Front brake disc warped?

[uclabiker06]

Hello to all,
Recently had the chance to take the old queen out of the garage to run some errands.  Parked the bike and when I came back I took off w/ out taking the disc lock off!  (and I didn't take off as slowly as I usually do) 

The next time I took the bike out the front brake would pulse at slow speeds w/ light pressure.  Brought the  bike back to the garage, took the front wheel off and re-torqued but that didn't help at all.  Actually now when I apply the brakes hard it pulses harder...feels like I'm taking hands on and off brake lever but I'm not

Any advice/suggestions appreciated...

[ducpainter]

Normally I wouldn't say this, but if you're sure it didn't pulse before...

You may have bent a rotor.

If you're not sure about it not happening before then you may just have uneven deposition of pad material.

http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

[uclabiker06]

No, it definitely didn't happen before.  If it did I would have noticed for sure.

[Howie]

Also make sure the blade (disc part) can move on the buttons.

[DarkStaR]

Since you are seem comfortable enough work on you own bike, take the calipers off, give the wheel a good spin (while on the forks with the front lifted of corse), and see if you can visually see if the rotor is bent.

Not an absolute way to tell visually, but if it's bent enough, you will notice it.

[DuciD03]

Since you are seem comfortable enough work on you own bike, take the calipers off, give the wheel a good spin (while on the forks with the front lifted of corse), and see if you can visually see if the rotor is bent.

Not an absolute way to tell visually, but if it's bent enough, you will notice it.

1+ above

after cleaning the disk with a scotchbright pad; and if its still there given your description of disk lock & hitting it hard; the best solution is to just bite the bullet and replace it; unfortunately you can not resurface motorcycle rotors like a car disk due to there thin profile .... hope that helps; just from a similar experience I had with another bike & similar previous owner that I believe had ding-ed the disk good; it took 4 months of fiddling before i finally replaced the disk ...

[uclabiker06]

Rotors move (float) fine.  I am going to take the front wheel to my neighbor who seems to have every tool that was ever invented.  We decided I will put the wheel on a balancer and use that in conjunction w/ a dial gauge tool he has which will precisely determine how bent the rotor actually is.  Will post results next week

Assuming my one front rotor (the one the disc lock was on) is bent can I just buy another one and be done w/ or do they come in sets of two?? How much do they cost and where to get them from?  If I have to buy two then I'll just get aftermarket wave style rotors, but don't want it to cost more than originals.  Yes, I know the brake calipers "suck" but their fine for me.

[Howie]

You do not have to buy a pair.  To check for a warped blade (the part the pad hits) you would need to remove it from the carrier and check it on a surface plate.  Considering the expense and inconvenience of purchasing new buttons and the labor. not practical.  If you look in the shop you will see they have a run out spec for the rear rotor, but not the front.  The good news is you can check the carrier, which is also the part more likely to bend.

Since the pulsation got worse after refitting the wheel you might try that again. 

If you didn't before, use this sequence:
      Raise bike.
      Loosen the axle nut.
      Loosen the axle pinch bolts.
      Tighten the axle nut.
      Lower bike and jounce to settle suspension.
      Now tighten the pinch bolts.
     

[uclabiker06]

Well, took the tire off and put it on a balancer and used a dial gauge.  The disc is warped.  The weird thing is that the other disc that the disc lock wasn't on is warped to according to the dial indicator.  So I will need new discs.  Anybody upgrading, who wants to get rid of a pair of stock discs that are not warped or grooved?

[Ddan]

Like Howie said, you can't really check the discs with a dial indicator because they are floating on the carriers.  This doesn't mean they aren't warped, but it doesn't mean they definitely are, either.

[uclabiker06]

Well, from what i understand there isn't anything else that can cause pulsing, so I am confident thats what it is.  I mean I don't know what else it could be so I am just going to get a new rotor or new sets of rotors.  Could the disc lock have bent or damaged the caliper?  The disc would bend before the caliper so it must be the disc.