Bleeding Dual Circuit 69 Brakes Again and Again and...

[alfacybersite <acs@domain.elided>]

Waaay back in #828 (boy you kids are getting prolific) Mitch Wolberg was
considering the match solution (one assumes carefully dropped into the
gas tank) in response to his unresponsive '69 Berlina's brake pedal.

Have an intervention for yourself and ask a friend to hide all of your
matches...for the time being.

IF all is correct, you should have good pedal. You mention having the MC
resleeved / rebuilt. Let's assume it is okay for the moment.

When at rest is the brake pedal even with the clutch pedal? If not crawl
underneath and adjust the long (at least it is on Spider's) shaft to the
brake pedal.

You didn't say if the boosters were replaced / rebuilt. If not, I would
assume the rear seal on both is leaking and the (elusive) valve plunger
cup seals are frozen solid.

Before you rebuild them (two kits per booster), get all four wheels off
the ground (safely), have someone hold the brake pedal down and try to
turn one of the front wheels. If you can turn the wheel, there is a
caliper problem. Then release. Obviously if dragging a lot, the piston
in the caliper is semi frozen and quite likely all calipers need
rebuilding. Yes, put in new pads at this time if required.

Assuming both wheels lock up nicely, then release properly, go to the
rear and do the same. Should you be able to actually turn both wheels
with brake pedal down (and they also release properly), remove the brake
bias adjuster.

Oh yeah, forgot to mention. Go out and buy about six more quarts of
brake fluidjust in case.

You won't enjoy this much, but dismantle, being Very Careful to make
notes of where everything goes and how it is adjusted. Be especially
careful of the rubber seals which [unless someone knows something I
don't (Tony Stevens?)]  because you will have to reuse them. There will
undoubtedly be a fair amount of yuck in there if the car has sat for any
length of time (and what '69 Alfa hasn't?). Clean all up with alcohol or
brake cleaner. Install.

Bleed brakes (sigh) again. Hey, it's only time and brake fluid. If it
improves significantly, drive it.

If not, remove one booster, dismantle (once again being most careful
where all goes and in what direction they are installed. Verify this old
guy's theories and see if there is not fluid and yuck in the main
diaphragm 'chamber'. Then see if there is heavy scoring in the inner
(aluminum) cylinder. If so, call IAP or (?) and buy two new ones. If not
and you're having ever so much fun, keep going.

Remove the lower (smaller) diaphragm and you will no doubt see a small
cupped piece of aluminum where the upward / pointy end of the diaphragm
fits into. The small aluminum piece which you will eventually find out
has a small seal on it. You'll truly enjoy removing it, but it will come
out. Don't score up its small sleeve. Clean all up, using either a steel
(my choice) or wooden dowel wrapped in 600 grit wet / dry wetted with
brake fluid and remove most if not all of the inner sleeves scores. Get
a small dowel and do the same for the lower plunger sleeve. Clean again
and reassemble with new seals, diaphragms, etc. Then do the next one and
install both. You did have the large diaphragm shells cad plated didn't
you?

Then bleed brakes again. If no improvement have all four calipers
rebuilt and...bleed the brakes again.

If no improvement, you'll have the satisfaction of knowing you have done
everything possible to rectify the situation. Would be a shame to ask
your friend where he hid the matches, but would certainly understand.

Biba
Irwindale, CA USA
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