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Re: Help...hard brakes
Recent fix on my CGT was a cleaning job. Probably the whole system had
never been completely flushed in 200K. Bentley proclaims the MC "not
rebuildable". You can however "reclaim" them if not too far gone. The
piston and seals must be sound. It's worth the effort to clean them up.
You can tell if it won't "pump", then you go spend the $$.
I removed the master cylinder: disconnect 4 lines (flare nut wrench
recommended), and the feed to the clutch, remove 2 bolts to booster, and
pull it out. You should get a new 0-ring, but may get by with the old
one if you are careful. Take out the screen and clean it (pry
carefully). Rinse out the reservoir with new brake fluid, and run lots
of clean fluid through the MC by pumping the piston rod. If you can
reverse flush with a pressure bleed cap, that will speed things up and
use less fluid. I also forced fluid back though each line fitting (plug
the other three in turn).
Get out ALL the dirt.
The problem with mine was almost certainly "black crud" in the return
vent. When fully released, there should be a path to atmosphere from
all brake lines. If this vent or any lines, pressure regulators, or
check valves are plugged, you will get temperature induced pressure
build up: the brakes may apply themselves! My MC had a third line into
the reservoir, I think that was the return line and check valve. When I
started, the port on the MC was black, when I finished, it was clean. I
followed with re-assembly, a thorough flush of the whole system, and a
Re-assembly is the reverse (famous last words). The screen just snaps
back into place. Be careful to keep the o-ring in its groove (don't
cut or crush). Don't over-tighten stuff. No dirt alowed, keep it
The good news: the brakes work perfectly. The bad news: one bleed
nipple broke off and my stupid trick with the screw extractor meant I
had to bleed it by an unnatural method, and will in perpetuity.
The ugly: haven't done the clutch lines yet. --Gary
Date: Mon, 28 Jul 1997 21:52:52 =0700
From: Ken <email@example.com>
Hmmm... My Coupe GT has been doing something like that lately. The
pedal every once in a while is much firmer than normal, then something
happens and it goes down slightly or gets ("soft") normal, and regular
braking resumes. It's very interesting. Not scary, as it is consistent
when it does it. Haven't been able to attribute it with a particular
RPM range or driving condition as of yet.