Technical data of the brake system (Hyundai Elantra XD)

Technical data

Data	Meaning
Master brake cylinder
- type	Tandem
– cylinder diameter, mm
CBS (Conventional Brake System)	22,22
ABS	23,81
Vacuum brake booster
- type	Vacuum
– effective diameter, mm
CBS	228,6
ABS	177,8–203,2
- ratio
CBS	5,5:1
ABS	6,0:1
Pressure limiter	4DR 5DR
– switching pressure, MPa	2,55 3,9
- decompression ratio	0,27:1 0,32:1
Front brakes
- type	Disc, ventilated
– brake disc diameter, mm	257
– brake disc thickness, mm	24
– brake pad thickness, mm	11
– cylinder diameter, mm	54
Rear disc brakes
– brake disc diameter, mm	258
– brake disc thickness, mm	10
– brake pad thickness, mm	9
Rear drum brakes
– inner diameter of the brake drum, mm	203,2
– brake pad thickness, mm	9,4
– cylinder diameter, mm	405
Parking brake	Mechanical, acting on the rear wheels

Anti-lock braking system

Data	Meaning
ECU control unit
– supply voltage, V	10–16
– temperature range,°C	–40…110
Control lamp: ABS, EBD
– supply voltage, V	12
– current consumption, mA	80
Wheel speed sensor
- resistance, Ohm	1275–1495
– output frequency, Hz	15–2000
– output voltage, V	0,15
– air gap, mm	0,2–1,2
Hydraulic unit HECU
– weight, kg	2,5
- engine	12V, 30A
– engine power, W	180
– productivity, cm³/s	5,5

Adjustment data

Data	Meaning
Brake pedal installation height, mm	170
Brake pedal travel, mm	128
Brake light switch gap, mm	0,5–1,0
Free travel of brake pedal, mm	3–8
Clearance between brake booster pushrod and master cylinder, mm	0
Parking brake lever travel when tightened with a force of 196 N	8 clicks
Minimum permissible thickness of front brake pads, mm	2
Minimum permissible thickness of brake disc, mm	22,4
Minimum permissible thickness of rear brake shoe linings (drum brake), mm	1
Maximum permissible diameter of brake drum boring, mm	205,2
Minimum permissible thickness of the rear brake disc, mm	8

Tightening torques, Nm

Data	Meaning
Nuts securing the master brake cylinder to the bracket	8–12
Brake Master Cylinder Bracket Mounting Nuts	13–16
Vacuum hose fitting to air expansion chamber	15–18
Bleed nipple	7–9
Brake pipe union nuts	13–17
Caliper guide pin mounting bolt	22–32
Bolts for mounting the caliper to the steering knuckle	65–75
Hollow bolt securing the brake hose to the front caliper	25–30
Wheel brake cylinder mounting bolts	12–18
Front wheel speed sensor	8,2–9,7
Rear wheel speed sensor	8,2–9,7
HECU Control Unit and Hydraulic Block Fastening Bolts	8–10
ECU and HECU hydraulic unit bracket mounting bolts	9–10
Six brake pipes to the hydraulic unit	13–17

Warning: New self-locking nuts must be used during installation.

General information

The vehicles use a hydraulically driven service brake system.

The system works as follows:

• the brake pedal is connected to the master cylinder;
• when the pedal is pressed, pressurized fluid from the master cylinder is transferred through metal tubes and flexible hoses to the front and rear brake mechanisms;
• the wheel cylinders are hydraulic modulators that convert the fluid pressure created in the main brake cylinder into movement of the brake mechanism elements;
• the front and rear pistons of the brake caliper move and, due to friction against the brake discs and drums, provide the required deceleration of the vehicle;
• when you release the brake pedal, the pressure in the system decreases.

The brake pads and pistons return to the neutral or home position and braking is stopped.

When the brake fluid level drops, the brake master cylinder fluid level sensor turns on the indicator lamp in the instrument cluster. If the indicator light is on, first check that the parking brake is released, as the light indicates a low fluid level and the parking brake is applied.