Brakes Fading

[Mythos]

If the throw in the brake pedal is getting longer until it just bottoms out and you have no braking at all at full throw, that is a hydraulics problem or possibly piston in caliper is getting stuck (but then your brake would also be dragging). If the throw remains more or less constant but the brake fails, that might be pads or rotor.

Because you mentioned a couple pumps brings it back, that suggests low pressure. You pump some down from the reservoir and that restores the pressure. That sounds like fluid leak or air in the line but the fact that the pedal comes back to 100% on its own tells me otherwise.

It sounds like the brake works but the pressure is not returning to the master cylinder after you release the brake. In other words, the caliper is remaining closed after you release the brake pedal. The brake pads would be dragging the rotor. You might not feel that with the weak back brake especially carrying a passenger.

First test on a rear stand. Spin the rear wheel. Does it spin normally or is the brake dragging? It should turn one full revolution in Neutral if you give it a good spin by hand. Then apply the brake a few times. Does it stick after the brake was activated? Yes? caliper piston is sticking. No? Continue to work the brake pedal and spin. Can you duplicate the problem? Yes? Caliper piston. No? Do you loose pressure in the pedal but the wheel spins freely? That has to be air in the line or a bad master cylinder. It's also possible that the problem would only happen when the system gets exceptionally hot from heavy use. Do a road test.

It's normal for a rotor to get hot to the touch after even after mild use. Try riding the bike and applying the brake just one or two times. If the rotor feels hot after a few minute ride, it might be that your caliper piston is sticking. Try putting the rear up immediately after the test ride and see if the wheel spins normally.

PITA but you could disassemble and clean the whole caliper and pistons and replace seals. That is a part of sched maintenance. My bike has 11000 miles, I've never done it. The Kaw has 47000 miles and no rubber parts replaced yet.

The rear brake is the easiest thing to bleed. Don't TIGHTEN the bleeders during bleeeding, just barely snug is enough and you won't wear out the threads. Watch for seepage in the days after the bleed and wash away with water often. Give it a tiny crick more torque if necessary. DO NOT overtorque the bleeds or the threads may leak even with new bleeders. It's not unusual to have seepage weeks after opening the bleeders and that is why I don't bleed unless I really need to. They often seal up on their own after a while but wash away that seepage often because it will etch paint.

Read the intro and steps 13 to 21 here:

https://hayabusa.org/forum/threads/genii-front-and-rear-brake-fluid-clutch-fluid-bleed-drain.170084/

I hope that helps solve the problem. It's all I got. I don't know much about master cylinders yet.

 

[Mythos]

I can't believe this would be pads. Pads might have poor grip but they cannot effect fluid pressure.

It could be a leak but I do not see how that would allow pressure to come back without pumping the MC. Also, you would see your fluid level drop in the reservoir and probably brake oil deposits and paint corrosion if there was a leak.

To me, it sounds like the piston is sticking but even so, it would be odd if you lost all pressure in the pedal unless there was also a leak.

 

[sixpack577]

I just re-read the original post, and he says the front brakes do it to, just not as badly.
To me, that says brake pads...race material.
EBC " Extreme Pro" ceramic embedded pads are street pads.
I cannot say if the ceramic carbon the op has are race or street.
If they are race pads, which it now sounds like, that IS the problem.
If your not constantly on the brakes(typical street riding), then as soon as the race pads quickly cool, they loose their initial bite, until they heat back up.
Either that, or both front and rear brake lines were replaced and both bled improperly.
After brakes are bled, the lever should be pulled and zip tied to the bar, let sit overnight to an entire day, and bled again.
This will make sure All the air is gone from the system.

 

[ali123]

I remember him wanting to do ALL the maintenance recommended... and I THINK he DID replace all hydraulic fluids.... I think we are looking for a unicorn here when the real problem is simply a little air in the system from when he replaced fluids.... bleed the d-poop outta them brakes.......... done.

 

[jellyrug]

Tian

Wat gebeur as die poliesie jou vang gedurende 'n wedren? Hier by ons is dit tronk toe vir drie maande, motorfiets word gekonsfiskeer vir dertig dae.

 

[Tian]

I'm sorry... did u say u were in a wheelchair for 5 or 6 months?

Nope.... just for a while in the wheel chair i think it was almost 6 weeks. But in bed for 5 or 6 months.

