Race and road car suspensions

Posted on July 30th, 2006 in Handling,Opinion,Suspension by Julian Edgar

I don’t claim to be well versed in race car driving, although I’ve driven a production race car for a few laps of a circuit and I’ve driven road cars on skidpans and race tracks and at manufacturers’ proving grounds.

Conversely, I have driven probably about half a million kilometres on roads. Like you probably also have, I’ve driven on smooth freeways, on rutted dirt, on gravel and patched bitumen, and roads with corners and roads with straights. Roads with hills; roads that are flat. Roads with lots of traffic; roads with none. Roads that are easy; roads that throw corners and dips at you with startling, frightening suddenness.

And I know that the most common attribute of roads is their inconsistency. Not only do roads suddenly change as you progress along them, but the same road can have an utterly different character if the weather or traffic change.

The times that I have been on racetracks have shown me one thing: their variability is simply vastly less than roads. Yes, there can be changes in weather and traffic, but you don’t usually need to be wary of cars coming the other way, cars that might cross the centreline, for example. You don’t need to wonder where the next corner goes and – after one lap – you don’t need to worry if the surface has deteriorated overnight, or an errant truck has sprinkled gravel or diesel across your path.

And roads have bumps, lots of bumps. You need only watch racing cars on street circuits to see how smooth the tracks they drive on usually are. Even the groomed-for-racing street circuit looks bumpy when being traversed by racing cars; a road car barely notices.

So, as I have written here before, I think that setting up a road car on a race circuit is madness. Simply, the way you want it on a racetrack is not the way you want it on a road. Or not the way I want it, anyway.

In fact, when I drive modified cars on the road, the more the owner talks about race track times, the shittier I know it’s going to be. It’ll bounce from bump to bump, be twitchy and over-responsive to any control input, and often have nervously sensitive steering. Simply, not what suits the road.

Click for larger image But the other day colleague Michael Knowling made a good point to me about this topic. We’d just been driving the Skelta, a very specialised car that’s really been purpose-designed for tarmac rally racing events. It runs a tubular steel chassis reinforced with carbon fibre sections, specially fabricated double wishbone suspension, huge brakes, and so on. In its debut performance it ran as high as second place in Targa Tassie, before dropping out with a driveshaft problem. I haven’t driven in the Targa Tassie event, but I have driven over a lot of those same roads in a Toyota camper. And they’re real roads – nothing like a sanitised racetrack.

And the point that Michael made to me? The Skelta rode and handled like a good road car! It’s got an incredible (well, incredible for a race car) 200mm of suspension travel and the wheel rates and damping set-up were quite appropriate for road use. (Then it was all stuffed up in the car we drove – it was fitted with an ultra-quick, heavy steering system.)

Click for larger image Another ex-Targa car we’ve driven is a Skyline GTR N1. As described in Driving Emotion, that car handled better than any car I’d then driven, but still had a decent road car ride.

These are race cars set up very differently to conventional racing cars; these are cars that have to flatter the driver when he or she meets something unexpected halfway around a corner, or when the road dips and dives through a wash of water crossing the road. On a racetrack no doubt they’d be slower than a car set up specifically for that track; in every real road circumstance they’ll be better.

It seems to me to be such a self-evident point that I’m amazed others still argue to the contrary, but a car with good track suspension will almost always be crap on real roads.

And race cars that run on real roads like Targa Tassie? Well, I reckon they’re heading in exactly the right road car direction.

One Response to 'Race and road car suspensions'

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  1. Andreas said,

    on August 10th, 2007 at 2:08 am