Aleko

I swapped my rear Shimano rotor with Shimano XT Ice-Tech rotor, and now the new rotor is continuously rubbing against the pads on both sides. The old rotor wasn't worn out, it only had about 200 miles on it, so my guess is that the XT rotor is just a bit thicker from the factory than the old rotor. Is there any way to "spread" the pads/pistons a little to allow for the new rotor to spin freely? Or do I need to get XT calipers to work with XT rotors (my calipers are "regular" Shimano, not XT)? Thanks in advance.

asmac

Have you done the standard brake adjustment of loosening the caliper bolts and, while squeezing the brake handle, retightening? Is the rotor properly seated and tightened? Is everything properly torqued?


Any minor variations in rotor thickness (which probably don't exist anyway and you can measure) shouldn't matter as there are going to be much greater variations in pad thickness due to use than variations in rotor thickness.

Wheever

The ice-tech rotor is probably a little thicker. Hydraulic brakes are supposed to self-adjust the calipers as the pads wear, so that the contact with the rotor remains the same, but in my experience they don't like to adjust back out again.

Here's what I did when I had to replace a set of contaminated pads and had the same problem you're having: I removed the wheel, and pushed a brake travel block between the pads; I then cracked the bleeder slightly and let a few drops of fluid escape, and quickly closed it before air could get into the line. This fixed it. Ostensibly, the spreading action of the travel block alone without cracking the bleeder should have pushed the calipers out, but for whatever reason it didn't work for me.

If you try this, make sure to attach a hose to the bleeder so as not to contaminate your pads. And when you open the bleeder do not allow too much fluid out, or any air in!

corrado33

Pushing the pads back with something plastic is standard practice when changing brake pads. You should not have to crack any bleeder valves. I will often use a tire lever. Make sure you push on the piston EVENLY, as if you get it cockeyed you're in trouble. Seriously, just shove a lever in there and push them back. They'll self adjust to the new rotor thickness.

fietsbob

people seem to be suposing you have XT hydro brakes .. due to the auto pad wear compensation
they move in if you touch the lever when the wheel is out, and dont retract, you know.

pressed001

yeah. So you gotta take the wheel off and push those pistons back in with (like said) a tire lever or something. And also, like already said, you will just have to try your best to center the caliper over the rotor which can be sometimes impossible or a complete PITA. One of my bikes still rubs ever so slightly and I can't do anything about it. But it also still doesn't have many km's on it so maybe riding it more would also help...
Also, don't touch the brake lever whilst the wheel is off...bad idea.