According to the Brake Fluid article on Wikipedia... [ame=http://en.wikipedia.org/wiki/Brake_fluid]Brake fluid - Wikipedia, the free encyclopedia[/ame]
Did mine a month or so back and used a variant on Ron's Mini's Garden Sprayer/Brake Bleeeder idea (see the 'how to's'). Worked fine and the car stops on a dime! Only note was that you do not need to do the 15-20psi suggested, 10psi works just fine
This isn't a typical example, the reservoir had a crack and the slave had a blown seal, the slave's content and first two ounces of fluid from the slave's line were all water; the beading fluid in the pan is water.
A segment in this how-to [ame=http://www.lonestarminiclub.com/forums/showthread.php?t=476]Brake Fluid Flush - Lone Star Mini Club Forums[/ame]
BMP has a clutch slave cylinder tool they SAY works with the MINI; anyone ever used it? It's like 25 bucks--I was thinking of getting it if works, just as added insurance to prevent a screw up. How essential is it to bleed the clutch? I haven't done it yet. I've flushed/bled the brakes countless times for the track (basically before and after each event), but I haven't touched the clutch yet. Car only has 17,000 miles on it, but a substantial number of those are on the track.
Good question! So far there are 2 votes for "yes, essential" and 5 for "not essential," so it's hard to say for sure.
Lets put it this way. BMW actually makes a tool for depressing the clutch the proper amount so as not to damage the diaphragm/seal inside the slave cylinder and assist in bleeding. So it would seem at least they think it should be done now and then.
Seems to me there would be benefits in keeping out any moisture buildup with the brake fluid through regular changes, including the clutch slave cylinder. In colder climates, moisture might cause problems with the clutch release.
+1 At one point in time when I was still running my old BBK I had to flush my brakes between each session. I average about 30+ track days each year.
Sorry, but it doesn't really get into much detail on the clutch slave. A bit more in depth post would be great .
It's that simple; I would only add the slave plunger must be fully compressed, no gaps between the accordion sections on the boot.
kimberlein verified air can be trapped in the slave, and bleeding the slave can improve clutch engagement in the R56. A simple gravity bleed of her slave yielded big bubbles and a section of clear fluid in the drain tube, most likely water. The R56 slave has a convenient finger actuated bleeder gate; no need for numerous turns with a wrench, just a half turn with thumb and forefinger. The plunger still must be compressed, but it offers less resistance than the R53, and although Kim used the early model OEM tool with an extension to take account for the deeper slave, the slave's plunger rod can be pressed inward by hand. So it appears there is no bad voodoo lurking in the R56 clutch hydraulics that one may risk disturbing if bled.
Keith, I am wondering if you need to depress the clutch slave in the R56. I have attached a copy of the BMW TIS manual that discusses bleeding the clutch slave and it makes no mention of any special tool for that.
Fluids take the path of least resistance, so any air trapped ahead of the slave cylinder gate would not be forced out. I have the TIS and there are a few omissions in other procedures also. EDIT: I think I see where it would be assumed the pressure plate spring would keep the plunger fully compressed, but there must be a point where the clutch release bearing is unloaded. While loosening the slave nuts it appeared the rod was not compressed all the way from what I could tell.
Here are some pictures. The first is the clutch slave cylinder after we removed the slave nuts and before we depressed the clutch slave rod. The R56 clutch slave plunger is longer than the R53 plunger, so Keith added a socket and an extension to make the threaded rod of the R53 tool long enough to depress the plunger all the way. Actually, like Keith said above, the plunger was pretty easy to push in. If we didn't have the tool, I could have held it depressed with only the strength of my girl hand while Keith bled the clutch slave. While the clutch slave cylinder rod was depressed, Keith opened the bleeder valve by hand (again though, I did it too, so man-hand strength not required). A ~3 inch air bubble came out along with what looked like water. After clutch slave bleeding, my clutch pedal was smoother and shifting seemed crisper. Just fyi, this is a 2008 MCS (I got it 6/08; build date 5/08) and the clutch slave had never been bled.