Brake rotor alignment

[Sparkz]

I have a nasty habit of pulling things to bits in a hell of a hurry and finding out later that there is a "trick" for doing it properly.

I pulled the wheels off my '87 FZR750 to have them powder-coated (yes, I read the thread on how that buggers the heat treatment, too late now!!) and obviously had to remove the brake rotors. I cleaned up the surfaces the rotors bolt on after getting them back and turned the rotors against them to make sure there were no bumps etc.

Now I find the front brakes shudder quite badly when braking from >100km/h. Is there a good way to check (and fix) the rotor alignment? What are the limits for run-out? I have heard stories about pieces of paper behind rotors to line them up, but that sound pretty dodgy.

Any kind words of wisdom appreciated!

[pete376403]

Are the mating surfaces of the hub and disks absolutley spotless? The factory use a thread locking compound on the bolts - any possibility of any (it dries really hard) betwreen the hub and a disk? Did you torque the bolts to the correct setting (20 Nm / 14 Ft/lb), tightening the bolts progressively in a crosswise pattern? Check the runout of the disks - 0.15mm / 0.006" - thats not much and the disks are pretty thin, easily bent.

(facts and figures courtesy of Celtic#6's service manual, which I have at present)

[Sparkz]

Thanks Mate,

Eventually got round to checking the rotors with a dial indicator borrowed from work. One was 1 thou out and the other 4 thou. Well within spec.

I then noticed that the rotor was offset on the carrier and was running concentric. DOH!! A few light taps to centre the rotor and the shudder is gone.

I just finished fitting a complete '02 R1 front brake system (not the rotors) to the Fizzer. It is a bolt-on upgrade and makes an awesome difference. Amazing that Yamaha have kept everything compatible from 1987 to 2002 as far as calipers go!