1961 Brake Booster

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mjabbasi
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1961 Brake Booster

Post by mjabbasi »

Looks like the Booster on my '61 has finally called it a day. While it was working up until some months back, the car was parked and not running for about 2-3 months. So I connect the battery and get the car started and it fires right up but when I put it into R or D to either go back or forth, the pedal jams and stays depressed. Switch off the engine, the pedal returns to its actual position. I had the system bled, again same problem. Start the car, the pedal itself depresses forward and the car won't budge, turn off the engine, the pedal is released. Also tried it with the Booster vacuum line detached which was when the pedal came back to its original position, connect the vacuum hose and it depresses again. According to my mechanic its the Booster. Now in light of the above I would like to know:

1. Do these symptoms indicate the Booster is at fault? The MC is new btw.
2. If so, are rebuild kits available instead of having to get a complete rebuilt Booster?
3. Best place to acquire either of the above.

Thanks.
Moin Abbasi

1961 Montecarlo Red Thunderbird Convertible
1962 Nocturne Blue Lincoln Continental Sedan
1963 Premier Yellow Lincoln Continental Convertible
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RedBird64
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Re: 1961 Brake Booster

Post by RedBird64 »

Booster Dewey has always been my go-to.

Scott
1964 Coupe Wimbledon white/Rangoon Red w/black int. Owned for 42 years. It was my folks car before that (second owners). VTCI # 12013.
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Re: 1961 Brake Booster

Post by RAVEN »

I can ask my local fellow who rebuilt my booster. A kit should be available, and you can attempt to rebuild your self.
The only thing which may cause some issue is the specific model type/generation of booster. Not knowing the specific unit may cause some confusion and error of the correct kit that you require.
I will ask and see what he can offer. One can only check.
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mjabbasi
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Re: 1961 Brake Booster

Post by mjabbasi »

Well I can provide this much information that the car was manufactured on 3C (3/3/61) and has the screw type Booster. I can send pics as well if needed.
Moin Abbasi

1961 Montecarlo Red Thunderbird Convertible
1962 Nocturne Blue Lincoln Continental Sedan
1963 Premier Yellow Lincoln Continental Convertible
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Re: 1961 Brake Booster

Post by RAVEN »

Any and all information possible will help to reduce the potential for an error. Photos will help to identify the unit.
I will send a PM with my e-mail address so you can forward the information.
CDN Member since 1975 #2086
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mjabbasi
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Re: 1961 Brake Booster

Post by mjabbasi »

Thanks email with pics sent.
Moin Abbasi

1961 Montecarlo Red Thunderbird Convertible
1962 Nocturne Blue Lincoln Continental Sedan
1963 Premier Yellow Lincoln Continental Convertible
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Re: 1961 Brake Booster

Post by RAVEN »

Update on this thread.
Upon contacting Moin via PM, and my local booster rebuilder, the 3 of us were able to sort out the specific booster he had, and were able to source a rebuild kit. If you source a booster through any of our TBird vendors they all list different units and their different application descriptions under 2000C/D/E. and can get very confusing. Moin has since ordered the specific kit, and is in the process, of having it shipped over seas for his local mechanics and himself to rebuild his booster.
The difficult problem is the main diaphragm. My local rebuilder says they are usually rebuilt and then reinstalled in the old casing. There are no castings to do exchanges, and this causes the most problems in booster rebuilds.
In Moin's case, he was unable to ship his booster from overseas, and guarantee that it would travel without getting lost, and not cost more than 5 times its worth. (freight from Pakistan, duties, rebuild, return freight, duties, all taxes both ways, insurance both ways, monetary exchange, time spent waiting)
Moin is patiently waiting for his rebuild kit, and will hopefully let us know how it all works out.
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Alan H. Tast
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Re: 1961 Brake Booster

Post by Alan H. Tast »

So was it a Bendix (early '61) with remote vacuum reservoir, Midland Ross (mid '61-'63) or something else? Particulars available for posting on rebuild kits?
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Re: 1961 Brake Booster

Post by RAVEN »

Midland Ross 10 screw booster. Full kit purchased and on the way to Pakistan. Moin bought directly, and to my knowledge no core charges applied. With a car build date of 3C (March 3) the Midland seemed logical, we just wanted to be sure.
When everything is proven correct and working, further details, on where and how parts can be purchased will be provided.

Just goes to show, when there is a want, there is a way to get what you need. Nice to see another Bird may keep its' wings.
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Re: 1961 Brake Booster

Post by MN63Tbird »

I am a little confused on the symptoms you reported. My experience with the booster on my 63 is that the vacuum is what helps the pedal return after it is depressed not the reverse. The check valve holds the vacuum during acceleration to give a uniform braking during stopping accelerating or stopping. Did you check to see that your vacuum check valve on the booster is working properly and not leaking vacuum? Thats a much cheaper fix. Just a thought.

