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50jetback

1955 P/B repairs - part problem

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I am having my P/B unit professionally rebuilt by a recognised Australian Brake and Clutch rebuilding Company.

 

I removed the unit from my car and delivered it to them with a photocopy of the relevant repair details from the Shop Manual and exploded diagram and parts identification from the Master Parts Book and a kit and all parts available from CARS.

1 x Master Cylinder Kit 1955-59 Buick Power
1 x Power Brake Boot 1955-59 Buick Moraine
1 x Power Brake Piston Seal 1953-60 Moraine
1 x Power Brake Shaft 1955 Buick Moraine
 

They were impressed and proceeded with the rebuild.

 

However a problem has arisen. The P/B unit works as it should when bench tested BUT every so often SELF ACTIVATES.

 

The rebuilders have decided the problem lies with a rubber seal which is not supplied in the parts kit or individually ( that I can ascertain as yet ).

 

So, I am urgently in need of the following part

Group No. 4.934  Part No. 5454981  SEAL, valve reaction plate to piston ( rubber ).

 

I am prepared to purchase a serviceable used unit or parts ( innards of the P/B unit ) - the rest is overhauled and ready to go. 

 

I have attached the exploded diagram and the part required is key AB. 

 

Would appreciate any suggestions as to where I may get the seal or reaction plate parts new or serviceable.     

img-160416065208-001.jpg

img-160416065135-001.jpg

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Willie was the first one to notice this, but I have passed the info on to two other people who had issues after a rebuild. The front dust boot doesn't have holes in it which causes sticking. I would check to make sure this isn't the cause, by pulling it away from the unit. If that is the cause, vent it in a way that makes you comfortable. 

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1 hour ago, buick5563 said:

Willie was the first one to notice this, but I have passed the info on to two other people who had issues after a rebuild. The front dust boot doesn't have holes in it which causes sticking. I would check to make sure this isn't the cause, by pulling it away from the unit. If that is the cause, vent it in a way that makes you comfortable. 

 

The first time I was made aware of what you're speaking of was 15 years ago when I sent a 54 power brake booster to Brake Specialist in California and the boot came back with the end cut out. I called them to complain and they explained that they do it in order for the unit to breathe. 

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Stuart

I took one of mine apart and found the seal noted on the diagram.  It is rubber, round and flat and someone should be able to easily make one if you have a pattern.  This one looks to be serviceable and you can certainly have it, but I can also scan it, send you the file and then you can print the pattern.

Willie

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10 hours ago, buick5563 said:

Willie was the first one to notice this, but I have passed the info on to two other people who had issues after a rebuild. The front dust boot doesn't have holes in it which causes sticking. I would check to make sure this isn't the cause, by pulling it away from the unit. If that is the cause, vent it in a way that makes you comfortable. 

The bench testing has been done without the boot in place ( in fact the one supplied is incorrect and won't fit so another will have to be sourced ) so we can rule out the boot venting problem.

 

Willie and Lamar have both mentioned the same problem so I will advise the overhauler to ensure we vent the boot when we find a suitable one. They are convinced the issue is the valve reaction seal.

 

Thanks for the advice.  

 

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9 hours ago, MrEarl said:

 

The first time I was made aware of what you're speaking of was 15 years ago when I sent a 54 power brake booster to Brake Specialist in California and the boot came back with the end cut out. I called them to complain and they explained that they do it in order for the unit to breathe. 

 

Thanks Lamar - I will let them know. When I pulled the unit the old boot cover was not sealed at the front and I assumed it had perished and torn away but this may have been done during a previous overhaul in the USA before the car was imported to Australia.    

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57 minutes ago, old-tank said:

Stuart

I took one of mine apart and found the seal noted on the diagram.  It is rubber, round and flat and someone should be able to easily make one if you have a pattern.  This one looks to be serviceable and you can certainly have it, but I can also scan it, send you the file and then you can print the pattern.

Willie

 

Thanks for your efforts Willie.

 

Brake people in Australia aren't very adventurous - something to do with litigation!!

 

Strangely enough they will be happy to replace the seal with a used serviceable one!

 

I will take you up on your offer of the seal you have and see if that resolves the problem. I will PM you to work out the " finer " details. 

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15 hours ago, old-tank said:

Stuart

I took one of mine apart and found the seal noted on the diagram.  It is rubber, round and flat and someone should be able to easily make one if you have a pattern.  This one looks to be serviceable and you can certainly have it, but I can also scan it, send you the file and then you can print the pattern.

Willie

 

Maintaining his "Buickman" status on a daily basis 

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OK, Stuart, here is your seal:  it is about 0.050 inches thick.  Save to your computer and print the pattern with the printer set to actual size.  I'll give you a day to make one out of sheet rubber and submit to the rebuilder (tell them that it was sent to you).  If you sent the whole unit to the States to be rebuilt, they would make the seal the same way! :D

Willie

powerseal.jpg

Edited by old-tank (see edit history)
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10 hours ago, lancemb said:

If needed I do have the innards to a 57 unit I'd sell complete.

Thanks to Willie we may be over this hurdle. will know later in the week.

 

Will keep your "innards" in mind - maybe you could PM me with a photo or 2 and price. My parts book only goes to 1956 - is 1957 the same Delco Moraine unit?

Would be handy to keep one " on the shelf ".

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