Poor Braking - Low Pressure 1971 Nova

[clinkster]

First, that is one sick nova! I have a 70 only hope to aspire to have one as nice as yours! Its just my humble opinion but my first reaction was that the booster is way to small, which looks like you came to the same conclusion. Also in regards to the bubbles, you might want to try to re-bleed the master. Sounds like the master still has air in it. I had the same issue on my buddies car where he thought he did a good job of bench bleeding until we put in the car and mushy/too much brake travel. Turned out he could not overcome the spring pressure by pushing with a screwdriver and only bleed half the master. I just rehooked the bleed kit up with it installed and had him push with the pedal slowly until all bubbles were gone and that cured it. Dont know if that is your problem with air bubbles or not just thought i would throw that out there. btw: i would love to see more pics of it, interior as well. nice job.

[Novette_71]

so many news .....

first, i doublechecked the vacuum hoses for the brake booster. the idea was to have the vac pump and the engine both connected to the BB (with a one way valve in between).

so whenever the engine vac is larger than the activation point from the pump (15 psi) it will help evacuate. at idle (engine 10 psi) the pump is on its own ...

BUT : sometime in the past during restoration I was smart enough to put the PCV valve with a T-fitting to the same port as the brake bosster, so behind the throttle, that was screwing up my engine vac of course .... hahaha. i dont know what went into my mind .... i saw it andf thought DID I REALLY DO THAT ??? WTF.

I fixed it. and i installed the new booster dual 8".

now THIS is amazing : my MC is connected with flexible lines. you know how normally the MC is angled a little bit in the engine bay, like a wing lets say, front is a bit up.

when i replaced the BB I made myself some room and brought the MC towards the front ... angling it a bit like a spoiler, front down, maybe 20° or so. that was rather by random, i put some towels not to scratch anything and that was the position it was placed in by coincidence. all lines stayed connected. advantage with the flexible lines setup.

when i put it back onto the new BB i opened the lid to doublecheck fluid level and wanted to bleed it again. BUT the pedal was hard from the beginning and no bubbles !!!! i bled everything again to be safe, still (thanks god) no bubbles.

since i changed nothing i wonder if the tilting to the front when the MC was loose actually helped removing the air, like self bleeding .... you have two bores in the rear chamber, with the nose facing up they can never escape and stay there, but with the nose facing down maybe they found their way out by themselves ????

anyways braking is excellent now, a good feeling