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Re: 1961 Brake Booster

Post by RAVEN »

In essence it is the atmospheric pressure on the back side of the diaphragm which applies the brakes, and this is caused by the vacuum (negative pressure) on the front side of the diaphragm, allowing the pressure to move the diaphragm. By releasing the vacuum (turning the vacuum off) the pressures are equalized and the internal springs return the diaphragm to a neutral position and brakes are released.
This is the simplist description I can explain how the booster works.
The vacuum does not pull the brakes off, the vacuum assists in appling the brakes, thru differential pressures, springs and valves.
The booster operation is explained in further detail in the shop manual.
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Re: 1961 Brake Booster

Post by Kiwi-Bird »

I got a booster kit freighted to Australia from Harmon Classic Brakes
1962 T Bird hardtop
2004 Suzuki Bandit 1200S
MN63Tbird
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Re: 1961 Brake Booster

Post by MN63Tbird »

The description of the brake booster is partially correct. After you turn on the car you have vacuum on both sides of the diaphragm. As you depress the pedal which depresses a rod that connects to the diaphragm and master cylinder there is a valve attached that releases the vacuum on the up side of the diaphragm. This allow atmospheric pressure in to the upside of the diaphragm. Now with downside of the diaphragm having a vacuum and the upside with atmosphere pressure, there is a pressure differential that assists to pull the rod to the master cylinder with your pressure on the brake pedal . As you release the pedal the valve closes and allows vacuum on the upside of the diaphragm. Again as the pressure on the upside is reduced it helps pull the rod AND brake pedal back to the original position. Yes the booster helps on the hydraulic pressure required to open the brakes but it also helps on the spring action that returns the brake. A bad diaphragm will feel like no power brakes just like the brake feel when the car is off. It will also mess up the engine running a bit due to a constant drain on the vacuum.

A lack of vacuum will cause the pedal to stop or slow on its return ( I know this from experience while driving). A bad check valve will also cause poor pedal travel. It sounds like a vacuum issue and as I think about it more maybe the valve in the booster that releases the vacuum on the pedal depression may be the issue. It sounds like it does not close keeping atmospheric pressure on the upside of the diaphragm at all times. When you turn the car on the vacuum is created on the downside of the diaphragm. This will assist to pull the pedal down and the rod pushing on the master cylinder. Turning off the car releases the vacuum on the downside allowing the pedal to return by allowing atmospheric pressure on both sides of the diaphragm. Sounds like the diaphragm is not leaking. Have you tried gentle rapping on the booster housing to see if it is just stuck or slightly plugged valve, That may help jar it loose.
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mjabbasi
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Re: 1961 Brake Booster

Post by mjabbasi »

Ok I just read the above and that is exactly what is happening. Start the car, pedal depresses automatically to the floor and the car won't budge. Turn off the engine and the pedal slowly comes back up. Now if this is NOT a diaphragm issue and only a check valve problem, is a rebuild necessary, because in all seriousness I would love to avoid that if possible. That independent check value on the outer front 'passenger side' of the Booster, is that an available, serviceable and/or replaceable part if that is the culprit? Its made of what appears to be plastic with 2 inlet/outlet ports.

I ordered the rebuild kit yes and even if I (hopefully) do not need it, its always good to have something spare lying around just in case.
Moin Abbasi

1961 Montecarlo Red Thunderbird Convertible
1962 Nocturne Blue Lincoln Continental Sedan
1963 Premier Yellow Lincoln Continental Convertible
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mjabbasi
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Re: 1961 Brake Booster

Post by mjabbasi »

Update, will try to be as brief and concise as possible:

Rebuilding kit arrived and the rebuild started yesterday.

Booster removal took all of 20 mins and upon disassembly alot of leaked brake fluid came out. Condition of the original rubber parts was quite good with no rips, tears or deterioration.

Removal/installation of the old/new diaphragm was a delicate process but not as complicated as expected. Everything was washed, lubricated and seals replaced and Booster reassembled and installed.

Upon starting the car there was alot of vibration and rough idling. Removal and plugging the vacuum hose smoothed out the engine which indicated a vacuum leak inside. Booster removed again and part of the edge of the diaphragm was not crimped tight enough which was corrected and the Booster re-installed. Vibration and rough idling gone but the brake pedal was back to where it was at the start, depressing by itself and jamming the brakes.

With alot of help and advice from forum member Raven, he asked if we checked and rebuilt the 'control valve' which we did not. It was just washed and cleaned from the outside, so we removed the Booster yet again and dismantled the control valve and it was clogged with internal dirt, gunk, grime and jammed frozen. It was washed, resealed and lubricated, everything put back and the brakes are finally back to normal.

Moral of the story: Rebuild everything. If something looks good on the outsides doesn't necessarily mean its the same on the inside and if seals are parts are included in the kit for it, use them all. I was surprised at how quickly the Booster was removed and installed and the whole rebuild if done once and done properly is pretty much a 2-3 hour job at the most.

Special thanks to Raven for his assistance, guidance, encouragement and diagrams of the Booster.
Moin Abbasi

1961 Montecarlo Red Thunderbird Convertible
1962 Nocturne Blue Lincoln Continental Sedan
1963 Premier Yellow Lincoln Continental Convertible
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