Two quick questions. I had my front MC powder coated and just put it back on my '08 Fatboy. I also had the MC rebuilt as part of the paint job. As I added DOT 4 brake fluid for the first time, and began to purge out the air, I noticed some black "stuff" rising up from the holes at the bottom of the MC. I am wondering if this "stuff" was some sort of oil used in the cylinder during manufacturing or assembly? I sucked out as much as possible with my Mitty-vac. Anyone know what this "stuff" was?

Also, and this is stupid, but I forgot to note which side of the MC the thicker part of the cover goes (remember the cover has a wedge shaped profile) ?? Logically is seems that is should have the thicker side towards the center of the bike.

Thanks a bunch, Chris.

 

A black powder looking substance in brake fluid could be absorbed moisture. brake fluid is hygroscopic. I recently rebuilt my front m/c and there was quite a bit of it in there.

 

Having mine flushed and fresh brake fluid back in is on my winter list. I have always flushed mine every 10k miles or 3 years whichever comes first. I would think if a drop or two of water got into your system that would ghooo up a brake system in a hurry. Water in a brake system is not a good thing.