Rusty Bowtie
General Category => Moose's Tech Corner => Topic started by: TFoch on July 07, 2016, 12:25:50 PM
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I was driving my 33 home last week from my friends shop. Came to a stop at a stop sign about 2 miles from home. As I let off the brake pedal to continue home the pedal was stuck about half way down. I pulled it up with my foot to release the brakes and continued on my way. A little ways down the road I had to stop again. Same thing, brake pedal stuck.
My first thought was the pedal pivot got dirty and needed cleaning. I pulled it apart, cleaned and lubed it and it felt fine. I started the car and backed out of the garage and when i stopped the pedal stuck again. Disconnected the pedal from the master cylinder and it worked fine. So I disconnected the vacuum line from the intake manifold and plugged it and went for a ride. The pedal didn't stick and other than some added pedal pressure to stop the brakes worked fine. We checked the vacuum at the intake and that was ok (15).
So it looks like I have a bad power brake booster. Only 3,400 miles on it so my buddy at the shop I bought it from will warranty it.
Didn't know if anyone here had ever had the same problem.
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Tom
I assume you have one of the small boosters. Noticed that on mine it did not have a one way valve that keep the vacuum sealed inside the booster. Was able to make a stock GM valve work on mine. (just one item to look into?)
Also..is the push rod from the brake pedal to booster straight and not at a binding angle?
Ed
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Tom...The brake booster has an internal spring that pushes diaphragm push rod and vacuum valve back to its neutral position. Sounds like it broke. Wouldn't be the first time I've a relatively new spring break because of a flaw in the material . Back in the day you could buy kits to rebuild a booster but most likely not the case with yours.
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POWER brake boosters need an engine vacuum of a solid 18--23 inches of vacuum to operate properly.
My 35 std 3w coupe with zz4 sbc 350 with GM hot cam W 1.6 roller rockers would only get a max of 14 inches at idle using a vacuum gauge. It never felt right driving the car.
After I discovered the problem I went with a SSBC electric vacuum pump and the diff in pedal feel was 100% improvement. Think I have an 8" booster under the floor.??
That's not fixing your sticking pedal/booster problem, but you may want to look into it.
mike lynch 8)
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Ed, I do have one of the small boosters under the floor. I do have a spacer to keep the pedal to the booster shaft straight. Moose the shop I bought it at will replace it. Unfortunately none of the booster are made here in the USA. I should get the new booster sometime next week.
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I got my new booster under warranty. Got it installed in the car and went for a test drive. Brakes are back to normal. Glad to have the car back on the road!
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That's gotta be a whole lotta good feelings to have working brakes again.
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Brakes are a good thing ;D ;D ;D ;D ;D ;)
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Great news Tom...Enjoy