Results 1 to 14 of 14
  1. #1
    mtbr member
    Reputation:
    Join Date
    Sep 2009
    Posts
    287

    Rotor Cause of lost power

    I've lost power in the front brake.
    - Swapped the pads, didn't help
    - Brakes are firm - don't think they need rebled
    - Swapped lever and caliper - no help.
    - Swapped the wheel which gave me a different rotor - I have power again.

    What can go wrong with a rotor. Don't think it got lube or anything.
    These are XX rotors in CR Mag Calipers. Guessing it was some sort of organic pad.

  2. #2
    ...idios...
    Reputation: SteveUK's Avatar
    Join Date
    Apr 2006
    Posts
    5,663
    I don't mean to offend, but you did fit the rotor the right way around?

    What use is a philosopher who doesn't hurt anybody's feelings? -
    Diogenes


  3. #3
    mtbr member
    Reputation:
    Join Date
    Jul 2010
    Posts
    690
    Did you ever sand the rotor to break through the heat glaze?
    Quote Originally Posted by ridelikeafatkid
    "MOMMY, I WANT TO RIDE LIKE THAT FAT KID!" true story.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Jan 2009
    Posts
    828
    scuff pads
    scuff rotors
    clean pads/rotors (i hear alcohol but ive used reg. brake cleaner)
    bed the pads in correctly

  5. #5
    mtbr member
    Reputation:
    Join Date
    Sep 2009
    Posts
    287
    @steveuk - yeap they are on the right way and not offended.

    @trboxman - that's the only thing I haven't done. can you share any details? What grit of sandpaper?

  6. #6
    mtbr member
    Reputation:
    Join Date
    Jul 2010
    Posts
    690
    80g or 100g should work just fine. Don't get carried away, you're just trying to sand through the glaze and provide a new surface not remove a bunch of material.
    Quote Originally Posted by ridelikeafatkid
    "MOMMY, I WANT TO RIDE LIKE THAT FAT KID!" true story.

  7. #7
    Nouveau Retrogrouch SuperModerator
    Reputation: shiggy's Avatar
    Join Date
    Dec 1998
    Posts
    48,315
    Quote Originally Posted by trboxman
    80g or 100g should work just fine. Don't get carried away, you're just trying to sand through the glaze and provide a new surface not remove a bunch of material.
    Better to use 800grit and lots of water.
    mtbtires.com
    The trouble with common sense is it is no longer common

  8. #8
    Newt Guy
    Reputation: FrostyStruthers's Avatar
    Join Date
    Jul 2010
    Posts
    837
    Got for a ride. Put some muddy goop from the trail into pad/caliper area. Spray with hydration pack hose a bit to moisten good. Ride. Use brakes. Repeat if necessary. Brake power back. Wash bike if you deem it appropriate post ride.
    Yes, steel is most certainly stronger than aluminum EVERY time.
    ~Frosty Struthers

  9. #9
    mtbr member
    Reputation:
    Join Date
    Sep 2009
    Posts
    287
    Thanks guys. I didn't sand much or hard on the rotors and got a noticeable difference. Not like I want to be yet but again I didn't sand much.

    Maybe that is just what happens when using organic pads??? I know organic pads are supposed to be used with XX calipers but not sure why. Not sure if CR Mags have the same requirement. Maybe I'll just go back to normal elixir sintered pads.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Jan 2009
    Posts
    828

    Good job!

    Quote Originally Posted by shiggy
    Better to use 800grit and lots of water.
    maybe if i wanted to polish them....

    i use course scuffy pads on my die grinder ...... (prob. equal to 80grit)

    ya also have to break/bed the pads in before they will work 90/100%....

  11. #11
    mtbr member
    Reputation:
    Join Date
    Jul 2010
    Posts
    690
    Quote Originally Posted by shiggy
    Better to use 800grit and lots of water.
    Way too fine IMO. They aren't surfaced that finely from the factory. I'd surface them dry with wet/dry paper and wipe them down with alcohol...or if I felt the need for a lubricant I'd use the alcohol as a lubricant.
    Quote Originally Posted by ridelikeafatkid
    "MOMMY, I WANT TO RIDE LIKE THAT FAT KID!" true story.

  12. #12
    mtbr member
    Reputation:
    Join Date
    Jul 2010
    Posts
    2,452
    A rough sanding will make the pads bed easier. Just like bedding channels car pads sometimes come with. However, I fear taking out too much is too easy with 80 or 100 grit. It's a personal choice.

    I use 400 grit and a glass surface to sand the pads. sanding an angle on the pads can cause problems me thinks. All it takes is a couple of passes. Blast your calipers with a brake cleaner, taking care to catch overspray. That'll get rid of any bad juju that might be making your brakes slip (dried soap, shock lube, chain lube). Wipe the rotors too.

    I'm not to keen on the rotor sanding stuff. It's possible to sand in peaks and dips that may be felt later on when braking. Rotors won't wear in like pads.

    All this is assuming that your brakes are bled right.
    Last edited by bing!; 08-22-2010 at 10:54 PM.

  13. #13
    sm4
    sm4 is offline
    mtbr member
    Reputation:
    Join Date
    Jan 2010
    Posts
    32
    Sanding that will have alot scraches particle at disc surface, During applied brake the pad
    will collect the partical, Once partical stick at pad become more and bigger that will chew
    up your disc surface.

  14. #14
    mtbr member
    Reputation:
    Join Date
    Sep 2009
    Posts
    287
    Quote Originally Posted by riding29
    Thanks guys. I didn't sand much or hard on the rotors and got a noticeable difference. Not like I want to be yet but again I didn't sand much.

    Maybe that is just what happens when using organic pads??? I know organic pads are supposed to be used with XX calipers but not sure why. Not sure if CR Mags have the same requirement. Maybe I'll just go back to normal elixir sintered pads.
    I used 100 grit. Also used brake cleaner to clean up the rotors afterward, but it was the sanding that gave me the power back.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •