Guys,
Look, I`m no expert by any means, but let me jump in late on this subject
with some brake bleeding tips that I assume a lot of you know but I sure
didn`t until people who did know set me straight:
1. If you can help it, try not to do everything at once. That way you
can check your work as you go and catch problems before they get lost in a
major project.
If you must break down the system all at once, bench bleed the MC
before putting it back. Not as difficult as it sounds, but installing a wet MC
can be messy if you don`t plug the holes. This bench bleeding does not appear
to be essential, but It does help to reduce the possibility of trapped bubbles
there.
I understand that a clutch slave cylinder can also benefit from bench
bleeding; however I`ve never tried that.
2. Double check for leaks. Common sense. You can`t get the air out if
you keep sucking it back in.
3. Before bleeding, run the shoe adjusters up tight against the drums.
This won`t help if the drums are worn thin.
4. Expect a system that has been vacated to be troublesome but not that
troublesome.
5. No matter what gadget you have on the shelf, try the old-fashioned
down/up pedal pumping method first. Starting at the furthermost wheel from the
MC, open the bleeder on the down stroke, close it before the upstroke. Wives
are good at this and hardly ever complain unless it goes on too long.
6. Avoid agitating the fluid by aggressive, over pumping. That only
makes froth in the system, and you have to wait till it settles down and start
over. If you yell at wife at that point, give up. You`re going nowhere, my
friend.
Five or six easy strokes, max, at each wheel should do for the first pass.
Repeat that, if necessary, but if you don`t get it on the third or fourth try,
you got some fundamental problem. And don`t let the pedal pusher shove the
pedal hard to the floor. Another fine reason for not loosing your temper. That
might damage the MC and your marital bliss.
7. If after that the brakes still won`t bleed, try pinching off the
rubber hoses, one by one, to disable each front wheel cylinder, then the
rears, checking the pedal as you go. Use specialized hose pinchers, mostly
available from auto parts stores. Cheap here is okay. If you get a hard pedal
at the pinch of any hose, the trouble may be at the cylinder that one
services. To find out which rear wheel may be the culprit, if not both, remove
the hard lines, one at a time, at the rear 3-way and replace the fittings in
turn with a bleeder screw. Again, test the pedal at each operation.
I helped a friend overhaul the system on his MGA. After nearly giving
up, using this method we found that the cause of an apparently impossible
non-bleed condition was a defective new aftermarket rear wheel cylinder that
would not properly float in the back plate. We replaced that, and bled the
thing on the next try. Watch that aftermarket junk!
8. Another place that traps bubbles is the unions, 3-way, etc. Try
tapping them.
A note on bleeding tools: I probably have one of each--Mytivac,
compressor powered vacuum device, pressure bleeder, reverse bleeder, one-man
device...whatever. The Mytivac does seem to help bleeding the slave; however
nothing beats foot of wife on pedal. But we`ve been married 40 years, all of
which I`ve had LBCs, and that helps.
Bert Shirey
60 Bugeye/ 66 Midget 1098
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