1997 ISUZU TFS SERIES brakes

5-20 BRAKES
BLEND PROPORTIONING VALVE (IF SO EQUIPPED)
Structure and Operation
Structure
Side
I shows P-valve ; side II shows bypass valve.
Bypass valve seals the routes
4 and 5 using the seal 2 at
the piston
1 end.
In addition, spring
3 presses against the piston 1, and in
order to seal out the route
4 and route 5 sufficiently, spring
3 presses seal 2 against cylinder end surface.
The left figure is a characteristic curve diagram.

BRAKES 5-21
Operation
The operation of the P-valve by the master cylinder
pressure is unchanged up to the brake points
A and B.
If master cylinder fluid pressure penetrates into the second
break point
B, the fluid pressure pressing against the seal
2, (which isolated route 4 and route 5), passing the route
4 of the master cylinder side, overcomes the operating
force of the spring
3 + fluid pressure affecting the seal 2 of
the wheel cylinder, and presses the piston
1 to the right
side, resulting in the opening of the routes
4 and 5, and
canceling of the P-valve operation.
Then, because the master cylinder fluid pressure and the
wheel cylinder fluid pressure, up to the point
C, operate on
the identical surface of the seal
2, both have identical
ascending ratio.
However, because of the operation of spring
3 in the wheel
cylinder side, wheel cylinder fluid pressure operate to
preserve the balance against the master cylinder fluid
pressure on the lower level with the difference in pressure
resulting from this spring.
Valve Maintenance
In the case of fluid leak or other abnormalities, faulty valve
should be replaced.
The valve is set up at the right hand side of the 5th
crossmember near the rear axle.
Note:
The blend proportioning valve is not repairable and must
be replaced as a complete assembly.
BLEEDING OF THE BRAKE HYDRAULIC
CIRCUIT
If air enters the bake lines, it will cause poor brake action.
Therefore, bleeding should be performed if the brakes have
been used with the level of brake fluid in the reservoir
excessively low or if brake pipes have been disconnected in
the course of brake servicing.
Bleeding operation calls for co-operative action of 2 persons.
Set the parking brake firmly while bleeding.
Perform bleeding operation with ENGINE RUNNING, to
prevent damage to push rod seal.
Make sure exhaust is suitably ventilated.
Bleed the hydraulic system with the fluid reservoir filled to
the specified level.
Bleed the system starting with the rear wheel cylinder
farthest from the master cylinder.
A : Load sensing proportioning valve (If so equipped).

5-22 BRAKES
1. Fill the brake fluid reservoir with brake fluid.
Handle the brake with reasonable care to avoid spillage as it
is damaging to paint.
Note:
Take care to prevent foreign matter from entry, when
replenishing or replacing brake fluid.
When pouring brake fluid, if diaphragm in the oil tank cap
is stretched, be sure to place it into original position,
(fasten it), and then cap it.
2. Connect a vinyl pipe to the bleeder screw on the wheel
cylinder, caliper bode or LSPV and the other end of the pipe
in a transparent container.
3. Pump the brake pedal several times and hold it depressed.
Loosen the bleed screw to release brake fluid together with
air bubbles.
Tighten the bleeder screw before pressure is released
completely.
4. Repeat the step in paragraph 3 above until the air bubbles
disappear completely.
Securely tighten the bleeder screw when the air bubbles
disappear completely.
5. Repeat the step in paragraph 4 above on the remaining
wheel cylinders.
Bleed the system starting with rear side farthest from the
brake fluid reservoir.
6. Fill the brake fluid reservoir to the specified level.
Pour brake fluid carefully so as not to produce air bubbles.
7. If the cap diaphragm is stretched, fasten the diaphragm and
the sure to cap it after it is placed to the original position.
Note:
Never reuse the old brake fluid.

