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Latest post Tue, Apr 11 2017 11:56 AM by FX. 3 replies.
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  • Tue, Apr 4 2017 2:30 PM

    Rear (rotor) brakes too tight/hot

    I just dissected a thread from 2005 about rear brake pads being too tight, rotor overheating, etc. I put new (HD) pads, rotor, wheel bearings, tire & caliper seals, pins & pistons on my '00 Road King. Afterward it was a little snug turning the R wheel while on the jack & backing up in "N". New pads & rotor??? I went on a 2.5 mile ride (city). I lost the rears about half way. Upon return the rotor had blued where the pads ride. I don't recall if I had pressure build-up in the caliper afterwards, but I did in the master (I'm sure the fluid had boiled, due to complete lack of pedal pressure). I re-bled the system & drove it a mile using the rears (& fronts) about 4 or 5 times. I didn't lose the pedal but the R rotor was HOT, the fronts were still cold. Another mile would've easily been enough to transfer enough heat to boil the fluid again.

    Somewhere along the line I ended up with @ 1/16" freeplay in the outer pad. :<) Inner pad was still tight :<(. I have that PITA caliper that requires axle removal (4 piston caliper). If I pry inward on the caliper from the swing arm, the tire/wheel spins freely. I miced (sp) a new piston from a spare kit & compared it to one of the old pistons. Battery's dead in my micrometer but I would guess the new pistons are @ .004" taller. Which would probably be enough to gain enough clearance to make everybody happy & spinning freely. I'm not sure how I'm gonna fix this w/o taking everything back apart, but.......any suggestions other than pounding the crap outta the caliper assembly with a HEAVY mallet bending it slightly inward? I actually did that & it's actually....better, but not perfect. I guess I could try flat sanding the inner pad. Food for thought....or not.

    And, HEY all you genius engineers: How about looser & self adjusting clearances along with some kind of piston/pad return mechanism? 

  • Wed, Apr 5 2017 5:33 AM In reply to

    • FX
    • Top 10 Contributor
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    • Joined on Sun, Mar 12 2006
    • Tonawanda NY
    • Posts 5,096
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    Re: Rear (rotor) brakes too tight/hot

    TT, half way through your post, I was thinking "flat sanding the inside pad", then you said it.

    Do that, and see how it is. It sounds like the caliper is not 'floating' as it should.

    FX

    Don't force it, get a bigger hammer.

  • Mon, Apr 10 2017 7:03 PM In reply to

    Re: Rear (rotor) brakes too tight/hot

    This one is fixed. I'm not really sure what the actual problem was. I fixed it by flat-sanding the inner pad. Based on all the measuremnts I made, my best guess would be a SLIGHTLY bent caliper arm. I had to take @ .020 off of the inner pad to get decent clearance. I started out using some 80 grit emory along with some elbow grease. Screw that. I got out the belt sander with a 40 grit belt for a quick finale. So, "I'm on the road again".

    - Willie N.

     

  • Tue, Apr 11 2017 11:56 AM In reply to

    • FX
    • Top 10 Contributor
      Male
    • Joined on Sun, Mar 12 2006
    • Tonawanda NY
    • Posts 5,096
    • Moderator

    Re: Rear (rotor) brakes too tight/hot

    Good to hear ya got it fixed. Happy motor'n

    FX

    Don't force it, get a bigger hammer.

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