Corner Weights

Corner weights Corner weights are the amounts of weight carried on each tire, i.e., left front, right front and so on. By adjusting the suspension, the weight can be redistributed. But it is imperative that the mechanics follow a set sequence and also ensure that the equipment being used is set up correctly. The equipment needed to set the corner weights includes the following: •

Electronic scales

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Platform – to mount the scales (complete with leveling adjusters)

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Measuring devices – rule, tape measure, height gauge etc.

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Weights – to replicate the driver’s weight

Car Preparation Before the weights can be checked, the car must be prepared to give accurate measurements. The engineers will have accurate details of the driver’s weight. They will determine this weight by weighing him on two scales; he will sit on one set of scales and have his feet resting on another set. Both of these weights will be taken with the driver in his full suit, helmet, and boots etc. Although the corner weights can be set with the driver inside the car, some engineers prefer weights as they are more consistent and don’t move about! When distributing the weights inside the car, the mechanics will replicate both the weight of the driver and the disposition of that weight. For instance, the typical weight of a drivers feet and legs are around 18 lb.’s or 8 kg.’s when seated. The mechanics will place an equivalent amount of weight inside the car where the driver rests his feet, with the remaining weight placed in the driver’s seat. Other items to be prepared, before checking the corner weights, include: •

Fuel – fuel cells will be filled to one half of the race distance (full tank on circle track cars)

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Tire pressures – must be set to the hot settings (ensuring correct height measurements)

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ARB – the anti-roll-bars will be disconnected

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Suspension units (dampers or shocks) – the dampers will be set to zero

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All other suspension geometry - (caster camber, toe, ride heights, etc.) will be set

Just prior to rolling the car onto the scale pads, the pads and scales will be checked for level, and their readings zeroed. With the car placed on the scales, the engineer will study the weights of each corner (the amount of weight each tire is carrying). He will primarily be concerned with the cross weights, i.e., the left front to right rear cross weight total should match or be close to the right front to left rear weight. Although this cross weight is very important to the handling of the car, the engineer will occasionally move weight around by adjusting the suspension.

Brake Lock-Up A typical need to move weight around is where a car is continuously locking one front wheel when braking into a corner. Moving weight onto the locking wheel will reduce the amount of lock-up and allow the driver to brake harder or later into the corner. However, this must be done

with care as reducing a locking-up problem may have an adverse effect on the handling at another part of the track (corners going in the opposite direction, for instance). Another major consideration for the engineer is the weight carried across the front axle. For aerodynamic considerations, the front of the car should be level with the track and therefore the weight should be even on both front wheels, however as previously mentioned, it may be necessary to add weight to overcome a brake lock-up to one front wheel.

Regulations Governing Ride Heights On some race cars (NASCAR’s for example), altering the weight carried on one corner will also change the ride-height. As most race series have regulations limiting the minimum height (measured when the car is static), the engineer will continuously check the ride heights at the same time as the corner weights. As with most race car suspension adjustments, the corner weights will be a compromise. The team with the best handling car will have chosen the correct balance of required weights, versus other geometrical considerations.