How to Replace the Front Brakes

How to Replace Your Front
Brakes
by Lars Grimsrud
SVE Automotive Restoration
Musclecar,
Collector & Exotic Auto Repair & Restoration
Broomfield,
CO
This tech paper will discuss the replacement of the front
brake pads and rotors on the C-4 Corvettes. This paper deals specifically
with the ’84 – ’87 model years, and applies generally to
the ’88 through ’96 models. The rear brakes use the same
process, so you can use this procedure as a guide for the rear, as
well.
General
The disc brake system on the C4 series
Corvettes is a well designed, simple to maintain system that uses
components that are right off the racetrack. The component parts are
designed for very quick service/replacement, and can be easily serviced
with very basic hand tools.
The brake pads used on the Corvette are
unique to the ‘Vette. They are a high performance, semi-metallic
pad. You cannot buy a non-performance, non-metallic pad that will fit a
C4. Due to this, the pads are a bit more costly than a semi-metallic pad
for your Buick Regal. There are two different part number series for the
C4: The 1984 through 1987 cars use the early pad. The 1988 through
’96 cars use a different, much more costly, pad.
Several
different manufacturers supply pads for the ‘Vette. Personal
preference is a factor in name brand selection, but I have found the
Raybestos pads to be well built, well backed (by warranty), readily
available, and very well researched and tested by the manufacturer. They
offer two grades of pads for the ‘Vette: the “PG”
series and the “SS,” or “Super Stop”
series.
The “PG” series is a stock, high performance
replacement pad. It will meet or exceed the performance of the GM pads.
The “SS”series is a step up from this, and provides superior
high-temperature braking performance for continuous or heavy braking
applications, such as when autocrossing or very sporty driving. It has
been my general experience that the pads designed for high temperature,
heavy duty applications tend to be less effective under light, cool
braking conditions: they come into their peak effectiveness when hot. For
this reason, I prefer the standard, “PG” series for use on
cars that are used primarily for around-the-town driving and weekend
pleasure. Both the “PG” and the “SS” series come
with Lifetime Warranties.
In addition to the pads themselves, the
rotors may need attention. Excessive heat can warp a rotor, causing a
pulsating brake pedal and pulsating braking performance. Pads worn past
their limit, exposing the metal backing, can groove and gouge the rotors.
It is my personal preference to NOT turn rotors that are not warped or
scored: if the rotor is performing smoothly, is not damaged in any way,
and only shows light wear, I prefer to simply replace the pads and leave
the rotor alone. This extends rotor life significantly. If you need to
have the rotor turned due to a pulsating pedal or other rotor damage, make
sure you take it to a reputable machine shop that has good, modern
equipment: I’ve seen many rotors set up and turned by inexperienced
people on poorly maintained equipment that results in a rotor that does
not run true, or which has a finish which is not conducive to good braking
performance or pad life.
Tools Required
Floor
jack
Jack Stands (2)
Wheel Lug Wrench
15mm Combination
Wrench
17mm Combination Wrench
13/16″ Combination
Wrench
Large, heavy duty screwdriver
�” Drive Torque
Wrench
13/16″ �” Drive Socket
15mm �” Drive
Socket
�” �” Drive Socket
5-lb heavy duty
hammer
Parts & Prices (front pads)
(Raybestos
Brand)
Year Series Part Number
Approx. Price
1984 – 1987 PG PGD294
$54
SS SSD294
$59
1988 – 1996 PG PGD412M
$130
SS SSD412
$145
You may also need a bottle of new brake fluid (good to have on
hand in any case).
Procedure
Section 1: Replacing Pads
Only
1. Raise the front of the car and secure with
jackstands.
2. Pop the top off the Master Cylinder and remove
about � of the brake fluid. I have a syringe I use for this, but you can
use anything from a spoon to the lid off your bottle of new brake fluid to
scoop it out.
3. Remove the front wheels and open the
hood.
