rear brakes... yes, again, or rather, more, but strangely different.

-hello folks, i need help!... ok, i'll get right to it. -2005 st1300 non abs... brakes (all) working great, but pads thin. -changed brake pads all three sets (all honda parts before & after). -cleaned all pistons (did not make them come out any further than they already were due to pad wear). *-forced rear pistons back in with c-clamp:. -noticed bad sound/grinding after 4-5 days, found the inner rear pad fell out of front clip, rotated on the pin, and was grinding against rim (light scrape on rim, damage not too bad),... placed back in clip. -all pads appear to be in correctly now. -riding for a couple weeks.
-problem:
-the rear brakes work, foot pedal and smc, and they release the disc fine, but i do not have the stopping power i used to have. -i can not make the back tire lock-up for instance where (i think?) i used to be able. -any ideas? -did i destroy something by forcing the pistons back in... like the proportional control valve? -maybe just a bad set of pads? -maybe they are taking a long time to wear in because i braked with them improperly installed?

-i apologize for more rear brake questions... but i think i read most of the articles and did not come across reduced rear brake performance. -i'd replace the smc (or clean it) if i thought that would help, but the reduced performance is with the pedal also.

help!

-my next step is to replace the rear pads again, or at least pull them out and look at the wear, scuff them up a bit in case i got some grease on them.

First, I'm sure more knowledgable info to come.
To me it sounds like the rear brakes are hanging up, I would take the rear apart again and look at the pads to see if both sides are touching.
Then I might operate the rear carfully to make sure all the pistons are coming out smoothly, don't operate enough to push them out all the way.
If the pistons are operating smoothly, I would reassemble making sure all the "slide" areas are clean and lubed up.
If all of that is good and PROPERLY reassembled and the rear is still soft I would bleed them.
Good luck, let us know what you find.

-i guess i'm really concerned as to whether forcing the rear pistons back (via c-clamp) does damage, like i said, i didn't force them back much, maybe 2-3 mm but i'm worried that i damaged a component by not bleeding them back properly. -i'm hoping that either they still aren't in there right (wrong side of little tabs for instance), or i got grease on the faces of the pads somehow.
-so that is my question, does forcing the rear pads back do damage, and if so, what component do i need to replace/repair?

+1

I'd strip and clean the rear caliper and replace the seals after cleaning out the grooves.... if the pistons look at all less than clean and pristine all over, I would replace them too.

Re-assemble with some red rubber grease on the seals, push the pistons in very carefully, fill and bleed the whole rear brake system.... not forgetting the process to bleed the front end as well....

jcc said:

-so that is my question, does forcing the rear pads back do damage, and if so, what component do i need to replace/repair?

Click to expand...

I'm not familiar with the linked brakes, but in general forcing the pads/pistons back into the caliper is a normal step in the pad replacement procedure, it shouldn't hurt anything.

Edit: saw you cleaned the pistons before retracting them, so the following most likely doesn't apply:

If the pistons were especially corroded/caked with crud then its possible you could have scratched a seal when you pushed them back in, which may cause a slight fluid leak that should be visible if you look closely. I wouldn't think the leak would be severe enough to cause a decrease in braking power, just cause a mess from the leaked fluid, and cause your fluid reservoir to get low on fluid over time.

-just to note, there is no soft feel, they feel fine, just not performing (stopping) as they used to. -i'm hoping there is no need to go through that bleed procedure if i don't have to... i never opened a line or ran low on fluid so i wouldn't think there would be any air in there. -i should be able to lock up the back tire with a bit of force on the pedal, no?

-pistons were in great shape... low-mile bike, only 23k miles.

If the brakes fell solid but not stopping as should....
I would think maybe you didn't break in the pads properly ( maybe due to the front pad not being placed in properly ) and the pads may be glazed.

Pushing the pucks back in may cause sticking if not clean and/or damaged the seals, but prob wouldn't effect the stopping power.

I would pull all the pads and slighly ruff them up to remove glaze if there, then reinstall.... I'd also do a full bleed just in case there's air in the lines somewhere. They don't have to feel soft for a little bit of air

Brakes should be the last thing you skimp on doing well


PS edit; were they OEM pads or after market... were they the same?

No, pushing the pistons back in will not hurt anything, putting new pads in, which are thicker, would require you to do so.
If your not positive everything is put back together right, take it apart again and reassemble. make sure everything is clean and lubed up.
If they still arn't good you are going to have to bleed them.
.02

-ok, it's nice to hear that pushing the pistons back in won't hurt anything... i was worried after i read on another post that the bleeder should be opened to push the two outers back in. -the pads that were on the bike were oem, as well as the pads i installed. -i have verified through this site's pictures that i have the correct pads in there (the little notch on the end). -so i'm going with Rekoob's idea of removing them again, scrubbing them up a bit with a sandpaper block and making sure they are in there right, and not wearing funny. -i already did that with the fronts trying to improve the stopping, because they are easier. -of course while i'm there i'll make sure the pistons are moving freely, let them out a bit, clean them up again and make sure they rock back and forth (the outers) and make sure the center one moves in fairly easily. -of course i'll be forcing them back in again -i do think it's a pad problem though as they return freely, just don't grab like they should. -might just replace them if the dealer has a pair (not likely).

