Technical A-Z

  • Camber

    A Camber will help to optimise tyre grip. With modern tyre constructions (eg radials) it is normal to have around one degree of negative camber (top of wheel leaning in towards the chassis)

  • Caster

    A Caster works in conjunction with toe-in and king-pin angles. It gives the steering a self-centring action when coming out of corners and also aids overall car stability

  • Movement Ratio

    This can be either from the wheel to the damper (spring) assembly or to an anti-roll bar. The geometry of this will determine how quickly the car will respond to bumps, corners etc. It is used in calculating spring and anti-roll bar rates.

  • Oversteer

    This is when the back of the car slides out before the front. A combination of throttle and steering adjustments is used to control it. Most often experienced on rear-wheel drive cars.

  • Roll Centre

    Roll Centre is the theoretical point around which the chassis rolls in cornering and one can be found at each end of the car. Nowadays we tend to keep these fairly low in order to prevent a condition known as 'suspension jacking'.

  • Roll Stiffness

    This is the stiffness a chassis has to oppose cornering forces. The lower the stiffness, the more the chassis will roll in cornering.

  • Scrub Radius

    Also known as the king-pin offset, this is the distance from the centre of the tyre to the point where the king-pin axis intersects the ground. If very large, it can cause the steering to 'snatch' under heavy braking.

  • Toe / Tracking

    It is important to minimise tyre wear whilst aiding steering and straight-line stability. It also helps to take up any slack in the suspension / steering joints that may be present.

  • Torque Steer

    Torque Steer is mostly found on powerful front and four-wheel drive cars. If excessive, the drive train tends to wrench the wheel from the driver's hands. It can be controlled with a special steering/suspension geometry setup.

  • Understeer

    Mostly found on front-wheel drive cars (especially early Minis etc). It's when the front of the car slides wide in a corner as if you'd just hit a patch of ice. Advanced rally-driving techniques use left-foot braking to help lessen this effect and keep speed up through the twists.

  • Unsprung Weight

    This refers to the parts of the chassis that aren't "sprung", for example the wheels, brakes, suspension components etc. For optimum handling, keep these as light as possible within the bounds of stiffness and strength.

Latest Technical Articles

Article Categories

Article Archive