I have recently become the owner of a 1963 Cadillac Fleetwood Sixty which is very different from from my other "fun" car, a 1964 Austin Mini. I have been working through some minor problems but one in particular has me baffled regarding the power assist brakes. I lose the power assist when I take car out of park. I have replaced the main vacuum line as well as a few smaller vacuum lines under the hood. Knowing that vacuum is used to release the parking brake I checked all the vacuum lines under the dash and everything is connected and looks like it is in good shape. When I put it back in park the brake pedal comes back up and it seems that the power assist is working again.

I am hoping that this is something others have experienced and you can steer me in the right direction. I love the car and it gets plenty of thumbs up cruising down Main St. in our little New England town of Falmouth, MA. Oh, and although many have suggested it, the Mini will not fit in the trunk of the Fleetwood!

Thanks for helping a newbie.

Glen Carliss

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Glen, the neutral safety switch could be leaking vacuum.  Unhook the vacuum line to the NSS, and cap it. One line comes from the firewall, the other goes to the parking brake vacuum actuator.

Thanks, Russ. I will give that a try tonight.

When you put car in a drive or reverse gear vacuum is sent to park brake actuator via the neutral safety switch which releases the brake. Perhaps the park brake actuator is busted or hose has popped off. With car off, set park brake and remove hose to park brake at NSS and apply suction with vac pump or sucking on hose. Park brake handle should start moving and release brake. If not, actuator is defective. (I have several good park brake assemblies on hand). Since this seems to be related to the park brake function I would look at vacuum line to it and actuator closely. In the interim you can plug the hose as Russ indicated.

Thanks, Jason. That is two things you have helped me get straightened out. I appreciate the quick responses.

I disconnected the vacuum hose coming through the firewall at the check valve. There was some improvement but the brakes still seem to lose vacuum. If I come to a slow stop with my foot on the pedal lightly it will suddenly drop to the floor. Most of the time it will come back up with a few pumps. I bled the brakes a while ago and I think I should have one more go of it. The brake fluid was very dark colored so I will drain the fluid in the master cylinder and add all new fluid and flush out the lines. Does anyone have any other suggestions? Should I be thinking about replacing all the vacuum lines?

Thanks for your help!

Glen, the brakes going to the floor, is air in the lines.  You are going to need to change the 3 rubber lines on the car. 2 in the front, and 1 in the rear.   I have them on my shelf, if you can not find them locally.

The vacuum lines under the hood are probably brittle at the ends, so its a good idea to change them out.

Glen, congratulations on your new Cadillac. I would replace the master cylinder or rebuild the one on the car. Your symptoms of the pedal dropping to the floor under light pressure indicate you have worn seals or debris in the bore causing fluid pressure to bleed by. It is best to replace the booster also when replacing the master cylinder.

hope this helps.


Yup, your correct.  I missed that one.

You need to check the inside of all four tires ,to see if you see and smell brake fluid on the inside of a tire
If you have brake fluid on an inside tire ,that brake needs to be repaired ( brake cylinder leaking )
Need to replace ,brake fluid soaked brake shoes
If no brake fluid is found on tires ,changing your MC should correct the problem
Only if that does not fix the problem , would i change the brake booster
No need to change the booster ,if you do not need one
There are Two kinds of MCs ,so get the same one you have now ,by bringing it to the parts store
The peddle would be soft only( spongy ) if air is in the system
The peddle will go to the floor ,if the system has a leak of some kind and you will be loosing fluid ,that you should see underbthe carb
Open the MC to see ,which bowl is empty or down on fluid
The front bowl works the rear brakes and the back the front brakes
Bleed the brakes correctly and adjust them while you are at it
Replacing the rubber hoses in the brake lines ,is a good idea ,as sometimes they break inside and prevent propper fluid flow ,if you do not know there current condition ,or last time they we changed
These brakes will stop this big heavy car on a dime ,when using Raybestos brake shoes ,and when working as they were designed ,stock as Cadillac intended
Never any brake fade or any other stopping issues
64 is in my family from day ONE ,so i have had a lot of time to get know the cars in and outs ,doing most of the maintenance myself for a lot of years
A labor of Love

I must say, I am flabbergasted by all the responses. The wealth of knowledge in this club is an amazing resource for anyone trying to do what I am doing. I have been around cars all my life, and as I mentioned before, I own a '64 Austin Mini and know that car inside out. But this Cadillac is much more complex, and I have no experience with vacuum systems. Thank you to everyone who responded.

I have ordered a rebuilt master cylinder and when I get back from a business trip the end of next week I will dive in on replacing it. The master cylinder and the brake line fittings leading into it are rusty as hell, so I anticipate some problems and will probably end up replacing the brake lines to the nearest junction. I will keep you posted on my progress.

A special thanks to Jason Edge who responded to a problem I was having earlier with my windshield wipers. He introduced the club to me and it is the best thing I could have done to make the slow process of getting this beautiful car in tip-top shape a fun experience.

Glen, with everyone's input and insight, this website will only get better as we go along. I think we all learn something from each other every day! Glad to have you on board with us! Jason.

Spray the rusted lines to the master cylined with PB blaster or other rust buster ,before you go away and when you return
Give the stuff time to work in
After that clean the surface with alcohol ( small wire brush ) and spay with a lube spray ,like WD - 40
That will give you a shot ,at not twisting the brake lines coming off the MC if they are bad

These year Cadillacs are very much simpler designed cars than those we drive today,( no computer or emissons )and in the 60's many people could be driveway mechanics ,as the cars did require more tune ups and general maintenance ( ever 6,000 miles )

There is a -Help - section in the header that has a lot of info
You can also --Search --on the home page - top right corner
All threads are stored for future reference ,-so ask away

Everyone here should own a Service Manual for there year car ,as these year Cadillacs have an extremely usefull manual ,due to the comprehensive detail the manual affords the owner
Possibly on of the best service manuals available for any given car ,that good
If you are a hobby mechanic ( and you better be , owning one of these cars ) you can simply put , read -how to repair and maintain your car ,right there

Regarding the vacuum systems ,it needs to be a sealed system
Cut off the hose ends and reinstall them ,if you can without splitting the hose ,as that needs replacing
If you find a vacuum valve in the heat and AC systems , that is leaking ,plug the hose with a screw ,until you can replace the valve
Just to get the system sealed

Best to get the engine to run correctly and solve those vacuum issues there , as the intake manifold is the entire cars source of of vacuum ,to operate those cabin vacuum systems
You can test all the vacuum valves in the comfort control system and the dist vacuum advance ,by putting the hose end in your mouth and sucking on them
Until you know the engine is right ,you can plug the fitting at the back of the intake manifold ,to seperate the engine from any vacuum issues that are learking in the cabin ,and deal with them ,at a later time




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