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Thread: Brake caliper bleeding screw discussion - removal / prevention / bolt alternative etc

  1. #1
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    Brake caliper bleeding screw discussion - removal / prevention / bolt alternative etc

    What are your thoughts on bleeding screws, they seems to be a common problem where they get seized up easily and worst of all their 6mm - 7/16 hex heads round off like cheese. The part that makes me laugh most is when the rubber grommet goes over the top buy doesn't cover the nut part, so when the rust sets in it's game over. Apart from dipping them in grease what do you track guys have as alternative? I feel this might be the wrong crowd to ask as most people here will end up saying "just a new bleeding screw". Combine that with often wrenching and bleeding as your typical track car maintenance, I bet they don't seize up. However, I've been thinking what about just putting in regular bolts ( don't worry about threads, could be just a botch custom welded nut on top) so that way you never have to suffer and make it as simple as removing brake caliper bolts with a socket. Of course it's not like it's going to burst out with fluid, you can always quickly swap with the bleeding screw, do you brakes, then put the bolts back in.
    My idea kinda reminds me of catalytic converters used once a year to pass emissions and back in the loft they go.

    https://i.imgur.com/6YukDw9.jpg
    Anyway, I'm dealing with couple rear calipers that were never driven on since fitted, and no amount of heat and cool downs will brake them free. I feel bad for the guy that put his project on hold and now the whole calipers might need replacing. I've done the heat/cool down as the JewTube tutorials, heating the nipple instead of the surrounding metal which I think is kinda wrong but I get what the cycles are suppose to possibly do to the rust. It ain't coming out! Left it overnight with some penetrating oil and tomorrow last resort is to put a nail inside, get my welder, and put a nut to get a socket onto it.

    So what do you think about this? What cool better alternative ideas do you have for the bleeding screws? I haven't even checked if somebody like Turner/Dinan makes cool little overpriced "racing spec" gadgets...

    Update: See #15


    https://i.imgur.com/fxFgX1k.jpg
    https://i.imgur.com/hORtukj.jpg

    The welded nut idea worked flawless, the only pain was sourcing long 35mm instead of the common 27mm bleeding screws. Regardless if they are m7, m8, m10. Now I can just crack them open with a 13mm socket and never worry about rounding them off.
    Last edited by S1Driver; 11-10-2019 at 11:03 AM. Reason: Success, thanks for all the help and replies

  2. #2
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    Well, the answer is new bleeders, and no they don't rust on track cars ... they get opened a few times a year at least.

    Having said that, they can still round if some he-man decides to go crazy on them. Get new ones, then ALWAYS use a 6 point socket to crack them open, don't use a wrench. After they are cracked, use the wrench to bleed, then use the socket again to do the final tighten. They don't need a lot of torque at all.

    Your idea with a bolt is interesting, but the issue is that the seal is a taper, so you'd need to find something cause you probably can't grind a perfect taper into the bolt. Also, you can usually find oversized bleeders with a larger nut on them so they'll be a bit easier to deal with.

    What are you using for heat? I've never had issues with MAP gas, even on ancient street cars that haven't been cracked in like 10 years. Get that sheit red hot, then put a vise grip on it.
    Last edited by ScotcH; 10-12-2018 at 05:04 PM.
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  3. #3
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    No issue on a track car that has frequent bleeds as long as you dont over torque. I have bled brakes on e36 and e46 cars for a long time and have zero rust or corrosion issue. When one rounds, it's probably time to buy a few rebuilt calipers anyhow or replace the bleed screw.

  4. #4
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    I recently bought reman’d Centric M calipers for $38 apiece after the core return. Pretty hard to beat that deal when you have a broken bleeder on a caliper and probably need new seals as well.

  5. #5
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    I bought a couple of bleeder screws from NAPA when I rounded one of the front screws. NAPA ones come with 7mm nuts and I haven't had any problem with them yet. I bought OEM ones to replace it but haven't done it so since it's working just fine.

  6. #6
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    Has anyone had leaks from the bleed screw threads?
    It only happens on track after a big brake application.
    I replaced the bleed screw and it still happened. Am I looking at new caliper?

  7. #7
    NeilM is offline Member BMW E36 M3 Expert
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    Quote Originally Posted by Nugs View Post
    Has anyone had leaks from the bleed screw threads?
    It only happens on track after a big brake application.
    I replaced the bleed screw and it still happened. Am I looking at new caliper?
    Perhaps so. The pressure seal isn't made by the threads, but by the tapered end of the bleeder screw against a conical seat in the caliper. If a new bleed screw hasn't fixed it then its seat in the caliper is suspect.

    Neil

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    Quote Originally Posted by Nugs View Post
    Has anyone had leaks from the bleed screw threads?
    It only happens on track after a big brake application.
    I replaced the bleed screw and it still happened. Am I looking at new caliper?
    I bought some rebuilt calipers last summer. I can't remember the brand. Anyway, the bleeder screws that came with the caliper were a sloppy fit. Once I replaced them with new bleed screws, they were fine.
    If God meant for man to motor-swap LS engines into track cars, He wouldn't have created Corvettes.

