Rebuilding front brake on EX500

**El Zilcho** · 03-29-2010, 04:05 PM

I decided to rebuild the front brake on my EX500. The bike has about 33,500km on it and has never had the front brake serviced in any way (other than spraying brake cleaner on it). I thought I'd take pictures of the process and share with everyone.

First, I drained the brake fluid out of it. It looked black. Not pretty at all. The feeling of the brake lever going all the way in had some "edge" to it even though the bike was parked.. haha. Anyways... There is a banjo bolt that connects the brake line to the caliper and two bolts that attach it to the fork. After undoing them all, this is what it looked like:

That hole in the middle is where the brake line was connected. The screw with the cap on the left is the bleeding valve.

The other side looked a bit dirtier:

You can see the brake pads. One on top with the yellowish color, and the other one, a bit smaller, a bit angled in the picture above. Underneath that pad there are two round dirty cylinders. Those are the pistons. You can see them more clearly in the picture below after the smaller pad has been removed:

You can see something that looks like two smaller cylinders inside the bigger ones that have + shaped grooves in them. Those are just plastic fillers. They are parts of the pistons. Believe it or not, but the actual pistons are the outer cylinders with some metal shining through the dirt.

Next, I removed the other brake pad. This one required a bit more manouvering since, as you can see it can slide up and down on the side bolts, but it won't easily go all the way up to the point where you can just take it out. This may not be the best method, but I finally managed to get it out of there.

Then you can take a better look at the pistons:

This is how the whole thing looks like, being taken apart:

After removing the plastic pieces, you can see that the pistons are actually metal cups.

Now, here comes the interesting part. The pistons have a tendency to get stuck. At least these pistons were. It was not an easy task to pull them out. Nothing I tried would work, until I put a bit of WD-40 around the cylinders. After a few hours I was able to remove the pistons without too much effort.

This is the whole caliper taken apart into pieces:

Here's a closer look at the cylinders. There are two seals in each of them: one (thinner) right at the edge of the cylinder, and another one (thicker) a bit deeper:

Here are all the parts washed and shiny, ready to be put back together.

**El Zilcho** · 03-29-2010, 04:05 PM

Here it is after the seals were replaced and the pistons were seated back in the cylinders:

From here it's pretty much an easy thing. This is right before putting the pads back on:

The pads still had some life left in them so I haven't replaced them. Here it is after the whole caliper was back in one piece:

The last thing was attaching the caliper to the fork, and filling it with the brake fluid. I must say that the brake lever does feel a bit stiffer now. Previously it seemed a tiny bit spongy compared to the current feeling.

**frekeyguy** · 03-30-2010, 05:34 PM

nice write up!

**toastywaffles** · 04-05-2010, 01:01 PM

nice!

Next time, get the pistons out of the brake caliper before you remove the banjo bolt. It will save you about 5 1/2 hours of work

I.e, just loosen the banjo so that you can later loosen it by hand, remove the caliper from the fork, slide the brake pads out and pump the pistons out. Don't forget to add more fluid to the MC!!!