works better in the standard mode."

What of Chris Harris and his Jag XF's dampers taking time to 'warm up' on cold days? Cross says he'd be surprised if the ambient temperatures - even in the Welsh borders - would be sufficient for that to be a factor. Harris begs to differ. I'll leave them to have that chat anon.

And consider instead the simplistic notion often bandied about that a stiffer suspension set-up automatically equates to a 'sportier' one. That's our - as in motoring hacks - fault. "Comfort and refinement is really important to customers; it's sometimes less so with you guys," says Mike, going on to explain how a 'softer' car can often be the faster car on your typical bumpy British B-road.

Dan and Mike chat in a totally unposed fashion...
Dan and Mike chat in a totally unposed fashion...
As ever it comes down to tuning and calibration and making sure everything is working in harmony. Which is apparently how Renaultsport can get away with ostensibly fierce spring rates on cars like our PH Fleet Megane, the Cup chassis we've opted for running springs 38 per cent stiffer than even the regular 265's. Mike points out that the ride frequency won't have changed by as significant a figure and says we can tolerate significant and rapid vertical movement so long as pitch and roll are well contained. Which translates as that 'four-square' sensation of all corners of the car working together in unison that feels so satisfying. "They seem like very well sorted cars," he says, with particular praise for an Megane R26.R he had a go with. "They've clearly gone to a lot of trouble matching the damping to the spring rates."

The only thing this really proves is that perpetuating the myth that soft can't be sporty and stiff can't be comfy is over-simplifying a complicated engineering problem. Something that perhaps needs articulating more clearly.

Dan

 

Comments (61) Join the discussion on the forum

  • andybu 18 Jan 2013

    We've lost our way on demanding that the car manufacturers must produce good ride allied to good handling. Lotus proved it could be done 40 (ye gods!) years back.

    I am still judging every new car I drive by a fading comparision with time in a Lotus Elan Sprint. Stiff chassis, soft springing but very controlled damping, small wheels, oh - and tires with some compliance too. The end result was magic; if you were precise on corner entry and the car attitude then it was phenomenally quick through the corners. Also proved you don't need 1,000 BHP to be quick either.

    Autocar and other road testers are beginning to signal that smaller wheels & tyres are often better but it needs more customers to say the same. Then things will change.

  • boma 15 Jan 2013

    I've said this before somewhere, but in the 12 years I lived in Leicester and regularly commuted 200 mls cross country via A/B roads back to Abersoch in North Wales, my record time was not set in the M3 Evo, 318 touring, track slag Integra, or either of the other 2 quick Hondas I had, but in my old (and still incredible) Citroen BX GTD Turbo (diesel)...

    Of the numerous suspension set-ups I tried on the Integra (GAZ adj, Ohlins adj, Spax, GMAX), the best actually ended up being the hardest overall springs, but with softer inital non-linear spring curve, and best quality dampers - Eibach Ground Controls with Koni Yellow adjustables. Despite having front spring twice the rates of a std Teg, it was still really good over rough roads, those Konis were excellent.

    But the best thing I ever did to the Integra to improve turn in, corner balance and adjustability was upgrade the rear Anti-Roll bar. I think that's where most manufacturers and enthusiasts probably miss a trick with FWD motors. An upgrade in the rear would give them all the turn in and adjust-ability they want, without sacrificing ride.

  • Slippydiff 11 Jan 2013

    pagani1 said:
    Mike Cross is a giant and Jaguar are lucky to have him. Lotus had such a chap in the 70's and their ride was also sublime. As an old fart my next and possibly last car is (fingers crossed) a Jaguar on the smallest wheel spec for comfort and peace of mind and body. My E46 on 16 inchers is half way there but on 18's is a no no. Isn't it cool that the Germans aren't as good as Jaguar in this area. Then their tarmac is far superior to the usual cheap ste that Highways specify.
    loomx said:
    You could just get the SE variant, or if you want the bumpers, it is a no cost option to remove the M-Sport suspension from the M-Sport.

    My previous car was a F30 328i SE, love it, very comfortable. Now have an M135i without the adaptive suspenion, its much stiffer than the 328i, but its still very comfortable and incredibly well controlled, it always feels well connected with the road even on very bumpy back roads.
    Agreed, the best ride/handling compromise I've experienced on a non- M Sport BMW was an E46 328I SE fitted with 16" wheels, sports suspension and sports seats. Pretty much perfect. I found my CSL a pretty good all-rounder too.

    Runflats have a lot to answer for on any modern BMW, they're the work of the devil, which is why the M sport division have steadfastly resisted their fitment, likewise Alpina.

    I'd tend to trust the views/findings of Mike Cross over those of Mr Harris any day . . .

    Some interesting and apt comments about suspension/spring/damper rates on here. I was lucky enough to own an Impreza WRC car up until four years ago. Then the car was ten years old and was running some fairly antiquated Bilstein Mono dampers, but the ride ? like that of a magic carpet, compliant, controlled and long travel.

    As someone else said, run the softest springs possible with plenty of suspension travel, it'll make for much faster progress along give and take B roads.

    the proof of the pudding ? Try an Impreza 22B along a wet bumpy B road, then try the same stretch of road in the P1 with it's Prodrive developed suspension . . . . One makes you feel like a rally driver, the other will feel pedestrian, but ultimately will be quicker . . .

  • loomx 11 Jan 2013

    V12 Migaloo said:
    I will no longer buy BMW's or Audi's because of their particularly hard ride. My last beemer, a 525i M Sport Auto would not allow my head to stay still even on French motorsways. On some roads I could feel my fillings move, and all for the sake of handling when 98% of the time the steering wheel is in the dead ahead position. I resolved this by buying an XJ, great ride and handling comprimise, albiet with a little more roll then the beemer on smaller round abouts but by far a better prospect and set up on a day to day basis. For christ sakes I could make a marina handle just as well as the beemer if i fitted 19"s and concrete dampers..
    You could just get the SE variant, or if you want the bumpers, it is a no cost option to remove the M-Sport suspension from the M-Sport.

    My previous car was a F30 328i SE, love it, very comfortable. Now have an M135i without the adaptive suspenion, its much stiffer than the 328i, but its still very comfortable and incredibly well controlled, it always feels well connected with the road even on very bumpy back roads.

  • pagani1 11 Jan 2013

    Mike Cross is a giant and Jaguar are lucky to have him. Lotus had such a chap in the 70's and their ride was also sublime. As an old fart my next and possibly last car is (fingers crossed) a Jaguar on the smallest wheel spec for comfort and peace of mind and body. My E46 on 16 inchers is half way there but on 18's is a no no. Isn't it cool that the Germans aren't as good as Jaguar in this area. Then their tarmac is far superior to the usual cheap ste that Highways specify.

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