Car springs are a very familiar accessory for car modification enthusiasts. Many junior car modification players will reduce the height of the car body by replacing short springs to obtain better visual effects and better control. performance. But what role do car springs play in their cars? Our main purpose of modifying car springs is to improve handling, that is, to use harder springs or shorter springs. The spring controls many factors related to control, and changes in the spring will cause very complex changes in control characteristics. The increase in hardness can improve the rolling suppression capability of the suspension and reduce the rolling of the body when cornering. The reduction of the vehicle height can simultaneously lower the center of gravity of the vehicle body, reduce the transfer of vehicle body weight when cornering, and improve stability. The reduction of the vehicle height can also take into account the aesthetic effect. Many people talk about matching 4K or 6K springs, but what exactly does this K value represent? According to the physical formula F = K The spring is soft and lacks support.
To be specific, a 4K spring means that when you apply a force of 4Kg to the spring, the spring will compress or extend 1mm, and the same is true for 6K. The choice of K number here depends on your orientation and the damping setting of the shock absorber. Why some people say not to use the original shock absorber with short springs is because once you choose the K number of the spring incorrectly, the damage to the original shock absorber will be great. If the K number is large, a certain amount of comfort will be lost. If the K number is small, it is easy to exhaust the stroke of the shock absorber. If the coordination is not appropriate, it is easy to lose the tracking performance of the car. There are two types of springs: straight coil springs and progressive springs. As the name suggests, straight coil springs are springs with the same spiral direction, wire diameter, and pitch from beginning to end. The expression of the K value mentioned above is only for straight coil springs, because its K value is constant. For progressive springs, its K value changes as the amount of compression changes. The biggest feature of straight coil springs is that the spring coefficient K value is constant. The direct benefit of a constant K value is that it is easy to control when adjusting the vehicle height, making it more suitable for competitive shock absorbers.
In competition, the constant K value is very important. In addition to providing a faster response, it can also make the damping adjustment of the matched shock absorber more accurate. Most of the stir-tooth shock absorbers are matched with it, and the adjustment is easier and more precise than the progressive spring. The processing of straight-rolled springs is relatively easy. You can do a small experiment to experience it: use a steel wire to roll a straight-rolled "spring" and a progressive "spring" to see which "spring" is easier to make. The answer is of course a straight coil spring. Just wrap the steel wire around the cylindrical mold one by one and then demould. Progressive springs need to control the winding diameter and spring pitch of each turn, and require special coil spring technology. Of course, it does not mean that the processing difficulty is high or low, which means its performance is high or low, but their applicable conditions are different. The other is a progressive spring, also called a variable elastic coefficient spring. It adopts the design of unequal pitch and unequal ring diameter, that is, the ring diameter at both ends is small and the middle ring diameter is large. The larger the diameter of the middle ring of the spring, the greater the rigidity, and the same is true for the pitch.
The compressed force of the springs at both ends is less than that of the middle part, so when small bumps and impact forces are small, only the two end parts can absorb them, ensuring a certain level of comfort. In response to situations such as vehicle body dive due to braking, steering roll, etc., the middle part with a larger K value can provide support, which can better suppress vehicle body rolling (Rolling). The K value of the progressive spring increases as the amount of compression increases. When the unequal pitch spring is compressed, local line-to-line contact will occur, causing the number of effective turns to change, thereby causing changes in the elastic coefficient K. The most direct way to change the elastic coefficient K is through the change of the upper and lower ring diameter of the spring. The original car or the original car upgrade kit basically uses progressive springs, taking into account both comfort and support. Regarding the auxiliary spring, there is a saying that the auxiliary spring is a patent for non-field competition shock absorbers, such as street shock absorbers and off-road racing cars, but the auxiliary spring design will not appear in field competition shock absorbers.
However, this kind of statement has attracted a lot of criticism, so what is its principle and what effect does it have? The auxiliary spring usually appears on the coiled shock absorber with a straight coil spring. It is distributed on the upper or lower part of the main spring according to the design structure of the shock absorber.
Since the K number of the auxiliary spring is smaller, its shape variable is larger than that of the main spring under the same pressure. When driving, the auxiliary spring is in a compacted state due to the weight of the vehicle, so it cannot be used to provide additional compression buffering effect. The role of the auxiliary spring is reflected in the sudden stretching of the shock absorber. When the shock absorber suddenly stretches (usually when the wheel suddenly hangs in the air, such as a "leap" action in an off-road event, or when a sunken part is suddenly encountered during driving), assuming there is only the main spring, then if The elongation speed of the main spring is less than the extension speed of the shock absorber, and the phenomenon of "detachment" may occur in a very short period of time - the spring is separated from the spring seat of the shock absorber.
The consequence of this is that the shock absorber will receive a sudden impact when the spring re-contacts the spring seat, which will affect the life of the shock absorber. The occupants in the car will also feel a strong impact, and the wheels will Also due to the loss of the downward pressure of the spring, the tracking performance will become worse or even out of control! The compression amount of the auxiliary spring in the driving state can have a tendency to restore the free length when the shock absorber is suddenly stretched, and maintain the distance between the spring body and the shock absorber spring seat with a larger amount of elongation. The contact can make up for the problem of insufficient main spring travel, avoid the phenomenon of "off support" of the spring, and even "push" the shock absorber to act faster to fill the gap between the tire and the ground more quickly. The existence of the auxiliary spring ensures that the spring will not lose control of the shock absorber during large strokes, thereby maintaining contact between the tire and the ground. Therefore, auxiliary springs are widely used in cross-country events and track events with complex and changeable road conditions. There are also some modified shock absorbers for street cars that pursue comfort, and they will use the design of main and auxiliary springs.
The choice of spring hardness is determined by the ruggedness of the road surface. The more rugged the spring, the softer it is. But how soft it is is a key issue. Usually this requires the accumulation of experience, and it is also required by each car manufacturer. An important topic for each team. Generally speaking, soft springs can provide better comfort and maintain better tracking when traveling on rougher roads. However, when traveling on ordinary roads, it will cause the suspension system to swing up and down significantly, affecting control. For a car equipped with good aerodynamic components, soft springs will cause changes in car height when the speed increases, resulting in different handling characteristics at low speeds and high speeds.