Upon close inspection the factory rubber bushings holding the shock absorbers in place showed signs of cracking and deformation. Both the top and bottom bushings were well overdue for replacement. Factory bushings aren’t available anymore, so I decided to use this as an opportunity to get familiar with my new to me Revopoint 3D scanners.
I got the scanner out, sprayed the bushings in chalk, and made scans of the surface. I then imported the scan data into FreeCAD and made models of the bushings. I opted to make the bushings out of cast polyurethane rather than 3D printing TPU as layer adhesion could be a concern and this is a high load environment.
I went for 2 part 3D printed molds held together by M3 screws. As a release agent, PTFE spray was used with moderate success.
Mold for the top bushings
Mold for the bottom bushings
Highlighted in yellow is the original scan data used to make the mold. The molds would then be filled with Poly 75-70 , a 2 part polyurethane with a hardness of 70A Shore. I wanted to keep the bushings soft to keep the flex for off roading, but not so soft it feels floaty on a highway. Upon feeling the 70A PU bushings I made, they feel softer than even the worn out factory ones. Unfortunately I don’t currently own a durometer, so the hardness of 70A was a guess powered by some very vague forum knowledge. Therefore, I’ll definitely revisit this and make the bushings out of 85A or even 90A resin.