Crashed on an end of july then in end september went to surgery for marrow transplant in my foot and reconstruction in my foot-was in bed till middle december, then went to some doctor who bends and pulls it and teached me to use the foot again. So january i was moving around comfortably again. The time i spend in the wheelchair was the time my shoulder muscle took to heal then i moved over to cruches. If the doctor just did the surgery the same day i had the accident i would have been up and running by that october. Happened 2015 on my gen1 k7.

 

[Tian]

If the throw in the brake pedal is getting longer until it just bottoms out and you have no braking at all at full throw, that is a hydraulics problem or possibly piston in caliper is getting stuck (but then your brake would also be dragging). If the throw remains more or less constant but the brake fails, that might be pads or rotor.

Because you mentioned a couple pumps brings it back, that suggests low pressure. You pump some down from the reservoir and that restores the pressure. That sounds like fluid leak or air in the line but the fact that the pedal comes back to 100% on its own tells me otherwise.

It sounds like the brake works but the pressure is not returning to the master cylinder after you release the brake. In other words, the caliper is remaining closed after you release the brake pedal. The brake pads would be dragging the rotor. You might not feel that with the weak back brake especially carrying a passenger.

First test on a rear stand. Spin the rear wheel. Does it spin normally or is the brake dragging? It should turn one full revolution in Neutral if you give it a good spin by hand. Then apply the brake a few times. Does it stick after the brake was activated? Yes? caliper piston is sticking. No? Continue to work the brake pedal and spin. Can you duplicate the problem? Yes? Caliper piston. No? Do you loose pressure in the pedal but the wheel spins freely? That has to be air in the line or a bad master cylinder. It's also possible that the problem would only happen when the system gets exceptionally hot from heavy use. Do a road test.

It's normal for a rotor to get hot to the touch after even after mild use. Try riding the bike and applying the brake just one or two times. If the rotor feels hot after a few minute ride, it might be that your caliper piston is sticking. Try putting the rear up immediately after the test ride and see if the wheel spins normally.

PITA but you could disassemble and clean the whole caliper and pistons and replace seals. That is a part of sched maintenance. My bike has 11000 miles, I've never done it. The Kaw has 47000 miles and no rubber parts replaced yet.

The rear brake is the easiest thing to bleed. Don't TIGHTEN the bleeders during bleeeding, just barely snug is enough and you won't wear out the threads. Watch for seepage in the days after the bleed and wash away with water often. Give it a tiny crick more torque if necessary. DO NOT overtorque the bleeds or the threads may leak even with new bleeders. It's not unusual to have seepage weeks after opening the bleeders and that is why I don't bleed unless I really need to. They often seal up on their own after a while but wash away that seepage often because it will etch paint.

Read the intro and steps 13 to 21 here:

https://hayabusa.org/forum/threads/genii-front-and-rear-brake-fluid-clutch-fluid-bleed-drain.170084/

I hope that helps solve the problem. It's all I got. I don't know much about master cylinders yet.

1st part i cant tell

2nd part-

3rd part-At first he brake works.
Then the more you use it the deeper the press goes down. Then when it is at the bottom, there is no braking power at all.
When i am pumping it like a couple of times it will start coming back, first a little until say half a press. Then i need to leave it alone for a little while say maximum a minute then it will start working again the instant you touch it.
Where you mentioned the caliper stays closed-it appears to do opposite, its open and when you press it the pads does not move. No sound or feel of pads dragging. That i did check but not on paddocks just under the petrol station lights. Pushing the bike forward and backwards.

4th test part- the brake is not dragging when on paddock.... i did some errants after work and did a chain lube when we got back home. The wheel did spin freely. No draging.
I will drive it hot again tomorrow, till it disappears and then paddock it and spin the wheel with testing it as you suggested and post the result... :-)

5th part- as mentioned in part 4, did some errants after work, paddocked it and lubed the chain, then the wheel did spin freely... i did check on that and listened for drag sounds but nothing...

Thanks for the advise and bleeding tips! I will keep it in mind....

 

[Tian]

I remember him wanting to do ALL the maintenance recommended... and I THINK he DID replace all hydraulic fluids.... I think we are looking for a unicorn here when the real problem is simply a little air in the system from when he replaced fluids.... bleed the d-poop outta them brakes.......... done.

