What is the difference between a power booster and your manual brake
your pedal. A few things, but one of the biggest complaints in a Chevy
II is not
enough pedal travel. First review this information and then see
my pedal travel conclusions.
Also see my Brake Bracket
info on the manual to Booster conversion.
What is my conclusion? My 66' assembly manual says the
brake pedal needs to be "4 inches +-
.12 from top face of pedal to toe pan for normal position" with a power
booster. Mine was a little bit low
. In my case
the pedal hitting the floor and full travel was about the same thing.
(Panic stop condition in some cases) Is that OK? When there
is sound deadener and carpet added in the future, it wont be.
Also the feel that low just isn't what I am use to. You don't
normally use full travel if the brakes are good, no air in the system
etc. Are there fine differences between 64-65 and 66-67
pedals that cause the pedal to appear too low? Is this a 64-65
booster vs. 66-67?. I don't know, I only had this one to measure and it
may have come from a Gen 1 car.
If you need to adjust the pedal there are some options. Warning,
these are critical brake components, take care with any modifications.
Cut the end off the rod, thread it and put a clevis on
it. Will it work? Some have done it, but remember the
offset in the mounting, the rod will now be at an angle and there may
be some binding in the clevis if you are not careful. Also the
booster is not designed for sideways pressure and may cause wear
appears to be a forged rod, not held to a tight OD. Some work
will be needed to thread it.
1.A Cut the rod and thread both sides and use a union and lock
nuts to adjust. Is there enough rod to do this?
2. Adjust the pedal curvature/angle. This is done by making
strategic cuts in the pedal, bending it and getting a great welder to
weld it back up. You make the pedal higher while leaving
the mounting points alone.
3. Fab a short extension from the brake
4. Find a different style booster. Many aftermarket ones
come with a threaded rod. Usually they come with a 4 bolt
pattern and the master cylinder centered. That is great
clevis. Two holes would need to be added to the firewall
and a bracket between the bottom bolts to tie in with the
re-enforcing bracket. Also cutting of the firewall
some to center the booster. Also there are dual diaphragm
options, as long as it isn't too long, but a Chevy II is a tight fit.
I decided to buy a new booster designed for a Chevy II
A booster that would adjust and possibly work a little better.
The original was OK, but any improvement helps. I learned few
really know these
1st and 2nd gen Chevy II boosters. First place I tried to order
from said it would ship "tomorrow no
problem". 2 weeks later they refunded my money. It
was going to be another month. Many places list a picture
for the booster but a little checking shows
many of the pictures are generic and you don't know for sure what you
Next place I ordered from, no problem. The booster they
sent is a CPP single stage booster. The online picture
showed a heim
joint to attachment to the Brake Pedal. That would be perfect
since this booster is also offset the same as the stock one to fit the
came with a clevis. See pictures below. Is that a
problem? I think so, see #1
Nice n shinny new booster with the stock offset.
The front. 2 advantages over the stock one. First the check
valve is on the correct side. Next the Master Cylinder mount is
recessed. Overall the Master Cylinder is closer to the
firewall. No need to beat more clearance into the spring
towers. Disadvantage is the travel is a little shorter, but
I didn't write down exactly what it was. About a 1/4" shorter if
I remember. I have had no problems bottoming out.
Clevis sent with booster vs. stock one. New one on right.
I went to Smileys Racing in Mesquite Texas and bought a male and
female heim joint. I went near by to Eliots Hardware and
bought the 1/4 28 female connector. Now I have enough to make it
work no matter what. The trip costs more than the parts so I got
whatever I might need in one trip.
The heim joint in the middle worked and gave me the distance off the
floor I wanted. Still lower than the manual, but that is
OK. Also I used a big SAE washer with the bolt that went
through the heim joint into the brake pedal. I have been in
racing and seen the ball
pulled out of a heim joint. The washer was just to make sure that
if something ever did go wrong with the heim joint the washer would
keep the end of the heim joint attached to the pedal.
Now for the street test! A little more boost than the stock booster. Can
I "lock it up"? Yes, with the 205 front & 235 wide rear tires on a
dry warm day. The key is the car stops great. See the
CPP Master Cylinder
page for the last part of
the brake system upgrade that made the system work great.