Eureka!! Tom (perhaps*)
That phenomena of the master cylinder not permitting the return of the
hydraulic fluid would provide for *exactly* what I've been observing! This is
particularly true after the discovery I made today.
I made another test drive this morning after backing off both rear wheel
adjusters two more "notches" (both adjusters had been positioned in an
identical manner yesterday.) The result was, as expected, more pedal travel
until the brakes became "hard" - about 3 inches. After two miles of the test
drive, the pedal became so hard there was essentially "no travel", and brake
drag was becoming increasingly more evident.
When I returned to my garage, I checked both rear wheel hubs for temperature.
Neither was hot. I immediately put the car up on jack stands, and checked the
(suspect) right rear wheel. Couldn't rotate the wheel. Removed the wheel and
moved the adjuster fully back; still couldn't rotate the drum. Then, almost
incidentally, I checked the left rear rear, and found it, also, was locked and
backing the adjuster all the way out didn't free it either.
It was becoming clear to me that it wasn't temperature causing the problem;
instead, it was a problem causing the temperature, a pressure buildup in the
rear hydraulics keeping the shoes actuated.
*Reasons for the "perhaps":
1) The suggestion of, "How old is the master Cylinder?" is that you might
expect this to be the cause of the problem, if it were a newly installed MC,
incorrectly shimmed. That's not the case. It has been there so long, I don't
remember when I last replaced it, and it has worked fine with no known
problems.
2) How could the "gross" over tightening of the right adjuster precipitated
the malperformance of the master cylinder?
Initially, I was inclined to dismiss what you were suggesting. Perhaps, we
were all (including the garage) focusing on the wrong area because that's
where the problem was initiated and also where it was manifest. The
hypothesis of a master cylinder not allowing the return of the brake fluid
would answer all of the observed info. Brakes locked up after initially being
okay, and becoming fully locked without generating much heat (until driven
against for a considerable time).
THANKS, TOM!! I am *at least* 98% confident that you have identified the
cause of the problem that has eluded me for about a full month. In the course
of chasing it, I did a complete rear brake overhaul, which wasn't absolutely
necessary at this time, but would have been required soon.
GLORY BE TO THE LIST!!
I also want to thank the other "sages" of "The List" who have given
considerable thought and numerous helpful recommendations in the pursuit of
the problem.
And, Tom - Do you think this problem could be solved by shimming (or doing
something else to) the installed MC, or should I think about a replacement??
Dave
'681600
Kailua-Kona
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