A Four Post suspension rig has been an essential tool throughout our suspension development process. This equipment and methodology is utilized by professional race teams including leading Formula One, IRL, CHAMP, NASCAR and Grand AM teams. Additionally, auto manufacturers utilize this tool when developing suspensions for their high performance production vehicles.
A four-post rig is a piece of test equipment that places the car on four pads mounted atop computer controlled hydraulic rams. At each corner of the vehicle, accelerometers are mounted in the pad, on the wheel and on the body, as well as a linear potentiometer to measure suspension travel.
Test runs move the car front to back, side-to-side and corner-to-corner. First at slow speeds and large suspension travel rates and then at faster and faster speeds at incrementally smaller travel rates. Concurrently, all sensors are data logged throughout the test, with the results processed through sophisticated proprietary analytical models.
During the run, there are also visual cues which highlight issues with regard to vehicle vibrations and chassis flex which could not otherwise be seen driving the vehicle.
After being evaluated by a suspension engineer, the results provide a very clear, overall picture of vehicle imbalances, and the effectiveness of spring rates and shock absorber damping. From this data, an engineering report is prepared telling us whether spring rates are too high or low at each end of the car, whether more or less damping is needed at the front or rear and whether the vehicle suffers from any specific imbalances. Additionally, the report includes overall measures of vehicle performance and comfort, which are compared against a database of 250 modern vehicles.
The report highlights areas in need of improvement and specific recommendations for their attainment.