"If you're not well versed in brake
systems get help from someone who is. If you modify your brake
system you could be liable if it fails and you hurt someone or destroy
property. Brakes aren't difficult to work on, once you've been
taught how, but they're one of the most important parts of a car, and
deserve a lot more respect than they usually get."
Parts you will need from a donor car:
- Rotors Including Bearings
- Spindles Including All Bolts Nuts Etc.
- Backing Plates
- Caliper Mounting Brackets and Mounting
Bolts
- Proportioning Valve
- All Front Metal Brake Lines
- Power Booster Including Check Valve (For power brake
systems)
Parts you should buy new or rebuilt (You can
take these from the donor car but unless you know it to be a good system
I would not):
- Master Cylinder
- Calipers (These are cheap for rebuilt
ones approx $20.00 each)
- Front Flexible Brake Lines (Kennedy
American had these on special for under $20.00) Replace these
-- do not reuse old ones.
- Brake Pads
Find a donor car, almost any 1971 and up AMC
with front disc brakes will make a good donor car. I highly
recommend that you not use the four piston caliper setup from 1970 and
down disc brake cars, (instruction are included to swap this older type
to the newer type) they are far more expensive and harder to maintain
and from what I am told they just plain don't work as well.
There
were 2 types of single piston caliper systems used in different years,
not sure which was used when, but there were Kelsey Hayes and Bendix
systems, some people prefer one system some the other, both work well
and the instructions provided here will work for either brand.
Be
sure that you know what kind of car that you used for a donor so that
you can order brake parts later. Remove all parts listed above
from the donor car (take the calipers for cores if you are buying
rebuilt) this should be fairly simple and self explanatory. Be
sure to make a quick drawing of the proportioning valve and where each
line runs from each connection in the valve, when you go to install it
you will be glad that you did.
I have been told that there were 2
different proportioning valves used that had different pressure ratios
front to rear, to assure that you have a correct one for your car be
sure that the donor car is of similar weight, (Ambassadors and Rebels
will use one while Javelins, Concords, Gremlins, etc. will use the one
for lighter cars) If your donor car is of the wrong variety to use
the proportioning valve of the donor car you may look for the correct
valve from another car (don't know if they are available new or
not) or
you may purchase an adjustable valve.
If you choose the adjustable
valve you should have a brake expert adjust it for you I would not
attempt this myself, mis-adjustment is asking for trouble. Also
there is a short metal line going to a double female sleeve and then to
the rear brakes, be sure to get this line and the sleeve, if you do your
old rear brake lines will connect right up.
Have the rotors turned and checked to see
if they are in specs. Remove the drums and all brake hardware from
the car. Disconnect the metal line from the flexible line that
runs to the wheel cylinder, this can be difficult flare wrenches may help
or in my case I had to resort to vise grips. Remove the nuts
holding on the backing plate and spindle. Remove all the bolts ,
there is a gotcha here one of the lower bolts may hit a 90 degree turned
spacer between the lower control arm and the strut rod, save yourself
the hour I spent removing the strut rod and stripping a bolt and take a
hacksaw and cut off the bolt, you can use one from the donor car.
Since the bolts come in from the front on the disc system this will not
be a problem in reassembly. Remove the master cylinder, power
booster and all front metal brake lines as well as the brake pressure
warning unit.
Install the spindles, backing plates and
mounting brackets, if you watched how everything came off this should be
easy. The calipers should mount toward the top front of the rotor.
Mount the rotors onto the spindles and secure the bearings with the
washer, nut and cotter pin and put on dust cap. Connect the new
flexible brake lines to the calipers, another gotcha here, if you car is
equipped with the loveable trunnions, like mine, then the metal part of
this brake line may want to run right through the middle of your
trunnion.
I overcame this problem with a tubing bender, if you
have to do this connect the line to the caliper first then bend the
brake line down and toward the middle of the car to run behind the
trunnion. Bend it a little at a time and keep setting the caliper
in place until the line is no longer touching the trunnion. Others
have told me this was not a problem when they did the install, I have to
assume that the brakes lines come out of the calipers at different
angles depending on who manufactured the calipers you are using, if you
don't have this problem it will save you about an hour on the install.
Install caliper with brake pads.
Connect the free end of the
flexible line to the mounting plate inside the wheel well. Install
the power booster from donor car being sure to connect the vacuum line,
this is an excellent time to clean it up and paint it. Install the
master cylinder and be sure to bench bleed it first. Run all the
metal brake lines that you removed to their appropriate places and
connect securely, do not mount the proportioning valve yet, let it hang
by the brake lines until you have finished. The brake lines may
require some custom bending to mount to the firewall but this isn't too
difficult, just be careful not to crimp or break them. Once you
have the brake lines securely fastened then secure the proportioning
valve inside the engine compartment.
Lastly, bleed the brakes on all four
wheels, check for leaks, and test for stopping power.
Please also note that for true balance on
the brakes the braking system with disc brakes were designed to be used
with 10" rear brakes which I believe came on all disc brake
equipped cars and all V8 equipped cars, the I6s, with front drums, came
with 9" rears. There are some people running disc front with
the 9" rear brakes and working fine, but to accomplish optimum
balance between front and rear if the rear brakes are not already
10" drums these should be swapped as well (this swap is not covered
here).
Many people also mentioned the swap of
early disc (1970 and back four piston caliper non vented
rotors) to late
disc (1971 and up single piston calipers with vented
rotors). This
is accomplished the same as above except the master cylinder and power
booster are identical to the later model cars and the proportioning
valve and metal brakes lines should work just fine. All parts at
the wheel including spindles, backing plates, mounting brackets,
calipers, rotors, and flexible brakes lines should all be replaced as
above.
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