Changing brake pads... Caliper stuck/engaged?

Swapping out tires between the '81 and '82, as well as caliper+M/C.

All seemed smooth. Noticed the pads were on the low side on my caliper, had some good ones, swapped them out. Wouldn't fit at first, so I compressed the piston back in with a C-clamp. Installed everything. All seems good. Pump the brake a few times.

Now it's stuck. I mean, not completely locked up, but clearly engaged, hard to push in neutral, dragging. Why aren't they retracting completely?

I should know this by now, but I hate dealing with brakes and have a bit of an unreasonable fear of messing with them, because it seems something always goes wrong that I can't solve. Hydraulic systems just aren't intuitive to me...

Do I need to bleed the lines or something? What did I do wrong/neglect to do? I did have a friend pull the brake level without asking while the pads weren't in; I vaguely remembered hearing that you were never supposed to do that, but maybe it was in a different context. Does that matter? (I was kind of pissed... He's a smart guy, but sometimes he just doesn't think.)

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Also, I want to get new lines. I'm looking at this:

http://www.ebay.com/itm/Steel-Braided-b ... 59&vxp=mtr

Anyone able to tell me the measurements/what I should measure?

 

I should mention that the M/C+caliper off the '82 were working flawlessly, and had been flushed and generally serviced a few months ago. Put 6000 miles on them, no problems. Stopped much more firmly than the caliper+M/C that came on the '81. (It's a non-stock transplant M/C off of a Honda that I actually prefer, as it's an all metal device instead of the plastic Yamaha M/C; as I said, though, it works and works well, just don't know what I did wrong during the installation and/or swapping of pads.)

 

It's very simple:

"Flushed and generally serviced" and REBUILT are two different things.

REBUILD THE CALIPER.

Simple, easy, and the only TRUE FIX. Len has your parts.

 

Len also has DOT approved brake line assemblies.

Oh, and the original Yammie MC is cast aluminium, not plastic.

 

Don't forget to make sure that the very tiny port in the bottom of the MC is also clear. This port allows for pressure in the caliper to bleed off and release the pad from pressing on the disk. It doesn't take much debris in the brake line to clog this port.

 

If you pushed the piston all the way back, two things come into play...one is that the part of the piston that was exposed with the worn pads was pitted or dirty or rusty and now it's hanging in the bore.

As I said on another thread, before shoving a piston back I'll usually pump it out a little farther, pull the dust boot back and have a look, and flush any dust or crud out with WD-40 or brake cleaner before pushing the piston back.

Also, fully retracted, your caliper is now pivoting or sliding on a new area of that hardware. If it's dirty, rusty, dry, whatever, the caliper won't slide/move correctly and will only apply forcefully with the piston side, but will pinch the rotor even after you let off the brake...

Your 650 has that awful single pivot caliper. If the bolt and sleeve are not completely separated, cleaned and lubed with a good synthetic brake grease to the point that they move effortlessly against each other, that caliper can do what you are experiencing.

 

Also...I assume you used the old pad on the piston face when you compressed it? That's the only way to do it...using a c-clamp against the piston directly will distort and ruin the piston...

 

I never heard anyone mention using something over the c-clamp (except for Rick's use of bicycle tube to keep the paint nice), just to make sure not to do it at an angle.

So I should remove the caliper, take out the pads, remove the rubber cover over the piston, lube it with silicon brake grease and check for any pitting, and then retract it?

Does anyone know of a good, complete, 'here's the whole picture on everything related to motorcycle brakes' site/page/discussion/thread?

And I know Len has DOT-approved brake line assemblies, and if I had enough money that it wasn't an object, I'd happily buy everything I could from Len just for the peace of mind... But sadly, I am as poor as they come. I subsisted this last year on between 8k and 10k. That is mostly by choice, but it's my life nonetheless, and so I have to live it frugally. So if there are any tips on those custom hand-made SS brake lines that are much cheaper, from what I can tell, I'd be much obliged.

Anyone know off the top of their heads what the cost of a rebuild kit on brakes cost? I'm considering it. Also, if anyone has a brake rebuild thread handy, that'd be nice. (If no one comes up with those, I am of course able to google myself... Just, been googling a lot lately, feeling a little lazy and wanting to get off the computer.)

Tsakz, I guess you're right. It's just the paint on it that made me think it was plastic.

