[rohrt]

I converted to a dual reservoir MC. Nothing can ever be easy can it???? I took it for a drive and had a super hard pedal. The vacuum line was plugged in and the one way valve was working.

I heard the air leaking and found that I was leaking vacuum from the vent hole on the MC. I plugged the hold with a hose and got the booster working but then it sucks the brake fluid out the MC bore.

So I don't know if its the rubber seal around the pin or the fact that I replaced the O-ringed long booster pin with a non o-ringed booster pin.

No one carries a booster in town. This sucks no pun intended.

[SMW]

If you are leaking fluid, the master cylinder is bad.

[rohrt]

Wouldn't you think the fact there is vacuum on the bore would give a false reading?

That can't be normal can it?

[59safaricat]

Master cylinder seal(s) are leaking if the booster is taking in brake fluid. Be careful, brake fluid will quickly deteriorate the diaphragms in the booster and you'll have no brakes.

Personally, I don't use boosters of unknown age or much over 20 years old. Had a couple friends with vintage cars that almost lost their lives when the diaphragm in the original booster let go while trying to stop. One was in town and the other was on the freeway. Old brake boosters can work one second and complete fail the next.

Also, most boosters require a procedure and special tool to properly set the booster push rod length. If not adjusted correctly, the brakes will either drag or there will be quite a bit of pedal travel before the brakes are applied. Brand new master cyl/brake booster combos come pre-adjusted. It's just another reason to get a new master cyl/booster combo, slap it on the firewall, and be done with it for 20 years.

[Blued and Painted]

Its not the master cyl job to seal the booster. It should hold vacuum even with no master installed. If you apply manifold vacuum to the back of the master, no telling what could happen.

[rexs73gto]

The booster on my car went out in the garage, I was damn lucky. I came home from a cruise in pulled in the garage, went to leave about 2 hours later & no brakes , the pedel was rock hard & wouldn't stop in the drive way. I had to go back into 1st to stop it with the clutch. It was 33 years old.

[rohrt]

Thanks for all the replies.

Its all making sense now. The old single reservoir MC keep going dry but I couldn't find the leak. Now it makes sense the fluid was all getting sucking into the motor. When I got it out of the shed last week I found a huge puddle behind the exhaust.

I did some Cuban Chrome engineering yesterday and sealed the MC from the booster. I used RTV around the rubber seal and shaved down the old pin that had the rubber O-ring and used some O-ring sealer on the seals and pin.

It isolated the vacuum. but still no booster.

I went to a car cruise last night. The brakes were rock hard and did stop very easy but I could still lock them up with enough foot.



This 64 has a 9" booster. I doesnt' look like a 11" will even fit. I think I have some 9" dual diaphragm one from a second gen disc brake rear end car back on the farm. I wonder if they would fit.