I found some old notes on this on my wiki, and figured someone might find them helpful
There is a known issue with the Citroen C5, where the rear calipers may end up rubbing against the inside of the wheel (rear caliper corrosion syndrom).
Basically the issue is one of water ingress. Corrosion develops between the mating faces where the caliper is mounted to the suspension leg, and the caliper is slowly pushed out at an angle, ultimately causing it to rub against the wheel.
It's identifiable by metal being worn away from the caliper and/or the inside of the wheel.
Even if caught early, new brake pads will be required as they'll be worn at an angle
- If caught too late, new discs and calipers may also be required
- The calipers are very difficult to remove without destroying them, so plans should include the possibility of requiring a new caliper, even if the issue is caught early
- The handbrake on the C5 is on the front wheels (weird) so the rear wheels aren't too complex
- Remove the pad cover, pads and springs
- Replace the small bolt that holds the pad cover in place (do it tight - it'll be the only thing holding your calipers together!)
- Disconnect the brake pipe and cover the end (it is possible to do the job without doing this)
- Use a socket to loosen the first mounting bolt (they're threadlocked so will be stiff)
- With the first bolt loosely in place, undo the second
- Whilst carefully supporting the calipers, remove the two bolts and set aside.
- Clean all corrosion from the back of the caliper and the mating face on the suspension strut (using a file). Obviously no oil can be used.
- Once cleaned, apply copper grease to both faces and carefully re-assemble
- Fit new pads.
The following are known to potentially cause issues
- 'Caliper mounting bolts stuck' - Some owners have reported that the mounting bolts get stuck within the caliper, and application of a hammer is required to unstick them
- Supporting the Caliper - Because the C5 uses Hydractive suspension, there isn't a coil spring to cable tie the caliper to. Supporting it can be tricky as a result.