Disclaimer
Brakes are a critical safety issue. I did this on my car, and
it worked.
You have a different car and different skills, better or worse.
This is an interesting job but challenging, especially if you don't
have
good tools or have never done anything more complicated than a tune-up.
If
you are at all uncomfortable working on your brakes, drag a friend
over who
has some experience. Instead of doing all the work yourself,
you could
remove the calipers and take them to a shop for rebuilding, or you
could buy
a set of rebuilt calipers for around $200. You may wish you had.
If something I say doesn't make sense, please don't follow it (and let
me
know). All suggestions for improvement gratefully accepted.
Use
common-sense safety precautions. The AROC has technical experts
with vast
experience waiting for your phone calls, and most chapters have technical
reps who will come to your house to help you. Make it a club
project.
Void where prohibited.
Symptoms
In my case the symptoms were obvious. First, the rear calipers
needed
bleeding every week or so or the rear brakes would just slowly go away.
The
car doesn't stop very well with just the front brakes, and the fronts
lock
up much more easily if the rears aren't contributing. Second,
when I tried
to improve things by adjusting the pad-to-disc clearance, I got brake
fluid
dripping out of all four adjusters.
Preparation
Put the car on jack stands and remove the rear wheels. Have caliper
rebuild
kits handy, and new pads and discs if required. Tools needed:
17mm socket wrench pry bar/big screwdriver
15mm box wrench internal snap ring pliers
11mm socket wrench needlenose pliers
11mm flare nut wrench small screwdriver
10mm box wrench scotch pads/extra fine steel wool
7mm socket wrench aerosol brake parts cleaner
5mm allen wrench
When I refer to "the book" I mean the November 1975 Alfetta Workshop
Manual,
Pub. #2064. All torque figures are "dry", which means clean threads
but no
lubrication.
Remove Discs
You need to remove the brake discs before you can remove the calipers.
Check them while you're at it. Mine were under spec (book says
minimum is
9mm "after machining" and mine were 8.5mm "before machining") and were
replaced as part of the operation. Minimum pad thickness is 7mm.
They're
cheap enough that I recommend new pads and discs as a matter of course.
You
don't want to do this again next month.
The book says to remove the pads first, but after doing one side I found
that it's easier to remove the pads after the calipers are out of the
car.
1. Back Off Adjuster Screws. To get the discs off you need to
increase the
pad-to-disc clearance, so you need to back off the inner and outer
adjusters. The outer adjusters are on the outside of the outer
caliper
halves and have a 17mm hex-head hard plastic dust cover, a 17mm locknut,
and
a 5mm allen-head socket on the end. The inner adjusters are on
the back of
the inner caliper halves and have a 7mm hex head and no locknut or
dust
cover. I have read many descriptions of which way to turn what,
but here's
what I found:
a. Outer: Both of the outer adjusters are essentially just one-piece
screws
with ordinary right-hand thread, and they screw directly into the back
of
the outer pistons. Remove the plastic dust cover and loosen the
locknut
(both also right-hand thread). Turning the adjuster clockwise
"tightens"
the screw and pulls the piston outward, increasing clearance.
Three or four
complete turns should give enough clearance.
b. Inner: The inner adjusters do not screw directly into the inner
pistons,
as should be clear from their front-to-back orientation. There
is a
right-angle worm drive inside the caliper. Unlike the outer adjusters,
the
inner adjusters are mirror images of each other, but it's easy to figure
out
once you know what's going on. The inner adjuster on the right-hand
caliper
is just like the outer adjusters. Turning the 7mm hex clockwise
"tightens"
the piston and increases clearance. The inner adjuster on the
left-hand
caliper is the odd one and works in reverse, counter-clockwise to increase
clearance. Three or four turns again.
2. Remove Discs. The discs are sandwiched between two flanges
on the rear
axles, held together by 15mm hex bolts. These bolts will probably
be very
tight, and you can't get a socket on them. Use your best box
wrench and be
sure the wrench is square on the bolt before turning. You will
also need to
keep the axles from turning. I stuck one end of a long prybar
through the
wheel studs and put the other end on top of a jackstand. The
discs will
come right off once all the bolts are out. Let the axles hang.
