1987 SUZUKI GRAND VITARA wheel

MASTER CYLINDER ASSEMBLY
[GENERAL DESCRIPTION]
The master cylinder has two pistons and three piston cups. Its hydraulic pressure is produced in the
primary (“a” in the below figure) and secondary (“b”) chambers. The hydraulic pressure produced in the
primary chamber (“a”) acts on the front wheel brakes (right & left).
Also, the hydraulic pressure produced in the secondary chamber (“b”) acts on the rear wheel brakes
(right & left).
NOTE:
Replace all components included in repair kits to service this master cylinder. Lubricate rubber parts with
clean, fresh brake fluid to ease assembly. Do not use lubricated shop air on brake parts as damage to rubber
components may result. If any hydraulic component is removed or brake line disconnected, bleed the
brake system. The torque values specified are for dry, unlubricated fasteners.
1.Piston stopper circllp
2.Piston stopper
3.Piston stopper sealing
4.Primary piston
5.Piston cup
6.Secondary piston pressure cup
7.Piston cup
8Secondary piston
9.Return spring secondary seat
10.Secondary piston return spring
11.Secondary piston stopper bolt
12.Master cylinder body
A :Primary piston
BSecondary piston
Fig. 19-3
[Master cylinder OPERATION]
Normal operation
Depressing the brake pedal forces the primary piston“A” to move to the left in the below figure and
consequently the hydraulic pressure is produced in the chamber “a”.
By means of this pressure and the return spring force, the secondary piston “B” is also pushed to the left
and thus the hydraulic pressure is produced in the chamber “b”.
Fig. 19-3-1
19-4

One-circuit operation (Primary chamber “a” circuit failure)
Depressing the brake pedal forces the primary piston “A” to move as described previously, but since the
brake circuit connected to the chamber “a” cannot hold the pressure, no pressure is produced in the fluid
immediately ahead of the piston“A”. The piston “A” keeps moving while compressing the spring and
when it reaches the retainer, the piston “B” is pushed and begins to move. This causes the pressure to rise
in the chamber “b” and the pressure acts on rear wheel brakes (right & left).
One-circuit operation (Secondary chamber “b” circuit failure)
In this case, the leftward movement of the piston “A” has but little effect in causing the fluid pressure to
rise in the chamber “a” in the beginning, because the initial rise of the fluid pressure causes the piston “B”
to promptly yield and move to the left. However, when the forward end of the piston “B” comes to the
head of the cylinder and stops there, the Ieftward movement of the piston “A” becomes effective. Thus
the’fluid pressure is produced in the chamber “a” and it acts on front wheel brakes (right & left).
The below figure shows secondary piston “B” at halt.
19-5
Fig. 19-4
Fig. 19-4

[Caliper OPERATION]
Single piston floating caliper type
The single piston floating caliper type brake is
employed in this model. One cylinder and one
piston are used for this type. (The cylinder is
constructed as a monoblock with the caliper.)
Fluid pressure generated in the cylinder causes
the pad (1) on the piston side to press against
the disc. At the same time, the floating type
caliper body is moved to the right by the cylin-
der pressure, as shown in below figure, which
pulls pad (2) against the disc and so brakes the
wheel.
Caliper body
\Brake disc (rotor)
Fig. 19-6 - ’
The disc brake has no servo assistance as in drum
braking, and it is necessary to increase the work-
ing pressure of the piston and pad. For this pur-
pose, the wheel cylinder has a large bore. Even
only a little change in clearance between the disc
and pad has therefore a large influence on the
brake pedal stroke. It is necessary to have the
clearance adjusted to the minimum at all times,
by means of the piston (rubber) seal.
Piston seal (Rubber seal)Piston sealWinder (Rubber seal)
II
IPiston
Hydraulic pressure
“OFF“
Fig. 19-7
Clearance correction
Piston
Hydraulic pressure
“ON”
When oil pressure is applied to the piston, the
piston moves forward. The rubber seal, which
exerts considerable pressure against the piston,
moves with the cylinder. However, as a part of
the rubber seal has been fixed into a groove in
the cylinder, the shape of the rubber seal is dis-
torted toward internal end of the cylinder, as
shown in above figure. When pressure is taken
off from the foot brake pedal and fluid pressure
is released from the piston, a restoring force is
generated at the seal and pushes the piston back.
As the pads wear away and the clearance be-
tween the disc and pads becomes larger, the
piston moves a larger distance. The seal then
could change in shape further but, since the end
of the seal is fixed into the groove in the cylin-
der, the distortion is limited to the same amount
as previously described. The piston moves
further to cover the distance of clearance. The
piston returns by the same distance and the
rubber seal recovers its shape as described
above and thus the clearance between the disc
and pads are maintained in adjustment.
19-7
Cylinder

