Re: Brake bleeding

[jlandry@domain.elided (John A. Landry)]

LATE BREAKING NEWS: Curt Cleavinger <rcleavin@domain.elided> wins the 40
million dollar lottery and says:

>>What makes you think you're not getting all the air out?  I'm wondering if
>>you're just mistaken and you have gotten all the air out.  It takes very
>>little fluid to force all the air out.

>Well the pedal goes all the way to the floor with very little resistance,
>and the brake warning light comes on if the ignition is on. If I continue
>pumping, I can get some resistence and the light goes off. Why, you think
>it's another problem?

Well... sounds to me like a strong case for one seal inside your master
cylinder acting up.  The master cylinder has two separate pistons inside...
one for the front and one for the rear braking system.  If one piston is
not sealing properly inside the master cylinder bore (hence not producing
pressure) and the other one is, then the brake warning light will trip
because of this uneven pressure between the two systems.  This happens even
when there are no problems with the rest of the brake system.  The fact
that you can pump the brakes and regain some of the pedal firmness only
supports my conclusion.  The repeated pumping helps to seal a damaged
piston allowing it to build pressure.

>The rear disks? I know I need to go with a master
>cylinder and proportioning valve that are made for disks on all four 
>corners, but I thought that was just a matter of the old 'rear tires
>locking up first' issue (at least for the proportioning valve). Is
>the master cylinder just not pumping enough fluid to move the rear 
>calipers enough?

I'd start with a rebuilt master cylinder... or just replace the seals
yourself.  Either way is a reasonably cheap way to try and eliminate the
problem.  I bet you'll be pleasantly surprised with the result.  It will
eliminate your soft pedal, but of course you may still have proportioning
issues that can only be addressed by installing an adjustable valve (from
Summit or Jegs, etc.).

Let us know how it works out and for goodness sake... stop wasting brake
fluid!  <grin>

John L.
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