Maddad Posted July 29, 2023 Share Posted July 29, 2023 I just tried to get the bike out of the shed for the first time this season, when I dropped it off the center stand I grabbed the front brake and that was it. Front and rear brakes are on. The rear brake pedal is hard as a rock and it was never touched. I cracked the line at the master but that didn't release the pressure. Delay valve? Proportioning valve? Any suggestions would be appreciated. Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted July 30, 2023 Member Contributer Share Posted July 30, 2023 When was the last time the brake fluid was changed? The SMC on the left from caliper has a tiny opening that can cause the rear brake to drag - fluid goes through under pressure, can't come out if the system is gummed up with degraded brake fluid. There's a post somewhere in the maintenance threads about that. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 30, 2023 Member Contributer Share Posted July 30, 2023 You need to crack the bleed nipple at the callipers to release the pressure and get rolling. VFR brakes are special and need careful attention to avoid this sort of thing happening. Looking on the bright side, it is better for this to happen in your garage than when you are braking hard into a hairpin bend. The service manual is available on the downloads section of this website. Read this and service the brakes properly. ST1300 brakes are very similar and there are some good resources available https://www.st-owners.com/forums/threads/st1300-maintenance-brakes-avoiding-the-pitfalls.135125/unread Link to comment Share on other sites More sharing options...
Maddad Posted July 30, 2023 Author Share Posted July 30, 2023 Thank you for your input . The fluid was changed last year. Ultimately I cracked open one of the rear brake lines, the one from the rear master ,it released the pressure and was accompanied with a audible click. Last year I was replacing the rear valve stem ,my son thought he could help by appling both front and rear brakes with all his might,needless to say it didn't nd I believe that may have led up to this. After relieving the pressure every thing seems to be fine. The proportioning valve must have gotten stuck. I certainly won't jump on it and go 500 miles but it seems OK. Shake down will 10 miles to get it inspected. Cheers. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 30, 2023 Member Contributer Share Posted July 30, 2023 If you have to, the PCV can be easily diassembled for cleaning. It just held together with a circlip and o-rings. I'd certainly suggest as a minimum you need to do a very thorough flush and bleed of the brake hydraulics. It would seem there is at least one piece of crud floating around that can block stuff up. The brake masters have a teeny tiny compensating port that is the only way for fluid pressure to release after applying the brakes, and when that clogs you get at least binding and over heating. The SMC on the left fork leg is very prone to this and it also contains a one-way check valve and mesh screen that gets gunged up. Before you ride, press the left calliper hard forward to activate the SMC, this should apply the rear brake, and the rear wheel should rotate freely when the SMC is released. If this test fails you need to get it fixed before riding, or you risk an overheated rear brake or an unexpected lock-up. Link to comment Share on other sites More sharing options...
Maddad Posted July 31, 2023 Author Share Posted July 31, 2023 I plan on changing all my fluids. One thing that has me perplexed is the smc and rear master were locked solid against their respective stops. Again when the pressure was released I heard a faint click, pcv? A thorough flushing of the brake fluid is in order. Link to comment Share on other sites More sharing options...
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