Brake System
Service Data
Service Data
Service Data
| Item | Specification | |
| Master Cylinder | Cylinder Inner Diameter | Ø 22.22 mm (0.874 in.) |
| Piston Stroke | 45 ± 1 mm (1.77 in. ± 0.04 in.) | |
| Fluid Level Sensor | Provided | |
| Brake booster | Type | 11.0-inch Single |
| Booster Ratio | 10,5:1 | |
| Front Brake 16-inch (Disc) | Type | Ventilated Disc |
| Rear Disc | Ø 305 mm (12.00 in.) | |
| Disc Thickness | 25 mm (0.98 in.) | |
| Cylinder Type | Single | |
| Cylinder Inner Diameter | Ø 60.6 mm (2.38 in.) | |
| Front Brake 17-inch (Disc) | Type | Ventilated Disc |
| Rear Disc | Ø 325 mm (12.79 in.) | |
| Disc Thickness | 30 mm (1.18 in) | |
| Cylinder Type | Single | |
| Cylinder Inner Diameter | Ø 60.6 mm (2.38 in.) | |
| Rear Brake 15-inch (Disc) / Foot-Operated Parking Brake | Type | Solid Disc |
| Rear Disc | Ø 284 mm (11.18 in.) | |
| Disc Thickness | 10 mm (0.39 in.) | |
| Cylinder Type | Single | |
| Cylinder Inner Diameter | Ø 38.15 mm (1.50 in.) | |
| Rear Brake 15-inch (Disc) / Electric Parking Brake | Type | Solid Disc |
| Rear Disc | Ø 284 mm (11.18 in.) | |
| Disc Thickness | 10 mm (0.39 in.) | |
| Cylinder Type | Single | |
| Cylinder Inner Diameter | Ø 38.00 mm (1.49 in.) | |
| Rear Brake 16-inch (Disc) / Electric Parking Brake | Type | Solid Disc |
| Rear Disc | Ø 300 mm (11.81 in) | |
| Disc Thickness | 10 mm (0.39 in.) | |
| Cylinder Type | Single | |
| Cylinder Inner Diameter | Ø 38.00 mm (1.49 in.) | |
Specifications (ESC)
| Part | Item | Standard Value | NOTE |
| HECU | System | 4-Channel 4-Sensor Control System | Full Control (ABS, TCS, EBD, ESC) |
| Type | Motor, Integrated Valve Relay Type | ECU, TCU and CAN | |
| Operating Voltage | 10 V - 16 V | ||
| Operating Temperature | -40°C - 110°C | ||
| Engine Power | 310 W [Normal] / 370 W [Plus] | ||
| Active Wheel Speed Sensor (ABS) | Supply Voltage | Front: 4.25–20 V DC | |
| Rear: 4.5–20 V DC | |||
| Low Output Current | Front: 5.95–8.05 mA | Type 0.7 mA | |
| Rear: 5.9–8.4 mA | |||
| High Output Current | Front: 11.9–16.1 mA | Type 0.14 mA | |
| Rear: 11.8–16.8 mA | |||
| Output range | Front: 1–2500 Hz | ||
| 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 | 8 V - 16 V | |
| Current Consumption | Max. 150 mA | ||
| Output Measurement Range | -780 to +779.9° | ||
| Operating Angular Rate | 0 - 1016°/sec |
Service Standard
| Items | Standard Value |
| Brake pedal height | 130.4 ± 3 mm (5.13 ± 0.11 in.) |
| Brake pedal full travel | 176 mm (6.93 in) |
| Stop light switch clearance | 1–2 mm (0.04–0.08 in) |
| Brake pedal free play | 2–4 mm (0.08–0.16 in.) |
| Front brake pad thickness | 11 mm (0.43 in.) |
| Front brake pad wear limit | 2.0 mm (0.07 in) |
| Front Brake Disc Thickness [16-inch] | 25 mm (0.98 in.) |
| Front Brake Disc Minimum Thickness [16-inch] | 23 mm (0.90 in.) |
| Front Brake Disc Thickness [17-inch] | 30 mm (1.18 in) |
| Front Brake Disc Minimum Thickness [17-inch] | 28 mm (1.10 in.) |
| Rear brake pad thickness | 10 mm (0.39 in.) |
| Rear brake pad wear 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 |
| Bleeder 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 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 |
Lubricants
Lubricants
| Items | Recommended | Quantity |
| Brake fluid | POINT 4 | 414 ± 20 cm³ |
| Brake pedal bushing and bolt | Chassis grease | As required |
Special Service Tools
Special Service Tools
| Tool Name/Number | Illustration | Description |
| Piston Spreader 09581-11000 |
 |
Front disc brake piston spreading. |
| Piston Adjuster 09580-0U000 |
 |
Rear disc brake piston retraction. |
| Sensor Cover Installer 09527-AL400 |
 |
Used to install the wheel speed sensor cover (Sensor cover: Φ72.6) |
Troubleshooting
Troubleshooting
Symptom Table
Use the table below to find the cause of the problem. The numbers indicate the priority of the likely cause.
