I recently had a problem with my nearside front brake making some rather horrible grinding noises. Took the wheel off to investigate and found that the outside pad (although not worn down to minimum thickness) had moved in towards the disc sufficiently to drop out of the calliper and get jammed between the calliper yoke and the disc. While the brake performance was surprisingly unaffected; the horrible noise was the pad backing plate rubbing on the disc hub.
Now I know I'm heavy on the brakes and these discs have been on for 120k odd miles but my conclusion that the disc had worn enough for the pad to do what it had rather shocked me. I got the micrometer out and found that the disc was around 18mm thick, i.e. had worn down (as I thought) 8mm which I couldn't believe.
However, further investigation shows that 283 dia. discs come in 2 thicknesses, 26mm and 22mm. Service Citroen shows that it is the 26mm ones that are fitted to MK2 2.1TD hatchbacks, however the Brakeworld electronic catalogue shows the 22mm thick ones.
I can't even remember where I bought the ones on the car at the moment and I would have ordered discs for a 2.1TD but I guess I must have been supplied with 22mm ones and never checked when they were fitted. Even so losing 4mm of disc thickness over 120k miles still seems quite a lot.
The minimum disc thickness for all disc sizes is 2mm less than the original then I guess I should be fitting new discs every 60k miles.
So lesson learned, 26mm thick discs ordered and I will be getting the micrometer on the discs every pad change from now on.
