Nick, the bolt with a hole through it,holding the block with a flare connection to the cylinder, is called a banjo bolt. There should be two copper washers at each cylinder where the block, banjo bolt and cylinder contact; they are not used elsewhere in the system. You will notice there are small thin concentric ridges on the surfaces where the copper washer contacts. The washers act as a seal when the banjo bolt is tightened.
The copper washer is made of annealed copper which makes it very soft and malleable. After use, the washer is work hardened, so you must not reuse it without annealing it. It will be too hard and not seal. My advice is to use new ones from an auto parts store. Jim Carter has them with a new bolt, his part # MEE244. Other vendors you see on this forum should have them, also. Your local parts store may have them in the right size by themselves and that would be less expensive. I have reused the banjo bolt and block without problems. You can anneal the old washer yourself if you know how to do it.
Kent
P.S. Some systems use a banjo bolt connection at the master cylinder, so you may have one there.
Last edited by Lightholder's Dad; 06/07/2026 10:29 PM. Reason: clarification
