I have a 1971 TR6 with a REALLY puzzling brake problem.
Here's the history: The car had been sitting unused while
getting its cylinder head rebuilt. After reassembly, I started
the car and backed it out of the garage. The second time I
stepped on the brakes WHILE BACKING UP, the pedal went to the
floor and the brake warning light came on. I couldn't find fluid
anywhere. I bled the brakes and reset the brake-balance shuttle
switch. Everything was fine for a week, although on one occasion
when I touched the brakes, it fell like the right rear locked-up.
The car sat unused for a few weeks after that. When I BACKED
it out of the garage the next time, SAME problem. Again, no
fluid to be seen. This time I took it to the local British-only
garage (Vickery British, in Dallas). They thought the master
cylinder was bad. (I doubted this, since it had been replaced by
a rebuilt unit only 6 months before, along with the brake vacuum
booster, and I never saw any leaks around either.) They replaced
it and returned the car. No problem for a few weeks.
The car sat unused for a few weeks, then SAME PROBLEM. It
only happens when I BACK OUT it out of the garage! I returned
the car to Vickery. This time, they went after the rear brakes,
reporting that the drums had been turned beyond specs. New drums
and shoes. They kept the car for awhile, driving it every day to
make sure the problem wouldn't reoccur. Finally, they gave me
the car and it worked great. But it was raining, so the car sat
in my garage for a week. Next time I back it out... you guessed
it. Pedal to the floor, red light on the dash.
Does any one have any idea what is happening? Neither I nor
Vickery British can find any brake fluid when it occurs. The
reservoir is full. It only happens after the car has been
sitting for a week or so. The failure when backing out is NOT
coincidence! I've made a point of testing the brakes when the
car is warming up in the garage and the pedal is firm, but as
soon as I back up and press it, it goes away. (Sometimes it goes
away on the second press, but the first press feels spongy
anyway.) Pumping the brakes only brings the pedal back a little.
More information: Before this all occurred, I rebuilt the
rear suspension, requiring a complete tear-down of the rear
brakes. The left-rear cylinder was leaking and replaced. (The
right-rear has since been inspected and no leak found.) Could I
have reassembled it wrong somehow and caused this? Also, when
the shuttle valve is reset, it appears to have slid to the FRONT
each time. (I think.) Does this indicate the problem is in the
front brakes?
I'm out of guesses and Vickery doesn't know where to go
next either.
Carl Dreher
CTDreher@aol.com
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