Page 1 - Valve Identification Guide

Inline Tube - Out of Proportion
Tips for choosing the correct valve for your disc brake conversion

Which valve do I need? There are so many to choose from and they are all different sizes and the fittings change as
well. This is why it is difficult to pick out the right valve for you car. Some valves are used in conjunction with others
and many are singular units which require no other valves. Most people call these items proportioning valves but very
few are just that. Some are distribution blocks and others are hold off valves. Below we will go through all the different
years and the applications.

Proportioning valves come in all shapes and sizes. These valves vary depending on the car you are working on. The
problem is which valve should be used on which car. We asked the experts at Inline Tube and received the full scoop
from installing a used valve to going with a new one.

There are plenty of disc brake sets on e-bay, at the swap meet, on junk yard cars, but most people don't know what
will fit their car. It is important to know the exact year make and model of the car the brakes came off of. Most of the
parts cross over to work on a number of cars but knowing what to look for is the hard part. When ever I see a disc
brake set up at the swap meet and I ask what year it came off and the standard answer is 72 Chevelle. When I look
closer I can determine the exact year. The 69 to 72 GM A-bodies and the 67-69 Camaro are not the same setup.
Most people know aftermarket disc brake kits fit 64-72 GM a-body and 67-69 Camaro's but that does not mean a 67
Camaro can use a 72 cutlass set and consider the car to have factory disc brakes. Lets start at the beginning.

The first year for disc brakes on GM products is 1967. All cars before this point in time had four wheel drum brakes.
Disc brakes were introduced as an option from 1967-1972. Starting in the 1973 model year front disc brakes were
standard and front drums were no longer available. When disc brakes were developed so was the dual master
cylinder, so all 1967 and newer cars had dual masters. Disc brakes required different pressures so the master was
divided into two halves to provide pressure to the front and rear separately. This also meant that if a front line blew
out the car would still have pressure to the rear brakes and vise versa.

The first thing that has to be cleared up is that all 67-68 Factory disc brake cars came with dual piston calipers, if the
car is a 69-72 it had single piston calipers. All after market sets come with the later 69-72 single piston calipers but
this is not technically factory correct for the 67-68 cars. The single piston setup will bolt on all the 64-72 GM A-body's
and 67-69 F-body's. The first issue to converting a car to disc brakes is what kind of car is it. If the car is all factory
correct and that is a concern, single piston calipers on a 67 or 68 car will certainly catch the judges eye and throw up
a red flag. If the car is a driver or modified car no one will care if it has the single piston or dual piston calipers. The
first question we ask at Inline Tube is are you looking for original appearance or are you looking for something that
just bolts on and appearance may not be an issue.

The next issue is the proportioning valve since disc brakes were new in 1967 the valve was still being worked out for
the next few years. The 1967-70 valves could comprise of as many as three pieces and with out all the pieces the
valves would not work properly. In 1971 the valve was finally worked out and this design was used on most cars from
1971 into the 1980's. This is why it is important to know what are the correct pieces for your car. People generally
refer to all blocks as proportioning valves. There are metering blocks, hold off valves, adjustable proportioning valves,
residual valves, and what is the right combination? Once you get past the spindle and calipers the brake lines will
drive the average guy insane. With the wrong caliper the hose may not fit. With the wrong valve combination the lines
may not fit properly. The fittings sizes change with the year of the valve, and valves that look the same are not.
Factory lines do not work with aftermarket valves and in some cases headers will hit blocks located on the frame. I
have put together a set of photos to make anyone the expert. Next time you go to the swap meet you will know what
to look for. Inline Tube makes lines to work with all the valves but you still have to know what valve your car has on it.

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