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silicone fluid

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  • lyndon Sharpton

    silicone fluid

    OK I want to know what is the least that I have to do in order to convert over to Silicone fluid. the car has been in storage for the last several years. the calipers have been sleeved
  • Jack H.
    Extremely Frequent Poster
    • April 1, 1990
    • 9906

    #2
    Re: silicone fluid

    Pretty simple, COMPLETELY drain the brake system and flush it of residuals of DOT 3/4 fluid. Now, refill with DOT 5 fluid. The trick lies in making SURE you've bled the refilled system properly to get trapped air pockets out, but this isn't much different from a conventional brake fluid fill job....

    Comment

    • Craig S.
      Extremely Frequent Poster
      • June 30, 1997
      • 2471

      #3
      Re: silicone fluid

      Lyndon - Jack is right, whick usually means disassembly of each caliper, clean, assemble with silicone, and reseal each unit. Also, the same applies for the master cylinder. The time to do this is when the system is being replaced...Craig

      Comment

      • lyndon Sharpton

        #4
        Re: silicone fluid

        Has anyone just flushed the system with denatred alcohol an then used DOT-5 with out rebuilding the calipers an had good luck doing it this way?

        Comment

        • Terry M.
          Beyond Control Poster
          • September 30, 1980
          • 15573

          #5
          Re: silicone fluid

          Lyndon,
          There is an SAE paper in which they tested the technique of using the DOT 5 as a flush for a system already filled with DOT 3/4. I know this is not exactly what you are asking. The results were a real bad black residue after a couple of years. Their analysis, as I recall, was that the residual DOT3/4 and the DOT5 combined to make this sludge. The alcohol flush you propose would clean the lines, but I think it would be difficult to get all of the DOT3/4 out of the calipers or wheel cylinders without disassembly. Any residual polyglycol (DOT3/4) would combine to make this residue which has an uncertain boiling point. I believe they found this residue to be corrosive as well.
          Terry

          Comment

          • lyndon Sharpton

            #6
            Re: silicone fluid

            well thanks for the info, I think I will just stick with the dot 3/4 at this time I do not want to do a complepet restation on the car. I am just trying to bring it out of hiberation! Lyndon

            Comment

            • Dick W.
              Former NCRS Director Region IV
              • June 30, 1985
              • 10483

              #7
              Re: silicone fluid

              Lyndon, I think that you would be as well off to change your DOT 3/4 fluid once a year. It is a lot of easier to do that than to do a proper change over.
              Dick Whittington

              Comment

              • Craig S.
                Extremely Frequent Poster
                • June 30, 1997
                • 2471

                #8
                Re: silicone fluid

                Lyndon - I believe Duke has mentioned before that using dot 3/4 coupled with flushing of the brake system every 2 years gives completely satisfactory results, and DOT 3/4 is much easier to bleed fully and entrains air less. I plan to stick with DOT 3/4 and flush regularly, and forget about the brakes....Craig

                Comment

                • Patrick T.
                  Expired
                  • September 30, 1999
                  • 1286

                  #9
                  Re: silicone fluid

                  I changed mine from glycol over to DOT 5 with no problem. Gravity bleed all the glycol from the system, then gravity bleed the entire brake system through the MC with a gallon of denatured alcohol. This will take some time. I did this over a period of a week in the garage to give the alcohol of lot of "hang time" in the system.

                  Then fill the system with DOT 5 Silicone and gravity bleed until the smell of the alcohol is out and the fluid turns blue. Keep an eye on the master cylinder to avoid sucking air. I never had any problems and always had a hard brake pedal with no air. PT

                  Comment

                  • Duke W.
                    Beyond Control Poster
                    • January 1, 1993
                    • 15610

                    #10
                    Re: silicone fluid

                    The only "disadvantage" of glycol based fluid is the periodic flushing to get rid of the absorbed moisture if you want to prevent corrosion and eventual failure of the hydraulic components.

                    The only way I would ever attempt a switch to silicone is if I COMPLETELY disasseble the brake system, rebuild the m/c, calipers/wheel cylinders and assemble them with silicone, thoroughly flush and dry all the steel lines with denatured alcohol, and replace all the rubber hoses.

                    You want to rid the system of every last molecule of glcol. You will NEVER completely remove the glycol fluid by bleeding and the remaining glycol and its absorbed moisture will corrode the system.

                    Duke

                    Comment

                    • Terry M.
                      Beyond Control Poster
                      • September 30, 1980
                      • 15573

                      #11
                      silicone fluid

                      Duke,
                      I would rate a second disadvantage of glycol fluid the chance of paint damage. The fluid flush every several years increases the risk of paint damage. That not withstanding, I agree on the complete disassembly idea. Brakes are not a system on which one should take shortcuts. Perfect is just good enough.
                      Terry

                      Comment

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