The axle
assemblies appear to be symmetrical and so do not need to be marked
for
reassembly.
Remove Calipers
1. Brake Lines. Each caliper has a short piece of steel brake
line that
comes from the front of the caliper and screws into a junction block
mounted
on the transaxle and facing the rear of the car. Unscrew the
two caliper
lines from the junction (not the third one that comes from the front
of the
car). If you haven't done brake work before, be very careful
with these
lines and the compression fittings. Use an 11mm flare nut wrench
to break
them loose. They may be rusty or already rounded off, in which
case you may
need to use cruder methods to get them off (i.e. vise-grips).
Get new brake
lines. If the old ones are OK, back them all the way out of the
junction.
Bend the brake lines as little as possible. If you're careful
you won't
need to bend them at all. It's much easier to get them back on
again if
they line up straight. Have a pan ready for the brake fluid.
2. Hand-Brake Cables. Disconnect the hand-brake cable from the
levers on
top of the calipers. Remove the 10mm locknut and the long adjusting
nut on
the end of the cable, just above the right-hand caliper. Pull
the cable to
the left, out of the fitting on the end of the hand-brake lever on
the right
caliper, and then just lift it out of the fitting on the end of the
hand-brake lever on the left caliper. Sounds complicated, but
it isn't.
Just remember where it goes.
3. Caliper Mounting. Remove the two 17mm nuts that hold each caliper
to the
transaxle and remove the calipers. On the left side, you will need
to push
the exhaust to the side. Disconnect the rubber ring under the
trunk and the
rubber hanging bracket near the transaxle. This will give you
enough
sideways movement to get the left caliper off.
Disassemble Calipers
1. Remove Pads. Take out the two little wire retainer clips and
pull out
the two pins and the flat cross-shaped spring that hold the pads in
place.
2. Separate Calipers. You must do this if you need to replace
the o-ring on
the inner adjuster screw. You might be able to replace all the
other rubber
parts without splitting the calipers, but it would be harder.
The caliper
halves are held together by four 11mm hex bolts. One of them
holds the
bracket for the hand-brake lever return spring. Remove the spring.
Be
careful not to damage the machined mating surfaces. More brake
fluid will
come out. I removed the short steel brake lines from the calipers,
but you
could probably leave them in place.
The rebuild kits I got did not contain the two o-rings that seal the
passages between the caliper halves. If you are in the same boat
be careful
of the old ones. I was advised to keep them in brake fluid until
re-assembly. I re-used the old ones, and my calipers don't leak.
I have
heard that the Alfa Ricambi kits have all the o-rings.
3. Remove Pistons.
a. Outer. Remove the rubber dust boots. These just snap
into a groove in
the piston but are held to the caliper by steel retaining rings.
Work the
rings up with a small screwdriver. You will have new boots on
the kit.
Remove the outer pistons by turning the adjuster screws counter-clockwise,
pushing the pistons out of their bores until they stop moving.
The adjuster
screws will then be disengaged from the pistons, and you should be
able to
pull the pistons out the last fraction of an inch.
b. Inner. Use the same procedure to remove the dust boots
and the inner
pistons, but turn the left-caliper inner adjuster clockwise to push
the
piston out. Be careful not to scratch the pistons.
c. Do not disassemble the pistons further. There are moving
parts in the
back of the pistons that are part of the adjustment mechanism, but
there are
no parts in there that you need to replace and you risk damaging the
parts.
4. Remove Adjusters.
a. Outer. Very simple. Remove the 17mm locknut from
the outer end of the
adjuster screw. Under the locknut there is a small retaining
clip that
snaps into a recess in the screw and keeps the screw from falling into
the
caliper. Pry this off and pull the screw in through the caliper
to remove
it. You will see a flange in the middle of the screw with a black
(probably) o-ring in a groove just outside the flange. This is
what keeps
brake fluid from leaking out the outer adjusters, and you should have
a new
one in the kit.
b. Inner. Not so simple. The inner adjuster screw
is right there in plain
sight, but it is held in place by a snap-ring down in the bottom of
the
bore. Under the snap-ring are a hat-shaped washer and a spring.
