I have got a Thunderbird -61 with original drum brakes and Bendix brake booster with reservoir canister.
Brakes work, but pedal is hard, there is no way I can get the wheels to lock, how ever hard I press the pedal.
- I have checked the vaccum, it seems alright. I have replaced all rubber hoses. Engine have safe and stable idle run. Gear shifts OK.
- There is no air in the brake lines and no leakage, pedal is hard and does not sink any further even if I press it hard for a long time.
- Brake booster seems to work, have done the test to press brake pedal light and then start the engine, pedel will sink slightly once the enginge is runing, (vuccum is built up).
I still some how suspect the brake booster somehow is weak, but I do not know how to verify it.
Questions:
1 My expectation of brake action is that I should be able to lock the front wheels up while runing the car at for instance 40-50mph with reasonable brake pedal presure, is that correct?
2 Any one got any experience with simular type of problem?
3 Would a T-bird 62-63 Midland Ross brake booster fit in my T-bird -61? (To get rid of the auxiliary reservoir cannister.)

The check valve on the booster may be bad.

Have you had the brake drums off to inspect the overall conditon of the internals? I think that 1961 was the first year for "self adjusting" brakes. They still need to be installed and adjusted properly in order to function correctly. If you are not comfortable doing this, have an experienced technician take a look.

Thanks guys! The check valve might be something. Where is it located? Is it in the vacuum hose connections right on the booster or is it in the T connecting vacuum to the gearbox?
I overhauled the front brakes in jun-08 as one of the brake cylinders was stuck. I replaced some of the springs and with the drums back on I adjusted the adjustment screw to balance right/left drag. Would there be any special considderation?

The power booster vacuum check valve is located on the top left hand side of the booster (left of the master cylinder). It will have two vacuumm hoses attached to it. One comes from the manifold and the other goes to the tranny.

I had a similar problem with my 1962 and felt darn sure it was the ppower booster (after I installed a new vacuum check valve). Pull it off (with the master cylinder)and sent it to California to be rebuilt figuired I would do them both at the same time. Well Tbird HQ called me to say nothing wrong with the booster but the master cylinder was hot couldn't even rebuild thhe unit. So I had the booster rebuilt and the master cylinder replaced.

Some progess, but not quite how I want the brake to work. I have rebuit all 4 wheel cylinders and rebuilt the master cylinder. The brake drums and brake shoes look ok and are within spec. Have also replaced all brakelines and hoses and used silicon fluid. I have taken the brake booster apart and cleaned it.
Vaccum is good 18-20 inch Hg. Checkvalve is good, 10 minutes after turning the engine off I still have 18 inch Hg vaccum in the brake servo. Pedal feels good, hard and firm, no air in the system.
However, in my opinion the brake is weak. I cannot get the wheels to lock up, no matter how hard I press the pedal. Brake booster is working, at least to some extent, if I disconnect the vaccum you really feel the differance. If I start brakeing at speed, 45mph, at first brake force is weak, but it builds up, increase gradually, as if the booster were "slow" in action.
Have any one come across this? Should I replace the booster?
How good breaks should there be on a -61 T-bird with all drums? I operate it with my less sensitive, hard pressing, left "clutch" foot, if I were to use the right foot I would crash, initially applying way to little force.

I had a similar problem with my '66. To check the booster, start the engine and let it run a little while then shut it off and step on the brake pedal. You should get 2 or 3 power assisted applications of the brakes. If you don't get any power assist after turning the engine off and your check valve is good, you have a bad booster. Probably and internal leak. You may also want to check that the master cylinder plunger is adjusted correctly. I may be adjusted too long or too short. In my case it was the booster. Hope this helps. Good luck and keep us posted on what you find.

Brake Booster Dewey may have an answer if nothing else works.



http://boosterdeweyexchange.com/

Feedback on your suggestion. I started the engine and drove out of the garage. At the top of the hill were I live I turned the engine off and let the car roll along down. I applied the brakes and brought the car to stop again and again, the fifth and last time at the foot of the hill I imagine the brake power were slightly weaker. My conclusion of this is that there is no internal leak in the booster.
I will check the push rod length, but first I will have to make a push rod gauge as per the shop manual, or is there any other way to measure the push rod?

I always just adjust the rod so it just touches the plunger in the master cylinder not pushing on it, Worked fine for me a couple times. Could check master itself while apart maybe thats your problem