There are alot of opinions about brake bleeding, and alot of what I've read
on the list is true. But if I've learned anything about bleeding brakes
(from B-52 bombers and F4E fighters to automobiles of all types), patience
is indeed a virtue here.
Point #1: as mentioned previously on the list, bleeding the master cylinder
first is Job #1.
Point #2: as mentioned previously on the list, bleeding the brakes furthest
from the MC first and then working through in order to the nearest is
correct.
The problem of trapped air in the lines can sometimes be made worse by
pumping the brake pedal too often or too enthusiastically. This causes
foaming and disperses the existing trapped air to even more places. In
severe cases, two things can be done in the following order:
1. Gravity bleeding: once you have fluid going down into the system crack
the bleeder on the farthest brake and let it drip into a jar through a hose
attached to the bleeder. Walk away. Check the reservoir periodically and
keep it full. Close the bleeder after an hour or two and repeat on each of
the remaining brakes in the usual order. (That's right - you're Saturday is
now history and the family plans are shot to hell.) The slow self-siphoning
movement of the fluid through the lines will push the majority of trapped
air out without the threat of foaming.
2. Vacuum bleeding: now that most of the air is out, grab yourself a
Mity-Vac hand vacuum pump (21.00 at WallMart), and while you're at it grab
an assistant. While you crack the bleeders and pull a slight, repeat
slight, vacuum at the bleeder the last of the air will come out as the
assistant keeps that reservoir full. An instruction manual with the pump is
very informative. Repeat on each of the remaining brakes in the usual
order. To eliminate false air bubble indications, apply heavy grease to the
bleeder threads.
If there are no faulty components in the system this will work everytime.
Greg Schulz
VSCDA vintage racer, Grp. 2, Sprite #517
Former "Bubble Chaser", USAF, 1968-1972
388th Tactical Fighter Wing (TAC), 19th & 419th Bomb Wing (SAC)
Cedarburg, WI
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