SOMEONE PLEASE HELP ME !

[TheDirtyJuan]

So my rear brake caliper was seized and wouldn't move at all, so I took it off, cleaned end it, rebuilt with new seals and cleaned the pistons, lubricated it, slid back in fine, put new pads with a new disc, bled the whole system. I noticed obviously there's a small space for the pads to get pushed into the new disc, but why wouldn't it retract? I haven't gotten a chance to move the bike does that have anything to do with it because it's not moving? I just need to finish this and this is the last thing I need to do to ATLEAST bop around town. Any help or suggestions would be greatly appreciated!

 

[hillsy]

Are you saying the pads are locking on to the disc? They need to bed in to the disc as the disc will have some wear / grooves in it.

 

[Tim]

While it's largely a mystery to me, I don't think the pads/calipers are going to retract much without the caliper being on the bike pressing on the disc. Loose in your hand its not going to retract much if at all.

 

[TheDirtyJuan]

That's the thing it's on the bike and I put everything back on and bled it and it pressed against the disc but
It isn't
Retracting I'm at a loss

 

[hillsy]

Is the caliper floating freely? I assume it's a fixed disc / floating caliper arrangement?

 

[TheDirtyJuan]

I believe so, I'm guessing yes, it's on a pivoting piece on a rod that goes towards the swing arm. Sorry new to this stuff

 

[hillsy]

The caliper is supposed to move sideways (IE: in and out along the same plane as the wheel axle) so that the disc can move freely between the pads.


Look at this:

Parts 16 and 27 are the bolts that hold the caliper to the carrier. The sleeve (14) should be able to move over the bolt (27).


Another possibility is you have the axles spacers in wrong and the caliper is not centered over the disc.

 

[xb33bsa]

the pistons in use retract so little you almost cant see it and it should happen on the bench it is only the flex in the square crossection oring that pulls the piston back and of coarse any disc wobble
is it bled properly ?

 

[xb33bsa]

did you use the old squre oring seals ? what did you clean them with ? you cant use anything but brake cleaner and brake fluid on the seal

 

[MotorbikeBruno]

Just a thought....maybe it's not the caliper, but a plugged master cylinder hole? The little "return" hole can get plugged and cause similar issues. What shape is the master in?

Secondly, the groove that the o-rings fit in is VERY SPECIFIC to sizing. If you didn't clean it out REALLY F'ING WELL it will cause your pistons to "stick." I like to use the brass wheel on a dremel and a little brake cleaner to do so. That groove has to be free of any hardened crap that might be in there.

Otherwise some things to look for:

Are the pistons clean and have you scrubbed them down with scotch pad or similar. Any rust spots on it, or parts that were "eaten away" from sitting or moisture?

Did you lube the O-ring and piston before sliding them in?


The attached pics are what mine looked like. And the new piston, you can see why I replaced it from the right piston in the pic. There's corrosion that destroyed the travel area. It's gotta be smooth for a good functioning brake.
As others have stated, the little "dowel" that the caliper bolt goes through in the diagram needs to move freely back and forth. They rubber sides are a pain to get back together if you do have to grease it (you'll know what I mean IF you do pull it apart) but it's not too terrible.

 

[TheDirtyJuan]

So it was centered and it sat fine before I bled, then I bled it and obviously the pistons moved but now they're against the disc, is this because it's not
Moving and has nothing to bounce off against? I cleaned with brake fluid and brand new rings and stuff I'm confused as to why it's doing this !

 

[MotorbikeBruno]

Oh, also, like XB said, you may not notice the travel. Put them on the bike, press hard on the brakes after you bleed them well. Go for a VERY SHORT ride without ever touching the rear brake. Stop, proceed to touch the rear disc with your hand and see if any heat was generated. If it's HOT (be careful it can be really hot) then you've really got a stuck brake. If lukewarm, then it still needs some attention as it will get worse as it does heat up. It should be STONE COLD. Then try again to verify. Drive another mile or so use the rear brake a couple of taps and then drive another mile, stop, check heat on rear disc. You shouldn't have used the rear brakes enough to heat up the disc, should still be stone cold or very close to it. That's how I double check my work at least. Never had a caliper seize up on me so it must be working....

 

[DohcBikes]

So it was centered and it sat fine before I bled, then I bled it and obviously the pistons moved but now they're against the disc, is this because it's not
Moving and has nothing to bounce off against? I cleaned with brake fluid and brand new rings and stuff I'm confused as to why it's doing this !

Does your wheel still spin when you aren't engaging the brakes? I think that you think you are going to see space between the pad and the disc at rest. This is not the case. Unless your wheel is locking up, it's fine.

Theres nothing to make the pad "retract" as you are describing. It simply stops putting pressure on the disc when you release the master. You couldnt slip a piece of paper through the two surfaces at rest. If there was a gap at rest, braking would be delayed and sudden. No bueno.

 

[Tune-A-Fish]

^^^ yep dicks breaks are in contact continuously, only reason drums pull away is because they have a return spring and require manual adjustment unless a car and those self adjust every time you brake in reverse... if you can spin it at all go ride it and don't smoke the brakes until you bed them.

 

[TheDirtyJuan]

So just went for a 2 mile ride didn't use it and it's like ever so slightly warm, before I rebuild everything it was hot and locking up and a whole mess, do you think it's safe to start using?? I realized there is the smallest smallest gap

 

[Tune-A-Fish]

Yep, just ease into it a few times before you grab a foot full

 

[MotorbikeBruno]

If it's warm, you still may need to go back in there (so long as you didn't touch the brake AT ALL during your ride after leaving your driveway) But just take it easy and use it a few times here and there until you can verify it's good. Brakes will of course heat up, but if it was a short jaunt, it should have been stone cold. So keep an eye on it for your own safety ( and fuel mileage )

 

[TheDirtyJuan]

Well now I went up and down the block like 5 times only using the rear brake from like 30mph and it's pretty warm, is that normal? Both pads and disc are brand
New

 

[DohcBikes]

You used the brake and it got warm? Um gee i don't know but it sure seems normal to me.

 

[MotorbikeBruno]

Well now I went up and down the block like 5 times only using the rear brake from like 30mph and it's pretty warm, is that normal? Both pads and disc are brand
New

I'm not sure you understood the point of the experiment Your brakes get warm due to friction of course. Which is why you push the rear brake hard before you ride. DON'T TOUCH THE DAMN REAR BRAKE LEVER, stop a ways up, check rear disc. If warm or hot, you are still draggin (aka friction, not your pants unless they do that in your area I guess ) so you'll need to clean them out again. If it's cold, you are golden.