Yes.... would have been this weekend but no stock on oil.... so will get it next week and then will start the maintenance. Will work out better cause i have 600km to go then its the 50 000km service anyway.

I do get the feeling that i bled the brakes improperly.... so im going to do the tests @Mythos suggested to see whats happening and clean the pads and stuff with brake cleaner and then gonna bleed d-poop out of them brakes and clutch too :-)

 

[Tian]

Tian

Wat gebeur as die poliesie jou vang gedurende 'n wedren? Hier by ons is dit tronk toe vir drie maande, motorfiets word gekonsfiskeer vir dertig dae.

Waar woon jy?

Hier gebeur nie veel nie.... Ons poliesie is nog ver agter met tegnologie en voertuie. Keure wat ek al gevang was is ek laat gaan met n waarskuwing-gebeur maar meeste van die tyd. Of omkoop ook maar dis as hulle die skimp gooi vir n bribe :-)

Maar volgens wet word jy toe gesluit-N$4000 bail dan hof toe. Daar kry jy dan nog n boete by die 4000 van nog n 4000-20 000 afhangende van jou oortreding en spoed. As jy nie kan betaal nie is dit 6-18 maande tronk straf. Lisensie word getermineer vir 5 jaar dan moet jy weer leerling lisensie doen en uitpasseer. Fiets word geskraap en konfiskeer vir 3 tot 6 maande dan moet jy weer gaan vir roadworthy en registrasie. Maar daar is eiters 3 of 4 van daai gevalle waarvan ek gehoor het. En dit was mense wat weg gejaag het... dink een het n ongeluk gemaak en een weet ek het gebreek. Nie 100% seker van die ander nie net in nuus gesien van dit...

 

[Bailey9r]

Tian

Wat gebeur as die poliesie jou vang gedurende 'n wedren? Hier by ons is dit tronk toe vir drie maande, motorfiets word gekonsfiskeer vir dertig dae.

Tian ; Those are at walmart for 14.95 And it says right in the description OEM REPLACEMENT NOT FOR SPIRITED RIDING in other words stock replacement and not for hauling ass with GF on back.
BTW Nice looking girl, buy better brakes to keep her safe (Okay you B safe too) ;<)

 

[Mike Chambers]

Sorry man, i see it's called Traffic lights.

We have them here too, ( traffic lights) although most drivers get confused by them .

 

[ali123]

My GF and i was playing with her brother on his K9 1000. Did robot to robot racing etc. It was really hard acceleration and very hard braking. So i used both my brakes quite hard and when i approached a robot it was just like gone. lol.

This rarely happens only when we do higher speeds in city or playing like yesterday when much harder braking is needed this happens.

So the fading is normal then i guess with all the heat and so?

Except for Braded Hoses and Waved Disks, is there any other upgrades on brakes available?

my girl is absolutely fearless... but really I just think she doesn't understand how badly shes gonna get hurt if she comes off the bike.... I do.... I ran my 2002 hard with her on the back at 2am one night... and she almost fell off the back of the thing.. I told her THREE times to HOLD ON TIGHT... I even looked her in the eye and shook my head to signal I was gonna nail the throttle.... she kept screaming "go fast" ... faster... fastger... so I did... next thing I felt was her arm slip off me... then the other arm.....THEN... she grabbed the back of my jacket with her fist... her legs went underneath mine....my heart sank... surreal.... since that day... I wont ever do it again.... ever... shes only 110 lbs... she would have died....

 

[Mythos]

At first he brake works.
Then the more you use it the deeper the press goes down. Then when it is at the bottom, there is no braking power at all.

Sounds like the master cylinder is making enough pressure to close the pads but there is not enough pressure created to return the pedal to the normal unloaded position. If the pedal is going back to position, it's from the little spring they put on there so if you loose brake pressure, the pedal won't hang down and scrape in a corner.

When i am pumping it like a couple of times it will start coming back, first a little until say half a press. Then i need to leave it alone for a little while say maximum a minute then it will start working again the instant you touch it.

Pumping it builds pressure but not full pressure.

Where you mentioned the caliper stays closed-it appears to do opposite, its open and when you press it the pads does not move. No sound or feel of pads dragging. That i did check but not on paddocks just under the petrol station lights. Pushing the bike forward and backwards.

So the caliper is reacting normal to no fluid pressure. Sounds like the caliper is ok.

