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Thread: Brake Issue

  1. #1
    Join Date
    Mar 2019
    Location
    Sevenoaks
    Posts
    69

    Brake Issue

    Morning all,

    I really need some sound advice for what should be a very simple issue.

    I bought from AK with the kit, refurbished XJ40 running gear.

    Since having installed all the fluids in the car last week....my rear calipers continue to weep very slightly from the thread of the bleed screw (nipple). After thinking i needed to bed them in they continued to weep. After extraction, it was obvious they had score lines on the conical face. Surely this should be clean and flat......

    I therefore bought some OEM replacements which arrived clean and flat. Installed them last night.......just nipped them up...leaked, nipped up a little more....still weeped. Tightened up and off, on and off.....as i had to on advice from Roadcraft for their slave clutch unit to bed in and seal. Inspected this morning and i still have a weep both sides.....took screw out and they both now have score lines on the cone point.

    Is there a simple solution....or am i going to have to dismantle both brakes and formally inspect etc etc.....and take another 10 steps backwards.....to go the one simple step forward.

    Of course i have referred back to AK as i sourced them "new/refurbished".

    Any help or pointers gratefully received. Anyone else had this issue........Having tinkered with motorbike and car brakes over the years i havent had this issue before.

    Thanks

    Julian
    AK Cobra started 06/19
    Chevy 383 Stroker, TKO 600
    See my build on instagram: Julesdm14

  2. #2
    Join Date
    Aug 2002
    Location
    Through the Darien Gap
    Posts
    1,034
    Turn or two of PTFE tape on the thread?
    Steve Brown

    CRC Regional Rep - East Anglia

  3. #3
    Join Date
    Jun 2005
    Location
    Norton Cross
    Posts
    520
    Try a dowty washer. Worked for me when my brake flexie connection was weeping on calliper connection

  4. #4
    Join Date
    Mar 2019
    Location
    Sevenoaks
    Posts
    69
    Thanks Peter but this is not the flexi connection that is leaking. It is the bleed nipple.
    Quote Originally Posted by peterj1974 View Post
    Try a dowty washer. Worked for me when my brake flexie connection was weeping on calliper connection
    AK Cobra started 06/19
    Chevy 383 Stroker, TKO 600
    See my build on instagram: Julesdm14

  5. #5
    Join Date
    Apr 2005
    Location
    Worcestershire
    Age
    44
    Posts
    2,283
    If they are being scored whilst being fitted, you should see what is causing the scoring inside the hole on the calipers.

    IMHO a washer or PTFE tape should not be fitted to a bleed nipple, the cone should seal on the caliper.

    If the calipers are scoring the nipple, you should be able to see the fault on the caliper, if there's a fault on the caliper send them back to AK.
    Regards

    Craig Perry

    No, I'm not "repairing" it, I'm fine tuning its performance.

  6. #6
    Join Date
    Sep 2010
    Location
    Nova Scotia
    Posts
    831
    Do these score lines travel around the cone? If so, it's more or less normal. They are made when the nipple is tightened down. See below:



    If you tighten the nipple enough, it ought to seat without leaking. Of coarse this might mean snapping the nipple off if things are really bad. If the scoring is really bad, from over-tightening, it may leak after it's removed and re-installed.

    Another thought is that is isn't leaking, but residual fluid is weeping out and will eventually stop. I've checked this sort of thing by wiping with a paper towel, waiting awhile, then wiping again and looking for fluid on the paper. Sometimes this needs to be repeated a few times until all the fluid is soaked up.

    If you still have no success, then the caliper seat may be a problem.
    John

    “A prudent person profits from personal experience, a wise one from the experience of others.”

  7. #7
    Join Date
    Mar 2019
    Location
    Sevenoaks
    Posts
    69
    The score lines are around the cone where it has been seated...thus i would have thought it would seal......

    I am going to take a caliper off tonight and have a proper look into the hole! Bo**ocks....didnt want to start taking things off the car!!!! I do have a call out to Jon @ AK upon his return from hols. Calipers could be going back to him.

    PS. the weep is not latent moisture in the thread......this is a leak.

    Quote Originally Posted by Eggbert View Post
    Do these score lines travel around the cone? If so, it's more or less normal. They are made when the nipple is tightened down. See below:



    If you tighten the nipple enough, it ought to seat without leaking. Of coarse this might mean snapping the nipple off if things are really bad. If the scoring is really bad, from over-tightening, it may leak after it's removed and re-installed.

    Another thought is that is isn't leaking, but residual fluid is weeping out and will eventually stop. I've checked this sort of thing by wiping with a paper towel, waiting awhile, then wiping again and looking for fluid on the paper. Sometimes this needs to be repeated a few times until all the fluid is soaked up.

    If you still have no success, then the caliper seat may be a problem.
    AK Cobra started 06/19
    Chevy 383 Stroker, TKO 600
    See my build on instagram: Julesdm14

  8. #8
    Join Date
    Sep 2010
    Location
    Nova Scotia
    Posts
    831
    It will be interesting what the seat at the bottom of the hole looks like. If the calipers are refurbished units, it makes me wonder if a previous owner ruined the seats by trying to drill the bleeder screw out. Could be a rather ragged and jagged hole down there.

    Or is it bleeder screws? Are both leaking?
    John

    “A prudent person profits from personal experience, a wise one from the experience of others.”

  9. #9
    Join Date
    Jan 2006
    Location
    Chelmsford Essex
    Posts
    989
    Close inspection at the base of the hole should reveal the issue. I had similar issues with debris swarf in the hole. I ended up with new bleed nipples.and cleaned out the debris. You end up sucking air into the system so never achieve a solid pedal.

  10. #10
    Join Date
    Mar 2019
    Location
    Sevenoaks
    Posts
    69
    Well i took them off and could not see any obvious issues. The thread was clean and the seat looked re milled.......any way, they are now in a box on their way up to AK. Thanks for comments and help. J
    Quote Originally Posted by jon1d View Post
    Close inspection at the base of the hole should reveal the issue. I had similar issues with debris swarf in the hole. I ended up with new bleed nipples.and cleaned out the debris. You end up sucking air into the system so never achieve a solid pedal.

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