[OffRoadRoadie]

My 2004 XTR front brake has developed a loud squeal during very hard braking, but the rear disc is quiet 100% of the time. During normal braking the front brake is quiet. The squealing started near the end of a 30 mile downhill section that I rode without a rear brake, (the last 3 miles were extremely steep with 10-12 switchbacks on a 20-35% incline, and I did experience some brake fade) the XTR center-lock rotor has some minor discoloration on the spider arms, the rotor looks true and it doesn't rub the pads. I'm running the XTR metal/resin pad combo (f & b), 100mm Fox Float RLC fork on a SC Blur with less than 40 hours on it. Pad thickness is still within Shimano specs, so I haven't replace the front pads yet. Shimano doesn't sell the metal/resin pad combo as a pair, so I hate to purchase four pads just so I can get a single pair of metal/resin pads. Plus I want to keep the brake modulation the same between both brakes.

Would a warped rotor cause this? Should I try swapping the rear pads with the front? The rotor looks clean and I haven't cleaned with alcohol.

What gives?

 

[RedDwarf]

I managed to "heat glaze" my rear pads . . .

and after a good "scuffing up" with some sandpaper and cleaning everyting is back to quite.

Then I rode them in a major rainstorm and they are back to squeeking, so I'll try to scuff up the pads and clean the rotor with rubbing Alch. or "brake clean" see what that does.

 

[HTail]

Heat

I've found that after long descents, the brakes tend to squeal briefly until they cool adequately.