Here's my next theory:

There is an air bubble in there. It rises toward the reservoir but apparently it is stuck in the master cylinder because if it could get out of the MC, it would just float up to the reservoir and join the other air at the surface of the fluid in the reservoir.

You use the brake. It works normally one time. Fluid was pushed down the brake line but that air bubble up top has now been pushed into the line as well. That is why the pedal does not return all the way. The more times you press the pedal down, the more air gets pushed down the brake line which does not create nearly as much pressure as fluid. The air in the line does not have enough pressure to bring your pedal back at all. It returns on the safety spring only. The brake line is probably half full of air now. No brake. Pads won't move. Pump the pedal repeatedly, fluid is sucked down from the reservoir and gives you partial pressure but you have a bunch of air in there you are compressing and air just collapses very easily under pressure so weak brake.

Let it sit a minute, the air that was forced down to the brake line is lighter than brake fluid so it rises back up to the top of the MC. I don't know my MCs well enough to say but there must be a seal in there like the plunger in a syringe and that would trap the air from going harmlessly up into the reservoir and fixing the problem on its own.

So bleed that rear brake and make sure you do it right. Perhaps you have been releasing the pedal before you close the bleeder. That would suck air in.

Close bleed, pump pedal, HOLD DOWN, open bleed (squirt), close bleed, pump pedal, HOLD DOWN, open bleed (squirt), close bleed, pump pedal, HOLD DOWN, open bleed (squirt), close bleed.

DO NOT let that pedal go if the bleeder is open.

It seems odd that you have the problem in the front brake too. Maybe --if you are bleeding improperly on both, you are causing the same problem in both. The front has a lot more power so that might explain why you don't loose all the front brake.

 

[Mythos]

my girl is absolutely fearless... but really I just think she doesn't understand how badly shes gonna get hurt if she comes off the bike.

Yeah, I went fast with my kid on the back. Not WOT but half in 6th gear up to about 110 on the expressway with a bunch of other traffic. She didn't like it. It scared the crap out of her. I guess I'm glad she didn't like it because that was too dangerous. I don't want to do that anymore. It will be funny to tell her she went over a hundred someday though--after she's 18 and I don't have to worry about her mom stripping me of my parental rights. Man, I've been busted a few times for speeding on the bike and usually let go but with any passenger-----shhhEEEEit!! Probably jail. Definitely bike gets towed and a huge fine and probably a misdemeanor which sounds minor but if you are looking for work, its not minor at all. Play it cool out there. You can't count on the kindness of an officer every time. Their job is to keep the public safe.

 

[WuzzaCBXRider]

I forgot what year you have Tian, do you have Brembos? I can find EBC HH pads for both front rotors here for under $70 shipped to me. A rear set would be half that or less. Non Brembos are probably less. What do you figure shipping to you would be? And how long before you’d get them?

 

[Tian]

Tian ; Those are at walmart for 14.95 And it says right in the description OEM REPLACEMENT NOT FOR SPIRITED RIDING in other words stock replacement and not for hauling ass with GF on back.
BTW Nice looking girl, buy better brakes to keep her safe (Okay you B safe too) ;<)

Thanks bro....

 

[Tian]

We have them here too, ( traffic lights) although most drivers get confused by them .

Here people choose to simply ignore them.... Mostly cause the phone is in the hand you know then the legs are too unstable to move from the gas pedal over to the braking pedal.

A while ago one jumped a stop street and right after the stop street he stopped in the middle of the road to pick up a padestrian. So i kicked his car. Not sure if i did any damage but hopefully he will remeber that before he does it again in the future.

 

[Mike Chambers]

I just re-read the original post, and he says the front brakes do it to, just not as badly.
To me, that says brake pads...race material.
EBC " Extreme Pro" ceramic embedded pads are street pads.
I cannot say if the ceramic carbon the op has are race or street.
If they are race pads, which it now sounds like, that IS the problem.
If your not constantly on the brakes(typical street riding), then as soon as the race pads quickly cool, they loose their initial bite, until they heat back up.
Either that, or both front and rear brake lines were replaced and both bled improperly.
After brakes are bled, the lever should be pulled and zip tied to the bar, let sit overnight to an entire day, and bled again.
This will make sure All the air is gone from the system.

I also recommend changing the fluid at least every 12 months as they absorb moisture, I think it's called hydroscopic. Your reservoir can absorb water through the rubber lines.just a thought.

