Setup Dev 02 - Springs

rFactor setups, GTR2 setups, GTL setups, RACE setups, Sim Racing setups
The springs are the foundation of your setup and can be simple to deal with in one sense and difficult in another. Springs are primarily used to dictate ride height and body roll, though they can also be used to transfer grip to an under-used wheel in certain situations. Softer springs will extend the time that your car takes to respond to your inputs because your suspension is in "slow motion" of sorts. However, this does not necessarily mean it is a bad thing. A very experienced driver may want the faster response from a stiffer suspension, yet a less experienced driver may need the slower response so they have more time to catch and respond to the car. Neither is really going to be any faster or slower over the course of a lap in equal hands, they are just driven differently. For the sake of stability, softer is better. As your abilities advance, trying different spring packages may be worth while.

As a rule of thumb, softer springs equal greater mechanical grip and a more forgiving chassis. You want your spring package as soft as possible without the car bottoming out from the down force or the bumps in the track. We have all seen the images of a Formula 1 car shooting sparks out from the under tray at top-speeds. This is the bottom of the car hitting the track surface and is the primary definition of 'bottoming'. Common sense tells us that when the chassis of the car is making contact with, or dragging on, the track surface you are not reaching your highest possible speeds. Even though your car is not dragging at slow speeds, your car has the added aerodynamic forces pressing it into the track at higher speeds. These aerodynamic forces can easily exceed the stationary weight of the car. The springs need to be stiff enough to prevent the bottoming, yet soft enough to maximize it's mechanical grip when the aerodynamic forces are not there to help you.

There is also another form of bottoming, known as 'bottoming out the suspension'. This happens when the chassis itself may not be making contact with the track surface (thanks to bump-stops), but the suspension is compressed to the point that the spring is prevented from compressing any further. If you chassis is riding on the solid bump-stops, then there is no suspension movement and the car can not react to the track surface or weight shifts.

You want to prevent both versions of 'bottoming' in a stable and predictable setup. While this may take some tweaking to find the lowest ride height and softest springs, you can retain that information for the next track you visit. However, the differences in tracks themselves may force you to adapt, or evolve it into a track specific setup. A high speed track may require slightly stiffer springs due to the aerodynamic forces being generated at higher speeds. All-out speed may be more important then grip, so you may wish to run sacrifice mechanical grip in exchange for less drag. A low speed track will not generate the same aerodynamic forces and you rely even further on mechanical grip. This may cause you to run an even softer spring package then normal, but since the top-speeds are lower, so are the aerodynamic forces that may cause the bottoming. Cars that rely heavily on aerodynamic grip, may sacrifice mechanical grip by using stiffer springs and even lower ride-heights. The under-carriage of these cars may generate massive down force and the closer it is to the track surface, the greater down force it is generating without the added drag that an increase in wing angle may bring.

Springs do also dictate the amount of grip allocated to each corner of the car, in a generic sense of the term. A stiffer spring is "pre-loading" the grip to that particular corner of the car by pushing the wheel into the surface of the track. The harder the spring pushes, the more grip that is "pre-loaded". However, while you may have more grip initially, you approach and exceed the point of over-loading that wheel at a faster rate as well.

Changing the springs at each corner changes your corner-weight. Though the corner of the car may not literally weight any more/less, springs can alter the weight at which the wheel is being pushed down into the track surface. As you are navigating a corner at full potential of the car and tires, the outside tires will be using their full amount of grip. Any additional weight on that tire will result in a loss of grip. Corner-weight techniques can help spread the workload across two tires, offering more overall grip in corners of that same direction. An example of a track that you might have different springs on the left and right sides of your car is Lime Rock Park. Since Lime Rock has all but one right-hand corner, you can focus solely on the right-hand turns. Having stiffer springs on the right-side of the car will allot more grip to the inside tires and in turn will allow the outside tires a larger grip "budget" because the inside tires are taking more of the workload. You will be sacrificing grip in that single left-hand corner of course. For the most part, you do not have to be overly concerned with corner-weighting your setup. Focus on a symmetrical and balanced spring package and come back to corner-weight techniques later down the road.

When you are first developing your base-line setup, use the softest springs available on the rear of your car for maximum grip under acceleration, then balance the front springs to match grip between front and rear for a neutral setup. Typically, your rear springs will be softer then your front springs.

TIP: Stiffer springs will increase tire temperatures

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