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Re: [ST] bleeding brakes



Thanks Jim--I actually had done what you suggest yesterday up until "once
the brakes can actuate."  They never did, even though fluid was coming
out.

Thanks to those who suggested the mityvac.  Did anyone obtain theirs
locally (eg auto parts store chain?)  I'd rather not wait for them to
come in the mail.

Tony

  ----- Original Message -----
  From: "Jim Crate"
  To: ST@xxxxxxxxxxxxxx
  Subject: Re: [ST] bleeding brakes
  Date: Tue, 22 May 2007 22:04:25 -0500


  On May 22, 2007, at 8:20 PM, Antonio Bird wrote:

  > Despite modest mechanical abilities, I decided to try to bleed the
  brakes
  > myself. Bought and installed speed bleeders. Seemed to be going OK
  > until I drained the reservoir too low and let air in the system.
  Then
  > got floppy lever which did not push through the fluid when I added
  more.

  I once let air that way into the hydraulic clutch system on my car,
  which was further complicated by the hydraulic buffer loop that
  system included with its own bleeder. It took almost a full liter of
  fluid to bleed that system enough to actuate the clutch again. If
  I'd known it would take that much, I would have gone to the store to
  buy some cheap fluid instead of use my $9/liter racing brake fluid!

  Anyway, here's what I'd do. Set up to bleed the caliper closest to
  the master cylinder. Fill the reservoir with brake fluid (have at
  least a liter on hand, you can use cheap stuff and once you have the
  system properly bled, it will be easy to flush the old fluid with
  better stuff later).

  Open the bleeder screw enough for fluid to come out with no
  resistance, .5 turn is probably enough. Operate the brake lever
  through its full range of travel quickly and repeatedly until you
  have fluid coming out the bleeder screw. If there is much
  resistance, open the bleeder a little more. Once you have a good
  squirt of fluid coming out of the bleeder, then close the bleeder and
  see how soft the brakes feel. If they stop before contacting the
  bar, then you at least have brakes, because it is only stopping
  because it is pushing the pistons to the rotor.

  Once the brakes can actuate, then I'd continue by closing the bleeder
  a little, until you can feel some resistance when you squeeze the
  lever, but it allows fluid to pass so that the lever will go to the
  bar when you squeeze. Squeeze the lever quickly and firmly several
  times. When you stop seeing bubbles in the lines, then open the
  bleeder until fluid goes through with no resistance and activate the
  lever quickly several more times. You want fluid to move through the
  system quickly, so the air bubbles don't keep rising back up the
  line.

  After repeating those steps a few times, the lever should be getting
  more firm. Obviously, watch the level of brake fluid in the
  reservoir at all times. If you suck in air, you are starting the
  process all over again.

  Once the lever is pretty firm, and you've repeated these steps for
  both calipers, then move back to the first caliper. Squeeze the
  lever hard, and then open the bleeder very quickly. You want a sharp
  burst of fluid coming out of the bleeder, carrying with it the last
  bubbles. Repeat this as necessary for both calipers.

  You can repeat the final bleeding procedure the next day for even
  better results, as overnight tiny air bubbles will coalesce together
  into larger bubbles that will be easier to bleed.

  Hope this helps,

  Jim

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