Track-day Suspension Set-up Guide 101
Don't overlook the set-up of your car for track days. It can make huge differences to how the car handles and can produce drastically lower lap times. With a little effort, you can completely change a cars handling characteristics. Using this guide will help you understand what adjustments you need to make and how to tailor your set-up for different circuits.
Firstly, it's important to understand that the perfect set-up doesn't exist. Every set-up is a compromise of sorts, finding the perfect balance between handling, aero, braking, and power to achieve the best results on the day.
For example, you might think a car set-up for out and out top speed will be the fastest, but this could come at the cost of acceleration and grip in corners. Therefore, we need to hit that sweet spot somewhere in the middle.
One change at once!
An old-timer rally driver once gave me some priceless advice "Make one change at once". After reading up on race car set-up, it's very tempting to adjust everything all in one go. This is a bad approach!
Upon testing, if you find the car is slower or a real handful to control, how do you know what's causing that? How do you revert back? And how can you learn what each adjustment is doing to your car?
That's why you should make one change at once, preferably small ones and work from there.
Create a Playbook of Settings
Start a text document or note on your phone and write the settings down. What effects did it have, how did the car feel? What were the precise adjustments you'd made? What were the conditions on the day? Was it raining or cold? Next time you encounter that track again, or similar conditions, you'll have a datum point to start from.
Examine Circuit and Establish Corner Priority:
Setting up your car isn't so much an art, but a science. You don't need to find yourself a maverick, disgraced, slightly bitter, now retired, former Indy-car pit crew person with an ax to grind just like the movies. We can break a very complicated process down into a series of simple tasks. One of those is to establish a corner priority for the particular track you're at.
This principle places the most priority on corners that lead into long straights, followed by corners leading from a straight and finally all other corners.
This is done because if you have a 100mph straight and you can make a gain of 5% over this sector, you have a 5mph increase in speed. If you have a tight series of chicanes and the maximum speed you can carry through the section is 30mph and you make a 5% increase there, that's a mere 2 mph gain.
Corner priority is established in the following order:
- Corners leading directly onto a straight away
- Corners after the straight
- All other corners that lead into other corners
Further broken down, the priority would be:
- The fastest corner leading on to a long straight (long distance to take advantage of speed gains)
- Next fastest (down to the slowest) corner that transitions onto a long straight, repeat through all these corner types
- Then, the fastest corner after a straight
- Followed by, the next fastest (iterate down to slowest) corner after each straight
- All the other corners that lead into other corners
This the order of priority by which you should set your car up.
The goal of suspension adjustment: Maximise directional stability and ground contact
Various factors, including weight transfer, effect cars directional stability. Directional stability is the cars ability to maintain a course, whilst subjected to turning, braking, rough surfaces and even cross-winds. What most call 'handling' is actually the directional stability of a vehicle.
In order to maintain directional stability, we can increase a cars ground contact (the amount of tire in contact with the road, otherwise known as a grip) as we travel through a corner. This is necessary as the geometry of the suspension will alter through a turn and combined with weight transfer, effectively lighten one side of the vehicle.
Car Set-up: Suspension
Camber angle is the slight angle applied to tyres when viewed from the front, measured in degrees. Camber actually alters a tyres contact patch with the road. If you look closely, you'll note all cars run some camber, apart from dragsters and land speed record vehicles which aim to have as much grip as possible and so run no camber.
How to adjust Camber:
Fit camber plates or use the top mount camber adjustment in high-end coil-overs to alter the camber.
Effects of Positive Camber
The car will feel twitchy, with a tendency towards oversteer. You might experience hop or exaggerated torque steer during heavy acceleration. In corners, the rear end might lack grip and slide out, creating a real handful for the driver. Tyre wear will increase, with uneven wear on the outside tread.
Effects of Negative Camber
Negative camber will increase grip and stability in corners, inducing understeer, which is generally favored by most novice drivers. It is more consistent and predictable for inexperienced racers to push a car without getting into too much trouble.
Damper & Spring Rates
Rather than make this section too complicated, let's talk about the cumulative effect of adjusting damper and spring rates. It's not a bad idea to try driving a car that has way too soft a damp rate and then one with the suspension set to be far too hard.
Doing so is like tasting each ingredient on its own when cooking, you know what you're adding and what's needed to make the meal delicious. You'll know in the future what changes to make just by the feel of the car.
Below is a list of handling characteristics and how to reduce or encourage them:
Oversteer Correction / Understeer Induction
- Soften rear dampers, harden front dampers
- Raise front end up
- Lower rear end down
- Decrease front negative camber
- Stiffen front springs. Soften rear springs.
Understeer Correction / Oversteer Induction
- Soften front shocks / Stiffen rear
- Soften front springs
- Stiffen rear springs
- Lower front end (positive rake)
- Raise rear end
- Increase front negative camber
Finally, be Observant
After making changes, you really must test the car. How does it feel? Push it to the limit, try to exaggerate steering inputs until you get a sense for the car. Then you can spend some time evaluating the differences both in terms of lap times and driver feel. It's important to be consistent here and patient, sometimes it takes time to achieve a set-up that you feel comfortable with.
Don't forget, make only one change at once!