Honda 600 Master cylinder rebuild - watch the kits you buy they may not have
everything you need;
Cleaning parts: Clean them in clear water, DOT 3 and 4 fluids are made to
absorb moisture, and if crystallized will need to be liquefied to make
disassembly easier. Water will liquefy the dried up old fluid (criticized)
and make it easier to remove the parts. Don't hammer, beat or use long
screw drivers to disassemble the master cylinder. Open/remove all the
bolts, bleed valves, check valve assemblies and the end clip and washer.
then place the whole assembly in a bucket of clear water for a few hours. I
use compressed air to push the pistons out by plugging all the holes with
the exception of one bolt at the end, place it in a couple of plastic bags
and using a blow-gun attachment force the pistons out with one short blast.
Commonly missed components in the master cylinder rebuild is the: Check
Valve assembly - Union cap gasket, Check valve cap, Check valve washer,
Check valve and spring. Not all can be reused again. Special caution
should be made to replace the union cap gasket as the used one will always
be crimped along the inside edge making it unusable a second time. The
check valve cap is aluminum and is placed over the check valve for the front
calipers the check valve seat is rubber and placed over the check valve
(caution the rubber seat may become hard, and/or swollen making it unusable)
There are two check valves, both are specific to the front and the rear, one
has fewer holes than the other (caution the rubber may become hard, and/or
swollen making it unusable). Note: the front check valve has 8 holes under
the rubber seal, the check valve for the rear only has 6 and can not be
inter changed. Both fit into the spring with the larger end sitting on the
bottom of the brake fluid inlet body.
Also, a commonly forgotten area is the bleed back (or compensating port)
hole in the bottom of the brake fluid inlet body (Ref Honda Sedan shop
manual page 11-10) . There are two holes, the larger of the two is called
the inlet port (found in the rear or toward the fire wall) the Compensating
port is (is found in the front or toward the grill side of the engine
compartment). The compensating port on both can become plugged with
corrosion and should be checked to ensure the opening is clear.
Another short coming of the dual master cylinder is the primary and
secondary piston assemblies. Caution should be made to ensure the piston
assemblies are assembled just as they were disassembled. Don't mix up the
screws, wave springs or the direction of the cups as this will cause the
master cylinder not to work or work poorly.