Sportster Rear Brake Nightmare! Rebuilding the Caliper, New Brake Line & Still No Pressure

In this video, I’m back on the hardtail Sportster trying to solve the rear brake problem once and for all. I rebuilt the master cylinder, went through the rear caliper, replaced the seals, checked the piston and bore, tested fluid flow, and replaced the brake line I had cobbled together — but the brakes still refused to build pressure. I also tried pre-bleeding the caliper, vacuum bleeding through the bleeder screw, repositioning the caliper because the bleeder sits the wrong way on the hardtail setup, and deadheading the master cylinder to test pressure. After all that, it looks like the problem may still be inside the master cylinder, even with a new cartridge installed. This one didn’t end with a clean win, but it’s real garage troubleshooting on a custom Harley Sportster chopper build. If you’ve fought DOT 5 brakes, rear master cylinder issues, or hardtail brake bleeding problems, drop your ideas in the comments.