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Re: Bendix -Treadle Vac - Failure and Fix
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Here's a little tidbit from a Buick website:
"Brakes..... The 1956 models with power brakes left the assembly line with what was called a displacement master cylinder. Instead of an internal piston it used simply a large rod going thru a seal that displaced the fluid in the sealed reservoir. The failure rate was high. Most were converted to the piston type master but there still may be a few left out there." Imagine that... Source:buickstreet.com/buickstories.html This is telling me that the "Packard style" BTV was replaced with the one I posted earlier, that has the tall reservoir and normal piston with cups. I refer you to a previous post of mine here: BTV threads
Posted on: 2010/10/4 14:09
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Re: Bendix -Treadle Vac - Failure and Fix
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Turbopacman wrote: Quote:
The best way to solve the problem is to retrofit a dual line master cylinder and have a working car again. No matter what you do, how you dissect it, or how you rebuild it it is still as inherently unsafe as any other single line master cylinder. Eric, you are giving other single line MCs a bad rep. Craig
Posted on: 2010/10/4 14:54
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Nuke them from orbit, it's the only way to be sure! Ellen Ripley "Aliens"
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Re: Bendix -Treadle Vac - Failure and Fix
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Craig, STFU.
Here's another good story of a complete BTV failure on a 1958 Mercury and what the guy discovered while rebuilding it:thebigm.info/WorkBrakes.asp Another Mercury site showing the rebuild method. I especially found this part interesting: "A little more information on the counter bore........... The rubber packing fits into the counter bore as shown in the above illustration. The leading edge of the packing seal will go in first followed by the packing expansion bushing and then the washers, retaining ring and finally the leather seal. The counter bore must be free of scratches pitting gouges etc. on order for the rubber packing to do its job. Note that the leading edge seals against the bottom of the counter bore. You exert at least 150 -200 PSI when you step on the brake pedal. That is why the bore needs to be perfect. It really only seals in the first 1/16 of an inch in the bore ...right down in the corner. If you hone the bore you will scratch the surface of the casting disturbing the green anodizing on the casting and allow brake fluid to seep past eventually allowing brake fluid to fill the booster and cause a soft pedal. The green anodizing seals the casting from the corrosion forces of the brake fluid. So if you're loosing fluid and there are no leaks ..... Look again! When you pull the unit for service it will be full of fluid. Not to mention the vacuum reserve tank will fill up as well. Believe me it holds a lot of fluid. You will be filling all the time....With no visible leaks. This is the number one reason for failure. The casting condition is critical. However; It can be sleeved and re-anodized, but with caution. Additionally, the inner portion of the packing seal rubs against the plunger (shaft) it too must be free of nicks, scratches etc. Found here:ford-mel-engine.com/viewtopic.php?f=12&t=149 I also found this picture interesting: Attach file:  (26.13 KB)
Posted on: 2010/10/4 15:42
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Re: ANOTHER #%*!:( BTV failure
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Quote:
Eric, you are giving other single line MCs a bad rep. Craig Single Master Cylinders have a bad rep already. I had a customer tell me of a '59 Thunderbird that had a factory single master cylinder that he had sold. The stop light switch which is threaded into the master cylinder failed, blew apart, and with 2 pumps of the brake pedal, completely emptied the master cylinder of any fluid. With an out of control car, the new owner blew threw an intersection and was T-boned. They are trying to sue him, and the Brake switch company. I had another customer who has a 64 T-Bird. Single master cylinder. The seal went out on the master cylinder, he lost all the fluid into the brake booster, and with 4 pumps of the brakes lost all fluid. Pedal went to the floor, and he was forced to either smash into a truck, or run up on the curb and drag his T-bird down a cement wall to stop it. He chose the cement wall, and completely mauled his Car. I think it is better to have a dual chamber master cylinder, as you are ensured to have atleast a back up chamber to allow you to have brakes to stop the car.
Posted on: 2010/10/4 15:50
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Re: ANOTHER #%*!:( BTV failure
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Quote:
I think it is better to have a dual chamber master cylinder, as you are ensured to have atleast a back up chamber to allow you have have brakes to stop the car. Advice a sane person cannot argue with. This weekend I'm going to make a video and post it on here on how to properly disassemble the BTV using the proper tool, NO4MK1-.303. It will be step-by-step and professionally done.
Posted on: 2010/10/4 15:54
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Re: ANOTHER #%*!:( BTV failure
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Forum Ambassador
 
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Quote:
I also found this picture interesting: I also notice the same gasket there and in reading thru the articles, the Merc with the problem also has the flat lid. Think fluid loss would have been minimal if that port was open to atmosphere as Ross says it should be. Otherwise, with nothing else to suck, fluid goes. That almost has to be the reason. Also curious as to why he had so much problem with the leather seal. Almost sounds as if he had the wrong one or someone had a real heavy hand installing it to have it distorted like he said it was.
Posted on: 2010/10/4 16:01
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Re: ANOTHER #%*!:( BTV failure
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Yeah, I'm trying to figure out just exactly why he has a flat top on the first link, but the second link has a "bubble top" like all the horizontally mounted BTV's do.
Attach file: (24.52 KB)
Posted on: 2010/10/4 16:07
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Re: ANOTHER #%*!:( BTV failure
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Now examine this picture, from a Lincoln MKII site, from 1956:
Attach file: (71.80 KB)
Posted on: 2010/10/4 16:18
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Re: ANOTHER #%*!:( BTV failure
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HH56, notice the tube going from the port to the reservoir. I'm betting that THIS is the style of master cylinder that needs the sealed hole gasket. Packard owners are getting the wrong damn gasket!!!
Posted on: 2010/10/4 16:19
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