Brake Booster ID

S

Steve_KS

Member
My A came with hydraulic brakes. I believe I have a vacuum leak, car idles fast, motor wants to die if you give it gas or apply any load after starting it. Once you've driven a few miles then it seem mostly fine.



I pulled the vaccum line off the power booster and plugged it, the motor seemed to idle better so I'm guessing the power booster is leaking internally. Anyone able to ID the booster and master cylinder in this pic?


Thanks 1.jpg2.jpg3.jpg
 
I would eliminate the booster. I have hydraulics on all 3 of my A's, booster on none of them and pedal pressure input is still less than with mechanicals.
 
I agree with Jim. I would off the booster, especially since it appears you are using stock size tires.

As a side note it appears your master cylinder may be leaking hence the paint being removed off the booster.
 
Thanks for the help. I was thinking about removing it to simplify things but wasn't sure how well it would work.



If I do remove it I'll have to learn to bend brake tubing, then I may as well add a dual master.
 
This may be a stupid question but if I disconnect the vacuum line from the booster and drill a hole perhaps on the pedal side of the booster to keep the pedal from getting hard would that approximate the feeling of a system without the booster?



Just wondering if that would let me test the feel of no booster easily and cheaply before removing the booster or replacing it.
 
Before you go drilling holes are you sure the booster is bad in the first place?

Easiest way to check a booster is the pump your brake pedal with the engine off until the pedal gets hard. Then while holding pressure on the pedal, start the engine. The pedal should drop. This shows you have vacuum in the chamber. If it stays hard you have a vacuum leak.

I think I would still think about removing the booster tho. I feel it is not needed with the light weight and skinny tires. JMO.
 
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I would drive the car first with the booster disconnected and plugged to be sure you like the feel of the brakes without the booster. Theoretically you really don't need the booster IF the pedal geometry and master cylinder are proper for a non boosted system.
 
That was my worry, that the lever geometry may be crummy and that's why whomever put a booster on it in the past.



I am not 100% sure the booster is bad.

- My motor idles and runs poorly at startup, it starts quick but then any throttle application and it wants to die. The choke helps a little but not much.

- I disconnected the vacuum line at the intake and later at the booster and plugged it. The motor ran better in both instances so I thought the booster was the problem.
- I have pumped the brakes then started the car and the pedal did go down some. However I can't pump the brakes and make them hard just a little firmer. I am not completely sure what that means I haven't read it as a symptom of bad booster anywhere.


Any input is appreciated.
 
The original hydraulic systems on 1939-48 did not have a booster, and were for cars heavier than our A's. They worked quite well.
 
You will likely need a different master cylinder if eliminating the booster. Power brake master cylinders have a larger piston bore diameter and may not be able to supply the fluid pressure required to operate a manual brake system. With the vacuum line removed on my early 60's GM system (and reserve tank empty) there is so little braking force there it is scary!!
 
400926


Alias "fruit jar". You can get these in just about any piston size or bolt pattern you want. They are so common, the aftermarket even makes fancy versions...

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