Front brake master cylinder rebuild?

Clogan · Dec 29, 2022

My front brake lever suddenly goes almost all the way to the grip when I squeeze it, so I'm not riding until I fix it. I found nothing in my shop manual about it, but wonder if maybe a master cylinder rebuild is in order. A brake fluid swap and bleed did not help.

Looking for a recommendation for a rebuild kit; a quick internet search did not come up with anything specifically for my bike: 2016 Super Duke GT. Thanks in advance for any ideas.

BTW, there was a recall back in 2018 regarding the front master cylinder, but the VIN lookup site shows nothing pending for my bike. Wonder if this is the same trouble the recall sought to prevent?

Hammerhead · Dec 30, 2022

Mine was rebuilt as a recall during the warranty period (2yrs) even though no problem had surfaced. Must be some reason for the recall.

augiedoggie · Dec 30, 2022

Check caliper mountings and make sure calipers are not moving excessively when lever is actuated. Loose caliper or missing hardware or missing brake pad(it can happen) can require more hydraulic travel than your master can generate and allow excessive lever travel. Smaller bikes can be tested for master cylinder internal leakage by removing single caliper and clamping brake pad or flat metal plate to retain caliper piston(s). Once piston travel is prevented the lever is held tight for a time. If lever sinks slowly and no external leaks are apparent, you have internal master cylinder leakage and will require rebuild or replacement. Multi piston opposed twin calipers could make this method unworkable. You can be fairly certain if your calipers are not moving excessively and lever sinks with no external leakage you can probably safely expect your master has failed and leaks internally. Your ABS would likely not cause internal pressure drop.

Front brake master cylinder rebuild?

Top Contributors this Month

Recommended Communities