Member Contributer adeyren Posted June 24, 2015 Member Contributer Share Posted June 24, 2015 Hi all,back posting after a nasty illness. Am currently in French Alps six days into my tour. Been doing loads of high passes here. Problem is when I brake hard I get a vibration,drumming for a few seconds from the brakes then goes. First noticed it when doing high speed runs,starts at about 60 _ 80 mph, a vibration then smooth then vibrate again. Suspecting warped disc? Bike on center stand,back wheel spins freely,front wheel binds every 40% of revolution. P's how many BMW trail bikes have they sold? There are millions over here. In fact adventure/ trail bikes outnumber sports tourers by 20 - 1. I actually sat on a 1200 G'S ,like sitting on a battleship! Could only get one foot on the floor. Link to comment Share on other sites More sharing options...
kyojitsu Posted June 24, 2015 Share Posted June 24, 2015 Grubby calliper pistons? Prob not retracting properly, maybe brake fluid has overheated or has become contaminated and pushed them out. May need a local bike mechanic to help you out. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer adeyren Posted June 24, 2015 Author Member Contributer Share Posted June 24, 2015 Fluid is new three months ago.So sticky pistons might be favourite. Just want reassuring they ain't gonna fail on these steep descents! Doing the Stelvio Pass tmw in Italy, 48 hairpins going up which is not too bad it's coming down the other side! Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted June 24, 2015 Member Contributer Share Posted June 24, 2015 I've had this happen to me, went from smooth braking one day to shuddering the next. The cause was a slightly warped disc and I think you've got the same, given that it binds at the same spot when you rotate the wheel. In my experience it won't be the steel brake disc that is buckled, but the soft aluminium carrier that it attaches to. I have given my carriers a little tweak to straighten a bent carrier with good results (using great care, a dial indicator gauge and a pry bar). I would not try this however if it was the steel disc that was bent. Link to comment Share on other sites More sharing options...
Member Contributer gmtech94 Posted June 24, 2015 Member Contributer Share Posted June 24, 2015 Make sure that the rivets that hold the steel to the carrier are free and the rotor can float a bit ,these get crud in them and don't allow the rotor to move particularly in only one spot . Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted June 24, 2015 Member Contributer Share Posted June 24, 2015 Warped rotors will pulse the lever...Loose steering bearings will be felt as a pronounce click upon braking...Pad harmonics will vibrate the caliper... either lube the back of the pads withspecial brake grease or change the thickness of the pad... Link to comment Share on other sites More sharing options...
Earthshake Posted June 24, 2015 Share Posted June 24, 2015 While it may be warping, don't buy new rotors as your first course of action. One possibility, which I believe is more common, is a buildup of brake pad material on the rotor. When you keep the brakes applied after the bike comes to a stop, a small amount of pad material can be transferred to the rotor. This is more likely to occur when brakes are particularly hot, such as mountain runs like you are doing. I had a similar vibration that was remedied by using a very fine garnet sandpaper to clean the rotors, followed by a thorough cleaning with brake cleaner including the buttons to ensure your brakes are semi-floating as intended. The vibration is annoying, but I wouldn't worry about it until you return home unless it gets significantly worse. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted June 25, 2015 Member Contributer Share Posted June 25, 2015 To the last three posters, those are some interesting points, thanks for sharing them. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 25, 2015 Member Contributer Share Posted June 25, 2015 Make sure that the rivets that hold the steel to the carrier are free and the rotor can float a bit ,these get crud in them and don't allow the rotor to move particularly in only one spot . +1 Had the same thing a couple years back cleaned the buttons and everything was fine. Roll On .. Link to comment Share on other sites More sharing options...
Member Contributer adeyren Posted June 26, 2015 Author Member Contributer Share Posted June 26, 2015 Thanks all,I'm just gonna have to put up with it until I return home. I have enough tools on the bike to attempt a repair but if anything breaks etc Honda dealers are few and far between up here in Northern Italy. I've found that by grabbing a handful,releasing and grabbing quickly again it feels better. I've put up with it for the last 2200 miles just hope it lasts. Link to comment Share on other sites More sharing options...
TNRabbit Posted June 26, 2015 Share Posted June 26, 2015 Make sure that the rivets that hold the steel to the carrier are free and the rotor can float a bit ,these get crud in them and don't allow the rotor to move particularly in only one spot . +1 Had the same thing a couple years back cleaned the buttons and everything was fine. Roll On .. I have to agree....had a similar vibration problem & cleaning/rotating the disc bobbins helped immensely. Link to comment Share on other sites More sharing options...
Member Contributer adeyren Posted June 26, 2015 Author Member Contributer Share Posted June 26, 2015 You're right I think rabbit,checked my disc bobbins earlier and they are solid. Me thinks a front brake system is due for an overhaul when I get back!!! Cheers Link to comment Share on other sites More sharing options...
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