Triumphrat

rs_tt · 04-06-2007

Had to replace my rear tyre do to a puncture,took the wheel off ,had the tyre replaced,put the wheel back on all turned freely.
took the bike out for a reasonably spirited ride to wear the tyre in.
upon my return,i could hear the sound of hot metal , like an exhaust pipe cooling only louder, put the RS on the centerstand and noticed the rotor discolored coppery, tried to spin the rear wheel it was very tight,as the brake cooled it spun more freely but with some drag. Could this be the fluild expanding, or the pistons sticking?
has any body experienced this?
brake pads were replaced about 500k ago.and nothing looks warped or amiss.

triumphtimes · 04-06-2007

I had the same thing happen on the front right caliper of my RS about four years ago. Stuck closed so tightly that the bike seemed to loose all power, would have stopped itself. It did free up on it's own and I made it home not knowing at the time it was the pistons in the caliper sticking. It turned out to be the pistons sticking closed from being dirty with road grime and brake dust. You can probably just clean the caliper, but chances are the rotor will be warped and need to be replaced. If the rotor isn't warped you got lucky. My rotor was so bad I had to cut it in half to get it free from the caliper.

[ This message was edited by: triumphtimes on 2007-04-07 01:33 ]

rs_tt · 04-09-2007

So I`m stumped, I changed the brake fluid,pistons moved freely in the caliper,but I did have to release some fluid to push the pistons all the way in all the way .after a short ride the rear brake is hot and won`t release till it cools down. I think i may have to dis-assemble the master cylinder and see if theres a blockage.
any thoughts?

triumphtimes · 04-10-2007

I was able to do the same thing as you forcing the pistons in, but the pistons were still not clean and would stick. If you haven't cleaned the caliper and pistons thoroughly, I think you will continue to have the same problem. It sounds as though you are having the same problem I had, but I may be wrong. Is your rotor warped from the initial heat up?

rs_tt · 04-10-2007

Nope the rotor is not warped, did a search last night,and seems others have had this problem too. It also seems to be loosing fluid out of the resevoir (seepage ,like its pressurizing)one thing i did read was the brake line can break down inside and act like a one way valve.I think I`m going to rebuild the caliper,master and replace the line and pads(2monthes old) as they look like there crumbling.
Thanks for your help sofar triumphtimes
jake
ps, after the brakes cool the wheel spins with no drag at all :???:

rs_tt · 04-11-2007

So i`ve cured the problem, not quite sure what i did tho,took the complete systen off the bike,found a small stone wedged out of sight inside the clevis that attaches the m.cyl. to the pedal.This may have been keeping the brake slightly applied,also dis-assembled the caliper (made sure it was clean)again,flushed fluid through the system.greased every pin & re-installed.took the bike for a ride and no brake drag.
what a fluke if it was that stone :???: