Kia Optima: Brake System

Kia Optima DL3 2019-2024 Service and Repair Manual / Brake System

Service data

Service Data

Service data

Item		Specification
Master cylinder	Cylinder I.D.	Ø 22.22 mm (0.874 in)
	Piston stroke	45 ± 1 mm (1.77 in ± 0.87 in)
	Fluid level switch	Provided
Brake booster	Type	11.0" Single
Brake booster	Boosting ratio	10.5:1
Front brake 16 inch (Disc)	Type	Ventilated disc
	Disc O.D.	Ø 305 mm (12.00 in)
	Disc thickness	25 mm (0.98 in)
	Cylinder type	Single
	Cylinder I.D.	Ø 60.6 mm (2.38 in)
Front brake 17 inch (Disc)	Type	Ventilated disc
	Disc O.D.	Ø 325 mm (12.79 in)
	Disc thickness	30 mm (1.18 in)
	Cylinder type	Single
	Cylinder I.D.	Ø 60.6 mm (2.38 in)
Rear brake 15 inch (Disc) / Foot pedal parking brake type	Type	Solid disc
	Disc O.D.	Ø 284 mm (11.18 in)
	Disc thickness	10 mm (0.39 in)
	Cylinder type	Single
	Cylinder I.D.	Ø 38.15 mm (1.50 in)
Rear brake 15 inch (Disc) / Electirc parking brake type	Type	Solid disc
	Disc O.D.	Ø 284 mm (11.18 in)
	Disc thickness	10 mm (0.39 in)
	Cylinder type	Single
	Cylinder I.D.	Ø 38.00 mm (1.49 in)
Rear brake 16 inch (Disc) / Electirc parking brake type	Type	Solid disc
	Disc O.D.	Ø 300 mm (11.81 in)
	Disc thickness	10 mm (0.39 in)
	Cylinder type	Single
	Cylinder I.D.	Ø 38.00 mm (1.49 in)

Specification (ESC)

Part	Item	Standard value	Remark
HECU	System	4 Channel 4 Sensor control system	Total control (ABS, TCS, EBD, ESC)
	Type	Motor, valve relay intergrated type	ECU, TCU and CAN
	Operating Voltage	10V - 16V
	Operating Temperature	-40°C - 110°C
	Motor power	310W [Normal] / 370W [Plus]
Active Wheel speed sensor (ABS)	Supply voltage	Front : DC 4.25 - 20V
	Supply voltage	Rear : DC 4.5 - 20V
	Output current low	Front : 5.95 - 8.05 mA	Typ .7 mA
	Output current low	Rear : 5.9 - 8.4 mA	Typ .7 mA
	Output current high	Front : 11.9 - 16.1 mA	Typ .14 mA
	Output current high	Rear : 11.8 - 16.8 mA	Typ .14 mA
	Output range	Front : 1 - 2500 Hz
	Output range	Rear : 0 - 2500 Hz
	Tone wheel	Front : 48 teeth, Rear : 47 teeth
	Air gap	0.4 - 1.0 mm
Steering Wheel Angle Sensor	Operating Voltage	8V - 16V
	Current Consumption	Max. 150 mA
	Output measurement range	-780 to + 779.9°
	Operating Angular velocity	0 - 1016°/sec

Service Standard

Items	Standard value
Brake pedal height	130.4 ± 3 mm (5.13 ± 0.11 in)
Brake pedal Full stroke	176 mm (6.93 in)
Stop lamp switch clearance	1 - 2 mm (0.04 in - 0.08 in)
Brake pedal free play	2 - 4 mm (0.08 in - 0.16 in)
Front brake disc pad thickness	11 mm (0.43 in)
Front brake disc pad service limit	2.0 mm (0.07 in)
Front brake disc thickness [16 inch]	25 mm (0.98 in)
Front brake disc service limit [16 inch]	23 mm (0.90 in)
Front brake disc thickness [17 inch]	30 mm (1.18 in)
Front brake disc service limit [17 inch]	28 mm (1.10 in)
Rear brake disc pad thickness	10 mm (0.39 in)
Rear brake disc pad service limit	2.0 mm (0.07 in)
Rear brake disc thickness [15 inch]	10 mm (0.39 in)
Rear brake disc thickness [16 inch]	10 mm (0.39 in)

