So if you followed my saga I had a very stiff rear brake pedal that didn't quite stop the bike. So I first did a complete fluid change and bled the bakes. Same problem. I pulled the caliper and cleaned the rear caliper and pulled all three pistons out, and they looked perfect, no leaks in the caliper either. If you have never been in the caliper there are 3 pistons, one about quarter sized, and two about nickle sized. There are 2 rubber seals in each caliper. These are similar to "O" rings but are flat and not round. The upper one has what can be described as a groove cut in it which makes the rubber very thin on the edges. I noticed that the center and front piston each had a very small tear in the ridges of those seals. There were actually two pieces of rubber in each caliper floating between the two seals. Now by small I mean 3/16 inch long and about the diameter of 10 lb. test fishing line. I cleaned the pieces out, and put the pistons back together, put it all back together and problem continued. Back to the caliper. I pulled the caliper again but left it intact and pushed down on the foot pedal. To my surprise only the one outboard piston came out. The other two that had the torn seals stuck in. So now things are starting to make sense. Braking was bad because only one piston was working. Pedal was stiff because the 2 other pistons were wedged in with bad seals. Now the fix. I went to a Honda dealer and found inept personnel who indicated the seals were discontinued. But I remembered seeing them on BikeBandit in stock, so I called them. Their response was " Yep we can get them, still made in fact one set fits the CRF450 (2015) and the other fits the 1000RR (2015). So I ordered the seals, which cost abut $30.00 for all three sets. Installation was easy. Take a sharp pick and pop the old ones out. Lube up the new ones and put them back in. Thick one on the bottom, thin on the top, only goes one way and impossible to screw up. Lube up the pistons with Dot4 and gently push them back into the caliper body. Bolt it back together and put it on the bike. Bleed the brakes (again). Whole deal takes about 35-40 minutes if you have your tools out. An presto the brakes work properly. I could not believe those little pieces of torn seal were the culprit, but it didn't work before I changed them, and now it does. I never did it before and it was simple to do, including the bleeding. Hope this helps somebody else out.
Good to know , on a personal note, not that at this time I'm finding it worthy a mission to dig deeper, but this topic does put some thought into this.. The rear brakes on my newly Acquired 5th gen suck , compared to the 4th gen I had. just figured it was what it is with the linked braking BS, get use to it huh? Now I read this, food for thought, thanks.
