master cylinder replacement???

Discussion in 'Suspension and Brakes' started by spank 141, Aug 13, 2014.

  1. spank 141

    spank 141 New Member

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    I know you have to bench bleed a new master cylinder and the question is on a 98 cobra do I plug the holes the brake lines go to and bleed the master through the bleeders or do I just leave the bleeders tight and bleed the master through the ports for the brake lines?? I know its a dumb question but all info I am finding bleed the brakes through the brake line ports but they are masters that don't have the bleeders on them. Haven't been able to find info on a master that has bleeders. Thanks for any help this is bugging the crap out of me and I just want to do it right the first time.
     
  2. RichV

    RichV Well-Known Member

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    Bleeding the MC is something completely different.

    IIRC you just fill it like an inch overnight while it sits upright. I did it on a SVO MC which is different than a plastic tank MC, but process should be the same. Line holes are plugged.
     
  3. kb1982

    kb1982 Active Member

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    Ive replaced MC's on cars, trucks, and motorcycles, and ive never bench bled a single one. Im such a cool rebel like that. But in all honesty, I just think its only purpose is to speed up bleeding the brakes at the calipers. Yeh, I may repeat the process 4 times around the car without bleeding the mc before im happy, but im ok with that. But if u wanna bench bleed the mc, get bleeder fittings that screw into where the lines screw in. Attach hose to the bleeders and run it back into the mc. Fill the mc with brake fluid. Keep both lines submerged in the fluid in the mc, open the bleeders, and use something to push the piston torwards the front of the mc as if the brake pedal would work it. You should see air bubbles rise outta the fluid. Tighten up bleeders, remove hoses, and install the mc. When you remove the bleeder to install the line, fluid will leak out, but air will not get sucked back up in unless u hit the brake. Just remember, any piston that pushes, will also suck on the opposite stroke. Pushes fluid on the out motion, and want to suck it back on the in motion, bring air back in if it isnt sealed. There are my thoughts, but you too can be cool and a rebel like me if you soooo choose.
     
  4. kb1982

    kb1982 Active Member

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    If you go around a car 8 times bleeding the brakes, and it doesnt feel right, new mc or not, that sucker is just that. Sucking air back in somewhere. A check of all the lines and calipers is needed. If you have a brake that sticks and doesnt release when your off the pedal, but said caliper releases with the line off, its more than likely a rubber hose is collapsing not letting the fluid back out of that caliper.