1 copper ring is called composite casing 2. Search on the Internet. Zhejiang Zhong Da Bearing is quite famous for this. 3 d needs to measure your core outer diameter. Generally this is a series. If you quote the outside diameter and height of the core, there will be a standard size of 4. Nothing can replace it. This is mainly to reduce friction, reduce the processing difficulty of the bottom sleeve and guide the aluminum alloy. Isn't it a little tapered? This is the term "rod seat". It is the last one to act as a hydraulic buffer. Without this, it is easy to hit the bottom and reduce the life of the shock absorber. No need to install it at all, but it is easy to crash and the bottom is easy to leak oil.
The copper ring at the bottom of the shock absorber core has the same function as the above, except that this one is reversed, and all shock absorbers with large displacement will have this one. If it plays the role of antifriction and guidance, serious wear will definitely not work, so that the damping core will easily rub against the bottom wall, resulting in abnormal sound and seizure. I hope I can help you.