Then a Miracle Occurs (Post #143)

The master cylinder got a lot of attention. 
Getting the big end off the cylinder  required
a really big socket with a 3/4 in. breaker
bar and a 3 ft."cheater" pipe.  The hardest
part was creating a wood cradle to protect
the main body.

The damn brakes finally started working.  Wish I could say exactly what the problem was and how I fixed it, but I can't.  Maybe it was an Act of God?

Having tried every trick I knew and every trick everyone else knew, and having tired of doing the same thing over and over and expecting different results, I tried the "Hail Mary Pass", also known as "Fire all your guns at once and float off into space."

It was a multi-prong attack addressing every part of the brake system from the wheel cylinders all the up to the fluid reservoir.  I disassembled, cleaned, inspected, primed, and reassembled everything, noting dimensions and volumes along the way.  I elevated the rear to coax any air that might be trapped to leave the system and readjusted the shoe-to-drum clearances.  I laid in a supply of fresh fluid. 

Bench testing the Alfatross' master cylinder. After a complete dismantling I wanted to make sure it was leak-free.  The black bar on the right applies pressure on the piston.  The spring scale indicates the force used (50 lbs).

As mentioned in several earlier posts, over time I became increasingly suspicious that something was wrong with the master cylinder.  The symptoms suggested that it might not be moving a sufficient amount of fluid out to supply all 6 wheel cylinders. But after taking it down to its discrete constituent parts and not finding any problems, I started to look at the length of the "pushrod" that transfers brake pedal movement to the piston inside the cylinder.  I noticed that the spare 1900 master cylinder Peter Marshall sent me was outwardly almost identical to The Alfatross', but one major difference was the length of its pushrod--almost 50% longer than The Alfatross'.  I tried to transfer it to The Alfatross' master cylinder, but its diameter and threads were entirely incompatible with the shackle and jam nut that mate to the end of the brake pedal.  The solution was to order a 12" length of  BSF 5/16 X 22 (50 degree) threaded rod, and cut it down to about 90 mm.  There is a mushroom on the end of the original pushrod that presses against the master cylinder's piston. To simulate it I attached a nut to the end of the new pushrod and ground it down to a shallow dome.

The Alfatross' original pushrod (top) compared to the new
longer pushrod before adding the dome on the cylinder
end and shackle on the other.

Not surprisingly, lengthening the pushrod raised the brake
pedal inside the car.  This will be adjusted later during
road testing. 

With all that behind me and The Alfatross on the lift, I started bleeding the system using the one-person technique I came up with.  It allows me to operate the brake pedal lever from under the car while preventing air from re-entering the system when pressure on the brake pedal is released.  As described earlier, I spent a lot of time trying to perfect the Motive Products approach of pressurizing the brake reservoir for bleeding, but I finally gave up. The Girling reservoir cap does not easily lend itself to modification, and the reservoir's location and flimsy manner of attachment further compound the difficulty.  

After so many disappointments, at this stage I was prepared for another one. But no--the pedal began to firm up!  The Alfatross has brakes at last!  

Let's not get carried away.  It is conceivable that the problem(s) could return.  But right now it is enough to know that the problem can be fixed!  The next hurdle is to get the exhaust system back on.  With brakes, the exhaust system, and a running engine we can start the road testing--just in time for the New Mexico winter!












troublesome rr wheel cyl bleeder valve wrapped in teflon

heated and bent wrench already filed to fit bleeders tightly


reservoir Motive Products cap adapter location of reservoir and the way it is mounted made it difficult