Rear brake is changing.

[Flyinfool]

For the 6 years that I have owned this bike, I always thought the rear brake felt soft and had very little stopping power. I have readjusted the brake peddle to as high up as I can get it, and had to push it down as far as my foot could go to get any decent stopping power. I have bled the brakes several times with no change. I just resigned myself to the fact that this bike does not have grate brakes and went on with life.

 

Today on my way to work, it is a 25 mile ride that takes me 45 minutes, the rear brake was getting better and better with every stop, by the time I got to work the rear brake felt just wonderful. I really like the feel right now. BUT what concerns me is the fact that something is changing and I do not know what or why.

 

It will now stop very well and with a LOT more authority using just the rear than what it ever had before using both brakes. I don't know if it just suddenly started working correctly and I just had crap brakes all of this time, or is something about to blow out.

 

My first thought was that it is the well known issue with heat causing the rear caliper to lock up. But while at a red light the bike rolled freely forward or back. As soon as I got to work I put it up on the center stand and spun the rear wheel by hand and it was as free as it should be.

 

I know it is overdue for another fluid change and I was planning to upgrade to SS lines and maybe de-link at the same time, so that will get me my fluid change. I was hoping that the SS lines would get me a less mushy feel to the peddle.

 

Question is, what would suddenly make the rear brake work so wonderful?

Do I have a problem that may suddenly leave me with NO rear braking system?

What could have suddenly started working to fix a problem that I have had forever and just did not know I had?

 

I will see if the brakes are back to normal for the trip home this afternoon which could indicate that it is a heat build up issue. I'm going to borrow a 5/16 wrench just in case it is a heat issue and I need to crack the bleeder.

 

At least there are no wires involved with this issue........

[KIC]

Don't have anything to add, but figuring that my 89 hypochondriac will probably now develop the problem/symptoms I ought to follow this...

[dacheedah]

If i remember correctly there is a valve in there I had issues with once that makes bleeding a pita.

 

Maybe it had some air in there that finally found its way out. I know if it felt soft and u pumped it and then jammed on it and it locked it was likely air.

 

Or maybe your gremlins are looking for a new home

[Flyinfool]

And here I thought that I left all of the gremlins south of the WI border on my test ride......

 

In another 45 minutes I'll know if this is heat related or not when I head home.

[Big Lou]

may have wore pads ,, when you put them on did they have oily residue , or did you use any antiseize.. run through a oily mud hole somewhere .. any thing to contiminate the pads ,till they wore off,, grease the rear splines on the wheel

 

 

some thing got on them ,,

 

this is Dr. Lou"s class for the day

 

now to learn something

[bongobobny]

OK what comes to mind is crud in the proportioning valve that finally dislodged. I also thought froze piston that freed itself but that seems far fetched. Maybe brake pads that were glazed and finally lost their glaze???

[MiCarl]

Maybe the rear pads were hanging up in that rut that develops on the rear caliper and the pads wore down enough to get to the clean surface.

 

I repaired the ruts in my caliper this past winter. It was obvious from the shape of the pads that braking had been greatly reduced. I can't say I noticed a difference but it was a long cold break between the last before and first after.

[Flyinfool]

OK, now I am really confused.

When I left work the pedal felt like the old normal.

over the next 5 miles it progressively went back to the nice hard great pedal. I stopped to see if it was a heat issue. All 3 rotors were at about 110 deg F. That rules out a dragging brake causing excessive heat.

After another 10 miles there are several lights in a row that are timed so that you will stop at each one. the first one had the new hard pedal, the second and third had the old normal peddle, I had the old normal pedal the rest of the way home. when I got home, all three rotors were close to the same temp with the left front being the coolest, but all were cool enough to hold my finger on.

 

So this change in pedal is now coming and going for no apparent reason.

[KIC]

:icon_lurker:

[bongobobny]

Disassemble and clean out your proportioning valve...

[Big Lou]

CHANGE THE BRAKE FLUID. MAY HAVE TRASH OR WATER,, SUPPOSE TO CHANGE ONCE A YEAR ANYWAY:detective:

[dacheedah]

Disassemble and clean out your proportioning valve...

 

I second that, add some fresh fluids and maybe speed bleeders.

[Flyinfool]

I even have a set of speed bleeders that were going to go in when I install the SS lines. Now may be the time to do all of this.

[Condor]

Here's my guess... You have two problems. Since the brake pedal has always felt 'mushy' you've probably never gotten all the air out of the lines, and since they are due for a bleeding you have had some of the fluid crystalize, and a piece is blocking the expansion hole in the master. When the fluid heats up while braking it expands and if it has no place to go it will start to apply pressure to the caliper pads. Because of the air it never really locks the rear brake up, but it gradually starts to feel a lot better. Take a long down grade using lots of brakes and I guarantee you will eventually lock the rear brake up. Time to bleed and clean out the expansion hole. If you don't have Speed Bleeders, you need to get them.

[Yammer Dan]

Here is mine. Sticking piston.

[Flyinfool]

After reading all of the suggestions from everyone and sleeping on it, My thought is that I have a crud issue. If after a 25 ride home all of it in city traffic and none of the rotors were to hot to touch, this in my book rules out a dragging caliper. If something was dragging that rotor would be WAY over what you can hold your finger on. since the change comes and goes randomly it must be dirt somewhere it should not be that is blocking and unblocking something. A heat issue would not come and go in the distance of a city block.

 

I had already planned to upgrade to SS lines at the next fluid change.

I was still undecided as to whether to de-link.

Remembering back just a couple of weeks ago I nearly dumped the bike when I used the rear brake only to come to a complete stop on damp dirt that had some moss or alge on it and the front wheel locked up momentarily.

 

So the plan is that the bike is telling me it is time to spring for the parts to convert to SS lines, and do the de-link. Part of this will be cleaning out everything I can clean.

 

Enter shopping mode........

[billmac]

you have something in the caliper , since your going to change fluid anyway have someone pump the break and keep pressure on it and keep releasing the fluid. it should squirt out fast, when low take the bleeder out and hit one more time, put in the new bleeder and lines and bleed till full. If your not changing the pads I'd also take them out and push the cyclinders all the way back in to break any rust or dirt in the disk system.

[icebrrg3rd]

Jeff, you must have gotten the gremlin wet, and now he multiplied. Better get this fixed ASAP before he multiplies more!

 

Yup, I vote "yes" on de-linking, I had that issue several years ago, hit the rear too hard and locked up both, was on my side before you could blink. Delinked before I rode it again.

 

-Andrew