Rear brakes dragging after tire change…

[Adamcgeiser]

Hi everyone - frustrating question to ask for first post.  Seems simple, here’s what I’ve done and where I’m at:

Removed everything to have new tire mounted.  While off, did all final drive maintenance, etc.  Got tire back, followed the PPT instructions to the letter, and put on fresh brake pads.   All was well until I rode off-

*Rear brakes did NOT provide braking power at all.
*After getting back home, the rear rotor was incredibly hot; the rear pads were dragging. 
*Putting back on jack, when I spun in neutral, I got only a few inches of turn.  Clear issue here.

When I pulled the new (OEM) pads out, it looked as if they were contacting the rotor unevenly, so I wasn’t surprised that I got very little stopping power.  First thing I did was order a caliper rebuild kit + rear master cyl rebuild kit.  Did both of these (first time, all went well), and reinstalled everything.  Also took rear tire/everything off again and put it all back together, very carefully.  (I did follow the torque order/instructions).  I put the old brake pads back in, since they were probably 50%.  We bled the rear system completely - there should be no air in there at all.

*Seems like stopping power is better, but I’d say 75% of what it was before I ever took everything apart.
*Brakes continue to drag - when I jack it up, I get about 1/4-1/2 turn; when I put approximately the same force on front tire, I get about 2 turns.

I bled them again, adjusted the brake pedal (the pivot point was greased, etc.).  When I rebuild the rear master cyl, I ran a wire through that little hole to ensure it wasn’t clogged.  Super frustrated, I don’t want to ride it like this - anyone run into this before?  The rear brake system isn’t that complex… getting close to dropping at a shop and asking them to give a once-over, but concerned they’ll want to do all the stuff I’ve already done.

[sandy]

I rebuilt my front calipers and had the same issue. Took apart again and had to scrape corrosion out of the seal groove. It caused the piston to get stuck.

[Chrisj CMA]

One thing you said about uneven contact. Check and insure both brass springs are in place. One is on the caliper plate. That’s the one the feet of the pads rest in. The other spring is on the caliper and maintains tension on the pads

[Adamcgeiser]

Thanks for the quick replies, y’all.  I cleaned the caliper out pretty well when I rebuilt and the pistons went in pretty well once done . I just used a pick in the groove; it doesn’t take long at all, i might give it another go before letting a mechanic at it.  The number of potential issues feels pretty low, which is why this is driving me crazy.

I’ll have to look at the brass spring on the left side/where the pads rest on the caliper plate. 

Is it possible once everything is together and torqued down, for there to be anything misaligned that might cause the brake pads to engage unevenly other than a mechanical issue within the brakes?

[Chrisj CMA]

The only way misalignment can occur is if you left out a spacer. If you didn’t change wheel bearings then the only spacers you had access to is the one in the final drive and the little one between the wheel and caliper plate. The final drive spacer can fall out when the final drive is off the bike. You would have that extra part when done.

[rug_burn]

What occurs to me as possibilities:
   The caliper should be free to move around on those slide rails on which it's mounted before you pump the brakes for the first time.  If you compress the  wheel cylinders back with a c-clamp or something, is the caliper free?  You should be able to move it around by hand and slide it (with some effort) on those rails.  and that one rail should be screwed in tight to the mounting plate
   The other thing to consider is that the problem may be something blocking the release of pressure from the brake pedal.  Long shot, I agree, but at this point it makes me want to check everything.  Now rereading your post, you did something about this too.

[Adamcgeiser]

Took caliper apart again, used Simple Green and some other solvents to scrub and get the piston cleaned up.  Everything came out about as good as I think it’s going to.  It does spin a little further after riding now (1/2-3/4 spin), but I’d like to see it spin at least one full revolution.  What’s normal for rear tire?

Follow-up question, I noticed when riding, but only now that I’m paying attention, of course…

When applying rear brake firmly - I’m seeing the rear caliper twist a little bit (still not getting full stopping power).  It seems that if both pistons are getting the same pressure, they’d both be moving the same amount and it would NOT have this twisting effect.  Or it might just be twisting because there’s a ton of hydraulic pressure within it…  Maybe that’s normal, but maybe it’s not - anyone happen to know?
 

[rug_burn]

Maybe one of the pisons is sticking, and the other one is not... You could pull the caliper off, compress the pistons bac to where theyre flat with the case, noticing if one sticks, and then slowly pump on t he rear brake, again, noticing if on drags.   Maybe even if both pistons are clean and shiny (which they should be by now)  maybe there's a little galling on the inside of one of the bores.
    I know: that's really galling ain't it?