Whoa, pushing the pistons back in won't hurt anything as long as they are clean and corrosion free... otherwise they can do harm to the seals and the correct operation of the brakes..... and if you ride the bike, they are not going to be clean... and depending where you live, they might not be totally corrosion free....

I know you mention that later in your post, but we don't want people thinking you can just shove them in... sorry if that sounds a bit egg suckingly annoying but I see far too many brake issues related to dealer pad replacements where they simply don't clean anything, they just take the old ones out and shove the new ones in..... and the pistons just get pushed in.....

As a secondary note... read thru this thread; https://www.st-owners.com/forums/showthread.php?44264-Seating-Brakes

After install of new pads, I always go out and do a few stops from 40-50, medium- heavy braking power, then let them cool for 5 mins between each stop.... this seems to me to allow sort of settling in of the pads and a start to a long life of good stops. ( it also lets u know you put it all back together correctly )

-thank you all for the advice and for some good reading material (bedding-in of new pads)... i will return when i check it out and have something to report.

Did you pop the top on the brake reservoirs before pushing them back in? Not that it would cause a long term issue.

-i did not ...and it's interesting that you (T_C) should ask... i've read quite a bit on here about brakes (and there's a lot!), and that's the first mention of that i've come across... probably good advice to pop the tops off the reservoirs when pushing the pistons back in (yes, after thoroughly cleaning them). -although probably not completely necessary as they are not completely air-tight. -might be easier to get them to move.

jcc said:

although probably not completely necessary as they are not completely air-tight.

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They should be air-tight once the covers are replaced. Fresh humid air and brake fluid is bad combination. If at some point you would have added brake fluid and then tried to force the pistons back it could get rather difficult or you would find fluid being forced out of places it shouldn't be.

With reservoir caps removed, pistons cleaned, the pistons should be pretty easy to push back.

jfheath said:

If the fluid has been topped up since, there will be too much fluid in the system. This may be why you read that the bleed valve was opened in a previous post.

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The other common reason for opening the bleed screw when pushing the pistons back into the caliper, is to purge any contaminated fluid from the system, rather than pushing it back up to the master cylinder.

jcc said:

maybe they are taking a long time to wear in because i braked with them improperly installed?

Click to expand...

Your brake pads may not be seating as well as the old spent pads did. This occurs when the replacement pad material is not aligned exactly the same as the pad material of the spent pads. When this occurs a small portion of the new pad material will be bearing against an area of the brake rotor that has not been seen much wear, leaving behind a "ridge" of rotor material.

When an automobile brake rotor develops "ridges", the rotor surface can be made smooth again by taking a light cut with a brake rotor cutter (similar to a lathe). In your case ( I think I read approximately 37K miles), the rotors probably don't have much of a ridge, so the pads will wear around the "ridges" in short order. Or, you could remove the pads and relieve the area on the brake pads where the "ridges" are rubbing. I'd be inclined to leave the pads be, and let the pads adjust to the rotors.

-ok, so here is the story... first of all, a couple weeks back I did the brakes, and stupidly, the inner rear pad did not get in the clip properly, and eventually swung down but was held by the pin. I unknowingly rode like that for a week with decreased rear brake functionality (thinking they just had to wear-in), until I took a look and realized that the pad was hitting the rear rim! -it put a scrape all the way around next to the rotor of the rear rim (pic on right, could have been worse, small shallow scrape). -it made a little grinding noise when it was doing it, not as much as you would think, but it was the grinding that made me look. -so I swung the pad back into place... but still had not-so-good braking (once again I thought they now had to wear-in more due to the improper wear of one pad). -a week went by, no better. -finally, after reading alot on this forum, I had to figure it out, so off comes the rear tire. -in the pics you can see my pistons are looking good (pic on left), in fact, everything looked good except, of course, I wore the inner pad down on just one end while it was hanging (middle pic, pad on left was hanging)... that I expected to see. -what I didn't expect was that there was really nothing wrong. I roughed up the pads, made sure I put them back in properly, and... still, no good brakes. -finally, in desperation, I put the bike in first gear and put sandpaper to the rotor and watched in amazement as aluminum flake came flying off! -aluminum from my rim had coated the disc (and then probably coated the pad face(s)). -after 10 minutes of sanding my rotor until the aluminum stopped flaking, (it actually changed color, and went back to looking like clean stainless steel instead of a dull aluminum color), I went for a spin and my brakes were back. -weird. -ok, so that's one I hadn't read on here, lol. -one for the books.
-I plan on riding it for a bit, and then do a bit more sanding... thinking the aluminum on the pad faces will transfer to the rotor, eventually i'll be clean, in the mean time, I'm at 90%.
-I would like to thank everyone for supplying free information,... this site and the folks here, are great. -And thanks for providing an outlet of people to share with that understand.:biker:

-naw, no worries, it's not deep at all, just a poor photo... can barely feel it. -your photos, however, are crisp! -thanks again.