Tried and failed to install my new rear discs and pads. Got them out and discs all cleaned up with brake cleaner:

Love that on these Brembo discs the non-mating faces are already painted. Saves me a job!

Car jacked up, wheel off and calliper retaining bolts out. Slid the calliper off, got the pads out and then went to take off the calliper frame and was presented with this:

M14 splined bit needed and did I have one? Of course I didn't! Could have tried using a 3/8 extension bar but didn't want to strip it so had to put everything back together and drive down to local Halfrauds. By the time I got back it was tipping it down with rain so I left it for today. Off to stay with friends for a couple of days so hopefully Sunday's weather will be ok and I can get it done then. Anyway sure there's a lesson to be learnt here

Which is that Halfords really need to put an M14 splined bit in their 200 piece socket set

If anyone wants to know what tools are needed for rear brake discs and pads then I'll be sure to make a list for them and save someone else the same mistake!
P.S Yes i have piston rewind tool before anyone asks
