how can i change brake discs ?

10 mm is the minimum disc thickness. (Should be stamped on the edge of the disc).
Clean the new discs with a solvent like acetone to remove any oily preservative that might be on the discs to stop rust, before fitting.
The brake piston will have to be pushed back (there is a special tool but a G-clamp will do the same thing) because the old discs will be thinner due to wear and also you will be fitting new brake pads (which are thicker). Otherwise caliper will not go back on over the new disc and pads.

JD
August 2009

Dead easy these... jack up and remove the road wheels, undo the 2 13mm bolts that hold the caliper to its retainer, remove the pads and clean them up. Tie the caliper up out of the way. Then remove the retainer with its 2 17mm (I think) bolts behind. The discs then pull away from the hub with a gentle tap from behind. Its not essential to actually remove the caliper from the retainer but it does allow you to clean things up and fit new pads.

John
July 2009