Ok so I've had this issue for the last two race weekends. It's very weird and only happens in 2 corners. It happens when the brakes are applied with the bike vertical and into trail braking with light pressure at low speeds (low end of 2nd gear). It's a high frequency vibration that is fairly violent, it's enough that it shakes the fairing around. I had the rotors cleaned (aluminum oxide blasting) and dissassembled them (braketech irons) to clean the buttons and check the rotor for warps. The rotor sat perfectly flat on a 1/2" thick pice of glass and so did the carrier. I've eliminated the rotors because the bike brakes fine at high speed and the frequency is so high that the rotor would need to be damaged every 1/16", also using new pads after cleaning. I replaced the wheel bearings yesterday, they felt fine when inspected and had 5000km on them. What else could this be?? Steering head is tight and bearings are good (serviced two weekends ago as well as all the other bearings in the chassis/linkage). The problem was happening before I did the service as well so it wasn't something I did/didn't do during that.
I have a wicked vibration braking hard from triple-digit speeds. My OEM floaters don't seem to have any float and I think the rotors are oscillating axially when on the brakes as they're likely not tracking neutrally through the calipers/pads. My bike is kept as near immaculate as feasible...it's not crud build-up in the buttons. I'd try aftermarket free-float buttons (don't know what size or who) but I'm more inclined to just buy better than OEM rotors. I definitely don't want the braindead, mechanically induced, ABS symptoms of activation I'm currently experiencing at 150+.
They are full floating which is why I took them all apart and checked them on the glass. I turned them and placed them on the glass in multiple positions and they're flat as it gets and that's looking from outside in and inside out. I mean, if they were warped would I not get pulsing in the lever and it be worse at high speeds? They work great everywhere else but at slow speeds. And it's not a "wop wop wop" type of vibration but a serious chatter. This is why I had the rotors cleaned thinking it was pad material built up but it's still there. I will try my oem rotors on my spare wheel if this doesn't go away and then if it's gone swap my rotors to confirm. I'm just puzzled as to what else it could be.
Have you checked that your steering stem is torqued correctly? If that is loose that may explain some of the vibration. I'm not an expert though, just something that came to mind.
are u sure its not actual suspension chatter? the few times ive seriously chattered the front end on the brakes, the bike def felt like it was falling apart.
I haven't ruled that out yet. I'm going to be working with my suspension tuner this weekend to get it sorted. It seems like it could be suspension chatter but I haven't had it before so I couldn't say for sure.
got any video footage of the problem? maybe next time out point a GoPro right at the front tire to see if its actually chatter.
Did you change your process of front wheel installation? Could the forks be binding or sticking during initial transition from upright to turn-in? Put the bike on rear stand only, loosen the pinch bolts and axle, bounce the front end while holding the brakes, then torque up the axle and pinch bolts? I'm sure the pros on here have a better method, but maybe something like that? I know that works for dirt bikes, I can't imagine it would be too much different for road bikes (maybe a different order?).
Forks have been off and serviced since last year when I started having the issue. Axle slides in nicely. It's a zx10 so I only loosen the one set of pinch bolts for the axle and remove the calipers. Calipers go on last after the axle/pinch bolts are tight. This is the way I've always done it before and after the issue started. One thing I forgot about....the round before I had this start happening I bent my damper rod swapping out a spring. We straightened it as best we could on a vice trackside but it wasn't perfect. I've contacted my suspension guy to bring another rod that we could use to eliminate it causing the issue. I'm sure if it was still bent bad enough he would have noticed during the service but it's just one more thing to rule out. I've also gone from 32psi to 36-37psi and the issue was there with both pressures (Dunlop slick).
actually, to do this properly, u need to bounce the front end w/ the calipers off the bike. the brakes can shift the fork alignment if u hold the brakes or even have them on the bike. also u need to leave the axle torqued and just have the pinch bolts loose on one side, the side that actually lets the fork slide compared to the wheel.
Your rotors are parallel. Your carrier is parallel. Are your rotors and carrier parallel when put together? Send them to Jeff.
If we don't find the issue this weekend or my oem rotors solve the problem I will. They're full floating so they'd have to be really messed up to not be parallel.
Damn dude good luck getting that sorted. Definitely not good timing right before the first round. See ya at Shanny on the weekend. Steve
try a different front tire. From what i read, dunlop has more propensity to chatter being a hard carcass tire compared to others, and the zx10 (not sure which years) are the most prone to do this with the dunlop fronts. unless you are supported by a tire brand, mix up stuff. grab a good front take off from someone you know and try it with the dunlop rear.. but do one change at a time so you isolate what the cure is (if you find it)
It's the spec tire so no dice on swapping brands. I also didn't have the issue with the dunlops for a season prior.
Does the chatter coincide with any front spring rate changes? Or any other mechanical or geometry changes?
