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Master cylinder piston material

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  • Master cylinder piston material

    I have a friend that is sending me a master cylinder for a 30's chrysler coupe that needs a new piston fitted. Has anyone worked on these? I have both 6061 and a piece of 7074 just wondering which would be the better material. It sits behind a rubber cup, He is asking for .002 clearance on the piston, the cylinder is brass. I will need to polish out the bore prior to fitting and make sure it is round and true.
    Your thoughts.

  • #2
    I would use the 6061 . If possible you might anodize it and have the best resistance possible. If the owner would use silicone based fluid it would be a life time job. Of course if you want repeat biz, that might not be a good idea.


    • #3
      Clean the bore and measure it possibly off the shelf rebuild kit would work better.They shouldn't be fitted too tight as the cup is forgiving as to fit. Frank C.


      • #4

        No help on material selection, but an idea that might help you get some info...

        I sent the brake master and wheel cylinders from my 37 Buick Roadmaster Phaeton to a company called 'Apple Hydraulics Inc,' in Calverton, New York. They weren't the cheapest, but the work was outstanding. I highly recommend these people for classic car rebuilds. Now I know you want to do the work, but a call to them might gain you some info on materials. In my case they bored the cylinders and sleeved with stainless, replaced all of the pistons, rods, hardware and rubber. The total cost for 4 wheels and a master was about $750.00. I think this is a good deal considering I really want this 5800 pound car to stop when I step on the pedal The next thing will be the knee shocks...... All work no fun

        Happily working on my second million Gave up on the first