The rear struts serve a two-fold purpose. They act as both a dampening agent and a structural element. They do more than just absorb the shock from hitting bumps, but also provide structural support as an important element of the bike’s frame. They are a combination of a hydraulic shock absorber and a spring.
Our shocks were what are called twin-tube shock- absorbers. They function to dampen because they have two cycles, compression ( as the piston moves downward) and extension (as the piston moves upwards). Compression is “easier” than extension, which helps eliminate bounce, effectively dampening the impact. The spring sits around the inner tube and inside the outer tube of the twin-tube shock-absorber, and supports the vehicle’s weight as the shock absorber dampens.
We had to machine our own tool to disassemble the struts, because this is the first time in this course that we have restored the struts instead of just buying replacements. After doing some research online we decided that the best method would be to create a tool which would rest on the washer on top of the spring when the struts were held upside down. We would then use the milling machine to press upon the tool, thereby compressing the spring and allowing us to remove the aluminum clamps which held the spring in place. This would free the spring, washer and, of course, the two clamps we would remove. Then we would be able to check the dampener and be sure that it was still functional. We found a brass tube that was the same diameter as the washer so that we could compress the spring by pressing down on the tube. We then used the Milling machine to create a whole in the side of the brass tube that was large enough to remove the clamps through, but was not big enough to damage the structural integrity of the tool. We had to be careful about this because if the tool were to fail when we were using it to compress the spring, it would have been very dangerous. Luckily, it was a successful and safe operation, and the dampeners were functional. So our only task was to paint the dampeners and polish the clamps, and then reassemble using the same tool and the same process (just in reverse this time)