Most runners realize their choice of stiffness of suspension, the spring rate they choose, ie (say in lbs/inch, kg/mm or N / m) are important.
In fact, for low or non-aerodynamic racing cars, we at Racing Car Technology have found that the choice of suspension stiffness is the most important adjustment of the car to improve the grip of the tires and optimize performance.
How do you know which spring rates you need to order when buying suspension springs?
Parts suppliers, shock absorbers and suspension specialists and car preparation workshops are likely to make a choice for you unless you say what you want.
But even with very experienced people making the decision, the spring selection of most racing cars is little more than a sound guess. It doesn’t have to be that way.
When running, the stiffness of the spring counts.
What we show you in the Video is a unique way to measure the stiffness of the suspension. We called this simple test the Racing car technology Bounce Test ™ .
The accepted measure of the stiffness of the suspension is the “suspension frequency”. Or as I call it in the Video, “spring frequency”.
What we are looking for are the spring rates we need to achieve the desired spring rate.
With the Bounce Test ™ mentioned above, we have a spring frequency of 122 cycles per minute (CPM) for this Triumph TR3 race car, with springs of 550 psi in the car. If we want to go steeper, say 130 CPM, we can determine the spring rates, we need to do this in a simple Excel table.
Getting the right spring rates in the car is a big factor for optimizing tire adhesion. For us at Racing Car Technology, this is the biggest improvement we offer for non-aerodynamic racing cars. The biggest contribution to improving lap times.
On the road, it is the springs that give the necessary suspension Compliance to isolate the passengers from the bumps of the road surface. that is, soft springs are required for a good ride.
But in the race we do not care about comfortable driving for the driver. We are only concerned with increasing the stiffness of the suspension (by adjusting rigid racing springs) in order to achieve more Grip on the tires. To give you an idea of the stiffness we are talking about here, we have found racing cars for production, the springs needed for a better grip are about 2-4 times stiffer than the standard springs.
Our Bounce Test ™ is one of two basic procedures by which we determine the frequency of suspension. The other requires the measurement of the ratio of spring movement. We need them for coil-over suspensions where we can’t remove the shock absorbers to make the Bounce Test ™ .
Why is the Bounce Test ™ so important? Because it gives us a direct indication of the frequency of the suspension, front and rear, our most important number, and the starting point in the configuration of the car. And nothing could be easier, as you see in the Video. Right?
Well, there are subtle nuances and things you discover when you try this. Our experience with Bounce Test ™ over almost 20 years gives us confidence in the recommendations we make.
Now you can get a perfect grip on what you need to set up the suspension on your own race car with Racing Car Technology’s online training programs. Much of it works with Bounce test ™ . We have added a new dimension to the spring selection for the production of racing cars.