Get the
snap-ring out with snap-ring pliers and take the other parts out.
The
spring isn't strong enough to come leaping out but the snap-ring is,
so be
careful. You can then pull the adjuster screw straight out.
This one also
has a flange in the middle with a white (probably) o-ring in a groove
just
under the flange. Under the adjuster screw is one more part,
a short steel
rod with rounded ends. This rod is what transfers the motion
of the
handbrake cable through the lever on the caliper to the base of the
inner
adjuster screw.
c. Do not disassemble the inner adjusters further. If you
tried hard
enough you could probably get the rest of the mechanism separated from
the
inner caliper half, but there are no parts in there you need to replace
and
you risk damaging the parts.
5. Remove O-Rings from the Bores. Each bore has a square-section
o-ring
piston seal set into a square recess in the bore. You will have
new ones in
the kit. Get the old ones out with a small screwdriver.
Be careful not to
scratch the bores.
Clean Everything Each of us has a level of cleanliness that we're
comfortable with. These calipers are complex, with more moving
parts than
most. Use your judgment, but I wouldn't do this job without a
source of
compressed air and a couple of cans of brake parts cleaner. Clean
the
pistons and bores with Scotch pads or 0000 steel wool, but take it
easy.
You just want to remove any scum or deposits and definitely don't want
to
remove metal. Clean out the bottom of the inner caliper bore
as best you
can, considering you haven't taken it completely apart. You will
be able to
see the worm-drive part of the adjuster that you didn't remove, and
if you
work the handbrake lever you will see movement at the bottom.
Make sure the
handbrake levers move freely and that the pivot fittings at the ends
of the
levers aren't rusted in place. Get all parts clean and dry.
Reassemble Calipers
1. Replace O-Rings in the Bores. Lubricate the new square o-rings
with a
little brake fluid and seat them in the recesses. Make sure they
aren't
twisted.
2. Install Adjusters.
a. Outer. Fit the new o-ring on the adjuster screw and insert
it into the
outer caliper half from the inside. The o-ring will seat in a
recess in the
bottom of the bore. Replace the small retaining clip and install
the
locknut until it nearly touches the retaining ring.
b. Inner. Fit the new o-ring on the adjuster screw.
Before you install
it, put some grease into the recess at the very bottom of the bore
where the
worm drive is and where the little rounded steel rod will go.
Don't fill it
up, or you won't be able to get the adjuster screw in all the way,
and you'
ll never get the snap ring back in. Put a little grease on the
adjuster
screw below the flange and the o-ring. Some people use special
brake
grease, I used wheel-bearing grease. I'm not sure it matters
since the
o-ring is supposed to keep the grease and the brake fluid apart.
Given the
proximity of the exhaust to the left-hand caliper, use something that
will
survive high temperatures.
Use a little grease to stick the little rounded rod into the recess
in the
end of the adjuster screw. Insert the adjuster screw into the
bore, making
sure the rod isn't displaced, and make sure the screw is fully inserted
into
the bore. You should be able to see the recess for the snap-ring.
Hold the
adjuster in place with one hand and work the handbrake lever back and
forth.
You should feel the adjuster moving in and out just a little.
Install the spring and the hat-shaped washer. Install the snap-ring.
This
is a lot easier to say than to do, but keep at it. You need to
press
against the spring pressure and squeeze the snap-ring at the same time.
I
pressed down on the snap-ring with a screwdriver with one hand, opposite
where the ends of the ring come together, and with the snap-ring pliers
with
the other hand. The best technique turned out to be to get the
snap-ring
started down into the bore with the pliers and then to tap the ring
down the
rest of the way with a screwdriver or small punch. If I had the
right
snap-ring pliers this would probably not have been necessary, but it
works.
Just be sure the ring is fully seated in its recess when you're finished,
all the way around.
3. Install Pistons
a. Outer. Lubricate the piston with a little brake fluid
and insert it
squarely into the bore until it engages the end of the adjuster screw.
Turn
the adjuster screw clockwise to pull the piston in. It will be
a little
stiff because of the new square o-ring in the bore. Keep turning
until the
piston is all the way in, but no more. Install the new rubber
dust boots
and the steel retaining rings on each piston. The book says to
lubricate
the dust boots with ATE grease before assembling.
b. Inner. Use the same procedure to install the inner pistons
and dust
boots, but turn the left-hand caliper inner adjuster counter-clockwise
to
pull the piston in.
