Results 1 to 13 of 13

Thread: 1987 K75C 34.6K Oldest Karibic Bleu Brake Rotor Nut question

  1. #1
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    123

    1987 K75C 34.6K Oldest Karibic Bleu Brake Rotor Nut question

    I'm a bit embarrassed to have to ask this but here goes.

    I'm replacing the front brake rotors. The new nuts have a knurled side that is a smaller diameter than the non-knurled side. Which side rests against the washer and why is one side knurled?

    Pic attached. Not very sharp but you should get the idea. The knurl is on the bottom in the shown pic.

    Thanks in advance,
    Pete
    Attached Images Attached Images

  2. #2
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,758
    Pete,

    The nuts are self locking nuts (no lock washer or loctite required when new). You may be more familiar with Nylock self locking nuts with the nylon insert.

    The nuts you have, have a slight crimp in the diameter at the smaller end (the end facing down in your photo). When new, this causes a slight interference fit when the bolt reaches those threads. The bolt is started on the large diameter (top) end of the nut and after a few turns, gets tighter. These nuts, being all steel, have a higher temp capacity than nylon locking nuts (probably a good thing near brakes).

    These are officially intended as a one use nut, as the deformation (locking capability) is reduced slightly after even one use, but a drop of red Loctite will let you reuse these with no worries.

    After all that; necked down side out.






    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  3. #3
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    123
    As always excellently explained. Many thanks Lee!

    Pete

  4. #4
    Registered User 36654's Avatar
    Join Date
    Jul 2008
    Location
    Central PA
    Posts
    5,418
    Quote Originally Posted by pjar View Post
    I'm a bit embarrassed to have to ask this but here goes.

    I'm replacing the front brake rotors. The new nuts have a knurled side that is a smaller diameter than the non-knurled side. Which side rests against the washer and why is one side knurled?

    Pic attached. Not very sharp but you should get the idea. The knurl is on the bottom in the shown pic.

    Thanks in advance,
    Pete
    What does the rest of the bike look like?
    Cave contents: 16 R12RS, 13 Toyota Tacoma, 03 Simplicity Legacy, 97 Stihl FS75, Dewalt DW625 & SawStop PCS175
    1) My expectations are never low enough & 2) Incompetence is infinite ........David Brooks

  5. #5
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    123

    Rotor and Pad replacement update

    Hello,

    R&R went fine. I work slow and methodically so it took me a fair amount of time. The only temporary hitch was with new rotors and pads the pads would not insert with calipers mounted and torqued.

    I removed calipers, made sure pistons moved easily and were fully recessed, mounted calipers lightly (bolts tightened by hand) and then inserted pads while jiggling calipers as needed. That worked. After torquing the caliper the pads slipped up or down easily.

    Lee if you have another super slick black magic solution please share it. Thanks again for you help.

    The brakes perform well with no squealing or pulsing after a test ride. It was refreshing!

    Pete

  6. #6
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    123

    Attached is a pic

    Quote Originally Posted by 36654 View Post
    What does the rest of the bike look like?
    Picture attached with previous owner.

    The original owner added a fuel gauge (left) and temp gauge (right peeking out behind the brake fluid reservoir). The fuel gauge is unnecessary IMHO, but the temp gauge is nice and enables you to know if the fan engages at the right temp.

    Enjoy!
    pete
    Attached Images Attached Images

  7. #7
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,758
    Pete,

    Are you putting in new STOCK rotors or AFTERMARKET rotors?

    If they are aftermarket, if you have the capability, measure the thickness. Aftermarket rotors may be a few thousandths thicker than stock, which might make it a little harder to install new pads.

    Which pads are you using and are they FA-18 pad size? What is their thickness?

    Stock pads with stock rotors: remove pads, retract pistons, install new pads. Nothing special.





    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  8. #8
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    123
    Quote Originally Posted by 98lee View Post
    Pete,

    Are you putting in new STOCK rotors or AFTERMARKET rotors?

    If they are aftermarket, if you have the capability, measure the thickness. Aftermarket rotors may be a few thousandths thicker than stock, which might make it a little harder to install new pads.

    Which pads are you using and are they FA-18 pad size? What is their thickness?

