Shimano XT Brake problem.

The GF has the new style XT brakes on her bike & the problem is there is hardly any free play before they bite.

I’ve bleed them many time & with no effect. It also looks like there’s a lazy piston in each brake, but despite holding in the free piston & pumping out the lazy one & lubing it many times it still remains lazy.
There appears to be very little free play but adjusting the grub screw at the front of the lever that is supposed to increase free play only moves the lever further from the bar.

Any further tips or advice would be much appreciated.

what are you cleaning the pistons with?

pump them out a bit and use IPA (not the beer) or similar to clean them. Then lube with red rubber grease, wipe off the excess and push the piston back in. Repeat until it doesn't stick any more.

Out of interest, are you using aftermarket pads from a different manufacturer or non-standard rotors?

I notice that mine are worse for this in the cold weather. I think the seals stiffen up a bit or something. Maybe the fluid thickens up a tad.

I repeat retro83's comments regarding the ambient temperature making a significant difference. I think that the tolerances are that tight that when the temp drops the fit between piston and calliper is minute thus causing the problem.

My XTs appears to behave a bit oddly in sub zero temps, it seemed to pump up more than normally. Ok now its warmed up a bit.
Which levers are you running? Are they the servo wave ones? If so, you can usually adjust the bite point of the brake, not by a massive amount. If you have the std levers then you can adjust the bite by turning the grub screw in or out, as you have been.

I'm on XT servowave and was riding all through the snow and cold weather. The brakes (and XTR's on my hardtail) have been shit since. Sticking pistons, loads of hassle and I suspect that being frozen in the garage for 3 weeks didn't help them much at all either. Roll on summer!

Just to check which grub screw you are adjusting as on mine the free play one didn't move the levers at all. The free play one is the cross head on the very front of the lever body.

what owenfackrell said, though it might move the lever a little but not much. adjust the free stroke grub screw then use the barrel adjuster to get the lever position where you want it.

New style levers, servo wave.
Lubing pistons with Shimano brake fluid.
I have two other sets on my bikes & there fine.