Thanks for all the advice, guys. Y'all are wonderful.

I'd also like to mention that something I'd avoided until now was bleeding brakes. Just this whole unreasonable fear of brake systems, was hoping to avoid it, and when I had a general service right after I got the bike, the mechanic just went ahead and did it for me without me asking, so I hadn't needed to. Guess I should go buy the tool at Harbor Freight, since if I take the caliper off and put new lines, I'm going to be putting all new brake fluid and all that jazz.... *sigh*

 

Keeping the pad over the caliper helps you to push in the center rather than at one edge. Pushing the edge is how you cock the piston in the bore.

See if you got these guys nearby: http://www.pirtekusa.com/

They can make you any hose you want, fairly cheap and very quick.

http://www.yamahasportsplaza.com/

2G2-W0047-00-00 CALIPER SEAL KIT $37.25
4H7-W0041-00-00 CYLINDER KIT, MASTER $36.15

This is OEM Yamaha stuff. I haven't looked at what Len is charging.

At it's most basic, you only really need a foot of clear tube, an 8mm wrench and a jar to bleed your brakes. I don't like vacuum bleeding because you have to mess with sealing the bleeder threads to avoid sucking air in around the screw.

 

You need to remove the caliper and take out the piston.

Then you clean and polish the piston, and ensure it has no pitting in the areas swept by the seals.

Then you remove the old caliper seals and discard them. (They're 30+ years old.)

Then you CLEAN the caliper; making sure the channels the seals go in are DENTALLY clean. You need to be careful not to chew up the inside of the caliper in the process.

The "secret" to the whole process is getting the channels the seals go in clean; any remaining crud will prevent the new seals from seating properly.

Then you replace the seals. (They're nothing more than rubber rings.) Use lots of fresh brake fluid to lube before/during assembly.

Then you reassemble the caliper (press the brake-fluid soaked clean-n-shiny piston in place.)

Plus, with your caliper, you need to attend to the pivot pin, as explained above.

Here're a couple of pics of a 550/750/1100 style caliper; while the unit itself is slightly different, the principles are the same. Note cleanliness of channels. Note that while there is some pitting on the piston in the second pic, it is outside of the area swept by the seals, so it was perfectly serviceable.

 

-Check with chacal for the parts.

-Very true; or you can make your own "vacuum" rig with a turkey baster and a bit more tubing.

 

What is the basic procedure for bleeding brakes with that minimalist set-up of an 8mm/jar/ft of clear tube? Because I have all of those things.

Jpaganel, that was lots of great info, thanks.

Fitz, appreciate it. Don't even know what a turkey baster is, though, haha.

Something I don't understand: What causes a caliper piston to retract when one releases the brake lever?

 

The only way caliper pistons are designed to take direct force (aside from hydraulic force on the backside) is against the edge of the outer face, not against the center....that's what I was getting at. Some people will run the c-clamp screw side all the way down inside the piston cup and that'll ruin it. They aren't made to be pushed on against that surface.

The old pad is a convenient thing to use, since it's already seated against the piston face, rigid enough to handle the force, and guided to some degree by the channel/pins that support it, so it won't try to go off center and wedge the piston.

Folks will try to use things like big channellocks to compress them sometimes...that's asking for trouble...need your force centered directly in the middle of the piston.

 

The c clamp is a huge surface that applies equal force to the whole thing. It's mounted, not a hand clamp. I understand what you're saying now, but that wasn't the case for me. Good point.

 

The wrench fits the bleeder screw.

First, you got to make sure your screw is working. That means it unscrews and the hole in it is clear. If you have any doubts, replace it. Chacal has some nice screws, NAPA has some cheapo screws that will work.

Put the wrench on the screw. Put the tube on the screw nipple and put the other end of the tube in the jar. Splash a little brake fluid in the jar to cover the end of the hose.

Open the bleeder, apply the brake, close the bleeder, release the brake.
Lather, rinse, repeat until the fluid in the tube has no air bubbles.

Keep an eye on the cylinder reservoir to make sure it has fluid in it. If it goes dry you will have a giant air bubble that will take forever to bleed out.

People also have had some success with gravity bleeding. You tie back the brake lever, open the bleeder and fill the reservoir. That might take a while, like hours, but you don't have to keep squeezing the lever. I haven't tried this yet.

The fluid gets sucked back into the master cylinder and the cylinder follows it.

