The Last Step in your Suspension Upgrade
You fell in love with driving your Porsche when you purchased it, but over the years and miles the handling began to lose its crisp response as the wear and tear took its toll. Wanting to get that great handling and even more back, you made the decision and upgraded the suspension to competition or sport type coil-over struts/shocks that have adjustable spring height perches like those of the Bilstein PSS9 and PSS10 systems. To make your Porsche’s high performance/competition suspension truly effective in its braking and cornering, there is also another very important step in the process of optimizing your car’s handling; the distribution of the car’s weight on its four tires. This is because the tire that is supporting less weight, when compared to the other three, is likely to be the first tire to lose traction when encountering the constantly changing dynamic forces created through movement and speed.
Corner balancing of the car is a process of redistributing the static weight carried by each tire; the corner balance process needs to be done in conjunction with a four wheel alignment. A car that is properly corner balanced, will handle equally well in both left and right turns. An imbalance, not caused by a faulty suspension component or tire, can take place when the front-to-rear weight distribution is not optimized, including equal weight for the left and right sides of the car. The goal of corner balancing is to get the cross weight as close to 50% as possible.
A professional corner balance will likely be checked using four, purpose made weight scales that interact with a central control station. The four scales must be located on a perfectly flat surface (side to side and front to back) to insure accurate readings can be obtained. Ramps are positioned so that the car can be driven or pushed up onto blocks that are at the same height as the scale pads so the car can be easily moved onto or off the scales to make adjustments. It is also important to roll the car onto the blocks and bounce the car to insure that there is no binding in the suspension taking place after every suspension adjustment. The car should have the fueltank half full and the tire pressures properly set; race cars may require additional considerations. Also, the driver should be sitting in the driver’s seat or the driver’s equivalent weight must be added to the seat to get accurate readings.
The corner balance process changes the weight on a tire by adjusting the spring height at each corner of the car; this in turn can also affect the ride height of the car. Lengthening the spring decreases the force or weight on the tire (lowering that corner of the car) and shortening or compressing the spring increases the force or weight on the tire (raising that corner of the car). Adjusting the weight at any corner of the car will also affect the weight settings at the other three suspension corners. If the corner balance is not within an acceptable range, the car is rolled off the weight scales and one or more of the spring perches (heights) are then adjusted, the car is then rolled back onto the scales and the corner weights are re-measured. This process is repeated until the imbalance is brought to within the lowest value possible.
Adjusting or changing the corner balance of a car can be a time consuming and tedious process. Technicians that frequently perform corner balancing, usually develop an intuitive understanding of the process and will typically find the correct setting for the car relatively quickly. The positive results on the handling of the car can be dramatic; turning, braking and acceleration can all be improved, this really should be thought of as fine tuning the suspension. Corner balancing is vital for any race car and a good investment for those who want the best handling from their high performance street car and have also installed a suspension with adjustable spring perches.
Enjoy Your Porsche,
Tony Callas and Tom Prine