Ducati Monster Forum

I got a used front wheel and front 320 mm rotors over the winter; I installed; and the front end was readjusted by a motorcycle mechanic.

I've always noticed a "pulsing" on the front breaks, but seems to be more noticable these days.  I suspect that the rotor and / or the carrier were already warped.  so ... 2 q's.

Is there an accurate way to check if the rotors are warped?

Can you adjust (bend) carriers and resurfance floating rotors?

Cheers DD  [moto]

If you  can (easily) separate the rotor from the carrier - lay it on a pane of glass.  It's a guick easy way to check for warping.

As for your 2nd Q.. not really.  Some folks have had limited sucess with skimming warped rotors.  But the pulse some back a lot sooner than one would hope and is really worth the cost.

Get a micrometer and measure the disc in several places.  The measurement should be close, the owners manual may have a spec for what's acceptable.  That will tell you if the disc is the same thickness all around.  If it's out you really can't  recut it, you porbably need a new one.

Get a dial indicator and set it up to measure the disc from the side.  Rotate the wheel and measure in several places.  If this is out you can try to persuade the carrier back to position with a mallet.  Whack the carrier (not the disc), measure, repeat.  YMMV.  Alternatively you can convert your semi-floating rotors to full floaters.  Remove the disc and carrier from the wheel.  Prop one of the buttons up on a socket that supports the disc and carrie and whack the button with a hammer.  You're looking to compress the little spring washer so that it doesn't hold the disc in place.  repeat for all buttons.  When you finish all the washers should rattle and turn freely.  This has helped many folks and been a nightmare for a few, causing more vibration and noise than when they started.  YMMV.

A less invasive technique (and the first I recommend you try) that requires no measuring and little skill is cleaning and rebedding.  Clean the rotors with a 3M Scotchbrite pad and brake cleaner.  Scrub really hard.  Also clean all the buttons that hold the carrier to the disc.  There is a little spring washer in there.  When it get gooked up it can't turn and let the disc float like it should.  Clean them so that you can turn them all by hand.  Some folks lube them too but that makes me nervous so close to the disc.  Pull out the brake pads, sand them with 220 girt paper on a glass plate to deglaze, and clean them with brake cleaner too.  Reassemble and bed in the pads. 

Bedding in is a process of getting a fine, even layer of the friction material from the pad laid down on the disc.  Find a long deserted stretch of road.  Get up to about 60mph and hit the brakes hard to about 10mph.  Then let go and get back up to speed.  Ride about a minute to cool the brakes a little.  Repeat about 10-12 times.  Now ride easy for a long while with no brakes until they cool.  DO NOT STOP DURING THIS PROCEDURE!  Your brakes are going to get very hot, hot enough to transfer friction material from the pad to the disc.  If you stop the section under the pads will cool unevenly compared to the rest of the disc and they will warp.

Cleaning and rebedding has helped get rid of lots of pulsing brakes.

Finally, you can convert your full floaters

Before condemning the rotors make sure the buttons are clean.   If the blade is cocked on the carrier you will have run out.