Heard not to use wd40….is this to do with contaminating pad? Does the same apply for GT85? Which lube is best for the job?

Any piston seizing tips welcome

the fluid that is in the brake or red grease

regular lubes will mess up the seals,
use brake the fluid (as gw same as in the brake)

make sure you remove the pads 1st

and if you havent got any brake fluid…? Sorry, bit of a novice

and if you havent got any brake fluid…?

Buy some. Its only a few quid even from Halfords

silicone grease is the only thing to use on your piston seals. i only found out about it when i visited hope for training a few years ago. http://www.ukbikestore.co.uk/product/219/hopesilgrease/hope-silicon-grease-30ml.html 30ml will last a long time.

+1 for silicon lube, can also be bought from plumbers suppliers apparently, called Hunters Silicone Lubricant SC960(same stuff that Hope sell).

thanks

ah, thanks making this post OP, useful info has come out of it!

Has anyone tried phosphoric acid / soldering flux to clean out the bores / clean disc rotors?

I ask because I've tried acetone and it wasn't particularly effective…

You could just use a silicon spray ?
it evaporates quickly and shouldnt cause damage .
I have used IPA solvent on the pads and blasted the whole brake without any problems .