Doing only half the job
The function of the suspension is to allow tyres to follow the ups and downs of the roads, while at the same time the car’s body movement doesn’t replicate those ups and downs.
However, if that was all that was needed, a very soft suspension would achieve these aims very well – but the car would handle poorly. So the first two points subsequently need to be modified to achieve competent handling.
And for decades – perhaps eight or nine of them – this was the way in which suspension development in cars occurred. Cushioning occupants was primarily about spring rates; maintaining tyre contact was about damping; and achieving good handling was about dynamic wheel location, roll centre height and roll stiffness.
The trouble is, to my way of thinking, in the last decade or so that whole approach has gone out the window. The approach is now:
(1) gain best handling
(2) refine system to provide acceptable ride comfort
Now let me say loud and clear: in sporting cars that’s fine.
But in all cars?
How stupid.
Let’s put all this a different way. Pick a car from 30 years ago and pitch it in a handling contest against the current equivalent. Yep, the current car will win. Now fit the old car with low profile and wide rubber, massively stiffen its springs and damping and anti-roll bars – and I’d suggest that the old and new will now be very close in handling….as measured on real roads.
I’d argue those designers of that 1980s car could have had similar handling if they’d chosen to degrade ride comfort in the way of current cars.
But this is not a blanket condemnation of modern car technology. Electronic stability control is a fantastic handling innovation. All-wheel drive with variable torque direction is a fantastic handling innovation. Electronically-controlled power steering is a fantastic handling innovation (“handling”, because it allows higher degrees of castor, and so greater negative dynamic camber addition). Multi-link suspension systems and variable direction suspension compliance are fantastic handling innovations.
It’s not the current technology: it’s the current philosophy.
The outcome is rather bizarre. There are now many people who have never been in a car that rides well. They have no knowledge of what is possible: they simply believe that all cars ride in a manner in which in the past only trucks rode.
Recently I drove a diesel sedan from a car yard. The ride, factory standard, was so harsh I could hear my wife’s voice changing as air was forced out of her lungs by the bumps. Just in a normal suburban area of an Australian city. I took the car back.
“I won’t buy this,” I said, “the ride is so harsh.”
The young salesman’s face contorted in genuine disbelief. “How do you figure that?” he asked incredulously.
Clearly, he had never been in a car with a good ride.
It’s a bit like people who have listened to only MP3s played through tiny speakers. They have literally no idea of what good sound is like.
So what would be logical reasons that current car designers have chosen to degrade ride comfort at the expense of handling?
Oh, well speed limits have gone up hugely over the last 20 years, so better handling is needed to cope.
And another: the enforcement of driving behaviour is so much less rigorous than it once was, so everyone can now punt their cars hard on the road.
And a final: all roads are now so well surfaced that the poor roads of 20 or 30 years ago are now gone.
But not one of these is true!
Cars with suspension set up for smooth race tracks (or to put this another way, set up so that they get good media reviews from young, single, performance car drivers) are silly for general road use.
These days, the vast majority of new cars have tyre profiles that are too low, bump and rebound damping too stiff (especially at high damper shaft speeds), and springs that are too high in rate. For car occupants, roads are a procession of jolts, where they could be a smoothed and relaxing surface.
And all for what purpose? Very little that’s justifiable.