Replacing the brake disc of the rear wheel brake mechanism

You will need: TORX T30 wrench, wheel nut wrench.

If there are scuffs, deep scratches and other defects on the working surface of the disc that increase pad wear and reduce braking efficiency, as well as in case of increased lateral runout of the disc, causing vibration during braking, replace the disc. In specialized workshops, such a disc can be machined and polished on both sides to the same depth, but after processing, the thickness of the disc must not be less than the minimum allowable (10.2mm).

The minimum permissible thickness of the brake disc of the brake mechanism of the rear wheel is 10 mm.

Notes:

• The minimum allowable thickness of the brake disc of the rear wheel brake mechanism is indicated on its inner surface.
• If the thickness of one of the discs is less than the specified value, replace both discs.
• When replacing brake discs, be sure to replace the brake pads with a new set.

1. Remove the wheel from the side of the disc being replaced.

2. Remove the caliper (see Rear wheel brake caliper replacement), without disconnecting the brake hose, parking brake cable and secure with wire. Do not twist or strain the hose while doing this.




3. Remove the guide from the steering knuckle (see Rear wheel brake caliper replacement).



4. Loosen the brake disc fixing screw…



5.... remove the screw..



6.... and remove the brake disc.


7. Similarly remove a brake disk of the second brake mechanism.

8. Install the parts in the reverse order of removal.

Opel Astra J can be fitted with two wheel sizes: 15-inch and 16-inch. In this regard, some parts of the brake mechanisms installed on different vehicle configurations have different sizes. In particular, the diameters of the brake discs of the brake mechanisms of the rear wheels are 268 and 292 mm for installation with wheels of 15 and 16 inches, respectively. Keep this in mind when purchasing new brake discs.



Before installing the disc, carefully clean the mating surfaces of the hub and disc from rust and scale, as even the smallest particle sandwiched between the mating surfaces will cause the disc to beat and vibrate when braking.

Note. If you are installing an old disc, file the edges on the working surfaces of the disc that have formed on both sides as a result of wear with a file.