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Discussion Starter #1 (Edited)
I just did my first brake bleed on the wheel circuits of my 2008 K1200LT. I wouldn’t have tried it if it wasn’t for the guidance from John Zeigler and others. Thanks much.

I read all I could and even when to the dealer today in hopes of seeing the $300+ funnel tool BMW says is necessary. As it turns out my dealer doesn’t use it and doesn’t have one. They use a vacuum bleeder at the calipers and the usual turkey baster. Many ways to skin a cat!

That approached seemed a little messy to me. Some buy an extra cap and epoxy a funnel to it; building a tool very similar to BMW’s at a fraction of the cost.

I decided to try modifying the existing caps instead. I drilled a hole and tapped a 1/8” pipe thread into the center of the cap. A short nipple (with a nut shoulder) gets screwed into the top of the plastic caps. The cap can still be removed, but now with an open end wrench instead of an Allen.

During use, a threaded brass cap is screwed to the exposed end of the nipple; sealing the reservoir. When it’s time to do a brake flush, remove the cap and screw on a female 1/8” pipe fitting connected to a plastic tube. The tube can be connected to a funnel or just use a foot or so of the tubing. Keep the tube filled with fresh fluid, use speed bleeder nipples, and a wheel circuit brake flush takes only a few minutes, one guy, and very little mess. If someone else (dealer) needs to service the brakes, the extra parts don’t interfere at all with their method.

Two important details (learned the hard way).
1. The tubing can’t be too small. 3/8” diameter seems to work fine. 1/8” doesn’t work at all because the surface tension doesn’t allow the fluid to flow by gavity (bubbles don’t rise).
2. Because the vent tubes are still part of the connection in this method, you must raise the end of the vent tube above your fill fluid level. Otherwise, your fresh fluid will flow out the vent tubes to the floor.

#2 brings up another point and my question. I understood the purpose of removing the calipers, pushing back the cylinders and inserting blocks during bleeding was to prevent an overfill condition in the wheel circuit reservoirs. For example, new, thicker pad, would pushes fluid back into the reservoirs. But, if the reservoirs are vented and excess fluid can easily escape, why bother? Why not leave the calipers in place during bleeding?
 

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Richdude said:
#2 brings up another point and my question. I understood the purpose of removing the calipers, pushing back the cylinders and inserting blocks during bleeding was to prevent an overfill condition in the wheel circuit reservoirs. For example, new, thicker pad, would pushes fluid back into the reservoirs. But, if the reservoirs are vented and excess fluid can easily escape, why bother? Why not leave the calipers in place during bleeding?
I think the purpose of removing pads for bleeding is to clean up the pistons and rubber covers with brake cleaner spray so when you push them back in the grit doesn't do damage.
 

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1. I read all I could and even when to the dealer today in hopes of seeing the $300+ funnel tool BMW says is necessary. As it turns out my dealer doesn’t use it and doesn’t have one.
. . . .
2. Because the vent tubes are still part of the connection in this method, you must raise the end of the vent tube above your fill fluid level. Otherwise, your fresh fluid will flow out the vent tubes to the floor.

3. I understood the purpose of removing the calipers, pushing back the cylinders and inserting blocks during bleeding was to prevent an overfill condition in the wheel circuit reservoirs. For example, new, thicker pad, would pushes fluid back into the reservoirs. But, if the reservoirs are vented and excess fluid can easily escape, why bother? Why not leave the calipers in place during bleeding?[/QUOTE]

1. The special funnel is available form Beemberboneyard.com for $35. Definitely worth getting for blushing the ABS units prior to about 7/2006 when BMW changed the design.
2. Go to speedbleeder.com and get the Speed Bleeder for each of the calipers, two in front and one in back. Change out the stock bleeder valves for Speed Bleeder and save yourself a lot of hassle in the future. Makes bleeding brakes a one man operation. Also get the Speed Bleeder bag which looks like an IV bag on the web site. It comes with a hose and the old fluid goes into the bag. No need for a hose and plastic coke bottle and worrying about the plastic coke bottle falling over spilling brake fluid all over the floor.
3. You can bleed the brakes with the calipers in place. One reason to remove the calipers and shim them with wood shims is the one you mention, that is when you change out the old pads for new (thicker) pads. The other reason I've heard is that by removing the calipers, pushing the pads in and shimming them, you are pushing out as much of the old fluid as possible which would otherwise remain in the caliper. Frankly, I flush the brakes once a year on my bikes so I leave them in place unless I am changing out pads. :bmw:
 

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Hi Richard,

I did not remove the calipers on my 99 when I flushed the brake sys. I did push the pistons back and tap in wooden wedges to keep the calipers from filling up. Seemed to work fine.
 

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Discussion Starter #6 (Edited)
The Beemberboneyard fill funnel looks exactly like the design by Hager and Gilman.
http://users.rcn.com/dehager/service/abs3_filling_adapter.pdf
I didn't know it could be reasonably purchased or I might have gone that way. Still, adding the fill nipples works beautifully and cost nothing (or just a few dollars if you don't have a lot of parts about).

Loren, the wheel circuit reservoirs on my model (2008) are definitely vented as shown in the attached drawing. The vent tube is small and long so there is probably not too much water vapor sucking in. Since there is no room for an expansion bladder, I guess it has to be that way. But, it's another good reason to change the fluid annually.

I took a few notes as I worked to make my next year's brake bleed a little easier. They are brief and no substitute for reading and understanding a detailed procedure, but gives a quick check list of the necessary steps. If any one see an error or something really unclear, please let me know and I'll fix it. 2 formats of the same document.
 

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Wrencher Extraordinaire
2005 K1200LT
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Richard,


Well done. You can just use the F3 and R3 ports for a flush of the control circuit as per BMW bulletin a few years back. You still need to do all three ports for a bleed. I have found very little contaminated fluid in the other two ports anyway so it is almost not worth it.

I am still having a hard time visualizing what you did with the 1/8 nipples. Any photos?
 

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Discussion Starter #8 (Edited)
John
Thanks for the input. I revised the one page flushing outline and have attached it below. I wanted to replace the old one in my post above to avoid confusion, but I don't know how.

I also moved my cap modifcation to a separate drawing. The cap modification isn't necessary to using the flushing outline, but it sure works well.

Here's a link to cheap brass fittings. http://www.discounthydraulichose.com/Brass_Hose_Barbs_s/96.htm
 

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