Setting it up. Hows it done then ?

[RobM]

Setting a car up to oversteer, or understeer, or do any other type of magic dynamic that'll help you get round a track quicker. Hows it done? What bits do you stiffen and twist to make it do this sort of thing. The only way to make oversteer more common is to make it lighter at the back isn't it. So do you put weaker springs on or something. I dont know, anyone else know ???

[GreenV8S]

quote:Setting a car up to oversteer, or understeer, or do any other type of magic dynamic that'll help you get round a track quicker. Hows it done? What bits do you stiffen and twist to make it do this sort of thing. The only way to make oversteer more common is to make it lighter at the back isn't it. So do you put weaker springs on or something. I dont know, anyone else know ???

The short answer is that in general, stiffening the front of the car relative to the back encourages understeer, and stiffening the back relative to the front promotes oversteer. The most common way to make this sort of adjustment is with an adjustable anti-roll bar but you can get a similar effect by swapping the road springs. But as you can probably guess, once you get into it you'll find there's a *lot* more to it than that.

It's a fascinating area which I've spent a lot of quality beer time on over the last couple of decades, and started putting into practice in the last few years. If you're seriously interested, I think there are several things which are crucial in order to get to grips with this.

Most important, you need to learn to recognise what the car as doing. This means spending time behind the wheel pushing the envelope, but you also need to *think* about the feedback you're getting from the car not just keep driving round the problems.

You also need to understand the basic principles which determine how the car handles. This knowledge will enable you interpret the feedback the car is giving you and understand how you can change it. The best way to get this knowledge is to read a good book. Or several good books. Firsly on chassis dynamics, secondly (if you're dealing with high speeds) car aerodynamics. Thirdly, on the process of setting up car suspension. There a several well known books that cover all these areas to varying extents. I haven't found any one book that covers all of them thoroughly.

The third thing is to treat the process of setting the car up as a scientific experiment. If you just keep changing everything hoping you'll just hit the perfect setup you won't get anywhere - you need to make very controlled incremental changes and gradually move towards the handling characteristics you want.
I'd say go for it, if you're a keen driver you'll enjoy it all the more when you understand how to make the car handle the way you want. But don't expect a magic bullet. Because there's no one setup that is perfect for all conditions and all tracks you'll find this process never really stops, once you know what is going on you'll find yourself continually experimenting with different suspension settings or maybe just tyre pressures, looking for today's ideal compromise.

Have fun,
Peter Humphries (and a green V8S)

[RobM]

Thanks pete
its an interest i've had for a while, but never managed to persue it, cause i dont have the ability to interpret the feedback (yet!) or a car to experiment on. The project i'm working on has re-kindled the interest as it involves writing a realtime physics model that simulates vehicle dynamics. I was hoping to know if tweaking the rollbar strength was actualy having the effect that it is supposed to, or more often the case, attempting to create the effect in other ways, if you see what i mean ?
Thanks again
Rob.

[Paceracing]

Peter,
It's interesting to note that we both think in terms of suspension in exactly the same way!
The one book which stands out as a good starting point IMO is Competition Car Suspension by Alan Staniforth, no doubt you have read it cover to cover at least twice!
One piece of further advice on suspension adjustment is to be very careful how you drive the car after making changes. It is very easy to make an avarage handling car very unplesant, not to mention dangerous to drive. The flip side of the coin is that when you get it right, the car is completely transformed into a very rewarding, entertaining experience.
One last point I would like to point out is that building a setup which promotes oversteer can be like playing with fire. A car with exagerated oversteer takes a lot of getting used to, be careful.

Jas.