Rear brake sticking

[FJRMaineiac]

So I got the FJR all set for my first ride to work this spring (our dirt road was impassable to anything but a 4x4 up until this week :blink: ), but when I went to leave yesterday I discovered I had a flat battery. That's an easy fix (although expensive - they aren't giving batteries away these days). Yes, I had kept it on a Battery Tender every winter, but its 5+ years old now and its just done.

That's not the point of my question, though. In going over the bike I realized that my rear brake is sticking again. I had this problem last fall. I removed the caliper, made sure the pads could move freely and flushed the brake fluid. I think it helped, but it clearly didn't solve the problem. Has anyone else had a similar issue? Any thoughts on a fix? I have been trolling this and other message boards and about the only thing I could find that I haven't done was to disassemble the brake caliper and check for corrosion in the piston cylinder. I am also wondering if it is the master cylinder. I have seen something similar to this with old cars where the flexible section of brake line just before the caliper degrades over time and the I.D. becomes so small that it acts like a check valve not allowing the brake fluid to leave the caliper. However, this was always on older (10 years +), and I find it difficult to believe the same thing is going on with my '04 FJR. Your thoughts are appreciated.

The upside to this story is that while I am waiting for my lovely wife to stop by the motorcycle shop to pick up the new battery, I dusted off the old '86 FJ1200 and took that to work today. It is still a great ride!

 

[radman]

Rear brake lever pivot. Clean and grease at least yearly, along with shift mechanism.

 

[FJRMaineiac]

I'll certainly do that when I am working it over, but the lever seems to move freely. It feels more like the break fluid isn't moving back out of the caliper. I am wondering if there is some kind of obstruction in the line. However, when I flushed the break fluid in the fall, the fluid flowed easily from the master cylinder to the caliper and out the bleed valve. Hmm...

 

[FuzzyRider]

How much force is being applied to the rotors? Can you spin the rear wheel by hand in neutral? If you apply rear brake then release can you spin it at all?

 

[wfooshee]

If it's really sticking at the caliper and not the foot pedal then see if there's gunk built up on the exposed portion of the piston. Happens on front brakes pretty easily: crud builds up and keeps the piston from being able to recede into the cylinder. New seals might help, too. Generally that condition isn't discovered until you put new pads in, which sets the crud-infested part of the piston back into the seals and then the piston doesn't move freely.

 

[FJRMaineiac]

@FuzzyRider - when I press on the rear brake, the caliper sticks in that position. If I have applied sufficient force, the rear wheel will not turn with the bike on the center stand and in neutral.

I tend to agree with wfooshee - there has got to be some crud preventing the piston from retracting. I don't think it is on the outside of the caliper, though. I made sure those parts could move freely when I disassembled and cleaned them last fall. I am not sure if I can get the piston out of the cylinder without wrecking the seal, but I am going to try. I am betting that there is either some corrosion built up on the cylinder wall or that some sort of debris has found its way around to the brake line hole and is plugging it up somehow.

I was talking with someone at the office who seemed to recall a discussion about the DOT4 brake fluid being more prone to allowing corrosion than older (DOT3) brake fluids. Has anyone else experienced this?

 

[FuzzyRider]

So the piston isn't retracting. Anyone make kits with replacement pistons and seals? As for moving the piston, you could try clamping a thin piece of wood over one of the pistons and then pump the rear brake to force the other piston out.

 

[wfooshee]

There's only one piston on the rear, it's a sliding caliper, just like your '75 Vega.

And you probably don't need a piston as long as you can get it clean. Seals are a good idea, sounds like. Many sources, check the vendor board for recommendations.

 

[radman]

The rear caliper piston has a seal on the outside-unless bad, the piston should be in good shape. The pins (bolts) clean and lube with SilGlyde-

There is an adjustment at the rear master cylinder that should be checked. Open the bleeder, and push the piston all the way in. Should move smoothly. Install and press lever till you have rear brakes. If the pads are thin, it increases the tendency for the piston to **** in the bore. Missing shims will increase the likelihood of this. Use a Mityvac at the bleeder to check for debris in line-suck through two full cylinder reservoirs. Dot 5 silicone base fluid is the fluid probably mentioned in the corrosion article. 4 is the way to go.

