Underhood: Understanding The Operation Of Oxygen Sensors
The Chevy Trax and Buick Encore are considered sub-compact crossovers based on a car platform.
- Brake Caliper Bracket Bolt Front: 118 ft/lbs
- Brake Caliper Bracket Bolt Rear: 74 ft/lbs
- Brake Caliper Guide Pin Bolts: 21 ft/lbs
- Lugnuts: 103 ft/lbs
- Lateral Runout: .002” (front and rear)
- Thickness Variation: .001” (front and rear)
The Chevy Trax and Buick Encore are considered sub-compact crossovers based on a car platform. The platform GM chose was the Gamma platform used for the Aveo and Sonic.
The brake system is off-the-shelf GM for the mechanical components. Replacing brake pads and rotors is simple, but it is essential to know about the hydraulic and electronics that control the brakes.
The front brakes are straight forward with no surprises. Make sure to replace the abutment clips when new pads are installed. The wear squealers should be on the inboard pad.
The rear brakes on AWD models use a single-piston caliper with a screw-type parking brake actuator. On the upper caliper guide pins are round dampener that helps to reduce low-frequency vibrations. The dampener is made of metal and rubber and can degrade over time. Replacement dampeners are available from aftermarket sources.
Most front-wheel-drive models have rear drums. The drum brakes should be adjusted with a drum clearance gauge. The difference between the shoes and drum diameters should be between 0.40-0.9-mm. The drum should turn with very little resistance.
For both disc and drum cars, the final adjustment is performed under the center console at the base of the lever.
Electronic Brake Control
The Trax and Encore use the ABS modulator for more than just ABS or stability control. The modulator controls brake force distribution and hill start/hold functions.
The electronic brake distribution system replaces the hydraulic proportioning valve. The system actively controls the rear brake pressures for the best performance and comfort. If the red brake warning indicator is illuminated, the electronic brake distribution function is disabled.
Some Traks and Encores are equipped with a hill hold/start feature. When the truck is stopped on an incline, the system prevents rolling while the driver is moving their foot from the brake pedal to the gas pedal.
The system calculates the brake pressure needed to hold an incline greater than 5%. The modulator locks the pressure for up to 2 seconds by commanding the appropriate solenoid valves when the brake pedal is released. The stop lamps will stay illuminated during the hold operation even though the brake pedal is released.
Hill hold/start and electronic brake distribution functions require constant use of the valves in the brake modulator. If the fluid in the master cylinder or at the wheels is contaminated or degraded, the valves in the modulator can be damaged. The main area of potential damage is around the needle and seats of the isolation and dump valves.