Hi
I just bled my disc brakes. Xt m8100.
After finishing - I tried to braking but it started to stutter, it would bite and then release and bite again, this would happen rapidly like 5 times per second.
Could there be an air leak? I did struggle tightening the bleed screw as it’s quite worn and didn’t want to strip the threads.
Please let me know what you think.
Thanks!
If there were a leak that air could get in, I’d expect you’d be getting fluid out of that hole.
You didn’t get any brake fluid on the pads or rotors, did you? That would be my guess.
I always pull take the wheel off (to move the rotors away from the spill zone) and pull the pads out before starting, even if I’m just doing bleeding at the handlebar, because brake fluid will travel down the brake lines. And I clean up the bike really well before reinstalling the wheels and pads.
eta: and I tie a paper towel around the brake hose, down below the lever, to intercept any drip running toward the calipers.
How does the lever feel? If there was that much air I would suspect it would be pretty squishy.
But I would also guess that you got something on the rotor.
It could also be caused by a warped or bent rotor but I bet you would get terrible rotor rub while not breaking if that was the case.
I solved it - I mounted the caliper too far away from the rotor and there was about 2mm where the pads weren’t biting outside the rotor. Also adding to this, the rotor was slightly bent.
So new pads, re-fit caliper and solved 
Was a very odd issue bike shop couldnt figure it out …