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In addition to the large return spring, there are some springs, diaphragm and a tilt lever assy inside the power piston. If all is moving there freely, releasing the pedal will allow the inner piston spring to work that mechanism, closing the vacuum poppet to the apply side and opening atmosphere to both sides. Assuming nothing has prevented that, even though the power piston might stick or not retract all the way, there being no force applied on pedal should keep all in a state of normal relaxed atmosphere going to both sides of piston. The bigger issue would be if piston had not retracted all the way to the last 1/4 or so inch of travel, compensator valve might not tip and fluid would be trapped. Heat and expanding fluid could cause the brakes to drag or apply. The vacuum sucking the fluid out seems to be the result of that reservoir gasket not allowing for any relief opening.

There was a post earlier in this subject about the 1953 Buick power brake unit being discussed in Ralph Nader's book "Unsafe at any speed". The writer (incorrectly) identified it as a Bemdix Treadle Vac yo further emphasize how dangerous they are.

The 1953 Buick was originally equipped with a Kelsey Hayes PB unit which was problematic and there was a factory/dealer program to replace it with a GM manufacture Delco Moraine.

So lets take another nail out of the BTV coffin.

I am again (4th time) offering a free compesator valve to any owner feling that theri's might be defective. I do ask that the old one eventuially be returned so I can evaluate it. To date I have received only one (1) request.

Fred Kantter
Kanter Auto Products
Boonton NJ

For what it's worth - I had to move my as yet not running '55 Patrician. The parking brake wasn't working so I thought I'd try putting brake fluid in the reportedly non functioning BTV service brake. Remember this car hasn't run since the mid 80's. I opened up the top of the master brake cylinder, blew out the white fluffy crap with my air hose and filled it up with DOT 3. I got in and pressed on the pedal and it sank to the floor. I then pumped the pedal three time and each time got higher pedal. I got out and looked in the master brake cylinder and found the fluid level had gone down half way. I topped it off and closed it up and I have had brakes enough to push the car around and have the brakes stop it. After a week had passed, I still had pedal and brakes and the fluid level was the same.
I do plan on completely going through the entire brake system but never the less, the compensation valve fed the cylinder fluid and prevented back flow after doing nothing for 26 years. The pedal effort was the same as any other of my Power Brake cars with the engine off.
I don't know about anybody else, but I was rather surprised and impressed!

No argument the brakes have a nice feel and seem to work well when stopping the car. Unfortunately, just when 999 people say they have never had an issue, number 1000 comes along and says his just failed.

I'm willing to bet that a lot of the failures are not BTV related at all, but there is still that nagging feeling of "what if". Hopefully Fred can get a feel for what is happening, but without some participation in his evaluation program, it doesn't look likely. Honestly, that does surprise me with the number having said theirs failed yet nothing is offered to help the cause.

The white fluffy crap floating around has been thought to maybe be part of the reason the valve sometimes doesn't close tightly. The reservoir gasket is seemingly the reason fluid goes missing into the vacuum side. Unfortunately again, just conjecture.

Took a while but at this point, I've also finally come around to the thinking that reasonable options for anyone no longer comfortable with a BTV are needed. Some Chevy vendors seem to have reached the same conclusion with their kits. Too bad those won't work for us.

Joined:
2009/10/6 5:06
From Wilmington ,Ma. U.S.A.
Posts: 10

I recently purchased your rebuild kit & 5 1/4" leather seal for my unit followed the instructions, installed unit and still have a hard peddle.I have replaced all parts related to the braking system shoes, linings. lines hoses, etc. I even bought a rebuilt unit from Tucson Packard and have sent it back to Sandy 3 times,he has tested the unit and each time I have the same results,HARD BRAKES, I have also checked the unit as Sandy has told me with just the vacuum line on and with no effort it sucks the rod right in, when I install the unit and connect the fluid lines I am back to square one HARD BRAKES, even standing hard on the brake peddle I cannot lock the brakes up. Would appreciate any help from anyone who has had a similar problem. Thank You, Peter Update, Every thing in my brake system has being replaced, including the power booster which Tucson Packard has sent me three different ones to try because of my problems. and to date I still have a hard pedal,with very little braking. HELP would be welcomed. Fred I would like the free part you are offering . I just don't know what else I can do, just does not make any sense when all have been replaced.

Have someone open ONE wheel cylinder bleeder screw WHILE u push the brake pedal. If the brake pedal goes to the floor real fast then close the bleeder screw and test another bleeder screw on another wheel until there is a difference felt at the pedal. Which ever bleeder screw that opens and produces noticable resistence to pedal pushing will determine which wheel/brake line is causing problem.

Did u replace ALL THREE RUBBER hoses in the brake line too????

IMPORTANT: Once the pedal goes to the floor DO NOT LET UP ON THE PEDAL UNTIL THE BLEEDER SCREW IS CLOSED

Quote:

Simple: Replace the BTV with a modern unit.

Craig

YEs Craig. I agree. But lets face it. 1/2 of the world is simply not ready for us yet!!! Gufwah ha ha ha ha .

Functionality trumps showability, imo, not to mention I value my life. Other than show originality, there is no rational reason to retain BTV. A disc brake and modern vac unit makes perfect sense because improving stopping power of these lead sleds is a worthy objective. In most other respects, properly working original equipment is entirely satisfactory.

Update, Every thing in my brake system has being replaced, including the power booster which Tucson Packard has sent me three different ones to try because of my problems. and to date I still have a hard pedal,with very little braking. HELP would be welcomed. Fred I would like the free part you are offering . I just don't know what else I can do, just does not make any sense when all have been replaced, see previous postings. from: 56packard400