Check each part in order.
If necessary, replace these parts.
| Symptom | Possible Cause | Countermeasure |
| Low or Spongy Pedal | Brake System (Fluid Leak) | Repair |
| Brake System (Air Intrusion) | Perform the Bleeding Procedure | |
| Piston Seal (Worn or Damaged) | Replace | |
| Rear Brake Shoe Clearance (Incorrect Adjustment) | Adjust | |
| Master Cylinder (Malfunction) | Replace | |
| Brake drag | Brake Pedal Free Travel (Minimum) | Adjust |
| Parking Brake Cable Length (Adjustment) | Adjust | |
| Parking Brake Cable (Seized) | Repair | |
| Rear Brake Shoe Separation (Adjustment) | Adjust | |
| Lining and Backing Plate (Twisted or Cracked) | Replace | |
| Piston (Seized) | Replace | |
| Piston (Seized) | Replace | |
| Anchor or Return Spring (Malfunction) | Replace | |
| Brake Booster (Vacuum Leak) | Repair | |
| Master Cylinder (Malfunction) | Replace | |
| Uneven Braking | Piston (Seized) | Replace |
| Lining and Backing Plate (Oil Stains, Cracks or Warpage) | Replace | |
| Heavy Pedal Effort and Brake Problems | Brake System (Fluid Leak, Air Intrusion) | Perform the Bleeding Procedure |
| Brake Shoe or Lining (Worn) | Replace | |
| Pad Shim or Backing Plate (Cracked or Twisted) | Replace | |
| Rear Brake Pad Separation (Adjustment Problems) | Adjust | |
| Pad Shim or Backing Plate (Oil Stain) | Replace | |
| Pad Shim or Backing Plate (Slippery) | Replace | |
| Brake Booster (Vacuum Leak) | Repair | |
| Brake noise | Pad Shim or Backing Plate (Cracked or Twisted) | Replace |
| Loose Wheel Bolt and Caliper | Adjust | |
| Pad Sliding Problems (Uneven Pad Wear) | Replace | |
| Lining or Backing Plate (Dirty) | Cleaning | |
| Pad Shim or Backing Plate (Slippery) | Brake Pad Replacement | |
| Anchor or Return Spring (Malfunction) | Replace | |
| Brake Pad Shim (Damaged) | Replace | |
| Retaining Spring (Damaged) | Replace | |
| Foreign Object Caught Between Disc and Pad | Cleaning | |
| Corrosion on Disc | Drive the vehicle to remove corrosion between the rotor and the pads. |
|
| Cave-in Disc | Replace | |
| Poor braking performance (at highway speeds) |
Brake Shoe or Lining (Worn) | Replace |
| Master Cylinder (Malfunction) | Replace | |
| Brake Vibration | Brake booster (vacuum leak) | Repair |
| Pedal Free Separation | Adjust | |
| Master Cylinder (Malfunction) | Replace | |
| Master Cylinder Cap Damaged | Replace | |
| Brake Line Damaged | Replace | |
| Caliper return problem (while the tire is rotating, check for noise) | Replace | |
| Warped rotor | Replace |
Brake Bleeding Procedures
Brake Bleeding
1st Air Bleeding (Normal Brake System)
Make sure the brake fluid in the reservoir is at the MAX (upper) line.
Have someone slowly depress the brake pedal several times, then apply pressure.
Loosen the right rear brake bleeder screw (A) to allow air to escape from the system. Then securely tighten the bleeder screw.
Tightening torque: 6.8–12.7 N·m
[Front]
[Rear]
Repeat the procedure for each wheel in the sequence shown below until no more air bubbles appear in the fluid.
Follow the sequence as shown below.
2nd Air Bleeding (ESC Air Bleeding Procedure)
This procedure must be performed to ensure proper air bleeding and filling of the ESC unit, brake lines, and master cylinder with brake fluid.
Remove the reservoir cap and fill the reservoir with brake fluid.
Connect a clear plastic tube to the wheel cylinder bleeder screw and insert the other end of the tube into a clear plastic bottle half-filled with brake fluid.
Connect the diagnostic tool to the data link connector located under the instrument panel.
Select and follow the instructions on the diagnostic tool screen.
Have someone slowly depress the brake pedal several times, then apply pressure.
Depress the brake pedal several times, then loosen the bleeder screw to bleed air until fluid flows out without bubbles. Then close the bleeder screw (A).
Tightening torque: 6.8–12.7 N·m
[Front]
[Rear]
Repeat the procedure for each wheel in the sequence shown below until no more air bubbles appear in the fluid.
Fill the master cylinder reservoir to the MAX (upper) level mark.
3rd Air Bleeding
Repeat the 1st Air Bleeding (Normal Brake System) once.
Test yourself
A quick Kia Optima DL3 quiz: every answer comes with an explanation and a link to the manual page.