In both cases, the intersections of each pair of green lines show the instant centers from a side view. While there are many varieties, MacPherson strut and four-link/double-wishbone systems are the most widely used suspension types. They are calculated differently depending on the suspension types. Instant centers are points on a vehicle that do not actually exist in the suspension, although they are crucial in calculating anti-geometry. In the image below, the center of gravity can be seen as the red dot just below the door handle. This point is especially important because it can be thought of as the point by which all accelerative forces act upon. If the object were able to be suspended from the said point, the object would not rotate or move. The center of gravity is a point on any object that could be thought of as the concentration of mass. The center of gravity is important for all load transfers and spring compressions. This will yield accurate percentages but is a bit more complex and requires more measurements.Ī much simpler way is one proposed by legendary racing driver and engineer Carrol Smith in his book “Tune to Win.” We’ll cover this below. Although this is a good estimate, it does not give an exact value.Īnother method factors in the wheelbase of the vehicle as well as the height and length of the blue lines in the image below. One method uses the crankshaft as an estimate for the center of gravity, then measures the instant center’s distance away from the 100% anti-dive line. However, they all show anti-geometry as a percent. There are many proposed methods of measuring the anti-geometry of a vehicle. As there’s not much to show for this, the following measurements will only include dive and squat. The best way is to include a stiffer spring, called an anti-roll bar. They only minimize the dive, squat, or roll that accompanies it.Īlthough roll is important to notice and minimize, the methods of doing so are rather simple. This is known as “anti-geometry.” It is important to note that all mentioned methods do not minimize load transfer. Auto manufacturers predict this movement and compensate by employing anti-dive, anti-squat, and anti-roll suspension geometry. ![]() This is known as roll.Īll these compressions or expansions of the vehicle’s springs lead to changes in the contact between the tires and the ground. ![]() Finally, as a vehicle takes a left turn, the right side is compressed. Inversely, as you apply the gas, the vehicle compresses the rear end. The vehicle does the same by compressing the front end. When you apply the brakes while driving, you can feel yourself being forced forward in your seat. These changes are undesirable and cause the need for methods of resistance. With changes in the tire contact patch come changes in grip and turning behavior. This is known as load transfer.ĭue to the nature of vehicle suspension, a change in load on a wheel or pair causes compression or expansion of the vehicle’s springs and therefore creates a change in the tire contact patch. ![]() These are either longitudinal (from braking or speeding up), lateral (from turning), or vertical (from bumps and dips).ĭuring each type of acceleration, the weight of the car, which is supported on springs, is shifted one way or another. Vehicles experience many kinds of acceleration both on the racetrack and on the road.
0 Comments
Leave a Reply. |