Everyone knows the benefit of changing your brake fluid. How many of you change/flush your brake fluid only to notice the new fluid looks dirty in a short period of time. Also has anyone cleaned their calipers and noticed the bottom pistons not working very well. Keep reading to find out why.


I flushed the fluid in my CBR 954 about a week after I purchased my bike in October 2009. Today while doing some maintenance work I noticed my front fluid looked as bad as it did last year. I take my calipers loose and give them a good cleaning at about once a month to remove all the dirt and brake dust. Everytime I noticed how easy the top pistons moved in/out to clean them but the bottom pistons were very hard. I use a tooth brush and brake cleaner to clean the calipers. I need to purchase the caliper tool that allows you to turn the pistons for even easier cleaning. Lightly apply the brakes forcing the pistons out without the brake pads installed makes cleaning the pistons easier. The top pistons always come out easy and by using my hands I could push one side back in which would push the other side out making it easier to clean. Applying the brakes never forced both sets of pistons on either side out at the same time. I thought this was a little odd since you would think they would come out together to apply the brakes evenly. I would have to place the brake pads in between the top pistons and apply the brakes and let the pads stop the top pistons while allowing the bottom pistons to come out further to clean them.

Today I ran into a little problem. Just like before the top pistons were easy and the bottom did not want to move. I pushed a little harder on one of the bottom pistons trying to get it to move back in and suddenly one of the top pistons came completely out with brake fluid going everywhere. I tilted the caliper to keep the fluid from pouring out. I looked in the caliper was shocked at how dirty it looked. It looked like muddy water under the piston. Knowing now that I would have to bleed the brakes I decided what the hell I might as well split the calipers apart and give them a really good cleaning. Never before had I split the calipers in half to clean them. I was shocked at the amount of dirt I found in each half. It explains why the bottom pistons didnt work very well. When the calipers are mounted on the bike the fluid comes in at the top behind the first piston and goes under it through a small passage in between the pistons down to the second piston. The calipers are tilted on the bike so most all of the dirt that gets in the brake system ends up settling at the bottom behind the second piston. (see pic below) You can flush your brake system everyday and not get this dirt out. It was very thick and took spraying it with brake cleaner and wiping with a cloth several times to get all of it out. Also when I removed the banjo bolts there was build-up there too. All four halves had the same amount of dirt as the pic below. My bike has 23k miles on it and I know this is the first time the calipers have been taken apart and cleaned.

I ordered all new seals for both the front and back calipers from ronayers for a little over $38 shipped. I feel this is cheap maintenance that probably never gets done on most bikes. The seals may have been good but it makes me feel better to replace them. I also decided to upgrade the brake lines. I ordered Speigler black/black brake lines with some Motul RBF 600 brake fluid. I may also paint my calipers since I really dont care much for the gold finish. Black or red would match my bike better.