Cannot Get Pads Aligned with Rotor

[fencingdude101]

Hey everyone,

I've had a lot of front brake problems after installing new pads and rotors and rebuilding the caliper- Check out here for more info: http://www.riderforums.com/general-n...need-help.html
I won't bore you with the details, but go there if you care.

As for my question, I eventually realized that one of the pads I installed wasn't up against the rotor properly- only an edge of it was making contact, while the rest of the pad was 1-2mm off the rotor, tilted away. I took off the caliper, kinda jiggled the pads a bit, and stuck it back on. The brakes work better, but after a quick test around the block, they still don't feel right, and the new wear marks on the rotor tell the same story. They just don't provide very much braking power, about on-par with the rear brake, but nowhere near as smooth or feeling as well.
So, does anyone have ideas on why they may be off? I'm planning on taking it off again and seeing if I can make it align better, but is there something else I missed when installing them to cause this? Any ideas are welcome, thank you.

[DCMoney]

You've put something back together incorrectly, can you post pictures?

[fencingdude101]

Originally Posted by DCMoney

You've put something back together incorrectly, can you post pictures?

I'm at work for another 2 hours or so, then I'm taking a look at it when I get back. If I can't get it quickly, I'll take a few and post them up.

[flitecontrol]

Any possibility they gave you the wrong pads?

[alex.s]

one of two things. either A (unlikely) you didn't put the pad bolts in or they are dragging on the pad bolts. if this is the case put in lubed up pad bolts. if they are in and they aren't dragging then it is probably one of the pistons is stuck. how did you clean them? i only glanced through your other thread. if the piston walls and the cylinder walls aren't nice and smooth they will easily jam

[fencingdude101]

Originally Posted by alex.s

one of two things. either A (unlikely) you didn't put the pad bolts in or they are dragging on the pad bolts. if this is the case put in lubed up pad bolts. if they are in and they aren't dragging then it is probably one of the pistons is stuck. how did you clean them? i only glanced through your other thread. if the piston walls and the cylinder walls aren't nice and smooth they will easily jam

I don't mean to look dumb, but what do you mean by pad bolts? The big pad's ends have holes that fit into the caliper pins- it just sits pushed up against the end of the caliper. The small one isn't strictly attached, from what I remember. There's a anti-vibration spring that it gets pushed into and up against the pistons, but that's about it. This is on a Ninja 250 '03, but is there supposed to be something else holding them in? I was a little confused as to why/how a metal piece is the only thing holding them in- through pressure.

For the pistons being stuck, I put a decent amount of lube on them but had to push them back in with a vice when I did the rebuild. They slowly worked out after I rebuilt the caliper, but just last night I took the caliper off, the pads out, and pushed the pistons back in as a way to "reset" things. The large piston worked out a bit fine- but slowly- however the small piston just moves in and out a tiny little bit instead of working its way out (This is with the large piston clamped down). I didn't spend a bunch of time on it last night to figure it out, so I'm just about to head to the garage to see what I can do. I think I just pushed it in too far, but is that a sign of another problem? I thought I lubed them just fine, but maybe not.

[alex.s]

the pad bolts meaning the caliper pins. they are bolts with axles on the end that fit through the holes in the pad.

with the brake line off you should be able to move the pistons without too much force

[ds650rida]

Use a brake hone or a piece of sand paper and clean up the bore in the caliper. Both pistons should move out equally when the brakes are applied.

And dont forget to put some lube on the piston seals before reinstalling

[fencingdude101]

Originally Posted by alex.s

the pad bolts meaning the caliper pins. they are bolts with axles on the end that fit through the holes in the pad.

with the brake line off you should be able to move the pistons without too much force

Alright, just making sure we were talking about the same thing. Those are fine, they're lubricated and slide fine- the big pad has no problems sliding along them either.

In terms of the pistons, do you think I did something wrong when installing them? I could only get either of them half way in when I rebuilt the caliper, like I said the vice was used to get them the rest of the way. I'm going to spend a bit more time with it, then take the caliper off again and take off/clean the pistons again. See if I can get them to slide in easier than the first time.

[ds650rida]

When I rebuild a caliper I make sure I can slide the piston in and pull it back out with my fingers. So yeah I'd say 99% thats your problem.

[alex.s]

i think rich is correct. brake hone and sandpaper sounds like the answer here.

[fencingdude101]

Originally Posted by ds650rida

When I rebuild a caliper I make sure I can slide the piston in and pull it back out with my fingers. So yeah I'd say 99% thats your problem.

Originally Posted by alex.s

i think rich is correct. brake hone and sandpaper sounds like the answer here.

Point taken- I just rebuilt the caliper quick, re-lubed everything, and the pistons slid in perfectly, nice and smooth. Granted, after reinstalling and bleeding, the pistons still do that back-and-forth movement without actually moving outwards too far, but it's better and I think there's still air in the system. I'm going to let it sit for an hour or two, then try to bleed again and post an update. At this point, however, everything is flawless on the caliper side of things, with smooth pistons and smooth pins.

[agentbad]

Zip tie the brake lever to the bars and leave it overnight.

[fencingdude101]

Thanks for the help everyone! I bled everything one more time, but no air came out. With my morals down, I decided as a last ditch effort to pump the brake as fast as I can for 100-200 times.
Well, what do yah know?!
After about 75 times, the brake started to harden up, so I kept on going. Eventually, it started feeling really usable- the pistons actually moved out and the pistons were grabbing, with no pad alignment issue. I took it out for a ride, and while not perfect, useable and workable!
Thanks for the help again looks like it really was the caliper pistons.

Originally Posted by agentbad

Zip tie the brake lever to the bars and leave it overnight.

I'm planning on doing that tonight, hopefully it'll help a bit more.