The rear brakes in my hobby car are drums type. One of its brake cylinders have one of the pistons "really" stuck: it won't move by hydraulic force by pressing the brakes pedal; it won't move by slightly tapping it in or out of the cylinder body and didn't even moved after I caller the services of my Margarita (10 lbs hammer). It is really stuck...so what other thing I can try? Heat it? Freeze it? The body is cast iron, the piston is aluminum.

  • Hey bud! You aren't using your original account? It sounds like the piston is cocked in the calliper bore. Either that or rusted solid. – Pᴀᴜʟsᴛᴇʀ2 Nov 9 '18 at 23:27
  • Mount it in a hydraulic press, if it breaks it needed replacing anyway... :) – Solar Mike Nov 9 '18 at 23:46
  • @SolarMike - While I agree, the problem here is, Aram is in Cuba ... hard to get replacement car parts there. Very hard. – Pᴀᴜʟsᴛᴇʀ2 Nov 10 '18 at 0:42
  • The thermal expansion coefficient of aluminum is about twice as big as steel. So if the piston is Al, freezing it would be better, if the body is also going to get cold. Heating the casing quickly, before the heat can soak through to the piston, might also work. – alephzero Nov 10 '18 at 1:11
  • I totally forgot my original account :( anyway, I will try freezing the part and try to move it at least in, in a vice jaws. If it works, then I can move it enough to sand the cylinder walls and try again but outwards. – Aram Alvarez Nov 10 '18 at 1:58

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