slates
Expert Class
Posts: 377
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posted April 27, 2010 04:36 AM
warped rear rotor
I'm almost positive I have a warped rear rotor. It's more pronounced now that I put on new brake pads on. If I try to spin the rear wheel it grabs in one spot.
I want to make sure that it's not brake pad build up on the rotor. What abrasive material should I use on the end of drill or by hand to make sure it's not brake pad build up? I only get a little pulsating feedback when braking hard coming from the back of the bike. I always brake with front and rear.
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black zx14 - Brock's Gen3 Carbon, PCIII, no secondaries, Carrozzeria wheels, Sato rearsets, Pazzo levers, GPR V4 steering damper, Puig windscreen, Tiger Racing chain guard
  
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Superman T
Pro
Posts: 1831
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posted April 27, 2010 04:53 AM
Buy a new rear rotor, they are cheap!
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Hellmutt
Needs a job
Posts: 2013
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posted April 27, 2010 05:16 AM
You can use a mild grade of sandpaper ( I'd use 320 or finer ) with a block or a drill attachment -- just be sure to sand from the inside out, perpendicular to the rotation of the rotor -- then just blast clean with brake wash.
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British flying couch with endtables and an orange thumper
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Niner9
Novice Class
Posts: 75
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posted April 28, 2010 05:57 AM
I have this same problem, thing is I rarely ever use my rear brake?
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Hellmutt
Needs a job
Posts: 2013
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posted April 28, 2010 06:19 AM
Have either of you pulled the rotor from the wheel and reinstalled? If there's any debris between the rotor and wheel, it wouldn't seat squarely and appear/feel warped when running through the caliper. Other than that, if it is warped.......I wouldn't hesitate to simply replace it.
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British flying couch with endtables and an orange thumper
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INTIMIDA2OR
Needs a life
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posted April 28, 2010 06:23 AM
quote:
I'm almost positive I have a warped rear rotor. It's more pronounced now that I put on new brake pads on. If I try to spin the rear wheel it grabs in one spot.
I want to make sure that it's not brake pad build up on the rotor. What abrasive material should I use on the end of drill or by hand to make sure it's not brake pad build up? I only get a little pulsating feedback when braking hard coming from the back of the bike. I always brake with front and rear.
If there is build up on the rotor you should be able to see it.
If the wheel actually slows down when you spin it then you need a new rear rotor.
Why it warped is a different story.
Are there any signs of the rotor discoloring from heat?
Do you see any signs of something coming in contact with the rotor at the spot that grabs?
Check the caliper pistons to see if there's any gunk buildup on them.
That would allow the pads to stay in contact with the rotor cause the pistons aren't moving freely.
Also check the rotor bolts to see if they're loose.
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'06 Passion Red ZX-14
*Lee*
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BobC
Pro
Posts: 1736
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posted April 28, 2010 06:35 AM
 Edited By: BobC on 28 Apr 2010 14:36
If the brake grabs in one spot it could just be that the friction is greater there. Has the bike been parked wet, is there corrosion where the pad was sitting? Has the disc been overheated? If you stop with really hot brakes it can cause localised overheating where the pad is in contact with the disc, that would cause grabbing too. This should all disappear with more use and bedding in.
If it is warped I guess it wouldn't be too difficult to spin it against a dial-gauge. If you don't own such a thing you could improvise with a pointer and watch the gap. I've seen warped discs trued with a judicious tap in the right place from a hide mallet.
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Candy Thunder Blue 2006 ZZR1400
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INTIMIDA2OR
Needs a life
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posted April 28, 2010 07:28 AM
quote:
If it is warped I guess it wouldn't be too difficult to spin it against a dial-gauge. If you don't own such a thing you could improvise with a pointer and watch the gap. I've seen warped discs trued with a judicious tap in the right place from a hide mallet.
I've fixed many rotors with this method 
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'06 Passion Red ZX-14
*Lee*
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BIGZXDADDY
Expert Class
Posts: 270
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posted April 28, 2010 09:53 AM
roloc discs from scotchbrite on a die grinder works good for removing build up from the rotors and they are not abrasive enough to damage the rotors
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Hellmutt
Needs a job
Posts: 2013
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posted April 28, 2010 10:20 AM
quote:
roloc discs from scotchbrite on a die grinder works good for removing build up from the rotors and they are not abrasive enough to damage the rotors
good call!! forgot about those handy little rolocs
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British flying couch with endtables and an orange thumper
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SLVR_BLT
Zone Head
Chicken Strips!