 

[Mike Chambers]

Here people choose to simply ignore them.... Mostly cause the phone is in the hand you know then the legs are too unstable to move from the gas pedal over to the braking pedal.

A while ago one jumped a stop street and right after the stop street he stopped in the middle of the road to pick up a padestrian. So i kicked his car. Not sure if i did any damage but hopefully he will remeber that before he does it again in the future.

I wouldn't count on it. Like a computer, you often have to punch the information into them more than once

 

[Tian]

Sounds like the master cylinder is making enough pressure to close the pads but there is not enough pressure created to return the pedal to the normal unloaded position. If the pedal is going back to position, it's from the little spring they put on there so if you loose brake pressure, the pedal won't hang down and scrape in a corner.


Pumping it builds pressure but not full pressure.


So the caliper is reacting normal to no fluid pressure. Sounds like the caliper is ok.

Here's my next theory:

There is an air bubble in there. It rises toward the reservoir but apparently it is stuck in the master cylinder because if it could get out of the MC, it would just float up to the reservoir and join the other air at the surface of the fluid in the reservoir.

You use the brake. It works normally one time. Fluid was pushed down the brake line but that air bubble up top has now been pushed into the line as well. That is why the pedal does not return all the way. The more times you press the pedal down, the more air gets pushed down the brake line which does not create nearly as much pressure as fluid. The air in the line does not have enough pressure to bring your pedal back at all. It returns on the safety spring only. The brake line is probably half full of air now. No brake. Pads won't move. Pump the pedal repeatedly, fluid is sucked down from the reservoir and gives you partial pressure but you have a bunch of air in there you are compressing and air just collapses very easily under pressure so weak brake.

Let it sit a minute, the air that was forced down to the brake line is lighter than brake fluid so it rises back up to the top of the MC. I don't know my MCs well enough to say but there must be a seal in there like the plunger in a syringe and that would trap the air from going harmlessly up into the reservoir and fixing the problem on its own.

So bleed that rear brake and make sure you do it right. Perhaps you have been releasing the pedal before you close the bleeder. That would suck air in.

Close bleed, pump pedal, HOLD DOWN, open bleed (squirt), close bleed, pump pedal, HOLD DOWN, open bleed (squirt), close bleed, pump pedal, HOLD DOWN, open bleed (squirt), close bleed.

DO NOT let that pedal go if the bleeder is open.

It seems odd that you have the problem in the front brake too. Maybe --if you are bleeding improperly on both, you are causing the same problem in both. The front has a lot more power so that might explain why you don't loose all the front brake.

(Lol don't know how you quote like you do with the paragraphs lol but here is mine)

1st Part- The calliper makes enough pressure to close the pads, lever releases and pistons pulls back the way they are suppose to when lever is released-then less closing power with next press-then more less power and then finally when bottoms out a tiny bit of brakes, releases back to normal position and when you pressing again no pressure. lever moves as it suppose to but the pads nothing....

2nd Part-

3rd Part-

Theory Part- 2nd Part- With normal driving it works perfectly all the time.... Like 100%.
Normal driving is like doing average speeds of between 80 & 120 max on the way to work and home and errants etc. I really have no issues then. Its only when braking hard all the time... Like when we did that race-it was like 1st gear full throttle, 2nd gear full throttle, 3 rd gear full throttle till like 200-220kmh braking hard till a stop- repeat.... So the first 2 or 3 times its still working fine. Then suddenly it starts loosing pressure after each brake until none pressure over.

So can it then be that the bubble you mentioned then first gets the gap to move through when extreme braking is used? And then for normal riding the bubble just settles on the upper parts of hose/ressevoir like you mentioned and then does not get that much of force with normal riding to make its way through to the callipers to cause loose of pressure?

My gf's brother suggested that the brake fluid may be boiling when used hard and aggresively? Which then also forms airbubbles? Possible? Yes? Or no likely?

Bleed Part- I think we did bleed it the way you described.... Surely did not let go of pedal while bleeder was open that i am sure of....
We closed bleed-pump pedal until feeling normal, then open bleed-gently pressed down lever till it reached the bottom and while holding it there closed the bleed-pumped it again till normal feel-opened bleed and gently bottomed the lever and closed bleed while it was bottomed... Fine right?