I have a bit of pulsing in my front brake, a slow pulse not chatter. My thumbnail sez about once a wheel rotation or so. I put a dial indicator on the disk. I used a bolt in the fork leg caliper mount to make a stable dial indicator mount. and got about .007" of run out did little manual search and on the early 73-76? system Yamaha spec'd .006" (.15mm) max. On the later system (this bike) the manual specs .02" (.5mm)!!!! That seems like a pretty loose spec and a heck of a change. I grabbed a disk I had laying around mounted it and came up with the same run out so then I grabbed a mag wheel mounted it and came up with about the same run out on that wheel too. Anyone else measure this? I checked at the inner and out edge of the disk. I marked high and low on the disk and wheel and then rotated the disk 180 degrees and rechecked the run out and it appears to be the wheel's disk mounting flange not the disk where the run out is located. Anyone else explore this? I did a test run with the mag wheel and got little if any pulse. Am I chasing the wrong thing?
Edit; fork seals are good, pads are thick and light colored. Caliper mount slides are free, finger pressure moves them. I cleaned the disks with carb cleaner and paper towel twice.
Checked a third bike with mag wheel that one has .004", better than the other two.
The mounting flange on the spoke wheel hub was out about .0025 did a little file work and got down around .0015 put her back together the disk is a bit better now down to about .005" and will test run it when the rain quits.
I am guessing that the specs and what I measured are why yamaha went from a dual piston solid mounted to the single piston floating caliper. They couldn't keep the disks straight enough to keep them from pulsing. It seems that all the newer dual piston bikes run floating rotors now.
Edit; fork seals are good, pads are thick and light colored. Caliper mount slides are free, finger pressure moves them. I cleaned the disks with carb cleaner and paper towel twice.
Checked a third bike with mag wheel that one has .004", better than the other two.
The mounting flange on the spoke wheel hub was out about .0025 did a little file work and got down around .0015 put her back together the disk is a bit better now down to about .005" and will test run it when the rain quits.
I am guessing that the specs and what I measured are why yamaha went from a dual piston solid mounted to the single piston floating caliper. They couldn't keep the disks straight enough to keep them from pulsing. It seems that all the newer dual piston bikes run floating rotors now.
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