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Autopapyrus · Changan Uni-S (1st generation)
https://autopapyrus.com/guides/changan/uni-s/rear-brake-pad-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Changan Uni-S (1st generation): Rear Brake Pad Replacement

The rear axle of the Changan Uni-S (1.5 turbo) has disc brakes with a floating caliper. The parking brake is most likely electromechanical (EPB button). This matters: before retracting the piston, you must put the parking brake actuator into service mode. The exact procedure for this model is not documented in publicly available service materials. The general principle is below. Check the details against the manufacturer's service manual.

Difficulty: Medium Time: 1-1.5 hours Steps: 14 Tools: jack and jack stands, lug wrench, sockets and wrenches for the caliper guide bolts (usually 12-14 mm or Torx/hex, check on the vehicle), C-clamp or a dedicated tool for retracting the piston, copper grease for the guide pins and pad contact points, brake cleaner, wire brush, wire for hanging the caliper, torque wrench, diagnostic scan tool if needed

Part

  • 🔩 Rear disc brake pad set (one axle), matching the original pads in size and shape. Check the OE number on the pad you remove: it is more reliable to select the new pads by the size and shape of the old ones. Additionally: guide pin repair kit or grease, and rotors if they are heavily worn

Step by step

14 steps
  1. Park the car on level ground and chock the wheels. If the axle has an electromechanical parking brake, disable its automatic engagement and put the actuator into service mode (using the EPB button with the sequence from the owner's manual, or with a scan tool). Do not push the piston in without doing this: you can break the caliper actuator.
  2. Loosen the lug nuts, raise the rear of the car, place it on jack stands, and remove the wheel.
  3. Inspect the caliper, the brake hose and the dust boots. If the hose is cracked or there are fluid leaks, stop work and fix the problem first.
  4. If the caliper has an electrical connector for the parking brake actuator, do not pull on the wire and do not disconnect it unless necessary.
  5. Remove the two caliper guide bolts. Lift the caliper off the rotor and hang it on a piece of wire. The hose must not carry the weight of the caliper and must not be stretched.
  6. Remove the old pads and the spring clips. Note the position of the pads, the anti-squeal shims and the wear sensor, if there is one.
  7. Clean the clip seats and the bracket of dirt and rust with a wire brush, and check the guide pin boots. Measure the rotor thickness and runout. If there is a wear ridge, deep grooves, or the thickness is below the minimum (the value is stamped on the edge of the rotor), replace the rotors together with the pads.
  8. Apply a thin layer of copper or dedicated brake grease to the guide pins and to the contact points between the pads and the bracket. Grease must not get on the friction surface of the pad or the rotor.
  9. Retract the caliper piston. If the rear piston is the screw-in type (typical for calipers with an integrated parking brake), it must be rotated with a special tool while pressing it in. If you push it in with an ordinary C-clamp, you can break the mechanism. Watch the fluid level in the reservoir: it will rise, and you can draw off the excess with a syringe.
  10. Install the new pads with the anti-squeal shims and spring clips, put the caliper back on, and tighten the guide bolts. Use the torque specified by the manufacturer, usually in the range of 25-40 N·m (18-30 lb-ft). Do not tighten by feel.
  11. Install the wheels and tighten the nuts in a crisscross pattern. Lower the car and tighten the nuts fully to the specified torque (usually 100-130 N·m (74-96 lb-ft) for wheels in this class).
  12. Take the parking brake actuator out of service mode. Then press the brake pedal several times until it feels firm, check the brake fluid level, and top it off if necessary.
  13. Check the parking brake: apply and release it several times, and make sure it holds the car securely on an incline.
  14. Bedding-in: drive 200-300 km without hard braking and increase the load gradually. Always replace the pads on both sides of the axle.

Common mistakes and warnings

  • Brakes affect safety. If you have no experience with brake systems and electronic parking brakes, have a repair shop do the job. Do not press the brake pedal while the caliper is removed: the piston will pop out. Do not use pads of unknown origin, and do not mix pads of different compounds on the same axle. Do not breathe brake dust, and clean the parts only with dedicated brake cleaner.
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