  9. #9
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    Wrap some plumber’s Teflon tape on the threads (not the taper seat) and they’ll never rust or seize in the caliper.

  10. #10
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    Quote Originally Posted by cmstrilchuk View Post
    Wrap some plumber’s Teflon tape on the threads (not the taper seat) and they’ll never rust or seize in the caliper.
    Sorry, but no. This is not a place for plumbers Teflon tape. Teflon tape is for permanent applications and is not meant to be loosened and tightened repeatedly after applied.

  11. #11
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    I know we're talking about brake bleeders, a fairly basic and inexpensive part, but has anyone run the Stahlbus bleeders? Pricey but it seems like a precision made speed bleeder and interesting concept.

    http://www.stahlbus.com/products/en/...stem/index.php
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  12. #12
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    Those 'type' of bleeders have been available for a while. The motorcycle guys love 'em.
    I don't see a use for them on my car....I have a pressure bleeder that pressurizes the system. I attach the contraption to the brake reservoir, adjust air pressure to ~10psi, and loosen a bleeder valve and let it run for as long as needed.

  13. #13
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    Yeah, I have a pressure bleeder too. The bleeders that came with my reman calipers are sloppy fit like JBasham described, so they let a bit of fluid past the threads when they are opened. I just need to get some better normal bleed screws to see if they are a tighter fit.
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  14. #14
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    Fair point, mine do that a bit also.

  15. #15
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    OEM Brake calipers are fully rebuild now. I want to say thanks to Scotch for bringing to my attention, it's not the threads that create a seal but the tapered end. And yes it was butane torch, it's impossible finding MAP gas around here that can get metal cherry red hot but at the end it wasn't needed. The front's were just as bad to remove, even though I didn't round the M7 nipple, I still end up welding a nut rather professionally that I can now reuse them. So first part of the info for anyone who stumbles on this topic. Both rear and front calipers are using M7 bleeding nipple screw contrary to popular believe. Second, for 25 year old calipers they were in mint condition inside apart from the dust seals. The good ol' trick with the air pump pushing the piston out worked like a charm. Fitting the dust seals back on was a huge struggle with 2 pair of hands and J hooks, only to realize a neat trick by placing the seal at the very edge and pushing the piston back in till it all popped. Did the fronts by myself and it took me 20min instead of 4 hours and 2 people. The air pump popping the seal on a E36 doesn't work just FIY (too tight compared to couple of FWD cars I've done it on).

    https://i.imgur.com/fxFgX1k.jpg
    https://i.imgur.com/hORtukj.jpg

    And finally I don't know if there is some sort of records book, but make sure you put me in it, as I'm the first guy to ever use 13mm socket on bleeding screws. Yep, took me ages to find 35mm long bleeding nipples for BMW that doesn't cost a bomb, but eventually a company on ebay sold me x10 for tenner, for the same price as the common 27mm long screws, on the front you can get away with the 27mm but the rear needs the longer 35mm, I had a bunch of hex nuts (some regular, some automotive with the washer build in for a better hose seal, see pics) welded all x10 so I have spares and I can add on my other cars. Now simply take a 13mm socket, crack them open with ease, put your neighbours magic hose that he threw away after 6 months (it's just thin surgical tubing inside) and voila, perfect seal, proceed to bleed with 13mm spanner. And no you will not find anyone who sells oversized nut bleeding screws, I looked around didn't see any, and I'm sure there is a racing company out there who will rush in to say we do but I doubt 20$ per 1 is something I would pay. Or something stupid along those lines. Anyway I will update eventually with pictures on the actual car and how they are holding.

    The era of rounded off caliper bleeding nipples is over for me



    Part numbers in case somebody cares:
    https://i.imgur.com/auB42X9.jpg
    https://i.imgur.com/pzsCd0H.jpg
    https://i.imgur.com/okksk26.jpg
    ID:36mm seals front & rear
    Last edited by S1Driver; 11-10-2019 at 11:23 AM.

  16. #16
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    - - - Updated - - -

    Quote Originally Posted by aeronaut View Post
    Sorry, but no. This is not a place for plumbers Teflon tape. Teflon tape is for permanent applications and is not meant to be loosened and tightened repeatedly after applied.
    Permanent, shmermament. It will help prevent the threads from seizing, as would anti-seize paste but... Regular fluid flushing exercises the fitting and purges the rusty sludge. On a well maintained car this should never be an issue anyway.

    A common mistake I see is after bleeding a mechanic doesn't dry the fluid from the fitting but rather caps it still full of hydrophilic brake fluid, just asking for rust
    Last edited by ross1; 11-19-2019 at 04:51 PM.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  17. #17
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    Quote Originally Posted by spidertri View Post
    I know we're talking about brake bleeders, a fairly basic and inexpensive part, but has anyone run the Stahlbus bleeders? Pricey but it seems like a precision made speed bleeder and interesting concept.

    http://www.stahlbus.com/products/en/...stem/index.php
    Great idea but not sure I'd like to add complications (opportunity for failure) to my braking system.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

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