 

I guess what I mean is I don't understand how the master cylinder piston functions, what it does exactly. It is spring loaded, I found from explorations on the topic in wikipedia, which I figured had to be part of it. That just pulls the piston back, I guess?

Something I don't get: If I unscrew the bleeder screw, shouldn't brake fluid just pour out of it? Same thing with the caliper piston: if I pull it out, is it just raw brake fluid behind it? How do I disconnect the caliper without brake fluid going everywhere? Or do I just get a jar to collect it all and just replace all the fluid?

As far as the method above:

Put clear tube onto bleeder screw.

Put other end in a jar, submerged in a half inch of brake fluid.

Loosen bleeder screw.

(Fluid... doesn't start pouring out? Huh?)

Squeeze brake lever. (That doesn't cause fluid to squirt out? Or does it? I don't get exactly what will be happening here...)

My end point, the fluid in the tube having no air bubbles.... I don't get it. At what point does it fill up with fluid? Does it act like clear yogurt or something, slowly going down the tube with each squeeze, and eventually I'm squeezing fluid and air out together, and eventually all the air is squeezed out? Does the point of the exercise have me cycling all the fluid out of the line and putting all new fluid in? How long does this process take?

 

Exactly.

If the cap is on the reservoir, no. If the cap is not on, it'll be a slow pour. The passages are small.

Yes, there is just fluid behind the piston.

Loosen the banjo bolt, then remove the caliper from bike and unscrew the bolt over a jar.

Yes, it does. It's squirted into the tube.

More or less. You are displacing the old fluid and air with new fluid from the reservoir.

Yeppers.

Depends on the size of the brake system. I don't really know about yours. On a car this takes me 10-20 minutes, but the master cylinder there is much bigger.

 

Well that doesn't sound so bad.

As a temporary measure while waiting for seals to do the rebuild, I'm not sure whether or not I pushed the piston all the way back in... I'm thinking I'll push the piston out a good ways, remove the rubber cover, clean/inspect/lube, reapply with c-clamp all the way in, and see if that resolve it or not. Better than being vehicleless for a few days.

Thanks for all this; this thread, plus a lot of research and reading today has made me not so afraid of calipers anymore.

 

Usually you don't need to shove the piston ALL the way in, just most of the way. Far enough that when you put the pads in there's a big enough gap between them to fit around the rotor. But for rebuilding and putting new seals on the piston you do want to take that piston ALL the way OUT. Otherwise you can't clean the channels the dust seal and fluid seal ride in, which is the most important part of the whole exercise. This is on the calipers I'm talking about, as for the master the re--build kit is usually a new piston and seals.

I have posted a bunch of times that as far as bleeding, I prefer the "bungee cord the lever back" method. I bleed and bleed mine, pumping the lever, opening the bleed valves, repeat, until I get SOME resistance, and can see that the calipers are closing. Then, I open the cover to the master, tie the brake lever back so it's almost all the way to the bar, and let it sit over night. Air seeps up and out the master and after a few hours lever is rock hard. At least it works on my bike. If you have that weird master on the forks and not on the bars...might not be as effective.

 

I had pretty good success using a large oral syringe (free at the pharmacy)...just used the barrel part, put clear tubing on it, other end on the bleeder screw and propped the barrel upright on my fender brace. Fill the barrel with fluid, and pump the brakes.

Works the same as the jar method, but air prefers to go up, rather than down. So where the downward jar method the air has to be forced through by fluid, it tends to bubble up easily through the tube going up to the syringe barrel...just keep filling the barrel as the fluid goes in to replace the bubbles...

 

Well.

I have two calipers/master cylinder sets, both all connected. One is from the '81, where the owner neglected to ever change the brake fluid during four years. It has a stock M/C.

That one is off of any bike, and is just sitting as a gutted backup, so as an educational exercise, I squeezed the lever and popped it out, after taking the dust cover off. Ugly, really ugly. Rust and stuff. Saw what the problem could be.

So I go over to mine, the one from the '82 that I've put on the running '81. I remove the caliper, remove the pads, remove the dust cover, and start pumping the lever. Piston starts coming out...

...and it's pretty darn close to pristine. No pitting, and looks a pretty, mostly shiny silver. I push it out so far that it was difficult to even fit one pad in between the end of the piston and the inside of the caliper. I went ahead and cleaned it anyways (poured brake fluid on it, used some light sandpaper, poured some more brake fluid, put some silicon brake grease sparingly).