[Adamcgeiser]

Very happy to report- the brakes feel like they’re working great again.

Not great news: they still get pretty damn hot pretty damn quick, like they’re still dragging. When I jack it up and try to spin, I might get half a spin.

Going crazy. I can’t bring myself to take it in. Ive done 300 brake jobs (car). First time on bike in 10 years.

I have…. Put in a brand new rear master cylinder, rebuilt rear caliper, new rear caliper pistons, bled it several times, put on new pads and reused old (40%) pads. Everything is lubed and seems to move freely. Not sure if anything is binding when I brake but I definitely got my usability back.

 Can anyone tell me: when you brake, is there a little flex in the caliper?  And also : how many times does it spin with a fairly firm spin on the jack?

Thanks…

[da prez]

 It seems after all this , the flex brake line is bad.  Replace the lines.  If you remove the caliper but do not dis-connect and push the pistons back , put a piece of 1/4 inch plywood or a worn out brake pad in the caliper . Slowly pump the brakes  about half way out.   Try to push the caliper back in. There should be little resistance. Both pistons should move out about the same. Exercise them a few times. If they still don't work , the flex line may be bad.  BTW , I have the lines in the shop. There is a Valk owner near you.
  Ask for help .

                                                  da prez

[Adamcgeiser]

I think swapping to SS lines would probably be super beneficial. I’ll heed that. My caliper pistons glide in and out smoothly, I think that part is fine, though with nothing there they don’t come out at same rate. When there’s something to push they equalize quickly.

I just loosened up the pin on the left side of the calipe (when facing it), and when pulled halfway out, it works exactly as it should. The tire spins 2 times or so, and I didn’t retract or do anything to pistons. It’s like the bolt is binding on something.  When it’s empty everything seems to glide perfectly. When loaded it holds everything in place so the tire can’t turn. When looking at it, it almost seems like it is not perfectly aligned with the hole, but when all together it glides.

When putting back together I noticed every turn of it, it felt like I was pushing through something. I’m close to ordering a whole bracket/caliper off of eBay- is there another approach?  After all I’ve done to my caliper I’d like to keep it!

[LadyDraco]

I  know  this  Q will seem kind  of  silly, but ya  did put that thin thrust washer back on?
 They are  very easy to loose  and  forgotten  it's  paper  thin. but can mess up the  alignment.
Plus ruin a  hub in time.
You said  you had  remover the  rear  wheel.. Just wondering .
 

[Adamcgeiser]

Great thoughts - i'm open to silly questions, because I'm out of ideas.  The thrust washer is definitely there.  As part of my "what do I do next", I took the rear tire back off and reassembled.

No, it seems the pin (the big one on the left) just doesn't line up perfectly with the hole in the caliper bracket, so it turns and goes in, and slides, but when turning it in, it feels like it has resistance every 3/4 of the turn or so.

  It doesn't make sense - it's all the same parts.  I'm close to ordering a whole new unit from ebay but it doesn't add up that the parts I have aren't working... so I haven't done that yet. 

[Pluggy]

Parked and no foot on the brake pedal, the rear caliper should move up and down around the pivot bolt. It should also wiggle in and out slightly. It should "float". This is easily done by hand. If this can't be done, something is out of alignment.

Are the pads and o-rings genuine Honda? We can always trust those to be correct. Here is the positionong of all parts:

https://www.partzilla.com/catalog/honda/motorcycle/2003/gl1500cd-a-valkyrie/rear-brake-caliper

https://www.partzilla.com/catalog/honda/motorcycle/2003/gl1500cd-a-valkyrie/rear-wheel

The Honda service manual has the correct sequence of assembly. Using genuine Honda parts and following the manual, things should assemble for correct alignment. Consider removing the brake caliper, laying the parts out correctly and reassembling it.  It that doesn't fix things, consider removing and reinstalling the rear wheel per the service manual.

[Skinhead]

I would stay away from E-bday parts.  I've had bad experience with them, cheap Chinese knockoffs.

[Adamcgeiser]

I went through and did every suggestion on this board at least a couple of times, but after my note on the 6th around the PIN, I decided to go ahead and order a whole new caliper + bracket from Ebay.  I took it apart enough to grease everything and rebuild with the new seals, pistons, etc., and put it on.  It worked perfectly.

If you look at the top of my old caliper - you see the pin is ever so slightly out of alignment, which is where I think it was binding.  Not sure if it's the pin or the threading in the caliper, but either way - I got to get out and ride for the first time in awhile 

Now, I'm seeing that my brake light isn't working... obviously can't go far without that... what next???? Hoping it's something simple (it isn't illuminating for either my rear or front brake)

Thanks everyone.