I bevel the top and bottom edges of the shoes to stop squeal and to make sure the rest of the shoe hits the drum squarely. Most shoes do not have asbestos in them any more, but wear a mask as you do this outside the shop.
BRAKE BASICS BY Fat Pat Anderson
Is your pedel soft? Having trouble bleeding?
Brake Bleeding
We will start with bench bleeding the master cylinder. Most new master
cylinders sold today come with 2 plugs. These plugs are to be used to
block off both outlet ports. This is a foolproof bench bleeding method.
The whole purpose of bench bleeding the master cylinder is to get the
air out of the cylinder so that we don't push it down into the system
when we start bleeding our wheel cylinders and calipers.
Mount the master cylinder in a vice. Using the plugs supplied with the
master cylinder, screw them into the outlet ports and tighten. Next,
fill both reservoirs with the type of fluid you are going to use. (Dot 3
or Dot 5). Using a dowel rod or large Phillips head screwdriver, stroke
the piston using 3/4" to I" strokes. You will see the air bubbles coming
up into the reservoirs through the com-pensating ports.
Stroke the piston until you cannot stroke it any more. When you can't
stroke it any more, you are finished. This is the easiest and most
foolproof way to bench bleed a master cylinder. It also happens to be a
very good way to check a master cylinder if it is already mounted in the
vehicle. When you plug off both outlet ports and step on the brake
pedal, you should have a high hard pedal. If the pedal eases toward the
floor, then you know you have a master cylinder that is either
"bypassing" or leaking backwards out the pri-mary piston seal and should
not be used. Leave both plugs in the outlet ports and mount the master
cylin-der in the vehicle. Hook up the line going to the rear brakes and
leave the other outlet plugged. A bladder type pressure bleeder is by
far the best tool to use at this point, but they are very expensive and
my suggestion would be for each NTBA Chapter to purchase one so it would
be available for chapter members to use.
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I am assuming we do not have a pressure bleeder, so we are going to use
the "pump" method to bleed the brakes. (we will start with the wheel
furthest from the master cylinder which will be the right rear) First
get a clear glass container and put 2" of brake fluid in it. Now get a
vacuum hosethe correct size to fit over the bleeder valve
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(use a box end bleeder wrench on the bleeder valve before you slip the
hose onto the valve) and put the end of it in the glass container BELOW
the surface of the fluid.
Now (and this isVERY important) have a friend pump up the pedal making
sure that the reservoir is full of fluid. You MUST communicate with your
friend who is pumping up the pedal for you. He/ she should tell you when
the pedal is pumped up and being held. You then loosen the bleeder valve
and you will be able to see the air bubbles come out of the system into
the fluid that you have in your clear glass container. The person
pumping the pedal should not start pumping again until you tell them to,
after you retighten the bleeder valve. If your friend starts pump-ing
the pedal BEFORE you have the bleeder valve completely closed, you will
simply suck aerated fluid back into the system.
Repeat this procedure until there are no more bubbles coming into your
glass container and you are then ready to move to the next wheel. After
you have completed both rear wheels, you should have a high hard pedal.
Now we can remove the plug from the outlet port for the front brakes and
using the same procedure, we will begin at the right front wheel.
If we have disc brakes on the front, MAKE SURE that the bleeder valve is
as high as it can be. In some cases, the caliper may need to be removed
from the vehicle and use a piece of I/2" or 3/4" plywood to take the
place of the rotor.
If you use this method, you should be able to get the air out of your
new brake system and have a high, hard brake pedal.
As always, you can find me on the BBS most every evening.
Fat Pat
Editors note: Fat Pat "Brakeman" Anderson is a brake expert who has
produced brake videos and taught courses on brake repair and service.
Pat has a long history with automobiles, parts and T-buckets (though
with the sale of the flaming chicken Bucket, he is currently without the
best ride in the world!) Thanks Pat for this article, keep 'em coming!
