1991 MITSUBISHI 3000GT Service Manual

SERVICE BRAKES - Service Adjustment Procedures35-47Valve
Spring
Pressure
w-wPressure
,*’ISplit point
,*“”,’,’,’I’
,’,’
output
br.,’
,’pressure
Input pressure14U005E
2.Check the operation of the check valve by using a vacuum
pump.Vacuum pump connection
Connection at the brake
booster side @
Connection at the intake
manifold side @created and held.
created.
Caution
If the check valve is defective, replace it as an assembly
unit together with the vacuum hose.
PROPORTIONING VALVE FUNCTION TESTMOBFKAK1. Connect two pressure gauges, one each to the input side
and output side of the proportioning valve, as shown.
2. Air bleed the brake line and the pressure gauge.
3. While gradually depressing the brake pedal, make the
following measurements and check to be sure that the
measured values are within the allowable range.
(1) Output pressure begins to drop relative to input
pressure (split point).
Standard value: 3.75
- 4.25 MPa (533 -- 604 psi)
(2) Output fluid pressure when input fluid pressure is 8.0MPa (1,138 psi)
Standard value: 5.23
- 5.73 MPa (744 - 815 psi)
(3)
C$txrt pressure difference between left and right brake
Limit: 0.4
MPa (57 psi)
4. If the measured pressures are not within the permissible
ranges, replace the proportioning valve.
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35-48SERVICE BRAKES - Service Adjustment Procedures
BLEEDINGCautionM35FYAOUse the specified brake fluid. Avoid using a mixture of the
specified brake fluid and other fluid.
Specified brake fluid: Conforming to DOT314POO3C
1
14A045
When new
When wornWear
indicator
Lrakedisc
indicatorBrake
disc
14FOO4CBLEEDING THE MASTER CYLINDER
If the master cylinder is empty of brake fluid, bleed the cylinder
as follows.
(1) Fill the reserve tank with brake fluid.
(2) Depress and hold the brake pedal.
(3) Let your fellow worker plug the master cylinder outlet with
finger.
(4) Keeping the condition (3), release the brake pedal.
(5) Repeat steps
(2) to (4) three to four times while filling the
master cylinder with brake fluid.
BLEEDING THE BRAKE PIPE LINE
Bleed the brake pipe line with the engine running in the order
shown in the illustration.
Caution
When adding brake fluid on vehicles with ABS, be sure to
fit the filter to the reserve tank.
FRONT DISC BRAKE PAD CHECK AND REPLACE-
MENTM35FQAG
NOTEThe brake pads have wear indicators that contact the brake disc
when the brake pad thickness becomes 2 mm
(.079 in.), and
emit a squealing sound to warn the driver.
&ionI

SERVICE BRAKES - Service Adiustment Procedures
i14LO29C
1Al 0781
14LO291141029
1. Visually check the brake pad thickness through the inspec-
tion hole in the caliper body.
Standard value: IO.0 mm
(.39 in.)
Limit: 2.0 mm (.08 in.)
Caution
Replace the pad if worn beyond the limit. At this time,
replace the pads on right and left wheels as a set.
2. Remove the guide pin, raise the caliper assembly, and
support it with a wire, etc.
Caution
The guide pin has been coated with special
Igrease. Do
not wipe off the special grease on the lock pin, and do
not contaminate the lock pin.
3. Remove the following parts from the caliper support.@ Pad and wear indicator assembly
8 F$$ assembly
3 I@ Outer shim
4. Measure the rotating torque of the hub with the pads
removed to determine brake drag torque after pads are
installed.
5. Install the pad clips to the caliper support in position.
\14AO400
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35-50SERVICE BRAKES - Service Adjustment Procedures
Pad pin
1 AFnn97
6.Clean the piston and, using the special tool, push the piston
into the cylinder.
7.With care not to allow the piston boot to be wedged, lower
the caliper assembly and fit the lock pin.
8. Using the following procedure, check the brake drag
‘d ,
torque.@ Start the engine and depress and hold the brake pedal
for five seconds.@ Stop the engine. (Approx. 200 N
[44 Ibs.])@ Rotate the brake disc ten turns in the forward direction.@ Using a spring balance, check the brake drag force.
9. If the difference between the brake drag force and hub
rotating force exceeds the standard value, disassemble the
piston and check the piston sliding surfaces for dirt and
rust, piston seal for deterioration, and lock pin and guide pin
for sliding motion.
Standard value: 70 N (15.4 Ibs.)
[4 Nm (3 ftlbs.)] or less
1. Visually check the brake pad’ thickness. Through the
opening in the caliper body.
Standard value: 10.0 mm
(-39 in.)
Limit: 2.0 mm
(.08 in.)
Caution
‘L&iReplace the pad if worn beyond the limit. At this time,
replace the pads on right and left wheels as a set.
I2. Remove the clip and, holding the cross spring with hand,
remove the pad pins.
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SERVICE BRAKES - Service Adjustment Procedures35-51
iPad assembly
Shim A
Shim B
3‘IShim B
Shim A
14FOO9i.
_-TSB RevisionGrease
Grease3. Using a screwdriver, remove the pads and shims.
@ Inner pad (with wear indicator)
8 C$+r ;ad
(iJ Sh:: A
4. Measure the rotating torque
qf the hub with the pads
removed to determine brake drag torque after pads are~
installed.
5.Clean the piston and then push the piston into the cylinder.
6. Apply repair kit grease to both sides of the inner shims.
Specified grease: Brake grease SAE 5310,NLGI No. 1
Caution
1. Make sure that the friction surfaces of pads and
brake discs are free of grease- and other
contami-nants.
2. The grease should never squeeze out from around
the shim.

