Main Motorcycle: 01 Tiger 955i
Join Date: Jul 2010
Other Motorcycle: KTM 400RXC
Extra Motorcycle: Cannondale Caffeine HT ;)
Cleaning da pistons
x2 On tiger-g and hearhd6 This blatantly sounds like the pads are obviously dragging. There is an off chance that this could be in the mechanics of the master cylinder. If everytime you squeeze the master cyl piston is not releasing it will hold wear on your breaks. If this drag doesn't release quickly (because the rotor eats away the contacting pad) then it's prob on your caliper end.
Mine were like this a couple months after buying the tiger. The good news for me when this happened was that it taught me 2 things. 1- It taught me how basic Hydraulic brakes function (and helped me later when tackling brakes on my Cherokee) 2- It taught me the discipline of cleaning my brakes regularly, especially when I'd been riding in the dirt or mud.
Your pads never really receded. All that happens is the pressure lessens and they back slightly away from the rotor. Over time the sides of the pistons in the caliper slowly drag bits of dirt into this area and thus will hold pressure to tight.
If it's not already caused damage then don't fret; this is an easy common procedure on brakes. You could really do this on the side of the street even if needed; but I suggest a clean work area.
Grab a 6 pack of beer, some rubber gloves (brake fluid is nasty) brake cleaner (can be sourced at any auto store, the key is that it's bio-safe and a mechanical cleaner that leaves NO residue and is safe for brakes), and Brake fluid (I use 5.0 because I have it in the shop, it's important that you use what is in the bike and recommended; stay away from all the synthetic fancy stuff it's b/s)
Call your local dealer and grab an extra set seals and crush washers. They should only set you back a few quid each. You may not need them, but if you take this stuff apart your brakes are important so it's worth the small investment to freshen them while you're in there.
There could be a possibility of scaring on the piston, so if you don't mind having extra bits laying around I'd pick up at least one extra with the seals.
I suggest starting with your rear caliper first to get the hang of it before dealing with 2 up front.
As you read this remember I am not a grammatician, nor a mechanic; I may be totally wrong and this could also cause the apocalypse to occur and zombies to take over. I have no idea what I'm saying.
-Carefully remove your caliper from the bracket. Do not yet remove it from the line. Also if you're new to brakes do not kink the line, or add to much stress to it. Try to keep it relatively lax and neutral.
-Remove your pads. Simply remove the pin and allow the pads to drop out. Set these aside since yours are new. If fitting new pads it's smart to keep an old set around. When pressing pads, etc back into the caliper old pads make a great platform to press on, as you always apply pressure evenly.
-Hold your caliper in one hand It is important for the next step that you hold the caliper with the piston facing the ceiling.
- Finish your beer (or holler to a helper so you don't have to put the current one down) carefully begin actuating the brake lever. As you do this the piston should start slowly extending from the caliper.
- Allow the piston to completely rise out of the body of the caliper (I have, but don't recommend, needed to pop it out the last bit with a careful tug with a tool). At this point you want to set the piston in a safe place. (alternatively you can remove the caliper completely and eject the piston by forcing compressed air into the bleeder)
-Carefully disconnect the caliper from the brake line; I recommend doing this with the line elevated, then pin it in place to keep from spilling the fluid within. .
You're halfway there. Take a break and head to the local store for some more beer, and while out pick up more brake cleaner and the finest emery polishing cloth you can
- Start with the piston. Inspect it. You are looking for signs of significant wear. Use your judgement. The idea is that it needs to be smooth enough to hold pressure. If you find any major damage (deep scratches, chips, etc) it's time to replace the piston. Minor wear is expected. If you can see depth at all though or catch your fingernail (or lovely assistant's finger nail) in a scratch it's time to go. They aren't that expensive so don't hesitate to if you think you need it, otherwise all your work may be in vain.
- If you are satisfied it's time to start cleaning. The surface of the piston needs to be absolutely as smooth and pristine as possible. Just use brake cleaner and very fine polishing material (superfine sandpaper, cloth, etc).
- Once satisfied that the piston is clean check out your caliper. You're main point of concern should be the walls in the chamber that the piston travels. They should be free of any debris, and wear as mentioned with the piston. Check your seals out and you should replace them. Or skimp and risk it if the ones in there look good. If there is any major damage in the caliper check with a pro before proceeding. Failure of the caliper can be dangerous and expensive.
- Finally you're ready to reassemble. Shouldn't be difficult, be sure to very evenly and carefully compress your piston back into the caliper. Lube the passage with brake cleaner and use a flat surface to press on the piston. It should slide in if clean with relative ease.
-Keep brake cleaner handy and spray down your brake area at least weekly. I also carry some on long trips and hit my pad/caliper area if I've encountered a buncha mud.
- Reassemble, bleed your lines, sober up, and enjoy a much smoother and effective braking experience.
I hope this helps. I am not at home but may be able to add photos once I get there at some point. I made a write up of this on advrider or tigertriple or something. If I find them I'll add this.
Last edited by WVdyhrd; 12-22-2012 at 04:28 PM.