58 Edsel: Soft brakes only when in gear. Vacuum?

Ok, 58 Edsel. when in gear the brakes will slowly go to the floor, very slowly. When in Neutral it holds very strong. My guess would be Vaccum with brake booster, the lines seem good, but why would it only do it in gear?


I also have a simular issue with the throttle. When in Nuetral it revs great, when in gear it hesitates and bogs down right at first, then drives great.
I just cleaned tank, ran new lines and currently rebuilding the carb. It did get little better when I replaced a few Vacuum lines, but the problem is still there, I am hoping the carb cleaning will help that, but I find it odd two problems only when in gear.

Thoughts?

 

You have a vacuum leak somewhere. At idle spray in some carb cleaner around the intake, carb base, etc. If the idle goes up you found your leak.

 

I didn't think of leak being from source. I will be replacing all the carb seals this evening.

Sent from my DROID device using the TJJ mobile app

 

I had the same problem with my Y-block and I found a broken intake stud.

 

I don't think they should go all the way to the floor. Any leakage on the firewall by the brake master plunger?

 

Sounds like your booster is shot or bad vacumn leak feeding it.

 

Sounds like the booster is leaking. Look on the web and see if there are methods for testing the booster.

I would think you could do some kind of 'leak down' test on the booster. For example you could put a quarter turn valve in the line to the booster, and tee a vacuum gauge on the booster side of the valve. Get her running and up to vac, then close the valve and see how fast the vacuum goes to atmosphere. Of course you would need to know how fast a good one leaks back.

 

ahh the infamous Treadle vac booster, i would bet that its toast....

 

if it was the booster, why would it only be when in gear?

 

When you put it in gear, the engine drops RPM and Vacuum, then the booster could slowly colapse.

 

Possibly the booster. With the car off, pump all the vacuum out of the booster until the pedal is high and hard. Start it with a foot on the brake, the pedal should drop maybe an inch, but nowhere near the floor. At this point, I would recommend adjusting all the brakes first (they are all drum?) which will give you the best pedal possible.

Another test, disconnect the booster from the vacuum, plug the line of course. Now see how it behaves. If it does the same thing, it's not the booster.

A dropping pedal can also be a bypassing master. The fluid goes past the internal piston and spits it back into the reservoir, there is no leak. The pedal can drop with your foot on the pedal while stopped at a light perhaps, or may not be there when you go to stop. They can usually be sorted out with the car stopped and doesn't have to have the vacuum going to it. This theory goes with your soft pedal thing.

Bob