Alfa Romeo
GTV6 Rear Caliper Rebuild
David Porter
Capital Chapter
porterdm@home.com
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
15mm box wrench
11mm socket wrench
11mm flare nut wrench
10mm box wrench
7mm socket wrench
5mm allen wrench
pry bar/big screwdriver
internal snap ring pliers
needlenose pliers
small screwdriver
scotch pads/extra fine steel wool
aerosol brake parts cleaner
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 allenhead 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 handbrake 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 reassembly. 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 lefthand 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.). Rehang 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 crossthread 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.