Hi I need to change the rear pads on my focus. Just read through the Haynes manual about doing it and it says about clamping the brake hose and loosening the bleed nipple on the calliper to avoid damaging the seal in the master cylinder when winding the piston in. My question is, is it really necessary to do that? And has anyone else done it?

Many thanks

clamp hoses master cylinders are many pounds to replace

I think the rears are wind backs callipers

It's not essential, in fact most garages don't clamp and open the bleed nipple.

But clamping the hose and opening the bleed nipple is the safest way to avoid damage. Each to their own really, whatever you feel most comfortable with

I've changed brakes on my own vehicles before, just never disturbed the " hydraulic" system as worried about getting air in the system.