Join Date: Dec 2002
Location: Bonita, CA, USA
Another brake bleed thread
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?
'99 K1200LT Champagne(in Heidelberg)
'08 K1200LT Black
Last edited by Richdude; Dec 30th, 2010 at 4:48 am.