Brake reservoir lid for Shimano M355

thingiverse

Using automotive brake fluid (dot 5.1) in your brakes can cause serious damage, including destruction of the brake system and plastic components. I learned this the hard way after my brake reservoirs crumpled. For Shimano brakes, mineral oil is the only safe option. My brake fluid reservoir covers disintegrated, so I spent a day designing and 3D printing new ones. The M355 lid from Thingyverse leaked due to its design for injection molding, not 3D printing. These new covers should be leak-proof, but I haven't extensively tested them yet. Maybe they still leak slightly. The CAD files are messy since they're a traced photo combined with an STL file from Thingiverse (https://www.thingiverse.com/thing:3484736) for the seal and screw holes, and completely freehand for the rest. You can find the original files on Onshape if you really want them. It seems like the original covers are made of a plastic material that rapidly weakens when exposed to brake fluid. This makes their weakness literally their kryptonite, despite having a rubber component in between. If you don't like this text, it's easy to delete or ask for a version without one.