BRAKES 5-23
BRAKE LINE (HOSES AND PIPES)
Inspect all hoses and pipes for wear, bending, chafing,
cracks, dents, or any other damage.
Make necessary correction or parts replacement if these
abnormal conditions are found through inspection.
All hoses, pipes and joints can be damaged easily.
Do not allow the hose to become excessively twisted and
bent when working with then, and pay special attention to all
the brake lines not to damage them when repairing or
replacing other parts (axle, suspension, etc).
Inspection for leakage should be performed by depressing
the brake pedal fully.
If leakage is apparent at the circumference of joints,
retighten or replace these parts.
This procedure must be performed whenever brake lines
are installed.
After disconnecting the hoses and pipes, cap or tape the
openings to prevent entry of foreign material.

5-24 BRAKES
ADJUSTMENT PROCEDURE OF SERVICE AND PARKING BRAKE
Stem type
All brakes are self-adjusting.
Brake are adjusted by repeated stepping on the brake pedal.
The parking brake adjustment should be performed as follows:
1. Release the parking brake lever fully.
2. Loosen the lock nut (A).
3. Repeat stepping the brake pedal firmly and releasing it until
the rear brake auto-adjuster completes the function.
4. Rotate the adjust nut (B) until all slack disappears from the
cable.
5. Set the lock nut.
The parking brake lever travel is normal when the lever comes
out 9 to 11 notches when pulled with a force of 30 kg (66 lbs.).

BRAKES 5-25
Floor mount type
All brakes are self-adjusting.
Brakes are adjusted by repeated stepping on the brake pedal.
(After stepping on the pedal and releasing it, the rear auto-
adjuster, in the rear brake, produces a clicking sound.
the same operation should be repeated until the sound
disappears.)
Take the following steps after overhauling the rear brake
assembly.
1. Move the parking brake lever to its fully released position.
2. Parking cable must be loosened sufficiently.
(Loosen the adjust nut and the lock nut.)
3. Repeat stepping on the brake pedal firmly, and releasing it
until the clicking sound can no longer be heard.
If the difference between the brake drum inside diameter of
the brake shoes is adjusted to be 0.5 mm, the number of
times for depressing the brake pedal can be reduced.
4. Remove the drum.
Measure the brake drum inside diameter and diameter and
diameter of the brake shoes.
Shoe Clearance mm(in)
0.25 - 0.40 (0.0098 - 0.0157)
If incorrect, check the brake auto-adjusting system.
5. Turn the equalizer nut so that the parking brake lever
travels 6 or 7 notches when pulled up with a force 30 kg (66
lbs.).
6. Make sure there is not brake dragging and tighten the cable
lock nut.
Torque N
m(kgfm/lbft)
8 - 18 (0.8 - 1.8 / 5.8 - 13)

5-26 BRAKES
ADJUSTMENT PROCEDURE OF BRAKE PEDAL
The push rod serves as the brake pedal stopper when the
pedal is fully released.
Brake pedal height adjustment should be performed as follows.
Brake Pedal - Height
Measure the brake pedal height after making sure the pedal is
fully returned by the pedal return spring.
Note:
Pedal height (L2) must be measured after starting the
engine and increasing the revolution several times by
stepping on the accelerator pedal.
mm(in)
Pedal free play (L1) 6-10 (0.23 - 0.39)
LHD 174-184 (6.85-7.24)
RHD 193-203 (7.60 7.99)Height (L2)
Note:
Pedal free play must be measured after turning off the
engine and stepping on the brake pedal firmly five times or
more.
If the measured value deviates from the above range, adjust
the brake pedal as follows:
a) Disconnect the stop lamp switch.
b) Loosen the lock nut on the push rod.
c) Adjust the brake pedal to the specified height by rotating the
push rod in the appropriate direction.

BRAKES 5-27
Lock Nut Torque Nm(kgfm/lbft)
15- 25 (1.5 - 2.5 / 11 - 18)
d) Install the stop lamp switch.
Note:
Pedal height (L
2) must be 95 mm (3.7 in.) or more when
applying about 50 kg (110.25 lbs.) of stepping force.
Clearance
Between the Switch Housing and the Brake Pedal (A).
mm(in)
0.5 - 1.0 (0.02 - 0.04)