We here mention 3 things that can improve road holding and reduce your lap times when doing trackdays.
Correct corner weight set up:
When placing your car on 4 gages the diagonal loads must be the same with the driver in the seat.
This means the load of front left and rear right must be the same as the sum of front right and rear left. The ideal situation is to have a variation below 3kg.
When doing the measurements, the steering wheel must be in the middle position. If it’s turned to the left the load on left front will increase mainly because of the caster. The more caster the more load increase. And the diagonal load sum will differ from when the steering wheel is in neutral.
Obtaining the right set up is easy on a car with adjustable springs but if you can’t adjust spring rate you need to use shims under one of the springs.
Most people realize that aerodynamic downforce has a larger effect on a light car and that brake distance is shorter because the wind resistance reacts better when car is light.
One factor however also has huge influence on the road traction. Namely the friction coefficient between tire and tarmac. Only in theory the available horizontal forces is proportional with the vertical. A slick or trackday tire has increased peak friction coefficient when the vertical loads is reduced.
Most of us have experienced a Caterham 7 or Elise overtaking in corners with the same tires when you are at the limit. Now you know why so not only a low center of gravity improve cornering speed.
Low center of gravity:
When cornering the difference of the vertical load on the outer and inner wheels should be as small as possibly.
A car cornering with 100% load on the outer wheel compared to one with 50/50 looses 10% traction if trackday tires are used.
Therefor the Center of Gravity should be as low as possible by placing as much weight as possible at the bottom of the car and increase wheel track width to the limit.
By replacing the lead battery with a LiOn battery that can easily be placed very low. This is one of the reasons TDE sells LiOn battery. They work fantastic in a trackday car.