Front brake pads rubbing

[Young Will]

Installed some new brake pads from mikes. However after I installed the new pads I noticed the new pads rubbing against the rotor. Also I noticed on the old pads one of the pads was more worn out than the other. I was just wondering if anyone had some knowledge on what maybe causing this issue.

Thanks

 

[5twins]

It may be time for a caliper cleaning. The piston may not be moving and retracting as well or as much as it should. Have you ever cleaned the caliper out? If not then my best guess is that's your problem. There is a square sectioned o-ring "seal" in the wall of the caliper that seals against the piston. Over time, the groove it fits in starts getting filled with a build-up of dried out brake fluid. This forms a crust and that forces the seal out more. This eventually binds up the piston and makes it stick.

 

[Young Will]

It may be time for a caliper cleaning. The piston may not be moving and retracting as well or as much as it should. Have you ever cleaned the caliper out? If not then my best guess is that's your problem. There is a square sectioned o-ring "seal" in the wall of the caliper that seals against the piston. Over time, the groove it fits in starts getting filled with a build-up of dried out brake fluid. This forms a crust and that forces the seal out more. This eventually binds up the piston and makes it stick.

My caliper is a new reproduction from mikes I got about a year ago. Is it possible it got dirty that quick and needs a cleaning. Or is it also possible old gunk from the brake lines maybe dirtied it up? Before putting the new pads in I compressed the piston and took some fluid out of the master cylinder to make room for the new brake pads and the piston moved good. Do you think my best bet is cleaning the caliper?

 

[5twins]

Well, if the caliper is that new, it shouldn't be crusted up yet. How about your MC? Is that new too or original? If original, maybe it needs a cleaning. There's a couple small holes between the piston area and the reservoir. One lets fresh fluid into the piston, the other lets it bleed back when you release the brake. If that return hole is partially plugged, that might do it. Yes, the caliper piston seemed to move OK when you actually forced it, but maybe it can't on it's own. In operation, the caliper seal clings to the side of the piston and stretches out a little as you apply the brake. When you let off, the rubber retracts and pulls the piston back with it.

But, a little pad drag is normal. As long as it's not to the point that it's hard to turn the wheel by hand or the disc gets really hot after riding, you may be fine.

 

[Young Will]

Well, if the caliper is that new, it shouldn't be crusted up yet. How about your MC? Is that new too or original? If original, maybe it needs a cleaning. There's a couple small holes between the piston area and the reservoir. One lets fresh fluid into the piston, the other lets it bleed back when you release the brake. If that return hole is partially plugged, that might do it. Yes, the caliper piston seemed to move OK when you actually forced it, but maybe it can't on it's own. In operation, the caliper seal clings to the side of the piston and stretches out a little as you apply the brake. When you let off, the rubber retracts and pulls the piston back with it.

But, a little pad drag is normal. As long as it's not to the point that it's hard to turn the wheel by hand or the disc gets really hot after riding, you may be fine.

I rebuilt the master cyclinder about a year ago and cleaned it all out. The rubbing just makes a noise when I sit on the bike and roll it. I haven't tried riding it yet because I didn't think it should be rubbing. Should I ride it down the street and see if it's an issue. I didn't have this issue last time I changed brake pads because I used old pads on the bike that weren't that bad, maybe they didn't rub because they had already been worn down a little?

 

[5twins]

Yes, that could be it. Elevate the front wheel and turn it by hand, see how bad the rubbing is and how hard the wheel is to turn. If it's not too bad, take a short ride and check how hot the disc is getting. Caution, lick your finger tip before touching the disc. If it's getting really hot, you'll get burned if you don't. Once the new pads bed in and wear a little, the rubbing should decrease, but it may never totally go away. Like I said, a little rubbing is sorta normal.

 

[Young Will]

Yes, that could be it. Elevate the front wheel and turn it by hand, see how bad the rubbing is and how hard the wheel is to turn. If it's not too bad, take a short ride and check how hot the disc is getting. Caution, lick your finger tip before touching the disc. If it's getting really hot, you'll get burned if you don't. Once the new pads bed in and wear a little, the rubbing should decrease, but it may never totally go away. Like I said, a little rubbing is sorta normal.

I didn't run it because some thing looks like it may have been gauging into the top of my rotor. I think it maybe a fitting issue or in doing some thing wrong. I have had to put the pads in by taking the caliper apart and putting the pads in and re assembling. But I look it up and it said that you should be able to drop the pads in, but this is impossible with the metal shims. Also my clymer manual isn't helping much either.

 

[Young Will]

One of the metal shims is what is gauging the top of my rotor. Do you only run the shim on one side, I'm thinking that this is my problem