Master Brake Cylinder

Discussion in '80-Series Tech' started by LCphil, Jun 14, 2005.

  1. LCphil

    LCphil

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    I just changed my master brake cylinder and I'm not very impressed with the difference - almost no difference. I can push the pedal almost to the floor but the brakes are effective.

    What gives? I'd expect to have a harder pedal, there is no air in the system but if idling and my foot firmly on the pedal it will continue to depress slowly :confused: until it bottoms out somewhere close to the floor.

    Any ideas? Some trick that was missed or is that just the way they are?

    :confused:
     
  2. e9999

    e9999 You want to do what...? Moderator

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    there are a bunch of tests given in the FSM where they tell you how much the pedal should be depressed etc...
     
  3. LCphil

    LCphil

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    I'll take a look.
     
  4. Kalawang

    Kalawang

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    I assume you also changed the pistons. Try pumping the pedal and see if the brake comes higher. If it does, stay with it and see if it stays that high. You could also go back to Minerva and tell Emerson or Macky about your problem. Either of them will probably order their boys to bleed it at the wheels. The LC is supposed to be self bleeding, but that actually helps.


    Kalawang

    BTW, if you still have the old Master, I'd like to look at it and possibly buy it if you have no further use for it.


    Kalawang
     
  5. landtank

    landtank SILVER Star

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    Was the new MC a "new" MC or a reman or even worse not OEM?
     
  6. LX_TREME

    LX_TREME

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    That means air/bubble still trap inside your brake system, I use the Z method:
    Get somebody to help, your wife, friends or neighbor to seat inside the car.
    Leave the car idle you need to bleeds more:
    1st do : Driver Side ---------------->then 2nd the front passenger side,

    3rd Left Rear ----------------> Last one Right Rear you must repeat few times approximately 10-15 times but you also need to check and refills the brake fluid (Brake Master Cylinder) Good Luck :flipoff2:
    P.S: Need extra bottle Toyota Brake Fluid 1 or 2 should be good.
     
  7. CharlieS

    CharlieS

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    Did you bench bleed the new master cylinder?

    Charlie
     
  8. Kalawang

    Kalawang

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    I agree with that as a possibility. However if the pistons were not changed, that too could be the source of the trouble.


    Kalawang
     
  9. elmariachi

    elmariachi

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    I agree that you still have air in your system. I also think you are going to find that your pistons are sticking and your calipers need rebuilding....probably more so than the master cylinder did.
     
  10. sjcruiser

    sjcruiser

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    I'll second that question.

    How did you bleed the system? did you also do the LSPV? I've never heard of a self-bleed brake system as the fluid itself does not circulate. Also check the FSM for the bleeding procedure as the one suggested by LX_TREME does not seem to match from what I've read.

    Frank.
     
  11. LCphil

    LCphil

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    Kalawang,

    Sorry, just saw this. They bled the system at the wheels but were very fast with the installation that I missed if they bench bled the MC.

    I've ordered a rebuild kit for the MC and will rebuild it for a spare.
     
  12. LCphil

    LCphil

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    Brand new OEM Toyota MC.
     
  13. LCphil

    LCphil

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    Thanks. I'll get it back to the garage and them do it.
     
  14. LCphil

    LCphil

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    Why the pistons? It only has 36,000 miles and when all teh rotors and pads were changed the calipers were fine.
     
  15. LCphil

    LCphil

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    Thanks, possibly but at 36,000 miles? See also reply above to Kalawang.
     
  16. LCphil

    LCphil

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    Good idea. I'm sure they didn't think of the LSPV (neither did I my FSM is still packed). I'll get them to have a look. It has to get body work done at Toyota so I'll get them to do it all at once.

    It does seem much better now after a few days. I drove it yesterday and it was fine, but maybe I've just gotten used to it. When they bled it they did not have the engine running which I think would make a difference.
     
  17. IdahoDoug

    IdahoDoug

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    I wouldn't sweat any of the calipers or their pistons. Unless they're dripping brake fluid (which would let the pedal drop), your symptoms have nothing to do with them. Ditto the LSPV. Everything points to the MC, which should indeed have been bench bled. It may be that it's getting the air out as you drive, but I'd then expect you to have a soft pedal as some air may end up in the brake lines. Drive it another week and then ask that all 4 calipers and the LSPV be bled to provide a final purging of air bubbles. There is a specific sequence to this and its outlined in the factory service manual.

    DougM
     
  18. LCphil

    LCphil

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    Excellent. Thanks. I'll see how it goes.
     
  19. robbie

    robbie Guest

    One thing you may want to ask is if they adjusted the stud (that sits between the BB and MC) in the brake booster properly or if they did not adjust the stud they need to. It is adjustable for when you replace the MC and the differences of machine and resting height. This would bring the effective height of the pedal feel up higher(hope I said this right). As well I concur that it sounds like you still have air in the system as it should not bleed down(continued pressure and the pedal goes slowly to floor, and you can pump up the brakes). any how it sounds like some thing is up and needs to be adressed sooner than later. good luck robbie
     
  20. Kalawang

    Kalawang

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    By my experience, pistons are the primary suspect if you are not losing brake fluid. Their rubber collars wear out or are cut if the MC has scratches. However, I spoke to Macky about your car and he says there's nothing wrong with it or the brakes as far as he saw when you had it there. He thought you were in good shape.

    That leaves us air bubbles. I suggest you start the engine, leave it in idle and have your houseboy or driver pump the brakes until the pedal comes up. This might need some repetitions, but I have confidence that in fair time the pedal will stay up. If you feel the need, you can also just take it back to Minerva and have them bleed it.

    I've had the same problem and did the pumping thing.


    Kalawang


    BTW,

    For the Western readers, The Philippines has very cheap labor so ordinary income allows for household servants.
     
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