Then I got that old brake pad in there, barely. Put a socket on it, and unmounted my C-clamp and brought it outside. Slowly closed it all the way, nice and slow and even. Put the dust cover on. Bolted into place.

Pumped it up a few times.

Same symptoms. I can drive around the block, but it drags. Is there a chance that when my brake fluid was last done 2 or 3 months ago, the pads were more worn, and so now it's over full? Maybe I should just bleed the lines?

Maxmike, my master cylinder is on the handlebars, not the forks--it's just a brake lever/MC/Mirror mount/Mirror off a Honda of some kind. But I don't understand your method, though I'd like to try it... You say you 'bleed and bleed your brakes until you feel some resistance'. My brakes already have resistance; by bleeding, you mean following the tube and jar method, for instance? When/why would the resistance change if doing it this way?

 

Usually it's hard to get all the air out, tying the lever back is to get the last of the air out. If you have resistance at the lever, that means it's pretty much bled. When I do my brakes, when I first re-attach the lines the lever just pulls back and does nothing. So I pump it and crack the bleed valve, let out some air and fluid. Pump it more, crack valve, etc. Then, it's usually still mushy, tie lever back, air that's left will find its way up and out. It works.

I still think your actual problem is that your calipers are hanging. Could be sliding pins, or gunk behind seals, or who knows, but complete rebuild should get them operating correctly.

 

BINGO!!! Not "could be"... IS.

The problem is the CRUD BEHIND THE SEALS. And OLD SEALS. You need to pick one of the calipers, tear it down and do it right; and then replace the seals.

All of these other halfway attempts amount to nothing but screwing around; they won't get you anywhere. The only way to fix it is to do what needs to be done, which is to clean the seal channels and replace the 30-year old seals.

Until you do, it ain't gonna work and you're just wasting time, effort and brake fluid.

I'm out. Get back to us once you decide to do it right.

 

Do these use a stroking seal design to retract the caliper?

 

I went over and visited a shade-tree mechanic friend of mine, who when hearing my problems immediately asked, "Did you take the cap off?"

Told me to take the cap off and pump the lever a few times. Immediately helped a ton. After driving 12 more miles down the road after that, I did notice some sticking still, but I also realized that (!) my brake fluid looks pretty ugly. I need to flush it anyways. Not sure why I need it so soon (3 or 4 months... Odd), but it needs to be done. Thinking that might equalize the system--also, it might just be a little too 'full' for new pads? Is that possible, since it was filled with already-partially-worn pads when it was last done?

 

K, well, my point was that the piston looked like it had obviously been rebuilt and polished, and that makes sense with what the PO had told me, since he had a new M/C transplanted and had the brakes worked on--probably because he realized he couldn't sell it without having the front brakes good. I know he also didn't work on bikes himself, and I know the shop he used to have work done, and that while they charge too much, they do good work.

So thanks, Fitz, I understand your mentality on doing everything from scratch, and I respect it, I'm respectfully finding reason to believe my caliper is ok. If a brake fluid flush doesn't fix it, rebuilding will be the next stop on the list.

Thanks for your input.

Maxmike, do you leave the lid off the M/C while the lever is pulled back? If not, how does the air escape? If so, is the absorption of moisture from the air a problem to worry about?

 

Damn I left out a word of advice regarding pushing pistons back, now that you jarred my memory...it's better to push them in with the bleeder open...that way you aren't forcing the cruddy silt in the caliper back up into the system...and I didn't really think about it but yeah you could run into a situation where you push so much volume back into the master cyl that you'd actually pressurize the air on top of the fluid, since these caps won't vent positive pressure the way automotive caps will, that I know of anyway...that could add to residual drag, true...

 

It seems to be perfect now. Firm and no drag.

 

As far as tying the lever back, Well, actually I don't think you need to leave the cover off the master. There is already air in there after all. (at the top, I mean, you don't fill it all the way to the brim) We're talking about tiny amounts, a few bubbles, in the lines. It's a closed system, if you see what I mean, the air and fluid fits in there now, it will all still be in there, just with the air at the top of the MC. It's not like we're introducing NEW air that would blow the lid off. Wouldn't hurt to crack it open after it sits though.