Front Disc Brake
Front Disc BrakeCOMPONENT LOCATIONS - 4.4L
COMPONENT LOCATIONS - 4.2L
GENERAL
The front brakes on all models feature ventilated brake discs, with different diameter brake discs for each model. The 4.4L and 2.7L diesel models feature twin piston sliding calipers. Although similar in appearance, the sliding calipers on 4.4and 2.7L diesel are not interchangeable. On 4.2L models, 4 piston, opposed piston Brembo calipers are installed. The dust shields are common on 4.4L and 2.7L diesel models, and unique on 4.2L models.
Two steel damper weights are installed on the inboard side of the Brembo calipers to reduce NVH (noise, vibration and harshness).
On all models the brake caliper is attached to the rear of the front knuckle. The brake pads are made from an asbestos free material. The inboard brake pad of the left front brake incorporates a wear sensor.
With the sliding calipers, when hydraulic pressure is supplied to the caliper, the pistons extend and force the inner pad against the brake disc. The caliper body reacts and slides on the guide pins to bring the outer pad into contact with the brake disc.
With the Brembo calipers, when hydraulic pressure is supplied to the caliper, the two pairs of opposed pistons extend in the caliper. The two pistons in each side of the caliper force their related brake pads against the brake disc.
The front brake pad wear sensor is connected in series with the rear brake pad wear sensor, between the instrument cluster and ground. When a brake pad incorporating a brake pad wear sensor is approximately 75% worn, the brake pad wear sensor goes open circuit. When the instrument cluster detects the open circuit, it illuminates the amber LED (light emitting diode) in the brake warning indicator, displays an appropriate warning in the message center and sounds WARNING chime.
At the beginning of each ignition cycle, the instrument cluster performs a bulb check on the brake warning indicator: the indicator is illuminated amber for 1.5 seconds, red for 1.5 seconds, then goes off.
Front Disc Brake
Overview
The front disc brake system is a fairly straightforward design requiring no specialized techniques for diagnosis.
For information on the description and operation of the system: