![]() ![]() An ARB can balance this out.Ī softer ARB causes less lateral load transfer on its axle, compared to a stiffer ARB. When the available grip of the rear tyres is exceeded first, the car goes into oversteer when the grip of the front tyres is exceeded first, the car goes into understeer. Now we understand how an axle can lose grip under cornering, and is this precisely what causes handling issues. So while the total load on the axle remains the same (800kg), the total available grip is now only 955 kg. The coefficient on the left tyre decreases from 1.25 to 1.11, while on the right tyre it increases from 1.25 to 1.35. Continuing our example, let’s assume that due to lateral load transfer the vertical load on the left tyre becomes 500 kg, while the load on the right side becomes 300 kg. Vertical load will increase on the outside tires and will decrease on the inside tires. ![]() (400 x 1.25) + (400 x 1.25) = 1000 kg (axle)Ĭornering causes lateral (left/right) load transfer at each axle. If we have a perfectly balanced axle where each wheel is loaded with 400 kg, the total available grip at that axle is: By multiplying the two numbers, you get the amount of friction force provided by the tyre: At 400 kg of vertical load on a tyre, the coefficient of friction is 1.25. ![]() Let’s work through an example, using the chart above. You still get more grip, but proportionally less. To understand how balance is affected, we need to understand that as vertical load on a tyre is increased, the coefficient of friction of that tyre decreases. Unlike downforce, this is highly relevant for the Skippy. The ratio of roll stiffness between the front and rear axles affect the balance of the car, especially its tendency to under- or oversteer.We’ll cover this in a later article, since here we’re covering the low downforce Skip Barber car. The more horizontal a car goes through a corner, the better the chassis is at creating downforce. The main purpose of the ARB is to change the roll stiffness of the axle it’s installed on, which has two important implications:.Relative to the chassis, the left tyres move upwards, the right tyres move downwards, causing body roll. This is because the mass of the chassis is not willing to change direction, while the tyres that grip to the surface are. ![]() To give an example of an ARB’s importance: When a car without an ARB installed goes through a fast right-hand corner, the inertia forces the car to lean to the left side, which is on the outside of the corner. However, the ARB is essentially a torsion spring which stores some of the energy when twisted, so not the entire movement of one tire is transferred to the other. As a result, as soon as one wheel moves up or down, the other wheel is forced to follow that motion. The ARB connects the suspension elements of two wheels on the same axle. The red component in the illustration below is an anti-roll bar, which nearly every racing car has on its rear and/or front axles. First of all, you need to understand what an ARB is and what it does to the car. After the tyre pressures, which we handled in 5.2, another significant setting to tweak on the Skip Barber is the anti-roll bar (ARB) in the rear. ![]()
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