Tightening torque

Tightening Torque

Items	N.m	kgf.m	lb-ft
Master cylinder to brake booster	9.8 - 15.6	1.0 - 1.6	7.2 - 11.6
Brake booster mounting nuts	12.7 - 17.6	1.3 - 1.8	9.4 - 13.0
Air bleeding screw	6.9 - 12.7	0.7 - 1.3	5.1 - 9.4
Brake tube flare nut, brake hose	13.7 - 16.7	1.4 - 1.7	10.0 - 12.3
Front caliper guide rod bolts	21.6 - 31.4	2.2 - 3.2	15.9 - 23.1
Rear caliper guide rod bolts	21.6 - 31.4	2.2 - 3.2	15.9 - 23.1
Front caliper assembly mounting bolt	98.1 - 117.6	10.0 - 12.0	72.3 - 86.8
Rear caliper assembly mounting bolt	78.5 - 98.1	8.0 - 10.0	57.9 - 72.3
Brake hose to caliper	24.5 - 29.4	2.5 - 3.0	18.1 - 21.7
Brake pedal member bracket nut	16.7 - 25.5	1.7 - 2.6	12.3 - 18.8
Wheel speed sensor mounting bolt	6.9 - 10.8	0.7 - 1.1	5.1 - 7.9
HECU bracket mounting nut	19.6 - 29.4	2.0 - 3.0	14.4 - 21.7

Lubricant

Lubricants

Items	Recommended	Quantity
Brake fluid	DOT 4	414 ± 20cc
Brake pedal bushing and bolt	Chassis grease	As required

In order to maintain the best braking performance and ABS / ESC performance of the vehicle, please use genuine parts that meet the specifications.

( Standard : SAE J1704 DOT-4 LV, ISO4925 CLASS-6, FMVSS 116 DOT-4)

Special service tools

Special Service Tools

Tool Name / Number	Illustration	Description
Piston expander 09581-11000		Spreading the front disc brake piston.
Piston adjuster 09580-0U000		Spreading the rear disc brake piston.
Sensor cap installer 09527-AL400		Used for installing wheel speed sensor cap (Sensor cap : Φ72.6)

Troubleshooting

Problem Symptoms Table

Use the table below to help you find the cause of the problem. The numbers indicate the priority of the likely cause of the problem.

Check each part in order.

If necessary, replace these parts.

Symptom	Possible cause	Countermeasure
Lower pedal or sponge pedal	Brake system (oil leakage)	Repair
	Brake system (air inflow)	Perform air bleeding procedure
	Piston seal (worn out or damaged)	Replace
	Rear brake shoe separation (faulty adjustment)	Adjust
	Master cylinder (malfunction)	Replace
Brake drag	Brake pedal free separation (minimum)	Adjust
	Parking brake cable length (adjustment)	Adjust
	Parking brake cable (sticking)	Repair
	Rear brake shoe separation (adjustment)	Adjust
	Pad and lining (twisted or cracked)	Replace
	Piston (sticking)	Replace
	Piston (frozen)	Replace
	Anker or return spring (malfunction)	Replace
	Booster system (leakage of vacuum)	Repair
	Master cylinder (malfunction)	Replace
Uneven brake	Piston (sticking)	Replace
Uneven brake	Pad and lining (oil stain, cracked or twisted)	Replace
Heavy pedal and brake trouble	Brake system (oil leakage, air inflow)	Perform air bleeding procedure
	Pad or lining (worned out)	Replace
	Pad or lining (cracked or twisted)	Replace
	Rear brake shoe separation (adjustment trouble)	Adjust
	Pad or lining (oil stain)	Replace
	Pad or lining (slippery)	Replace
	Booster system (leakage of vacuum)	Repair
Noise from brake	Pad or lining (cracked or twisted)	Replace
	Looseness of wheel bolt and caliper	Adjust
	Pad sliding trouble (Pad uneven worn out)	Replace
	Pad or lining (dirty)	Cleaning
	Pad or lining (slippery)	Pad replacement
	Anker or return spring (malfunction)	Replace
	Brake pad shim (damaged)	Replace
	Hold down spring (damaged)	Replace
	Foreign substance stucked between disc and pad	Cleaning
	Corrosion on disc	Test drive vehicle to get rid of corrosion between rotor and pads.
	Caved disc	Replace
Poor braking performance (at highway speeds)	Pad or lining (worned out)	Replace
Poor braking performance (at highway speeds)	Master cylinder (malfunction)	Replace
Brake vibration	Brake booster (vacuum leak)	Repair
	Pedal free separation	Adjust
	Master cylinder (malfunction)	Replace
	Damaged on master cylinder cap	Replace
	Damaged on brake line	Replace
	Caliper returning trouble (while tire is turning, check for noise)	Replace
	Warped rotor	Replace

