I'm converting my 1969 vette to power brakes, but the booster mounts with 4 bolts where the old master cyl only uses two.

What do I need to do to mount the booster? It shouldn't be that difficult.

 

The procedure goes as follows:

1) Remove manual brake M/C along with the brake lines that connect to it.
2) From under the dash, bend the metal tabs back that retain the studs that
your old M/C mounts to and then remove the studs. Also remove the clip holding
the M/C clevis and pushrod to the pedal assembly and push out the pin attaching
the clevis and pushrod. You'll reuse the clevis, pin, and clip, but not the
pushrod.
3) Remove the two screws that don't seem to be attaching anything that you
will find below where your old M/C was mounted. These screws are threaded into
the pedal support under the dash and block off the second set of holes for the
PB booster.
4) Use the new brake booster to firewall gasket as a template to locate where
you will have to cut a new hole for the brake booster shaft to pass through.
Line up the four mounting holes in the gasket with the holes used for the
mounting studs and the two previously mentioned bolts. Use a hole saw that
matches the size of the big hole in the gasket. The old hole will be covered by
the booster when it is installed.
5) Enlarge the four mounting holes to 3/8" by drilling them out. This will
allow the four studs on the brake booster to pass through the firewall.
6) Important! Attach the clevis to the booster pushrod BEFORE mounting the
booster. Orient it so that it will line up with the pedal when installed.
7) Put the gasket in place on the booster studs and slide the booster studs
through the firewall via the four mounting holes. While you're doing this, make
sure that the clevis is aligned with the LOWER hole in the brake pedal. Attach
the clevis to the brake pedal using the same pin and clip that you previously
removed.
8) Now you can attach the booster by using four 3/8" course thread nuts and
lock washers tightening them from under the dash until the booster is secured
firmly to the firewall.
9) Attach the new master cylinder to the booster using the two studs sticking
out of the booster. You may have the adjust the booster rod that actuates the
MC piston. Just screw or unscrew it to adjust to the lenghth needed to lightly
compress the piston enough to keep them in contact at all times.
10) Bleed the MC first before attaching the brake lines and then bleed the
entire system.
11) Connect the booster to the intake manifold using 3/8" fuel/PCV line and a
corresponding fitting on your intake.

 

Wow, that is a pretty informative post. I was going to go vacuum power, too, but I heard so many things about hydroboost, I went with that instead. I just have to finish out the rest of the system to get the feel of it.

I know you might already have the vacuum booster, but if not, have you considered the hydroboost?

 

 

Hydraboost is great. Too bad you need power steering to use it.

 

Technically, you only need the pump. Pressure line from the pump to the booster, cap the pressure bypass, run the return straight back to the pump reservoir.

 

 

Hi

Technically, you only need the pump.

You don't want to run this type high flow pump for just the Hydraboost, do you ?
There must be a other possibility, like a small electric pump , to power this Hydraboost , that doesn't require any high flow hydaulic, but mainly pressure.

Gunther

 

Well, , the pump only supplies on demand once it comes up to operating pressure. As in just the power steering, no fluid flow, no pumping. That is why removing the power steering belt to "pick up some horsepower" while running at the strip results only in a test of your ability to loosen a couple bolts. If there is no demand, the pump isn't doing any work. It nearly freewheels. Obviously there is some frictional loss from just running the shaft on the bearings and spinning the gears but, once the sytem has pressure, it stops pumping. You'll experience this phenomenon in a system with low hydraulic fluid. The pump makes no noise when not steering and starts to howl and growl when you turn the wheel.

Yes, you could run the hydroboost from an electric hydraulic pump but the electric motor could end up quite large(around 5hp ought to get 'er done) since both the steering and the hydroboost are more critical of pressure, rather than absolute fluid flow. Look at the pumps they use on those lowrider things to get an idea of both the pump and electrical requirements.

 

Copy that!

 

Thanks for the great advice, it helps.