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Special Brake Bleed Fitting?


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I need more information on this fitting. What is its purpose? It must be used to bleed brake line. If so, how it it used? Are there ant special tools or fittings required.



2000 1100rtp

The story started went I decided to change brake pads before trip. The change went well but when I tested brakes the fronts would not release. The only way to lease was the crack the bleeder. When to the forum and learned that there could be a problem with deteriorating brake lines. Soooo, replaced lines with Galfers SS lines.

(Side note Lines were a week late and the rear line was 2 inches too long. Galfers said the line they sent was to spec but were will to exchange it for a shorter one. There service was good and there was good but I lost two weeks waiting for parts.)

The lines are in and the new brake fluid is in, flushed all fluid through ABS. The rear system is appear to be good but I and not get all the air out of the front system because I have no way to bleed right caliper. This caliper has this special fitting with a set screw on the top with a check valve underneath. I suspect are may be a special tool? I am keeping my fingers crossed that the ABS is happy.

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That fitting is the factory fill fitting. You can either (i) remove the grub screw on top and insert the pointed-nosed bleeder screw that moves the check ball off its seat, then reinstall the grubscrew, (ii) remove the grub screw and leave the bleeder valve installed, or (iii) remove the entire fill fitting permanently and replace it with the bleeder valve.


Two comments if you decide to remove the fill fitting:


1. The bleeder is available from the dealer in a package that comes with the correct rubber dirt-exclusion cap.


2. Be *careful* when removing the fill fitting.


The fitting is installed with blue locktite. You must either *lightly* heat the threads -- without damaging adjacent rubber seals/plastic bits/etc. to loosen the locktite -- or must *slooooowly* work the fitting loose to overcome the locktite, without applying any lateral force on the fitting. Failure to take care will result in the fitting snapping off, leaving its locktited-in-place thread stub in the caliper. Ugly situation.


I've removed a few from front right calipers and clutch bleed hoses. I've used light heat and no heat on the clutch bleed hoses and no heat on the calipers. Not sure whether the heat made any difference. Either way, not going gorilla is the key.

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I would add this: to remove the fill fitting, according to the factory service manual, the caliper should be taken off the wheel and held in a vise with the bleed port facing down. This is so none of the loctite used on the fill fitting drops into the caliper and fouls it. I found that the fill fitting was easy to remove once I got it good and warm with a heat gun. Then, very carefully, I installed a speed bleeder. Carefully because speed bleeders can break, and then you're faced with extracting the broken part. No fun, DAMHIK. though the speed bleeder site gave me excellent instructions on how successfully to do it. They'll do it if you can't, for free, but then you're without the part for however long.


all best, Lincoln

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Afternoon Hotdog


As Mark noted above, most of us old-timers just removed that darn factory fill device & tossed it in the trash. Then simply installed a conventional bleed screw (good to go from then on)


But as mentioned above: there can be problems getting the factory fill device out as well (heat related) and the warning about debris dropping into the caliper when breaking the factory fill device loose.


BMW did put out a service bulletin on how to bleed the R/H front caliper without removing the factory fill device.


A bleed screw (PN 34 21 2330 310) is all that is needed to complete the bleeding with the factory fill device still on the caliper. Just remove the top plug then screw in (PN 34 21 2330 310)


Note: The factory filling device check valve functions such that it's inner check valve is closed when the bleed screw (PN 34 21 2330 310) is screwed all the way in or all the way out. In between, fluid flows out freely.


Note 2: There is also a warning in the service bulletin to thoroughly clean out all the trapped brake fluid in the check ball area before reinstalling the top plug (prevents corrosion in the check ball area)


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