Brake bleeding procedures

Brake System Bleeding

1st Air Bleeding (Normal Brake System)

•	Do not reuse the drained fluid.

•	Always use genuine DOT4 brake Fluid. Using a non-genuine DOT4 brake fluid can cause corrosion and decrease the life of the system.

•	Make sure no dirt or other foreign matter is allowed to contaminate the brake fluid.

•	Do not spill brake fluid on the vehicle, it may damage the paint; if brake fluid does contact the paint, wash it off immediately with water.

•	The reservoir on the master cylinder must be at the MAX (upper) level mark at the start of bleeding procedure and checked after bleeding each brake caliper. Add fluid as required.

•	Repair should be done in a pair - Main worker : Check bleed screw operation (open/close) and detect air from the outside of the vehicle. - Assistance : Operate the brake pedal and the diagnostic equipment from the inside of the vehicle.

1.	Make sure the brake fluid in the reservoir is at the MAX (upper) level line.

2.	Have someone slowly pump the brake pedal several times, and then apply pressure.

Loosen the right-rear brake bleed screw (A) to allow air to escape from the system. Then tighten the bleed screw securely.

Tightening torque :

6.8 - 12.7 N.m (0.7 - 1.3 kgf.m, 5.0 - 9.4 lb-ft)

[Front]

[Rear]

4.	Repeat the procedure for wheel in the sequence shown below until air bubbles no longer appear in the fluid.

5.	Follow the sequence as shown below.

2nd Air Bleeding (ESC System air bleeding procedures)

This procedure should be followed to ensure adequate bleeding of air and filling of the ESC unit, brake lines and master cylinder with brake fluid.

Remove the reservoir cap and fill the brake reservoir with brake fluid.

•	When pressure bleeding, do not depress the brake pedal.

•	Recommended fluid........ DOT4

2.	Connect a clear plastic tube to the wheel cylinder bleeder plug and insert the other end of the tube into a half filled clear plastic bottle.

3.	Connect the diagnostic tool to the data link connector located underneath the dash panel.

4.	Select and operate according to the instructions on the diagnostic tool screen.

5.	Have someone slowly pump the brake pedal several times, and then apply pressure.

Pump the brake pedal several times, and then loosen the bleeder screw until fluid starts to run out without bubbles. Then close the bleeder screw (A).

Tightening torque :

6.8 - 12.7 N.m (0.7 - 1.3 kgf.m, 5.0 - 9.4 lb-ft)

[Front]

[Rear]

7.	Repeat the procedure for wheel in the sequence shown below until air bubbles no longer appear in the fluid.

8.	Refill the master cylinder reservoir to MAX (upper) level line.

3rd Air Bleeding

1.	Repeat 1st air bleeding (Normal Brake System) once.

Brake System

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