leosantanalg Posted September 18, 2018 Report Share Posted September 18, 2018 I have been so frustrated to the point that I bought a new bike!! lol, at least that was the excuse to buy a 300RR. back to the subject: I have changed brake rotors twice, changed pads twice and now just ordered a master cylinder rebuild kit!! what is going on?? the bike will brake but wont lock the wheels. If i m riding on grass and just press the brakes really hard front wheel was suppose to lock (it does on other bikes) but not on this one. I was told there was air in the line and bled it twice (unless i did it wrong) still not working. any suggestions?? i already tried water quenching, tap on line and flick the lever to release air at the top with cap open and still no locking! I need advise please... if the master cylinder kit wont work should I buy a new brake line or new caliper first??? Thanks all Quote Link to comment Share on other sites More sharing options...
heffergm Posted September 18, 2018 Report Share Posted September 18, 2018 (edited) If you changed the pads and rotors separately, like you left old pads on and changed the rotors, then you rode the bike, then you changed the pads and left the old rotors on and rode the bike, etc... ... if the original problem was brake/rotor contamination from something like brake fluid, which is pretty easy to do and can cause what you describe, you basically cross contaminated all the parts each time you changed them and rode the bike if you didn't change everything as a set. Any time you have a problem like this, if you're going to change the pads, pull the rotor off and hose it down with brake cleaner first. If the bike was like this from new, bring it to your dealer, something else is wrong. But there are only so many things it can be, and next on the list are the caliper and the master cylinder. Edited September 18, 2018 by heffergm Quote Link to comment Share on other sites More sharing options...
tshock250 Posted September 18, 2018 Report Share Posted September 18, 2018 More information needed. Is the lever spongy or firm? If firm then bleeding not required. Are you talking of lack of "bite" from the pads?, if so they may be contaminated along with the disc. Quote Link to comment Share on other sites More sharing options...
leosantanalg Posted September 18, 2018 Author Report Share Posted September 18, 2018 (edited) 4 minutes ago, tshock250 said: More information needed. Is the lever spongy or firm? If firm then bleeding not required. Are you talking of lack of "bite" from the pads?, if so they may be contaminated along with the disc. I cleaned the rotor with brake cleaner before putting new pads and last change I did as a set! They feel firm but wont lock in the end unless you press it so tight is not even real and there is no bite!! you know when you tap the brakes while riding and your front forks quickly compress? cant do it Edited September 18, 2018 by leosantanalg Quote Link to comment Share on other sites More sharing options...
scifi Posted September 18, 2018 Report Share Posted September 18, 2018 You need tyres with less grip, have you tried Mitas..? 1 Quote Link to comment Share on other sites More sharing options...
guy53 Posted September 18, 2018 Report Share Posted September 18, 2018 Try the cold water treatment, you never know Guy Quote Link to comment Share on other sites More sharing options...
oni nou Posted September 18, 2018 Report Share Posted September 18, 2018 4 hours ago, leosantanalg said: I have been so frustrated to the point that I bought a new bike!! lol, at least that was the excuse to buy a 300RR. back to the subject: I have changed brake rotors twice, changed pads twice and now just ordered a master cylinder rebuild kit!! what is going on?? the bike will brake but wont lock the wheels. If i m riding on grass and just press the brakes really hard front wheel was suppose to lock (it does on other bikes) but not on this one. I was told there was air in the line and bled it twice (unless i did it wrong) still not working. any suggestions?? i already tried water quenching, tap on line and flick the lever to release air at the top with cap open and still no locking! I need advise please... if the master cylinder kit wont work should I buy a new brake line or new caliper first??? Thanks all What make of brake pads are you putting in and are they sintered or not. Quote Link to comment Share on other sites More sharing options...
copemech Posted September 18, 2018 Report Share Posted September 18, 2018 gotta use the galfer pads, run them in for a bit and heat cycle normally, then make about 3-4 high speed stops heating the front and pull out your water bottle to douse them good, should steam off a lot! do that a couple times then let cool and resume normal operation. Quote Link to comment Share on other sites More sharing options...
lineaway Posted September 18, 2018 Report Share Posted September 18, 2018 (edited) The m/c is a piece of crap. Happens quite a lot. New bike? What did the dealer say? Edited September 18, 2018 by lineaway Quote Link to comment Share on other sites More sharing options...
cascao Posted September 19, 2018 Report Share Posted September 19, 2018 Sometimes brake need some time to work propely after you change pads or discs. Just ride and have fun. After half hour it should be nice. Quote Link to comment Share on other sites More sharing options...
leosantanalg Posted September 19, 2018 Author Report Share Posted September 19, 2018 13 hours ago, lineaway said: The m/c is a piece of crap. Happens quite a lot. New bike? What did the dealer say? I bought the bike in January. was perfect until i decided to pull the brakes apart for cleaning maintenance!! big mistake. from now on if it s not broken, I m not fixing! Quote Link to comment Share on other sites More sharing options...
leosantanalg Posted September 19, 2018 Author Report Share Posted September 19, 2018 12 hours ago, cascao said: Sometimes brake need some time to work propely after you change pads or discs. Just ride and have fun. After half hour it should be nice. this been going on for over 3 weeks!! water quenching, clean up, new pads... you name Quote Link to comment Share on other sites More sharing options...
leosantanalg Posted September 19, 2018 Author Report Share Posted September 19, 2018 14 hours ago, oni nou said: What make of brake pads are you putting in and are they sintered or not. they are galfer G1805 pads and galfer disc. before I had jitsie pads and they put grooves on both sides of the rotor! i replaced rotor and pads last time. Quote Link to comment Share on other sites More sharing options...
heffergm Posted September 19, 2018 Report Share Posted September 19, 2018 I don't suppose you're the guy that sprays WD-40 all over his brakes? If the pads and rotors are new and bedded in, the problem is either the caliper or the master cylinder. There's literally nothing else left. Quote Link to comment Share on other sites More sharing options...
leosantanalg Posted September 19, 2018 Author Report Share Posted September 19, 2018 (edited) 20 minutes ago, heffergm said: I don't suppose you're the guy that sprays WD-40 all over his brakes? If the pads and rotors are new and bedded in, the problem is either the caliper or the master cylinder. There's literally nothing else left. OK! if was you, which one would you replace first?? I m ready. I will put the new MC rebuild kit and see if it works. could it still be the MC even if the rebuild kit doesnt fix it? Thanks Edited September 19, 2018 by leosantanalg Quote Link to comment Share on other sites More sharing options...
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