DRUM BRAKE ASSEMBLY (Rear Wheel Brake)
[GENERAL DESCRIPTION]
The drum brake assembly has a self shoe clearance adjusting system so that drum-to-shoe clearance is
maintained appropriate at all times. For details, refer to OPERATION in the next page.
NOTE:
Replace all components included in repair kits used to service this drum brake. Lubricate parts as specified.
WARNING:
When servicing wheel brake parts, do not create dust by grinding or sanding brake linings or by clean-
ing wheel brake parts with a dry brush or with compressed air. (A water dampened cloth should be
used.) Many wheel brake parts contain asbestos fibers which can become airborne if dust is created
during servicing Breathing dust containing asbestos fibers may cause serious bodily harm. If any
hydraulic component is removed or brake line disconnected, bleed the brake system. The torque
values specified are for dry, unlubricated fasteners.
1. Brake back plate
2. Brake shoe
3. Shoe return spring (A)4. Brake strut rod
5. Shoe return spring (B)
6. Rod spring7. Shoe hold down spring
8. Shoe hold down pin
9. Wheel cylinder10. Stopper plateiI7
Fig. 19-8
19-8

[Rear brake OPERATION]
With the general drum brake type, when the
brake pedal is depressed, two pistons in the
wheel cylinder force the brake shoes outward,
restraining the turn of the drum.
The more the brake shoes get worn, the longer
distance the pistons must move. As a result, the
brake pedal travel (pedal-to-wall clearance)
increases. Then the shoe clearance must be
adjusted by the shoe adjusting screws. Thus
periodical adjustment is required for the drum
brake type in general.
This rear brake is provided with a self-adjusting
system which automatically adjusts the shoe-to-
drum clearance (pedal-to-wall clearance) caused
by such brake shoe wear.
Clearance correction
In each rear wheel cylinder, pistons, piston cups,
and a piston spring (1) are installed. When the
brake pedal is depressed, fluid pressure is applied
to the inside of the chamber on the piston (2),
(3).
Being actuated by this pressure, the piston (2)
moves to the left (piston (3) moves to the right)
in the following figure and presses the brake
shoe against the brake drum, thus producing
brake force.
(2)(3)
Fig. 19-9
At this time, the distance the brake shoe moves
is “B”,that is, the distance that “A” (the end of
the long hole made in the brake shoes web)
moves till it contacts the lever (1) which is fitted
in the long hole.
Fig. 19-10
When the brake pedal is depressed, the piston
and brake shoe move toward the brake drum
side by the aforementioned distance “B” and
“A” of the brake shoe web contacts the lever
(1). As the brake shoe gets worn and the brake
shoe clearance becomes larger, the force applied
to the lever (1) at the time of such a contact
becomes larger. When it exceeds 10 - 12 kg
(22 - 26 Ibs), the “A” of the brake shoe web
moves the lever (1) as much as the amount of
the brake shoe lining wear toward the direction
as shown with an arrow in the figure. Thus the
shoe is forced against the drum and the brake
force is produced.
19-9

The distance the lever (1) moves corresponds to
the amount of wear. In accordance with the
lever (1) movement, the fan-shaped ratchet (2)
also moves, for they are assembled as a unit. The
lever (1) and ratchet (2) remain in the positions
as they moved until the shoe-to-drum clearance
becomes even larger.
When the brake pedal is released, the brake shoe
is allowed to move back by the amount of
clearance “B” by means of the return spring. In
this way, the brake shoe-to-drum clearance is
automatically adjusted constant every time the
brake pedal is depressed.
The brake shoe-to-drum clearance “B” corre-
sponds to 0.6 - 0.8 mm (0.0236 - 0.0315 in.)
in terms of the brake drum diameter A tf A’.
And the amount adjusted by one notch of the
ratchet corresponds to 0.20 mm (0.008 in.) in
terms of the brake drum diameter A - A’.
The spring provided in the wheel cylinder
prevents the piston from moving back more than
the specified brake shoe-to-drum clearance.
Fig. 19-11
19-10

19-2. FRONT DISC BRAKE4) Remove caliper (cylinder).
REMOVAL
1) Loosen, but do not remove, front wheel nuts.
2) Hoist car.
3) Remove wheel nuts and take off front wheels.
Brake Pad
After taking down the wheel, remove brake
pads according to the following procedure.
1) Remove caliper antirattle clip.
Fig. 19-17
2) Remove caliper guide pin caps (2 pcs).
3) Remove caliper guide pins (2 pcs) by using 6
mm hexagon wrench.
NOTE:
During removal, be careful not to damage brake
flexible hose.
Also, don’t depress brake pedal.
5) Remove pads.
Fig. 19-20
Fig. 19-18
19-14

Caliper
After taking down the wheel, remove piston and
piston seal according to the following procedure,
1) Clean outside of reservoir.
2) Take out fluid with a syringe or such.
3)Wipe caliper clean.
4) Disconnect brake flexible hose from caliper
body (cylinder).
Fig. 19-21
6) Blow compressed air into cylinder through
bolt hole where flexible hose was fitted. With
this air pressure, the piston can be pushed out
of cylinder.
WARNING:
Do not apply too highly compressed air
which will cause piston to jump out of
cylinder. It should be taken out gradually
with moderately compressed air. Do not
place your fingers in front of the piston
when using compressed air to push it out
Fig. 19-23
5) Remove caliper (cylinder) and bolt. For
removal of caliper and pads, refer to steps 1)
through 5) of brake pad removal in this
section (p. 19-14).
Fig. 19-22
7) Remove piston seal using a thin blade like a
thickness gauge, etc.
CAUTION:
Be careful not to damage inside (bore side)
of cylinder.1
Fig. 19-24
19-15