It may be that you have a pipe fault.
The pipes need to supply a pressure to the pad cylinders and sometimes dont work for a variety of reasons.
1) A reaction with the pipe material. Some brake fluids react with the rubber and cause it to deteriorate. This used to happen because the rubbers for type 3 / 4 and 5 brake fluids were incompatible. If the rubber swells enough, then the fluid can't get through. Sometimes the rubber breaks down and the rubbish forms a plug.
2) A split in the lining. Some pipes are constructed with a thin lining inside the main tube material, which is inside the reinforcing braiding. If this splits, then fluid can get between the lining and the next layer. As you force fluid down the hose, the pressure between teh two layer squeezes the inner one closed, like standing on a hose.
3) Tube stretching, This is when the tube itself bulges instead of the pressure acting in the cylinder. In the easiest case you can see it bulge or the outer braid is damaged, in the worst case the bulge is small but over a long area so difficult to detect.
Obviously in a severe case it is relatively easy to see any of the first two. Lock the pads,Take the Bleed screw right out on one side, press the pedal and see the spurt that comes out of the hole.
Put the screw back and do the same thing for the other.
If that doesn't work then swap the connections to the cylinders, ie if you have two long masters swap them over, else just swap the from the Tee connector. If the trouble moves from one cylinder to the other, then you have a faulty pipe.
If it doesn't, then loosen whatever is stopping the pistons from moving and make sure they are free to move. (ie, put the pipe on one side only).
It doesn't take much wear for the piston to tip in the barrel and lock up. If the barrels are black finished you can sometimes see the shiny patches where the coating has worn.
I'm assuming that you have already taken the brakes apart to meticulously clean the piston, cylinder and seals. It only takes a minute bit of dirt to lock a piston.
Do te
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bloody top kart brakes by 'chris27' (21 Dec 2008 @ 18:04)
