How to improve the rear shock absorption of off-road vehicles
In the double wishbone structure, there are two main components that affect the height of the car body, namely the nested shock absorber spring and the lower part of the shock absorber (I give it an image name, called crescent arm).
Because the size of the crescent arm is strictly limited by the upper and lower control arms and cannot be changed, the simplest method is to lengthen the size of the spring to achieve the purpose of lifting. For a car with a girder, the bearing capacity of each wheel is about 500 kg, that is to say, the crescent arm has to bear 500 kg of longitudinal support force (the force is much greater under dynamic conditions), and castings are generally used to increase the mechanical strength.
For springs and shock absorption, the changes in the process of lifting are also different. Below is a comparison between a 2-inch high spring and shock absorption. It can be seen that the elevation angle of the front suspension is mainly determined by the extension of the shock absorber cylinder.
Treatment after promotion:
After lifting, the tire will become figure-eight, but don't worry too much. As can be seen from the above calculation, the retraction distance between the upper arm and the lower arm is about 0.3 cm, which can be completely adjusted by four-wheel positioning.
So the treatment after lifting is to do a four-wheel positioning. This is how ordinary cars are handled. But there are two things that riders should know. The upper limbs and arms have become fragile. As mentioned above, the upper limb arm should bear the lateral impact of the vehicle. After lifting, the angle between the upper arm and the horizontal direction becomes larger, and the moment of the same lateral impact force on the upper arm becomes larger. (torque = force * arm, arm becomes larger). As the saying goes, a tree weighs a thousand pounds, and if it is inclined, it will break easily.
The forearm also has this problem, but the forearm is stronger and has less influence. Strictly speaking, after the double wishbone is raised, the upper and lower arms should be replaced (lengthened and strengthened), the connecting rod of the balance bar should be lengthened, and the front transmission half shaft should be strengthened and lengthened. In this way, basically the whole double wishbone is equivalent to complete replacement.
The cost is relatively high. If you can replace the appropriate upper arm and replace the front transmission axle shaft, it is also exquisite in the modification. The front drive shaft is also fragile. There are many problems in this. Let me say a few more words. After rising, the included angle between the semi-axle and the horizontal direction becomes larger with the arm, the transmission path of force becomes more tortuous, and the pressure on the steel ball in the ball head becomes greater and fluctuates greatly.
On off-road sections with a large amount of slippage (such as river banks and mountain roads), the slipping tires have great inertia when idling at a high speed, and when the slipping tires gain friction, the deteriorated mechanical environment (the transmission angle of axle torque increases) can easily break the steel balls in the ball cage. Therefore, it is important to replace the front axle after lifting.