 

[kulwen]

A link that might have some info:

Link

 

[bikerskier]

The repairs to my 05, for a bad rear brake cost me around $375. I was pissed.

 

[SkooterG]

The repairs to my 05, for a bad rear brake cost me around $375. I was pissed.

What repairs? As in, what exactlty needed fixing?

 

[mcatrophy]

@FuzzyRider - when I press on the rear brake, the caliper sticks in that position. If I have applied sufficient force, the rear wheel will not turn with the bike on the center stand and in neutral....

About a hundred years ago, I rebuilt an MG-B (bought written off, new body-shell, transfer all the bits etc). Included rebuilding the brake runs.

To cut a long story short, on its first long run, the brakes seized on; I drove it on to a grass verge with the front wheels locked.

Crawled under it, and in a rare moment of inspiration, I loosened the bleed nipple by one wheel. After I wiped off the hot stream of brake fluid that had spurted over my face, the brakes had freed, and never gave a problem again.

I can only assume that when I'd put it all together, a bit of crud had eventually moved and was jamming something in the master cylinder to prevent the release of pressure.

Anyway, it might be worth bleeding the brake, see if that frees it.

Just a possibility.

 

[RadioHowie]

About a hundred years ago, I rebuilt an MG-B (bought written off, new body-shell, transfer all the bits etc

Just in case anyone EVER questions your sanity, the above incontrovertibly proves you have none.

Did the same thing once. Wound up setting the damn thing on fire.

On purpose.

 

[mcatrophy]

QUOTE (RadioHowie @ Apr 16 2009, 09:42 PM) <{POST_SNAPBACK}>
...
Just in case anyone EVER questions your sanity, the above incontrovertibly proves you have none.
...

No-one ever questions my sanity, everyone who knows me has no doubts as to the answer.

QUOTE (RadioHowie @ Apr 16 2009, 09:42 PM) <{POST_SNAPBACK}>

QUOTE (mcatrophy @ Apr 16 2009, 03:01 PM) <{POST_SNAPBACK}>
About a hundred years ago, I rebuilt an MG-B (bought written off, new body-shell, transfer all the bits etc

...
Did the same thing once. Wound up setting the damn thing on fire.
...

Had mine for over a year, only got rid of it when I proved my virility for the second time

(Click on image for larger view)

It was originally bought new by an American serviceman stationed here in the UK, left hand drive because he was going to ship it back to the 'States after his TOD ended. He wrapped it round a tree, 3000 miles on the clock.

I got it from a breaker's, but it was over a year sitting there while the paperwork got sorted since it was originally an export, got the body-shell from another garage that had it spare (?) for a good price.

Converted the bits for proper right-hand drive (it needed a new steering rack anyway), the biggest problem (for me) was the hydraulic runs for clutch and brakes.

Even made my own dashboard.

Oh yes, I had a bit of a problem with the acid burns on the back seat, under which the batteries were kept, because the PO had left it parked upside-down. Could smell sulphuric acid for months. But it did mean the batteries were stored dry, and after filling them with acid, they never gave me a problem (there were two 6-volt batteries, one either side of the transmission tunnel).

Of course, I was young, enthusiastic, optimistic, poor and very green. Now I am older, pessimistic, unenthusiastic, poor and very green...

 

[bikerskier]

The repairs to my 05, for a bad rear brake cost me around $375. I was pissed.

What repairs? As in, what exactlty needed fixing?

Diagnostics $40

Labor 96

Rear disc 145

Brake pad kit 36

Caliper shim 3

Support pad 10

bolt 10

shop charges 5

Total $345

I'm pretty sure I was worked over without a kiss.

 

[wfooshee]

Something really bad has to happen for you to need a disc! Like running the pads all the way down and using the backing plates for brakes.

That said, if you did that, then, um, you sort of deserve the bill you got. . . . . Sorry.

 

[08FJR4ME]

Replace the Caliper get new shoes bleed and call it a day.

Been through this episode to many times on to many vehicles.

Good Luck!

 

[bikerskier]

Something really bad has to happen for you to need a disc! Like running the pads all the way down and using the backing plates for brakes.
That said, if you did that, then, um, you sort of deserve the bill you got. . . . . Sorry.

Disc was heat warped but not marked up at all.