I’d like to talk about suspension.
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Ok, so everyone still here has some interest in engineering, good. I suspect the people who just ran for it might well end up as the subject of this post. We’ll see.
Lets visualise one corner of a simple car suspension system. You have the car body at the top and an axle at the bottom, to which the wheels are affixed. Inbetween these you’ll have a coil spring, usually made of steel. This spring holds the car above the road, compresses over the bumps, and returns the whole affair to the correct height afterwards. Running either through or next to this spring you’ll have a damper, which is essentially a tube full of squishable stuff and a series of baffles to allow it to slosh around at a controlled rate. This soaks up the bumps in conjunction with the springs, and affects how smoothly the car rides by controlling the impacts from the road surface. You may also have an anti-roll bar, which is a long bent piece of metal that’s bolted to the suspension on each side of the axle and fixed with a pivot in the middle of the car. When one wheel takes a big upwards hit, this bar bends and lifts the other wheel by a lesser degree to reduce body roll. Quite barbaric when you think about it.
Ok, so lets see how we might make this better. We can’t do much with the dampers because we already have some slick technology there in the form of self levelling systems, magneto-rheological control mechanisms, etc. We’ll leave those for the moment. The coil springs are quite heavy and also mounted relatively high up, so they raise the car’s centre of gravity in addition to weighing us down. We’ve had coiled springs since around the 15th century, so they’re about due for an overhaul – lets start by making them out of a lighter material that’s just as strong, and situating them lower down. If we’re careful with our choice of material they may even outlast the original steel coils. I reckon something like a fibre and epoxy composite might work really nicely here, as that’ll be very strong but also light. We can probably mess about with the shape so that it takes up far less room than a coil too. That anti-roll bar is a bit basic as well – the mounting bushes are always a weak spot and the bar can suffer fatigue. It’s be really nice if we could find a way to create an anti-roll effect from our new spring composite suspension, so we can either get rid of the bar or fit a much lighter one that has to work less.
Sounds like a good job. We’ve lowered our centre of gravity, toughened and lightened some major components for a longer lifespan and a big weight saving, made further components unnecessary, and saved space within the bodywork for other stuff. What we’ve done is to invent the composite transverse leaf spring… just as you’d find in a modern Corvette.
Now you see where this is going, and why it’s just as well the pub experts left at the start. They’re suffering from a condition I call Clarkson’s Cerebralitis – this is a terrible state of affairs where people listen to Jeremy’s hyperbolic and entertaining statements about a subject, take them as gospel and repeat them to all and sundry as fact. Now, I don’t believe for one minute that Grand Poobah Clarkson understands the complexities of car suspension, but I bet he knows eenough to appreciate that the ‘ox cart’ jibes at the Corvette aren’t really anywhere near the truth. What he’s doing is winding up the fanboys and having a bit of fun with Chevrolet, and that’s all well and good.
Unfortunately we live in a Wikipedia world where checking the facts is someone elses problem. I’ve lost track of the amount of times I’ve heard Corvettes compared to agricultural machinery from people who couldn’t actually point out the spring if they saw the chassis stripped down, and that’s getting annoying. What worries me even more is that some writers in car magazines have started to use the same analogy, and I’m not sure they’re in a position to assume the readers will see it as humour. This would imply that they too think it’s true, but I’d rather not consider that option.
In short, I have no real love of the Corvette (except possibly some of the big block late ’60s models) but I do appreciate that it has a lot of clever technology and modern features on board. Slating it because of a misplaced understanding of how it handles the rough stuff is like criticising Jean Paul Gaultier for designing clothes because we had that old-hat technology when we were cavemen.
