Racing Car Technology
    Handling and Suspension Setup
    Street and Track  Suspension   

Set Up Mistake No1:  Not testing. 

There are so many variables.  No one can predict the perfect set up, even for a spec formula where much of the suspension is fixed by the rules.  Therefore you have to do comparative testing.  Our Weight Transfer Worksheet gives you a good baseline set up and possible directions for improvement.  

As I write this, a sports sedan driver, on TV (Speedweek) said  "Not everybody can do it (go racing in sports sedans).  It's a big commitment (time and money) and it takes a while to acquire the knowledge you need to make the car work."  Nothing will accelerate your learning curve like properly planned and organized testing.

At Racing Car Technology, most of what we have learned has come through testing.  We have made good improvements in car speed for our customers and gained important insights in vehicle dynamics and car set up.

Set Up Mistake No 2:  Not "reading" the tyres.

The tyres are the most important and most complex component of the set up.  Regular tyre pyrometer temperature readings throughout a test day are very instructive.  It is arguably your second biggest pointer, after driver feedback, as to what is happening with the car.

If you change to a different tyre, it is almost a given that there will be setup changes that can make the car faster, even if it was optimized on the old tyre.  In general, a tyre with more grip requires greater overall roll stiffness.  Also, if the car is wearing or scuffing the tyres excessively, it might be better with less overall ride stiffness (stiff car tends to use up the tyres).  The WTW is exceptional value in helping you determine what is overall relatively "hard", and likewise, "soft". 

Set Up Mistake No 3:  Unknown springs, unknown ARB's. 

Many teams know their spring rates, but do not know the ride stiffness (spring frequency) and roll stiffness of their car.  The WTW is an obvious help in this regard.  As is our "bounce test" - a very simple way of measuring spring frequency directly, without calculation with motion ratios.

We expect race car front to rear roll stiffness to have a difference of around 10%-15%,  unless there is an overpowering reason to the contrary.  Many race cars have rear spring stiffness too low, and are unlikely to be optimized at that, even if the driver is only a little off the pace.  We have been able to get such cars on the pace with a rear spring change, sometimes rear ARB, and sometimes roll centre height change.   

Set Up Mistake No 4:  Not doing a workshop set up.

Not have sufficient suspension travel or free movement (suspension must have no binding).  Suspension travel and spring stiffness, are totally inter-dependent.  You must specify one with a view to the other. 

If you purchase a new race car, or a car from another race team, the car will not be "set up".  It costs too much to do a set up and fully acquaint a new owner with what is going on.  In any case, the new race team needs to do their own set up that they understand, and can work with.  How often do you see some one taking advice on a set up change from the car builder or faster competitor, and getting an in-conclusive result?  

An addendum to Mistake No 3 - not collecting (and using) data.  We use and sell the DL1 data logger from Race Technology.  

Set Up Mistake No 5:  Not having a plan for set up changes. 

"If I change this then I expect that.  But if I don't get that, then I have my response worked out, which I can implement, taking into account what feedback I am getting."  This is an ideal.  We might never achieve this level of understanding.  The Weight Transfer Worksheet can help by attaching values to some of the areas we have to think about.  For instance, are front and rear suspension frequencies in a range range we expect?  Is the percentage of roll resistance allocated to the anti-roll bars in a range that will make adjusting the anti-roll bars effective? 

Set Up mistake No 6:  Not having shocks valved in a range where they can be effective as a tuning tool. 

It is clear that any shock is better than no shock in terms of controlling the spring.  With no shock, the tyre grip is badly degraded by the cyclical loading and unloading of the tyre.   The shock you want for tuning the set up - valving that works to control the movements of the chassis - will be valved stiffer than a road shock, and within a finer range.  Once you are close, it is possible to go too stiff, with just a small change.

Set Up Mistake No 7:  Not understanding relationship between roll centre heights and geometric vs elastic weight transfer. 

This central to our understanding of how set up changes work.  See Origins of Weight Transfer 

Set Up Mistake No 8:  Not understanding toe settings.  See our article on Ackerman and toe settings on the home page.

Set Up Mistake No 9:  Over-reliance on caster, or other suspension geometry setting, as the magic tweak.

Set Up Mistake No 10:  Not exploring sufficient set up options to optimize the car.  

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