35-52SERVICE BRAKES - Service Adjustment Procedures
14FOO94
k.!! I14FOO427. Using the following procedure, check the brake drag
torque.@ Start the engine and depress and hold the brake pedal
’for five seconds. [Approx. 200 N (44
Ibs.)]@ Stop the engine.@ Rotate the brake disc ten turns in the forward direction.@ Using a spring balance, check the brake drag force.
8. If the difference between the brake drag force and hub
rotating force exceeds the standard value, disassemble the
piston and check the piston sliding surfaces for dirt and
rust, piston seal for deterioration, and lock pin and guide pin
for sliding motion.
Standard value: 70 N (15.4
Ibs.) [4 Nm (3 ft.lbs.)] or less
INSPECTION OF FRONT BRAKE DISC THICKNESS1. Remove dirt and rust off the surface of the brake disc.
2.Measure the thickness of disc at four or more places of the
pad contacting surface.
Standard value:
24.0 mm (.94 in.)
30.0 mm (1.18 in.)
,Limit:
22.4 mm (.88 in.)
28.4 mm (1.12 in.)
3.If the wear exceeds the limit even at one place, replace the
right and left discs and brake pads as a set.
FRONT BRAKE DISC RUN-OUT CHECKM35FSAF
1. Remove the front brake assembly; and support it with a
wire, etc.
TSB Revision2. Place a dial gauge approximately 5 mm
(.2 in.) from the
outer circumference of the brake disc, and measure the
run-out of the disc.
Limit: 0.10 mm (.004 in.) or less
NOTESecure the disc to the hub with wheel nuts.

L.
SERVICE BRAKES -Service Adjustment Procedures35-53
I14A0398
14F003r
i14A04014NOO27
7
FRONT BRAKE DISC RUN-OUT CORRECTION
M35FFAC
1.If the run-out of the brake’disc is equivalent to or exceeds
the limit specification, change the phase of the disc and
hub, and then measure the run-out again.
(1) Before removing the brake disc, chalk both sides of the
wheel stud on the side at which run-out is greatest.
(2) Remove the brake disc, and then place a dial gauge as
shown in the illustration; then move the hub in the axial
direction and measure the play.
Limit: 0.05 mm (.002 in.)
If the play is equivalent to or exceeds the limit, replace
the front hub unit bearing.
(3) If the play does not exceed the limit specification, and
then check the run-out of the brake disc once again.
Mount the brake disc on the position dislocated from
the chalk mark.
2.If the run-out cannot be corrected by changing the phase of
the brake disc, replace the disc.
REAR DISC BRAKE PAD CHECK AND REPLACE-
MENTM35FUAE
1.Check brake pad thickness through caliper body check port.
Standard value: 10.0 mm
(39 in.)
Limit: 2.0 mm
(08 in.)
Caution
1.When the limit is exceeded, replace the pads at both
sides, and also the brake pads for the wheels on the
opposite side at the same time.
2.If there is a significant difference in the thicknesses
of the pads on the left and right sides, check the
sliding condition of the piston, lock pin sleeve and
guide pin sleeve.
2. Loosen the parking brake cable (from the vehicle interior),
and disconnect the parking brake end installed on the rear
brake assembly.
3. Remove lock pin. Lift caliper assembly and retain with
wires.
Caution
Do not smear special grease on lock pin or make it
dirty.
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SERVICE BRAKES - Service Adjustment Procedures
4. Remove the following parts from caliper support.@ Outer shim@ Pad assembly@ Pad & wear indicator assembly@ Clip@ Inner shim A@ Inner shim B
d
14N0031
f\
/0014N013714A040;14N003:
14AO401
l%FLision
14N01365. Measure hub torque with pad removed to measure brake
drag torque after pad installation.
On vehicles with VCU-equipped LSD, disengage the drive
shaft and companion flange.
NOTESecure the disc to the hub with wheel nuts.
6. Securely attach the pad clip to the caliper support.
Caution
Do not deposit
&ease or other dirt on pad or brake disc
friction surfaces.
7.Clean the piston and then push the piston into the cylinder.
8.With care not to allow the piston boot to be wedged, lower
the caliper assembly and fit the lock pin.
9. Check brake drag torque as follows.
(I) Start engine and hold brake pedal down for 5 seconds.
[Approx. 200 N (44
Ibs.)](2) Stop engine.
(3) Turn brake disc forward
10 times.
(4) Check brake drag torque with spring scale.
If the difference between brake drag torque and hub torque
exceeds the standard value, disassemble piston and clean
piston. Check for corrosion or worn piston seal, andcheck
the sliding condition of the lock pin sleeve and guide
pinl/jsleeve.
Standard value: 70 N (15.4
Ibs,,) [4 Nm (3 ft.lbs.)] or less