Posts: 589
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posted April 28, 2010 12:09 PM
Wow, you can warp a rear rotor this big and thick on a 14? I rarely use the rear brake, heck it feels like it does nothing anyways.
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2006 Kawasaki ZX14, Muzzy Full Titanium Exhaust w/ Carbon Can, PCIII, BMC Street Filter
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zixxer14
Pro
Damn that was Quick
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posted April 28, 2010 06:27 PM
quote:
Wow, you can warp a rear rotor this big and thick on a 14? I rarely use the rear brake, heck it feels like it does nothing anyways.
Gotta ride it like a chop, use that rear brake, you wouldn't want to use the front it could flip right over. 
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slates
Expert Class
Posts: 377
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posted April 29, 2010 03:42 AM
Gotta ride it like a chop, use that rear brake, you wouldn't want to use the front it could flip right over.
Assume your kidding, but my original post says, "I always brake with front and rear." Now I have practiced and used hard braking to haul this bike down before from triple digits to make a 90 degree turn and when riding hard in the twisty's. I'm no light weight like Smokin either.
It is not severe, but the wheel doesn't rotate smoothly and definetly has a point that holds up more than the rest of the rotor. It's been an issue since new wheels were installed. The rotor bolts are snug. I need to have someone a little more mechanically inclined than me look at it.
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black zx14 - Brock's Gen3 Carbon, PCIII, no secondaries, Carrozzeria wheels, Sato rearsets, Pazzo levers, GPR V4 steering damper, Puig windscreen, Tiger Racing chain guard
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68gts2
Zone Head
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posted April 29, 2010 03:58 AM
I would try removing the calaper and remove the pads from them. Take a piece of medium grit sand paper and wrap it around a flat piece of wood. Scuff the pads with this and re-install them. Re-bed them slowly so as not to glaze them which is what it sounds has hapened to them. The pulsing will likely not be there anymore and you will love the price of this rotor fix.
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Chromed-out,in the dirt 08SE with all the good stuff!!!
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slates
Expert Class
Posts: 377
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posted April 29, 2010 04:14 AM
quote:
I would try removing the calaper and remove the pads from them. Take a piece of medium grit sand paper and wrap it around a flat piece of wood. Scuff the pads with this and re-install them. Re-bed them slowly so as not to glaze them which is what it sounds has hapened to them. The pulsing will likely not be there anymore and you will love the price of this rotor fix.
I would, but I just installed brand new EBC pads and they only have one ride on them.
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black zx14 - Brock's Gen3 Carbon, PCIII, no secondaries, Carrozzeria wheels, Sato rearsets, Pazzo levers, GPR V4 steering damper, Puig windscreen, Tiger Racing chain guard
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68gts2
Zone Head
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posted April 29, 2010 04:41 AM
You can re-scuff them and clean the rotor and calaper with brake clean while its apart. If you still think its warped take a metal coat hanger and make a pointer out of it and attach it to the swingarm bend it to where it is only a hair from touching the rotor. Spin it and see if there is a high or low spot.
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INTIMIDA2OR
Needs a life
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posted April 29, 2010 09:11 AM
quote:
It's been an issue since new wheels were installed. The rotor bolts are snug. I need to have someone a little more mechanically inclined than me look at it.
Hmmm , sounds like it was damaged somehow during installation.
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'06 Passion Red ZX-14
*Lee*
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slates
Expert Class
Posts: 377
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posted April 29, 2010 11:34 AM
Hmmm , sounds like it was damaged somehow during installation.
Could be....I'm thinking that maybe the bolts weren't crossed tightened a little at a time and they were tightened fully one at a time.
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black zx14 - Brock's Gen3 Carbon, PCIII, no secondaries, Carrozzeria wheels, Sato rearsets, Pazzo levers, GPR V4 steering damper, Puig windscreen, Tiger Racing chain guard
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