XJ11 frozen brake on R front

[KA1J]

The last time I took the XJ11 for a ride I suddenly noticed the brakes were grabbing and not releasing. Turns out to be the right front, not the part controlled by the proportional valve but from the handle brake.

There is a fair amount of heat marking on the rotor and to get going, I tried tapping the caliper with a small rock. Maybe because it had cooled down or due to the rapping, I was able to get home without it grabbing. In retrospect, the right brake didn't feel very effective lately but I usually use the foot brake because it applies to the front & rear at the same time.

First thing I checked was the spooge hole and it is clear. I removed the caliper & pads today and the piston appears free (I rebuilt them 5K ago). What doesn't seem right is when I squeeze the front brake lever, the piston pushes in as I expected but then it pulls back when I release it. I haven't done too many front brakes on bikes in my life, only the ones on my 3 Maxims & that's it over the last 8 years.

I thought the piston only went one way when the brake lever is depressed. Since the piston in the caliper is pulling back every time the brake handle is released, would this be showing a failed master cylinder?

The rotors are new and I'll break the glaze with a random sander & get new brakes but I'm wondering what else I need to do.

Thanks!

Gary

[skids]

Bleed the brake on that side at the caliper. You may want to spay some brake-clean into the caliper and into the pivot pin if it is a special.

[donebysunday]

Caliper

You may be able to get by cleaning, lubing the pins that the caliper slides on and a very little bit of lube on the caliper piston. Use a large C clamp to compress the piston after you have cleaned around it. You may want to push the piston out by pumping the lever for the front MC and clean deep, careful, not to much !

The last time I took the XJ11 for a ride I suddenly noticed the brakes were grabbing and not releasing. Turns out to be the right front, not the part controlled by the proportional valve but from the handle brake.

There is a fair amount of heat marking on the rotor and to get going, I tried tapping the caliper with a small rock. Maybe because it had cooled down or due to the rapping, I was able to get home without it grabbing. In retrospect, the right brake didn't feel very effective lately but I usually use the foot brake because it applies to the front & rear at the same time.

First thing I checked was the spooge hole and it is clear. I removed the caliper & pads today and the piston appears free (I rebuilt them 5K ago). What doesn't seem right is when I squeeze the front brake lever, the piston pushes in as I expected but then it pulls back when I release it. I haven't done too many front brakes on bikes in my life, only the ones on my 3 Maxims & that's it over the last 8 years.

I thought the piston only went one way when the brake lever is depressed. Since the piston in the caliper is pulling back every time the brake handle is released, would this be showing a failed master cylinder?

The rotors are new and I'll break the glaze with a random sander & get new brakes but I'm wondering what else I need to do.

Thanks!

Gary

[skids]

Anytime you compress the caliper it will push fluid into the master cylinder. Take a little out first and cover your paint!

[TopCatGr58]

Hey Gary,

You said you had cleaned the caliper. Did you remove the O-ring, and clean/scrape the corrosion out of the caliper groove that the O-ring sits in??

As was stated, bleeding the brakes can also help, because IF it has some air in the line, then with a little rubbing, it heats up and cause the air to expand causing it to rub more, etc! Surprisingly the piston usually does retract a little back into the caliper when the handle is released. Also cleaning and lubing the caliper where the pads slide against can also help them release.

T.C.

[KA1J]

Hey there folks,

Thanks so much for the replies! Really, thanks.

When I restored the calipers, I was very OCD to make them as new before putting them back into action. Yes, I bought a rebuild kit and cleared out the race before putting the new O-ring in. Perhaps I missed a step in lubrication of the pin the brakes glide on but I tried to follow the guidelines here about doing it properly. As I recall, I wire brushed the old rust off and then put the pins in a drill press to sandpaper them as new.

The brake fluid looks as new (2 years old) so there's not much heating that has affected it, so I'm guessing this problem had to be happening quickly, rather than slowly.

As to air in the line; I thought I got it all out when I put it all back together; I used a vacuum pump to draw the fluid down and thought I'd expelled the air but maybe I didn't do a good enough job.

There's still good brake pad left but it's less than I would have expected so this must have been dragging for some time. I really have to replace the pads. I have three Yamahas so I never use one most of the time, so these pads should not be so worn.

I will run fresh fluid through and polish/lubricate the pins and see what happens. And I'll do as TJ suggests and lube the caliper/pads. I really thought the master cylinder was the culprit.

I will do the above and then check back in with how it goes.

Cheers!

Gary

[3Phase]

Gary,

Before you get all carried away, change the brake fluid and bleed the brakes.


The brakes are supposed to retract slightly when you release the brake lever.

The brake piston rides in that large square-cut seal/'o-ring' in the housing. When you brake, the piston extends and slightly rocks the inner edge of the seal up along with it. When you release the brake, the seal can relax and roll back to its original position, pulling the piston back into the housing along with it. No return springs are necessary.

The brakes will start to grab when the piston sticks in the extended/applied position and bakes the brakes.

Air and water in the brake fluid will heat up, expand and not allow the piston to retract with just the force of the rubber 'o-ring' to pull it back. More heat makes it worse but it will go away when the brakes cool off and drive you mad when you try to figure out what's wrong.

When that happens, the pressure release circuit (spooge hole) in the master cylinder should let some of the heated, aerated/waterlogged brake fluid expand up into the brake fluid reservoir but if the circuit is even partially clogged it can hold enough line pressure to keep the brake pads rubbing against the disks, making more heat and more freshly baked spooge.


