Yamaha R1 Forum: YZF-R1 Forums banner

Status
Not open for further replies.
1 - 17 of 17 Posts

·
R1 Sometime In The Future
Joined
·
109 Posts
Discussion Starter #1
I was driving home today, and the rear brake was working fine one minute, then the next it was completely OUT! So I just drove using the front until I got home. I parked it for about 5 minutes, drove it around the block, and it was working again for a minute or 2, then went out again. My fluids are between low and full, so that shouldn't be a problem. Could air in the line be the cause? Any other ideas? Thanks
 

·
Super Moderator
Joined
·
27,468 Posts
Good be a loose connector or a loose wire somewhere. Most likely a ground. Possible it needs to be adjusted as well by the brake pedal.
 

·
Action figure sold separately
Joined
·
12,225 Posts
Are you saying you are loosing brake function at the rear brake, or that the brake light is intermittently not activcated with the rear brake. If it's the former, than it will not have anything to do with a loose electrical connection or wire. When was the last time you changed the brake fluid?
 

·
Look out for what truck????
Joined
·
258 Posts
geforcer said:
I was driving home today, and the rear brake was working fine one minute, then the next it was completely OUT! So I just drove using the front until I got home. I parked it for about 5 minutes, drove it around the block, and it was working again for a minute or 2, then went out again. My fluids are between low and full, so that shouldn't be a problem. Could air in the line be the cause? Any other ideas? Thanks
Could be a warped rotor. That would cause the pads to spread out, then when you try the brake a few times you pump them back and the brake will work, then as you ride some more they spread out and no brakes again.
 

·
R1 Sometime In The Future
Joined
·
109 Posts
Discussion Starter #6
Eyespy said:
Are you saying you are loosing brake function at the rear brake, or that the brake light is intermittently not activcated with the rear brake. If it's the former, than it will not have anything to do with a loose electrical connection or wire. When was the last time you changed the brake fluid?

brakes themselves don't work. when they do work, they work fine for a little while. then they get to where i have to press the brake lever all the way down for them to work at all, and they don't work with 100% braking power like they should. then they go completely out, and the brake lever has no feel of pressure in them at all.

turn the bike off for a few minutes, and it's the same thing as before pretty much (longer I let it sit turned off, the better the brakes work at first).

i'm thinking about bleeding the brakes (since the fluids never been changed out). i've checked for leaks, and haven't seen anything (might have missed though). i'm gonna check again in the morning though, and post back with any updates.
 

·
R1 Sometime In The Future
Joined
·
109 Posts
Discussion Starter #7
i rigged up a way to hold my brake lever all the way down last night (as mentioned in another thread to put pressure on the fluids to check for leaks). woke up this morning, and didn't see any leaks. started the bike, went riding for about 5-10 minutes, and didn't have any problems :S weird since it did it all day to me yesterday. any ideas what could have caused that?
 

·
R1 Sometime In The Future
Joined
·
109 Posts
Discussion Starter #8
well, another update. i think it might be a leak in the brake line. when i checked the brake fluids the other day, it was between low and full. now it's at the low line :( i checked for leaks earlier and couldn't find any though. guess i'll have to look harder.
 

·
Kitty kitty... RRRR
Joined
·
1,712 Posts
Have to agree with martinc - master cylinder looks like a best shot in guessing.

Had the same thing happen to me once, when I was using the rear brake (rear rotor is warped now, I'm waiting for a new one and got used to riding with almost no rear brake action). Out in the middle of highway - press the pedal, nothing happens. Stop, let the bike rest, pump 3-4 times - and voila, everything's back.
But my rotor is warped - so it might add to the cause too..
 

·
R1 Sometime In The Future
Joined
·
109 Posts
Discussion Starter #11
i forgot to mention in my last post that the problem started again...

thanks for the idea's of what could be the problem. my last post, i mentioned some fluids were missing since the time i checked before. do you think the master cylinder could cause this? i know my rotors are getting pretty thin, so could this be the problem? and last, the brake line, which i haven't seen any leaks yet..... but not to say it's not. i'm gonna check later when i get a chance, to see if i can find any leaks. since the last time i checked the fluids, no more has leaked out, so i find this also confussing since if some leaked out before, why has it not leaked more? thanks for the help
 

·
Registered
Joined
·
14,085 Posts
Ok,here is my take on this:

Maybe no fluid leaked at all;the fact that your disc is thinner and maybe the pads are wearing out much faster because of it makes the fluid reservoir level go down...its normal.

It really sound like a master cylinder seal gone bad.

My thumbrake is doing the exact same thing.
 

·
yield
Joined
·
17,851 Posts
thumbrake...!!!?? Jeez Martin what don't you have on your bike. I'm jealous
 

·
R1 Sometime In The Future
Joined
·
109 Posts
Discussion Starter #15
hmm, i just noticed some air bubbles coming out of the top of the brake reservoir. think that could be it?
 

·
R1 Sometime In The Future
Joined
·
109 Posts
Discussion Starter #16
this is aggrevating me, it just won't stop. i'm about to just order the master cylinder, and reservoir, and hope it works :p would anyone suggest ordering something like this on ebay? I can get the master cylinder and the reservoir, all in one for probably around $50 or so. or should i just buy new?
 
1 - 17 of 17 Posts
Status
Not open for further replies.
Top