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front brakes are fine then lock up at random times?


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it does it to me atleast twice a week ill be driving front brakes will be fine then they will just about lock up so i put it away and then the next day i go to drive it and its fine...its really making me mad anybody got any ideas

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They dont completely lock up they just start to drag. Im not even using the front brakes at the time it does it i will just be driving down the road or a trail and ill notice that they are starting to hangup when i havent even touched the front brake. Then i can let it sit for a while and come back and it is completely fine. Im thinking about getting all new brake discs and pads and rebuilding the front master cylinder anyways hopefully i can fix it. Building a sandrail right now though so i dont have the funds to put much into my banshee i wanted to buy a full frame and a arm skid plate for it and put new discs and brake pads on it and rebuild the master cylinder but ill do all of that this fall when im done with the other project.

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Is something preventing the master cylinder from releasing all the way? There is a feed hole between the reservoir and the bore that is supposed to be open when the master cylinder is released. When you first start applying the brakes, the piston cup goes past that hole and pressure starts to build in the system. If the master cylinder is partially applied, that hole is not open to the reservoir. As the brake fluid heats up, it expands and applies the brakes because the fluid can't go back into the reservoir, which makes more heat, which builds more pressure till they finally lock completely. When you park it, the fluid cools down, the pressure decreases. Another possibility is that some idiot put oil in the reservoir which swells up all the rubber parts.

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Before changing professions 27 years ago I was NIASE certified in brakes. Every once in a while I'd run into a caliper that would lock up but if the bleeder was cracked the piston could be freely pushed back. It's kind of hard to describe but what was happening is the inner liner of the rubber brake hose would split and allow the fluid to be forced out around the fabric woven into the line and it would collapse the inner liner making it impossible for the fluid to return to the master cylinder. Sometimes if left alone for a while it would release only to lock again after applying the brakes and forcing the fluid into the pocket pinching off the return flow again.

Hope that helps.

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