Guest reeseyboy Posted September 9, 2016 Share Posted September 9, 2016 I think I have a warped disc. No pulsing at the lever when braking from speed, but when slowly approaching a stop the brakes go firm/weak. I have clocked both discs with a DTI and I have a measured runout of 0.09mm; max runout in the Service Manual is 0.1mm. Dealer has agreed to inspect when the bike goes in for its 12k service in a couple of weeks. Has anyone else had this? I'm still on the original pads at 11k miles but have a set of SBS Sintered Street pads to go in next week. Link to comment Share on other sites More sharing options...
timg Posted September 9, 2016 Share Posted September 9, 2016 Did you notice any discolored or different textured areas on a disc or both? Did you check the thickness all around both discs? Have you cranked it down hard from a high speed run and held the brake tight for a bit at the stop? This can cause a change in the disc between the pads. The runout sounds good, so unless the ABS is messing up I can't think of much else. Link to comment Share on other sites More sharing options...
Guest reeseyboy Posted September 9, 2016 Share Posted September 9, 2016 Colour and texture looks fine. The floating bobbins are nice and free too. I'll have the ABS sensor out whilst changing the pads and give that a good clean. Haven't checked the thickness yet. Doesn't do it at speed though... Link to comment Share on other sites More sharing options...
bruceintucson Posted September 9, 2016 Share Posted September 9, 2016 Colour and texture looks fine. The floating bobbins are nice and free too. I'll have the ABS sensor out whilst changing the pads and give that a good clean. Haven't checked the thickness yet. Doesn't do it at speed though...Did you have front tire changed before this problem started? Seen a lot of rotors warped by in-attendance/ give a crap attitude by guy changing the tire. Even lying the wheel flat on one of the rotors can warp one. Rotors are very strong in one plane, not so much in the other. Link to comment Share on other sites More sharing options...
nsmiller Posted September 10, 2016 Share Posted September 10, 2016 I believe the FJ09 has floating rotors. Perhaps you're just not use to the way these behave? Link to comment Share on other sites More sharing options...
Guest reeseyboy Posted September 10, 2016 Share Posted September 10, 2016 I believe the FJ09 has floating rotors. Perhaps you're just not use to the way these behave? Hi. I referenced the floating bobbins in my last post; all good. Link to comment Share on other sites More sharing options...
Guest reeseyboy Posted September 10, 2016 Share Posted September 10, 2016 Colour and texture looks fine. The floating bobbins are nice and free too. I'll have the ABS sensor out whilst changing the pads and give that a good clean. Haven't checked the thickness yet. Doesn't do it at speed though...Did you have front tire changed before this problem started? Seen a lot of rotors warped by in-attendance/ give a crap attitude by guy changing the tire. Even lying the wheel flat on one of the rotors can warp one. Rotors are very strong in one plane, not so much in the other. Unfortunately not. Tyre has been on for the last 9000 miles, this issue only for the last month or so. The disc runout is 0.01mm away from Yamaha's own max spec for warpage, so I see a warranty claim on the horizon. Link to comment Share on other sites More sharing options...
Premium Member britelitebob Posted September 10, 2016 Premium Member Share Posted September 10, 2016 Guy in the video said the rotors were steel but their actually made of cast iron, steel rotors would overheat and wear out more quickly. And I doubt that the cast rotors are warped but more likely they we're bent as previously said or possibly a defective casting. BLB Link to comment Share on other sites More sharing options...
Guest reeseyboy Posted September 10, 2016 Share Posted September 10, 2016 Whilst I understand what you're saying, why would this feeling come on in the last couple of months when the wheel hasn't been out of the bike for a tyre or anything else. The DTI reveals that the rotor is 0.01mm from the max for runout so it must be defective? I'll let the dealer have this one. Link to comment Share on other sites More sharing options...
Premium Member 2and3cylinders Posted September 10, 2016 Premium Member Share Posted September 10, 2016 Whilst I understand what you're saying, why would this feeling come on in the last couple of months when the wheel hasn't been out of the bike for a tyre or anything else. The DTI reveals that the rotor is 0.004" from the max for runout so it must be defective? I'll let the dealer have this one. Link to comment Share on other sites More sharing options...
Premium Member 2and3cylinders Posted September 10, 2016 Premium Member Share Posted September 10, 2016 FSM has procedure that entails removing rotor(s) and rotating them 1 mounting bolt hole, then reinstalling angle checking runout. Then if still out of spec (or close to it), repetitive until moving rotor around to the next bolt hole etc until back to original position, and old then replace. A lot of work.... Rotors may be a wear item not covered by the warranty. I had an similar issue (see my thread) and a left caliper bleed nipple suckling air sealed with yellow Teflon tape and a good flush and bleed seemed to do the trick. BTW, what is your front brake lever travel and effort level like? Very short and relatively high? Link to comment Share on other sites More sharing options...
Premium Member wessie Posted September 10, 2016 Premium Member Share Posted September 10, 2016 I'd check for some sort of contaminant. A small stone can cause back pressure on the pistons in mild braking that would not be noticeable if you are applying a lot of force to the brake lever. Also, I have heard of brake pulsing/judder caused by a build-up of brake material on the rotor. Symptoms are similar to a warped disk. Run over the rotor with a wire brush on a drill. This signature is left blank as the poster writes enough pretentious bollocks as it is. Link to comment Share on other sites More sharing options...
bruceintucson Posted September 10, 2016 Share Posted September 10, 2016 I'd check for some sort of contaminant. A small stone can cause back pressure on the pistons in mild braking that would not be noticeable if you are applying a lot of force to the brake lever. Also, I have heard of brake pulsing/judder caused by a build-up of brake material on the rotor. Symptoms are similar to a warped disk. Run over the rotor with a wire brush on a drill. Was just going to chime in with the exact possible cause. Deposits on the rotors can come from getting the brakes very hot (period of strong use), coming to a stop and holding the front brake on while pads & rotors are still hot. Have run into this a few times, especially at trackdays. Learned to not hold the front brake on after getting the brakes hot. :-)A drill with a wire brush will probably work, I've had success with sanding well with 80 grit followed by brake cleaner on a green Scotchbrite pad (careful, brake cleaner can damage the paint on the wheels.) Ideally you want to clean the rotors with the calipers removed & tied back out of the way.As far as warranty, believe brake rotors are considered "normal" wear & tear items and are not under warranty-at least usually.Remove possible deposits from the rotors & let us know how it goes. Link to comment Share on other sites More sharing options...
parablob Posted September 11, 2016 Share Posted September 11, 2016 Hi I had both front disc,s replaced last month ,both where warped, my dealer put the bike on a brake testing drum and applied a slight pressure to the lever and the dial was moving up and down , the symptoms I had was a slight vibration on the front end Durring moderate braking from any speed, I had no pulsating at the lever and when the dealer checked both discs they where both out of spec, and had them changed, I now have smooth braking at any speed, my milage was 9600 miles and it started long after I had the tyres changed, Link to comment Share on other sites More sharing options...
Guest reeseyboy Posted September 11, 2016 Share Posted September 11, 2016 Hi I had both front disc,s replaced last month ,both where warped, my dealer put the bike on a brake testing drum and applied a slight pressure to the lever and the dial was moving up and down , the symptoms I had was a slight vibration on the front end Durring moderate braking from any speed, I had no pulsating at the lever and when the dealer checked both discs they where both out of spec, and had them changed, I now have smooth braking at any speed, my milage was 9600 miles and it started long after I had the tyres changed, Thanks for this. Link to comment Share on other sites More sharing options...
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