the blighters dont want to loosen and feel like they will snap!

what's the best way to get them loose - remove caliper and heat?

also, what size are they?

No need to remover the caliper to heat them, just don't get them red hot

Warm them up - apply plus gas and use an 8mm six point socket - gently !

As well as heat you can also gently tap the end of each nipple with a small hammer about 50 times. Don't overdo the tapping but it tends to break the rust ring on the thread.

decided to buy some new nipples in advance but the fella at main dealers said they never have any problems, no heat, nothing. didn't stock them and couldn't recall the last time he sold any.

i decided to be brave and got to work. they did come loose but it was nerve racking. even with a little penetrating fluid and rocking them back and forth they weren't really getting much looser as though rocking 1/10 turn back and forth with penetrating fluid would take forever if id wanted them out completely.

usually, once you get a rusty thread cracked and then get some fluid in there the thing comes out easily the rest of the way

even tightening them back up again wasn't straightforward. i used an easy bleed so its possible to determine when the nipple is sealed and it felt like they had to be really tight.

the whole episode|: loosening / tightening just felt like someone had at some point crossed the threads. they shouldn't have been out yet since new.

BTW 11mm socket / ring spanner on 2010 calipers

maybe they put them in with thread locker??