Now, work one side at a time:
4. Collapse/depress
the Caliper Piston: The Piston must be pushed/depressed ALL the way into
the Caliper. Many people use a C-clamp to push it in, and this works
great if you have one that’s big enough. I have found that you can
easily do it with a big screwdriver: get the tip of the screwdriver
wiggled in between the Inner Brake Pad and the Rotor. Smoothly and slowly
pry on the pad to push the Piston into the Caliper. This process will put
a mark on the pad (but you’re replacing it anyway…), but will
not damage the Rotor. As the Piston is pushed in, it will pump brake
fluid out of the Caliper and up into the Master Cylinder: keep an eye on
the Master Cylinder fluid level to make sure that it doesn’t
overflow and spill brake fluid all over.
5. The Caliper is
attached to the Caliper Mounting Bracket with two bolts: an upper and a
lower bolt. Remove the upper bolt using a 15mm box end combination wrench
on the bolt. You must also put a 17mm open end combination wrench on the
hex head of the Guide Pin located between the Caliper and the Caliper
Mounting Bracket to prevent it from spinning. The 15mm bolt may be a bit
tight: I usually whack my 15mm box wrench with the hammer to break the
bolt loose first. This saves my knuckles…
6. With the
upper 15mm bolt removed, the Caliper will simply flip back, hinging around
the lower bolt. The brake pads can then be slid right out of their
mounting slots in the Caliper Mounting Bracket. Note that the inner and
outer pads are different, so keep track of which is which.
If the
Rotor is not to be removed for turning, proceed to step 7. If you wish to
remove the rotor, go to the next section.
7. Noting which of the
new pads are inner and outer pads, simply slip the new pads into the
Caliper Mounting Bracket. The pads have a little anti-rattle spring at
the top: make sure this spring is centered and leveled.
8. Flip
the Caliper back up into position. If the Caliper Piston has been
depressed all the way, the Caliper will flip right down over the pads and
be in perfect alignment. Make sure the pad anti rattle springs are not
cocked, but that they are pushing against the Caliper Housing. If they
are, you’ll have to push on the Caliper against the spring pressure
in order to slip the 15mm Upper Caliper Bolt back into position and engage
the threads. Tighten the 15mm bolt to 22-25 ft/lbs torque.
9.
Install the wheel. Torque the wheel lug nuts to 100 ft/lbs.
10.
Repeat for the opposite side.
11. Once reassembled, and the car is
back on the ground, softly and slowly depress the brake pedal several
times using short strokes until you can feel the pedal become firm again.
This will move the Caliper Piston back out of the Caliper and put the pads
into contact with the Rotor. Failure to do this will result in the brake
pedal going to the floor the first time you stomp on the brakes! Check
and fill your Master Cylinder fluid level. Start the engine, and cycle
the brake pedal again to assure that you have a firm pedal. Perform a
road test to verify proper operation.
When I did this exercise to
test the validity of the steps in this article, the total time to perform
steps 1 through 9 was 13 minutes. I did, however, use an impact wrench to
do the lug nuts, so I had some “power assist.”
Section
2: Removing Rotors
If the rotors need to be removed for
replacement or turning, proceed as follows:
1. At step 6 in
Section 1 above, break both of the 15mm Caliper Bolts loose with the box
wrench & hammer. Remove both of the bolts, and remove the caliper
completely. Secure the caliper to the upper Control Arm with a piece of
string or wire: do not leave it dangling from its flex line!!
2.
Remove the two bolts attaching the Caliper Mounting Bracket to the
Spindle. These bolts are metric, but I prefer to use a 13/16″ box
end combination wrench on them: the 13/16″ wrench fits REALLY tight
and nice so I don’t screw up the bolt heads. And the reason I
don’t want to risk screwing up the bolt heads is that these bolts
are tightened to 133 ft/lbs(!). To break them loose, I give my
13/16″ box wrench several good whacks with my heavy duty hammer.
Once out, the Caliper Mounting Bracket can be removed, and the rotor
simply pulls right off of the Spindle.
3. To re-install, simply
slip the rotor onto the Spindle, install the Caliper Mounting Bracket and
torque the bolts to 133 ft/lbs. Install the Caliper with the lower 15mm
bolt only, and torque this bolt to 22-25 ft/lbs. while providing backup
on the 17mm hex with an open-end combination wrench. Return to Section 1
step 7.
This instruction sequence does not deal with brake
system bleeding, or with specific servicing of the ABS systems or other
related electrical systems.