4. Assemble Calipers Making sure the mating surfaces are clean
and the
o-rings are properly in place, replace the four 11mm hex bolts.
The book
does not specify a torque value for these bolts, so use your judgment.
Replace the brake lines if you took them off. Try to get the
angle exactly
the way it was, and tighten the flare fitting on the caliper.
You won't be
able to reach it easily once the calipers are installed.
5. Assemble Pads Install the pads in the calipers with the two
pins,
spring, and wire pin retainers. It's much easier to do this with
the
calipers on the bench than with the calipers installed. The pads
have
arrows on them, which should point in the direction of forward wheel
rotation.
Install Calipers
1. Caliper Mounting. Put them back on, torque the 17mm nuts to
4.7 - 5.4
kgm (35 - 40 ft-lb.). Re-hang the exhaust.
2. Hand-Brake Cable. Turn the fitting in the end of the lever
on the
left-hand caliper until the inner cable itself drops into the fitting,
then
pull the cable to the right until the cable housing is snug in
the lever.
Pull the end of the cable through the fitting on the end of the lever
on the
right-hand caliper until you can get the adjusting nut and locknut
back on.
Leave the adjustment loose.
3. Brake Lines. Carefully thread the brake line fittings into
the junction.
It is very easy to cross-thread these fittings, so be sure the threads
are
started in correctly before using a wrench. You don't need to
tighten them
very hard.
Install Discs Slide the discs up into the calipers and bolt them
in. You
should have plenty of pad clearance. The book calls for a special
tool to
torque the bolts because you can't use a socket. I tightened
them as much
as I could with a wrench around 10" long and called it enough.
If you have
the tool, the book says torque to 5.2 - 5.7 kgm (38 - 42 ft.-lb.).
Adjust Pad Clearance The book gives the running clearance between
pads and
discs as 0.10 - 0.15mm (.003 - .005"). Other sources recommend
.002". Use
the newly-rebuilt adjusters to achieve this result with a feeler gauge,
using the same technique as described above (clockwise for more clearance
on
all adjusters except the left-hand inner) . You can use two gauges
simultaneously if you want, one for each pad.
The only glitch in the adjustment procedure is the locknuts for the
outer
adjusters. The book calls for a special tool that enables you
to hold the
adjuster steady while you tighten the locknut. You can make one
by welding
a handle onto the side of a 17mm socket, or maybe by grinding some
metal off
an offset 17mm box wrench. Or you might try using vice-grips
or a 17mm
open-end wrench. One time I used vise-grips to hold a 17mm socket.
This
time I just over-tightened the adjuster a little (counter-clockwise)
so that
tightening the locknut would loosen it to the correct clearance.
Trial and
error, but easier for me than making a tool. Replace the plastic
dust
covers on the outer adjusters.
Adjust Hand-Brake Cable The book says that you should only just
take up the
slack in the cable with the adjusting nut, making sure that the levers
on
the calipers don't move at all, and then set the locknut. Otherwise
you
risk disturbing the precise clearance adjustment you just finished.
The
book also says that the wheels should be locked at 4-6 clicks on the
handbrake lever. I haven't been able to get the cable that tight
yet, but
it's pretty close. There may be some slack in the lever action.
One thing
to try would be to tighten the cable adjusting nut with feeler gauges
in
place at the pads to see at what point the clearance began to diminish,
then
backing off that point a little.
Bleed Brakes The calipers are now empty, but the master cylinder
should
fill them up pretty quickly while you bleed the system. Make
sure you don't
run out of fluid in the reservoir or you'll need to start again.
Check all
connections for brake fluid leaks. The book says that front and
rear
calipers must be bled simultaneously, one side at a time.
Recheck Verify pad clearance and handbrake adjustment after a
few days,
especially if you have replaced the pads or discs. Check for
leaks one more
time.
Alfa Romeo
GTV6 Rear Caliper Rebuild
David Porter
Capital Chapter
porterdm@home.com