Genuine Volvo S40 Brake Disc

Volvo S40 Brake Disc Parts and Q&A

• Rotor
  30818027
  Q: What should you know about Brake Disc and Brake Pad Set inspection and maintenance for diesel engines on Volvo S40?

  A:

  The work should be performed at prescribed intervals or when a defect is suspected in the braking system, symptoms which include the vehicle pulling to one side when the brake pedal is depressed, the brake system squealing or dragging when the brakes are applied, excessive brake pedal movement, poor brake pedal feel or the need to top-up brake fluid frequently, are likely to be indicating a problem. For front disc brakes, operate the handbrake, remove the nuts on the front wheels, jack up the car, and prop it up on axle stands for easier access to the brake calipers after removing the wheels. Inspect the thickness of the friction lining material, through the inspection window in the caliper, and remove the pads if required for further inspection. If any brake pad is worn down to or below the stated limit, all four pads at that end have to be renewed as a set and if one side is significantly more worn, they may indicate seized caliper pistons. Measure the thickness of the discs with a micrometer, making sure that they still have service life left in them, and examine them for excessive scoring or discoloration from overheating, replacing both front discs if any are below the minimum thickness. Ensure the handbrake is applied, check transmission is in neutral, spin the wheel to make sure it is not binding the brake and check all brake lines and hoses for hidden cracks or splits then refit the wheels and lower the car, tighten the wheel nuts to specified torque. For rear disc brakes, the procedure involves loosening rear wheel nuts, chocking the front, jacking up the rear, supporting the rear on axle stands, releasing the handbrake and removing the rear wheels, double-checking that the rear brakes are not binding and adjusting the handbrake if needed.
• Rotor
  30872940
  Q: What should you be aware of before starting work on front brake discs on Volvo S40?

  A:

  Before performing any work, be conscious of the risks of asbestos dust. Should one of the discs need renewal, both should be renewed at the same time to ensure even and consistent braking, and new brake pads also need to be fitted. Beginning by taking off the front brake pads and checking the disc friction surfaces for cracks or deep scoring (light grooving is quite normal and can be ignored). A cracked disc must be replaced and a scored disc can be recovered by machining if its thickness is above the minimum specified. Check the disc run-out with a dial test indicator placed close to the outer edge, if the run-out exceeds the figures given then machining may be possible otherwise renewal is required. Thickness variation of the disc can cause excessive judder, measure the thickness of the disc using a micrometer. After you have removed the brake pads and caliper, undo the two mounting bolts to remove the brake caliper bracket. Check if there is a mark to indicate the position of the disc in relation to the hub, if not make your own mark for refitting, take the disc off. Make sure the hub and disc mating faces are clean, removing any rustproofing compound from a new disc with degreaser and rag. Align the disc on the hub with the orientation marks, reattach the brake caliper bracket, tightening the bolts to the torque specified by the manufacturer, and lastly, refit the brake pads.