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Any tips on how to sort out my sticky piston. Nothing serious, just sticking a little bit. Is it ok to squeeze GT85 on the sticky one and squeeze the brake lever whilst holding the 'good' one in? Or will GT85 wreck the seals or something? I know to avoid getting it on the rotor!
Cheers,
Matt
Don't!
gt85 is baaaaaaaad for your seals (or at least it is on dot systems, makes them swell and fail.)
3 options (all of which to be done well away from the removed pads!:
1) Shimano brake fluid: dribble a bit on and push the piston out, get the edges of it wet with oil and push back in, repeat till it behaves like the other one does. You may need to block the opposite piston somehow (I ziptied a metal tyre lever over the 'good' piston) otherwise all you will do is pump the good one out whilst the stuck one stays stuck.
2) silicon grease. Same as above. You can get it in sachets in bike shops at an extraordinary markup compared to a pot of it from a plumber's merchant, which will last you a lifetime's biking.
3) A friend has also had similar results with red rubber grease though I don't know where to get that from.
Happy spannering.
Option 1 works for me.
Anne Summer's sells red rubber grease, I think.
Poor joke I know but cheers for the advice Julian. I'll give point 1 a go first.
I thought that I had a vague memory of GT85 being bad for seals.
Matt
There is a video outlining the process on the hopetech web site.
I bought some silicone spray from screwfix, but think the non aerosol presentation is probably better.
Make sure you use something nice and wide to hold the good piston in. XTR pistons are ceramic and can crack if you use anything sharp on them.