    Stock pads with stock rotors: remove pads, retract pistons, install new pads. Nothing special.





    Hi Lee,

    EBC rotors with EBC organic pads (FA-18). Thickness of the rotors is .2005" I'm thinking I may not have had the pistons completely retracted on the initial try. I haven't checked the thickness of the pads, but there is no binding when I spin the wheel. It feels normal.

    Pete

  9. #9
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    123
    Quote Originally Posted by pjar View Post
    Hi Lee,

    EBC rotors with EBC organic pads (FA-18). Thickness of the rotors is .2005" I'm thinking I may not have had the pistons completely retracted on the initial try. I haven't checked the thickness of the pads, but there is no binding when I spin the wheel. It feels normal.

    Pete
    This is why I'm not a mechanic because I sometimes overlook the obvious. The prior rotor/pad set up squealed a lot. I used CRC Disc Brake Quiet to try to stop the squealing. That worked for about 24 hours. When I removed the calipers I noticed there was build up of the Disc Brake Quiet on the outer edge of the piston and on the dust cover. That too may have contributed to my initial difficulty inserting the pads.

    Pete

  10. #10
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,758
    Pete,

    Sounds like your detective work has ucovered the likely suspects.





    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  11. #11
    Curmudgeon At Large Bobmws's Avatar
    Join Date
    Mar 2003
    Location
    Astatula, FL
    Posts
    1,309
    Quote Originally Posted by pjar View Post
    This is why I'm not a mechanic because I sometimes overlook the obvious. The prior rotor/pad set up squealed a lot. I used CRC Disc Brake Quiet to try to stop the squealing. That worked for about 24 hours.

    Pete
    They all do that, really. The trick is to brake harder, really. Just like pre-loading the shifter, it's a BMW feature, not a quirk.
    Bob Weis
    Bikeless! 2004-bmw-k12rs-hannigan-Sold!

  12. #12
    3 Red Bricks
    Join Date
    Jan 2007
    Location
    Pleasanton, Ca.
    Posts
    4,758
    Quote Originally Posted by Bobmws View Post
    They all do that, really.
    Not really.

    Less than 2% of the K75/100s that I've seen or worked on had squealing brakes. The ones that wanted that fixed were corrected with new pads and proper break in.

    Squealing indicates SOMETHING is not happy at the pad/rotor interface. Usually the problem is glazed pads. Sometimes it is just the pad material (I like the EBC HH pads). Sometimes it is the rotor surface that has developed issues.





    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  13. #13
    PeteG
    Join Date
    Dec 2009
    Location
    Woodacre, California
    Posts
    123
    Quote Originally Posted by 98lee View Post
    Not really.

    Less than 2% of the K75/100s that I've seen or worked on had squealing brakes. The ones that wanted that fixed were corrected with new pads and proper break in.

    Squealing indicates SOMETHING is not happy at the pad/rotor interface. Usually the problem is glazed pads. Sometimes it is just the pad material (I like the EBC HH pads). Sometimes it is the rotor surface that has developed issues.





    Lee, you are spot on again. I previously bought used rotors, one of them had some run-out, but much less than the ones that I was replacing. What I didn't know and didn't thoroughly research was to replace the pads when replacing the rotors. I used the original 29-year-old pads and they squealed like hell. So yes, they were most likely glazed. So far the new set up is working great (new pads and rotors). It was worth the expense. Thank you!

    pete

Similar Threads

  1. 1987 K75C 19K Front brake rotor replacement question
    By pjar in forum Flying Brick K-bikes
    Replies: 4
    Last Post: 11-15-2015, 02:14 AM
  2. Brake rotor question 96R11RT
    By mrhall in forum Oilheads
    Replies: 5
    Last Post: 01-11-2010, 01:13 PM
  3. 1987 K75c
    By pakratk75 in forum Flying Brick K-bikes
    Replies: 6
    Last Post: 06-09-2007, 07:28 PM
  4. 91 K100LT Rear Brake Rotor Question
    By warthog in forum Flying Brick K-bikes
    Replies: 3
    Last Post: 01-09-2006, 05:18 PM

Posting Permissions

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