Brakes - Do I need a new caliper?

[tweaver]

When I got out my bike this spring and removed the rear wheel to replace the tire, the brakes were frozen. (I'm guessing my kids were squeezing the break levers over the winter). Took some work to get the wheel off, then I set about trying to get the brakes to release. I've gone after the spooge hole (thanks ken, excellent article), I've wiped the gunk off the cylinder I've release the bleed valve and I can't get the cylinder to retract. Before I release the pressure on the system, I was able to get it to push out, but it won't go back in. According to the book, I need a new caliper at this point.

First question, do you XS11 wizards agree with the diagnosis. Second question, is there anything else I should try.

Any help appreciated.

[oldnortonrider]

Are you trying to push it in by hand, or using a C-clamp? I always use a C-clamp~~bleed valve open.

[prometheus578]

Calipers, like anything else brake related can get stuck.
Old brake fluid, well, not old brake fluid, but brake fluid absorbs water, etc.
Heat, water absorbsion and the like break down the brake fluid. turns it into jelly like gunk.... and then hardens.
Need to take the caliper apart and clean it out. I've never had to use a rebuild kit... just clean up what you've got.
Get a large pair of Vise-grips and two small pieces of thin plastic sheet.(cut two one inch squares from a plastic coffee can or something.)
Loosen, and then lightly retighten the bango bolt that attaches the brake line to the caliper, but don't take it out.
Keep the master cylinder topped off with fluid and pump the caliper's piston out. Yes, it'll make a mess.
Remove the banjo bolt from the caliper. Put the plastic squares over the outlets on the brake line and hold them in place with the vise-grips. This is to stop the brake fluid from running out... and if you don't let the master cylinder go dry, you should get very little air in the system to bleed out later.
Clean the caliper piston with VERY fine sandpaper. Clean the cylinder with VERY fine sandpaper if needed. Remove the large O-ring, and scrape the hardened brake fluid offa it with your thumb nail. Get a pointy object, like a dental tool and thoroughly clean the groove that the O-ring fits in.
Use no solvents or cleaners
Lube it up with fresh brake fluid, put the o-ring back in. Press the piston back in, etc, and you're done.
Bleed the system.

[Ken Talbot]

It is not very common for the caliper itself to be bad. Usually the problems come from spooge all through the caliper. With a bit of care on tear-down, you can often clean it up and put it all back together without needing a rebuild kit.

YMMV, BTDT...

eh, Prom?

[prometheus578]

Had to go back in and edit a spelling error, Ken.

[soccer4m]

piston

Hey Tweaver,,,dont give up,,,,the piston will go back in with a c clamp, just get it as straight as possible, tighten slowly and it will pop in. Keep the bleeder open, lube the piston and o ring with brake fluid and it will go in. I just had an old fixer with frozen pistons too and same problem, the pistons go out and only with a c clamp will it pop back in. So, crank away and it will go in. Just check to see if piston surface is good and smooth,,,,light sanding will not hurt...good luck, Mike in san diego

[prometheus578]

Soccer4m...
I don't believe he has the caliper apart yet.
He's stating the it will go out, but won't go back in.
This means it's gunked up inside.
If one just pushes it back inside... the retracting piston will "clean" all the gunk offa the cylinder walls only to have it float around and re deposit itself... the problem won't go away.
If the caliper is disassembled and cleaned, the piston will slide in and out smoothly. Takes very little finger pressure to push a piston back in a caliper, provided it's not hooked up to a brake line to cause pressure in the system.

[renegade_xs11g]

Prom is correct,

but I might add that if a caliper piston doesn't go back in easily, there is a good chance it's gunked up.

I've been working on brakes since about age 10, almost 30 years! almost anything on wheels, not an expert, just experienced, and

hydraulic brakes, master cylinders, calipers, wheel cylinders,
well any thing hydraulic needs to move fairly easy, the fluid is what extends or retracts the piston

the only time I use a C-clamp to compress the caliper is when I can't move them with a SMALL pry bar, and then I clean much the same as Prom has suggested

GOOD LUCK!

