Factory brake booster question

[fireguyfire]

I’ve got a vacuum leak in the factory brake booster in my 67 barracuda, and I don’t have vacuum assist on the brakes.
I’m guessing there is a diagram issue. This type of booster is the 2 part booster held together by a removable band clamp.
Are these boosters rebuildable or does a guy need to take them to a pro to have them done?

 

[Professor Fate]

It kind of depends on which booster you have; in '67 there was a 6 1/4" Midland/Ross booster, and a 7 1/2" Midland/Ross booster for A bodies. I believe the smaller one was used on big blocks, and the other on small blocks and slants.
If you have the 7 1/2" booster, great. Rebuild kits are readily available from classic Mustang suppliers, since the same booster was used on Mustangs and Falcons, among others. The main difference is in the front housing, which is stamped for either the Mopar four-bolt master, or the Ford two-bolt master; and then the appropriate filter housing. Rebuild instructions are in your FSM (you DO have one, right?).
If you've got the 6 1/4" booster, I have not found a good source of hard parts, but they may be out there. Otherwise two good "Go-To" names to have them rebuilt are:
https://www.powerbrakebooster.com/
Home - Harmon Classic Brakes
They also are reliable sources for many parts.

 

[fireguyfire]

Where do I measure to determine the size of booster that I have?
Mine is the original and my car is a formulas S 67 with a commando engine.

 

[fireguyfire]

Oh, and yes of course I do have an FSM.

 

[lemondana]

I had mine rebuilt by Harmon. wasn't cheap but is beautiful, the gold anodized. I haven't installed it on the car yet.

 

[Professor Fate]

Where do I measure to determine the size of booster that I have?
Mine is the original and my car is a formulas S 67 with a commando engine.

View attachment 1716304247

It's the diameter of the housing, give or take a bit.
A couple of pictures from Harmon's website for clarification:
6 1/4:

7 1/2:

 

[intergalactica]

Were the original brake boosters on the '67 273 Commando V8 Barracudas painted black or were they zinc dichromate gold plated?

 

[RustyRatRod]

Do some diagnostics first. It might save you some dough. Check the big vacuum hose at the booster to see if it's getting vacuum. Remove the check valve, hose and all out of the booster. Hold your thumb over the opening in the check valve and have someone start the engine and see if you have vacuum there. Sometimes those check valves go bad. If you have no vacuum there, pull the check valve off the hose and try the test again. If you now have vacuum without the check valve, your check valve is all that's bad. It's entirely possible the booster is bad. But a simple test that costs nothing isn't a bad idea.

 

[AJ/FormS]

And well, if you have a 300* camshaft well .

 

[Professor Fate]

Were the original brake boosters on the '67 273 Commando V8 Barracudas painted black or were they zinc dichromate gold plated?

I've seen them both ways, not sure which, if either, is strictly "correct".
Both rebuilders can do them both ways.

 

[lemondana]

I think the larger can came out in 70, as more cars were coming with disc brakes. I have seen alot of the smaller cans on the 67-69 that had drum brakes. The few that I have, have the gold zinc plating underneath the black paint. If you're building a nice car with nice paint, I would have it plated, for a daily driver regular driver-the black paint would suffice. I am working on a 38 Plymouth, will get power disc brakes. Have a B Body Bendix dual diaphragm that I might use. They were all painted black, If I do use it, it will he gold zinc plated.

 

[scatpackbee]

In the book called “Dodge Muscle Portfolio” which features articles and test drives from when the cars were new. The 1969 Dart 340 they tested back then in that book had a black painted brake booster and black disk brake master cylinder, if I remember correctly.

I will try to post the picture to confirm this when I get back home.

 

[scatpackbee]

My mistake….

It appears in these period pictures that the booster was cadmium plated and the master cylinder and cover were painted semi-gloss black from the factory.


Black and white photos are a 1968 GTS.

The colour pictures are from an episode of Car And Track TV program from 1969 test driving a 1969 Swinger 340.