Brake Booster not enough compression

[Rick Yasenchack]

I bought my 63 2-door convertible 62 series a few years back, previous owner said a new brake booster was just installed and that was why brake pedal was a rock.  Did not know.

Just had engine reworked and I completely redid brakes.  Engine back in and running, brakes still like rock.  Mechanic only getting about 12-15psi I beleive he said.  He is not sure what to do other than add electric booster pump, going to test booster in morning

Any suggestions before summer ends in Ohio

[Rick Yasenchack]

Thanks guys.  I was not looking to have one rebuilt, it came with after market booster.  Out of frustration I spent the money for new booster and master cylinder from Summit Racing. 

After 2 years, 2 professionals, I'm wondering what have I gotten into.

After installing the new unit, bleeding the brakes and master cylinder twice, I went from rock hard pedal to almost no pedal.  The 2nd bleeding involved myself doing the master cylinder, the front then the rear brakes.  This  improved some, but no where near safe brakes.

Quitting for the day, any comments appreciated, hoping my mechanic friend can come by tomorrow. 

[Russ Austin]

Did you bench bleed the master cylinder before installing it? 

[Rick Yasenchack]

I did not the first time.  The second time I bled the master at the line connections.  The 3rd time I bled the master using the kit provided, which I did not see in the box.  Brother in law noticed.

Using the kit, I was able to see the air removed and two lines pumping 100% fluid.  Each time I then bled the brakes.  The 3rd time I started with the front, not that I thought it mattered. 

[Dennis P. DiBari]

Hi Rick,

     As Russ said, the bench bleed is the necessary first step for an overhaul.  Are any of your brake cylinders leaking - inside the drums wet?  If not, any hoses cracked?  Just a thought.

Dennis DiBari, NY

[Russ Austin]

The master cylinder needs to be removed and out into a vice. Level the master cylinder to get all of the air out. reinstall and bleed the wheel cylinders from the furthest to the closest wheel. 

[Rick Yasenchack]

okay, thank you Russ.  Learning is painful.  So for base knowledge, what I did with the kit provided is not good enough?

We are very close to driving for the first time in 2-3 years.  Idles rough and brakes not quite feeling safe

[Russ Austin]

There is probably trapped air in the master cylinder. Get it level in a vice to bleed it.  You will also need a steady vacuum to the booster. 

[Dennis P. DiBari]

Rick,

     Remember to check/change the vacuum hose from the Booster Check Valve to the back of the carburetor.  Make sure it is a Certified 11/32" Vacuum Hose - no substitute will do!  Good luck with the brakes.

Dennis DiBari , NY