[andyjensen]

I have new XTR disc brakes, 160 mm rotor on XTR hub, mounted on a 29'r and on a Reba. When I completely pull the front brake lever in the brake should be completely stopped - but on my front wheel I have some slop - probably 1/4". I can force my wheel forwards or backwards 1/4" fwhen fully depressed. This shift in the brake makes me know that I must be feeling this slop in hard and even normal light braking. Mechanic said I have bad stanchions on fork. I disagree. The shop help said there actually is some play back and forth in the XTR brake caliper itself, almost like the brake pads don't seat properly - solidly. Anyone know why my XTR brake allows my wheel to move about 1/4" with the lever/brake fully depressed?

 

[XSL_WiLL]

The rivets in the rotor could've developed play. The splines could have machining tolerances. The pads may not fit properly (could be a problem if not using OE pads), the bushings in the fork may be worn out.

Look to see where it's moving while holding the brake.

 

[andyjensen]

Hard to tell where it is moving, as I hold the brake lever I can't really see accurately what is going on. The brakes have so few miles on them - less than 500 I'd say, and I ride with care. I'm a knucklehead mechanic with disc brakes - they kind of scare me - like I'd end up with oily parts scattered across my garage floor and all kinds of air bubbles! Something about cables... The mechanic thought it was the bushings - but the wheel moves statically in the bike stand when the brake is fully dpressed.

 

[rockyuphill]

Get a big elastic band to hold brake lever down and get up close and personal with the hub/fork/rotor/caliper area. Anything that results in that much play at the tire should be visible close to the hub/axle.

 

[shinewheel]

I had an XT front disc in a 160 mm size which showed the same play. It was loose rivets attaching the disc to the spline. Put your finger over the rivet head and rock the wheel back and forth , you might feel some play there. I rode that disc for a couple years without noticing any ill effects, but if you isolate this as the problem you might want to return the disc to Shimano for replacement.

 

[Bikeeveryday]

qr?

loose quick release? loose headset? loose caliper mounting hardware? Loose lock ring/ rotor bolts? hub adjustment?

 

[jeffscott]

XTR hub means you have the centerlock rotor...

For some reason the centerlock rotors are loose on the hub (at least with Mavic's).

I had to take buddies rotor off put a light grease on the splines and put it back on.

Problem solved.

 

[andyjensen]

I'll try rubber bands and look at this thing. I'll also check the splines and maybe add some grease. I appreciate the time you've all taken with your advice. I will say when you buy XTR, and lay out this kind of dough you don't expect any problems at all. So much of the XTR package is the industry standard, and I just assumed the brakes would be as well. Overall I'm not real happy with them - they have little play in the lever - it's all or nothing. I loved the V-brake where I could modulate the power exactly - albeit through my energy and effort.

 

[rockyuphill]

The XTR brakes retract the pads further to minimize any rotor rub possibility, so there's a bit more lever travel to re-engage them. But for racers brakes just slow you down.