[oldnortonrider]

When I use the C-clamp, I put a small piece of wood between the end of the piston and the clamp~~make sure I don't score the piston......................

.....................doing this while the line is still hooked to caliper; less air will get in there. Sometimes hard to get it all out, the more things that are dis-assembled....................

[tweaver]

Man you guys are awesome, less than 24 hours. I'm a computer pro and I don't get comprehensive answers that fast from people we pay to answer . The bike is an XS11SF (79) and I've had it since 91. This is only the 2nd time she's ever done anything but get up and go. I'll get working on her tonight (gotta take the kids to speed racer this afternoon) and let y'all know, but based on the work I've already done, I think you're right on the mark.

[Ken Talbot]

Originally posted by tweaver
Man you guys are awesome, less than 24 hours.

And if you look at the timestamps on the replies, you see how much less than 24 hours!! If you hadn't gone to bed so early, you could have had this job half done by breakfast..

[tweaver]

Wohoo!!! It's fixed. Won't get back on the bike till next weekend, I leave for Mackinac island with my daughter tomorrow morning early (class field trip).

Thanks so much for everybody that replied and especially for the detailed description by prometheus578.

Now, if you want the somewhat amusing, sordid tail read further, otherwise, if you are ever in Michigan, look me up, I'll give you the scenic tour.

Before I start, I'd like you to know, I'm not totally incompetent with my hands. If this had been made out of wood, I'd have had it fixed in half an hour. As it is, I'd never touched brakes before.

By the time I'd contacted you folks, I already had the entire rear brake off the bike and partially dis-assembled on my work bench. The first thing I had to do was bleed out the air I'd let in trying to clean the spooge hole out. I worked on it for quite some time and made no progress. Then it occurred to me that maybe working the piston by hand just wasn't providing enough pressure. Yup, you read right, I realized later how silly that was. So I got a piece of plywood, bolted the master cylinder to it and clamped the wood in my vise. Then created a makeshift brake lever out of a couple more pieces of wood. Once that's built, I pump a fair amount of air out of the system and the piston finally starts to move again. But it's slow going and I'm almost out of brake fluid to keep the reservoir full. I take a short brake and show my daughter (9) how the whole thing works (never let an opportunity for education slip by, especially on something cool like this). Naturally she wants to work the lever so I let her. While I'm watching the piston to see if it comes out, I hear this horrible sucking sound. Yes, I let the reservoir run empty and air has just been sucked in to the hose. not only that, but I'm out of brake fluid and everything is closed (small town).

Next day, with more brake fluid, I start again. There's air in the system, but it's not much so I just start pumping, and the thing pops out almost immediately. That's how close I was last night, maybe an ounce of fluid away. So, I take the brake line off and block it as prom said with plastic and vicegrips and proceed to clean the piston and cylinder and prescribed. Before I re-attach the brake line, I fill the space under the piston with brake fluid and pat myself on the back for clever thinking. Less air to pump out. I re-attach the line and begin bleeding the system. Just when I think I'm almost done I see a puddle of brake fluid forming on my work bench. I think, what happened, Is the bleeder valve leaking? Is the brakeline not on right? Nope. Some dumb guy forgot to block the piston and I pumped it right out again. AAArrgh - so much for my clever idea. So realizing that I haven't yet applied enough wood to the job, I block the piston and begin pumping out the air.

Hope you've enjoyed this story about how not to work on your brakes. The piston is now moving in both directions as it should. All the parts are now very shiny, having been cleaned in a veritable bath of brake fluid (stuff tastes nasty by the way). And I've re-affirmed that I can fix anything, given the right knowledge and enough wood.

[prometheus578]

"Nice goin', Tim."

I "wooden" be surprised if your daughter wants to be a mechanic when she's older.