If the brakes still stick after you've put in fresh brake fluid and bled the air out of the system, then you should dive in and look for dirt and rust under the 'o-ring'.

Dirt and rust distorts the seal and it will press against the piston so tightly that it can't rock and roll with the piston. When it can't rock and roll it can't keep the brakes off the rotors and the brakes will bake, making more spooge to clog the system.

.

[KA1J]

Hey there 3Phase, Just like hearing good advice from T.C., its nice to hear back from old friends, and the new friends.

I'll replace the brake fluid tomorrow. I will though have to order new pads, these have become very worn and way early. I'll use my Bosch random sander to liven the rotor again. As it is, there's are signs of heating that have to be addressed. & that smell, oh, that smell...

Gary

[3Phase]

Yep, I know what you mean. Mmmm... burned brakes. Yum. Not!

.

[Ken Talbot]

The last time I took the XJ11 for a ride I suddenly noticed the brakes were grabbing and not releasing. Turns out to be the right front, not the part controlled by the proportional valve but from the handle brake.

2 possibilities:

Could be a blocked spooge hole in the master cylinder. Easy fix, just needs a bit of fine wire to poke it clear, then flush the system with fresh fluid.

If you haven't had that caliper apart for a while, it could also be a build-up of cr@p under the rubber o-ring in the caliper. The build-up causes more friction around the piston, and prevents it from withdrawing from the rotor when you release the brake lever. Clean out the cr@p and the piston will resume its normal pull-back when pressure is released.

Edited - looking back at previously replies, 3phase has basically said the same thing, but much more elegantly!

[KA1J]

The first thing I checked was the spooge hole, using a syringe needle with the tip removed. The fluid is as new and I'd cleaned the reservoir about two years / 1000 miles ago. The needle passed with no obstruction and when I gently pulled on the brake handle, I could feel the master cylinder components move against the needle and I released so as not to damage anything, but the hole is clean.

I'd given the caliper a thorough going over 2 years ago and thoroughly cleaned out the race where the O ring fits and I cleared all the old gunk behind the piston. I put in a new piston O ring & cleaned out the caliper, even repainting it to make it as new. The fluid in the caliper is clean & there's no discoloration or particles in it today.

The brake pads though... Nasty and all kinds of brake dust in the well inside the caliper from the pad wear.

I'll need to remove the rotor to resurface both sides.

And I still need to do the dremel fix but for now its the one brake...

[DiverRay]

I'd given the caliper a thorough going over 2 years ago and thoroughly cleaned out the race where the O ring fits and I cleared all the old gunk behind the piston. I put in a new piston O ring & cleaned out the caliper, even repainting it to make it as new. The fluid in the caliper is clean & there's no discoloration or particles in it today.

What you cannot see is WATER in the brake fluid! DOT 3 should be changed every two years, no matter what it looks like. What I did with the '79 is cleaned everything and went to DOT 5, as it's NOT hygroscopic so does not have the problems of DOT 3 or 4. You will probably need to clean behind the O ring in the caliper as well, due to aluminum oxidation.

[jkorn]

I would like to add something to this post that might be relevant. My 79 XS 11 has spent more time static than moving the last couple of years. Wanting to take it out for a ride, the front brake lever would not "Return" to the full out. Well the lever would but the piston in the master cylinder would not. No pressure until almost all of the way in. Like the Little piston was not coming all of the way back out the it's normal place. After talking with a friend, deceided to spray a little wd40 into when the bolt on the lever meets up with the small piston. Worked the brake many times, went back an hour later worked more, came back an hour later and BACK to normal. The bolt on the lever meets up with the piston with just a little throw. Seems it got kind of stuck most of the way in.

It was NOT the little hole some talk about. So glad I did not have to Rebuild it AGAIN... Jeff

[cajun31]

I would like to add something to this post that might be relevant. My 79 XS 11 has spent more time static than moving the last couple of years. Wanting to take it out for a ride, the front brake lever would not "Return" to the full out. Well the lever would but the piston in the master cylinder would not. No pressure until almost all of the way in. Like the Little piston was not coming all of the way back out the it's normal place. After talking with a friend, deceided to spray a little wd40 into when the bolt on the lever meets up with the small piston. Worked the brake many times, went back an hour later worked more, came back an hour later and BACK to normal. The bolt on the lever meets up with the piston with just a little throw. Seems it got kind of stuck most of the way in.

It was NOT the little hole some talk about. So glad I did not have to Rebuild it AGAIN... Jeff

Be aware that the DOT 3 brake fluid used in our bikes absorbs water over time. As a safeguard .. even if you brakes are working ... you should change the brake fluid. It is highly recommended that it be changed completely every 2 or 3 years. It cuts down on the crud that can be formed by contaminated fluid which is what causes the pistons to start sticking and the spooge hole to clog. When you refresh all the fluid in the system it will actually help keep that hole clean and free of debris. It really helps to employ a tool such as a mity vac. If you live around a harbor freight store they have several to choose from at varying prices. It sucks the old fluid out and all you have to do it keep filling the master cylinder until you notice the fluid coming out is as clean as the fluid going in. Makes bleeding the system very quick.

[jkorn]

Good point on the mity VAC. Need to get it out of storage, forgot how it made bleeding much easier...