Re: brake bleeding etc.

[Tony Lupton <t.lupton@xxxxxxxxxxx>]

Hi Folks,

[Just when you got a digest without any brakes]

Lot of people have come up with lots of good solutions for bleeding
brakes on your own: speedbleeders, upwards-running plastic tube, and
plastic tube with a built-in check-valve (heard about it yesterday at
work). These are all well and good, but risk getting any rubbish in your
master stuck under a MC seal (Ask me how I know. On second thoughts
don't - it was an expensive exercise). Then there's ways that don't
involve touching the pedal: positive pressure applied to the fluid
resevoir, negative (vacumn) pressure applied to the bleed screw.

I was mulling over all this last night, and a question arose (having
been inside a master cylinder): how can you guarantee there aren't
pockets of old fluid left in the master cylinder, if you're not flushing
the master cylinder by depressing the plunger.


Since I know people are going to ask anyway, the expensive exercise
started out as a simple brake fluid change on the 90 (using the
traditional open bleeder, depress pedal, close bleeder, release pedal -
never again). Couldn't get a decent pedal. Open up the MC. Because it
had been goodness know how long since the master had undergone full
travel, bits of junk got caught under the MC seals and the seals were
torn. At least the sleeve was clean and corrosion free. New seal kit and
repeat bleeding process. Couldn't get a decent pedal. Come back the next
day and try again when not frustratrated. No Pedal. Call mechanic and
book car in. Flatbed truck arrives and takes car away. Mechanic can't
get decent pedal and sends MC and proportioning valve away for pressure
testing. MC ok, proportioning valve shot.

Total cost: 2L of brake fluid (+ what the mechanic put in), MC seal kit,
proportioning valve, flatbed truck, no car for three days. Ouch. I don't
want to repeat that experience in a hurry.

Tony
1979 Alfetta 2000
1985 Alfa 90 2.5i
The Alfa 90 page http://www.geocities.com/MotorCity/Downs/7709
- -- 
Tony Lupton                            *           CiTR Pty Ltd
Email: t.lupton@domain.elided         *    *         339 Coronation Drive
Phone: +61 7 3259 2382                  *          PO Box 1643
Fax:   +61 7 3259 2259                             Milton Qld 4064
                                      *            Australia

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