[MDK210]

900 miles ago (I keep records) my mechanic installed Galfer SS front lines and ASV levers. I drove around and had some brake fade so he bleed the entire system going through two reservoirs only producing tiny bubbles. A week later after riding around, hitting bumps, getting the fluid hot on some longer rides it started up again as expected so we did the same thing and very tiny bubbles if any. Last week it started again so I decided to get some speed bleeders, even for the MC, which I installed and instead of using the reg Silkolene stuff I went to the fancy Motul RBF600 factory line to see if it would improve with the higher heat resistance. Took it out for a short 30 test ride today and almost zero fade but on the last two stop signs before I hit my house more brake fade so while it was hot I bleed the entire system and NO bubbles anywhere! What the hell am I supposed to do? Bike only has 11K miles so I doubt it's the MC and even then how would I test it other than seeing if bubbles were coming out? I only mention the levers because before the new lines/levers it all worked great. My wife's new 2011 250R doesn't have these issues when I use it as the control in my experiment...

Thanks for any ideas.

 

[steve_t]

Brake fluid change?

 

[Freebird]

Check to see if you have brake drag. Easiest way is by putting the front wheel and rear on the stand and spin them to check for excessive drag. I had this issue with the front brakes on an older FJ1200 I had and it was cause I had adjusted the front brake lever incorrectly causing them to drag and over heat in about 15 minutes of riding down the freeway without even applying them. If you do not have a brake dragging causing the fade then I am stumped, with the set up you have you should be good for track speed with no fade, certainly no fade issue on the streets.

 

[KarlyDJ]

You might still have an air bubble. if they redid the lines there can be a SUPER stubborn bubble at the top of the line by the master cylinder. Lay down a shit ton of towels and try crackin the bolt at the top of the line (since most dont have bleeders up there). Dont get any of that shit on your paint. Should spurt out right away. If not, was a good try since its a common problem after changing the lines.

 

[MDK210]

thanks for all the info guys. I did what you said Freebird and the rotor was cold as ice. I'm riding to Denver and back which is about a 4hr ride so I'll see if any more bubbles arise as a result of this trip. KarlyDJ: I have a MC bleeder so this should perform the same thing you are suggesting correct?

 

[nevada]

so what exactly is it doing?
lever getting soft? pulling back to the bar?

it sounds like a bad MC.

ive got a good one i'll sell you, if you decide thats what it is.

 

[MDK210]

so what exactly is it doing?
lever getting soft? pulling back to the bar?

it sounds like a bad MC.

ive got a good one i'll sell you, if you decide thats what it is.

sometimes when I apply the front brake it gets soft towards the end/losses its braking power so the lever will end up going all the way to my bar and still not have complete stopping power so I need to apply some rear.

I'm not sure how to determine a bad MC but if it is I got a Brembo on my list

 

[Freebird]

sometimes when I apply the front brake it gets soft towards the end/losses its braking power so the lever will end up going all the way to my bar and still not have complete stopping power so I need to apply some rear.

I'm not sure how to determine a bad MC but if it is I got a Brembo on my list

I would swap back to stock levers and see if it resolves it. If so you know the levers are the culprit. I feel the aftermarket levers are the culprit due to a little bit different ratio of fluid volume they apply and my be causing a conflict with the stock MC. In other words the aftermarket levers may not be 100 percent compatible with the MC. If you swap back to the stock levers and the fade is gone you will have your answer.

 

[MDK210]

oh snap! I think I may have figured it out! Riding to and from the stunt show in Denver today was about 4hrs or so and I didn't realize it until I parked the bike in the garage. Say I brake then left off some (not completely) then apply the brake again, that is when the lever keeps getting softer. So if I don't return it the lever to it's original position it will just keep getting softer until I do. It appears the lever snaps back all the way but I think sometimes if I left off the brake lever softly it may not go all the way back thus causing it to be soft when I re-apply the brake cause it never returned to its full position. Errrr...so I how do I fix this?

 

[J10]

Mine has the same issue. I am going to look at the calipers next. The spring back would be controlled be a spring in your MC. Theres a rebuild kit $30 ish and it comes with that spring I think

 

[hedz0r]

oh snap! I think I may have figured it out! Riding to and from the stunt show in Denver today was about 4hrs or so and I didn't realize it until I parked the bike in the garage. Say I brake then left off some (not completely) then apply the brake again, that is when the lever keeps getting softer. So if I don't return it the lever to it's original position it will just keep getting softer until I do. It appears the lever snaps back all the way but I think sometimes if I left off the brake lever softly it may not go all the way back thus causing it to be soft when I re-apply the brake cause it never returned to its full position. Errrr...so I how do I fix this?

sounds like a blown seal in your master cylinder.

 

[MDK210]

roger that. I look into it, thanks!

 

[LarryJ]

BTW I have a master for sale off of an 05/06 ZX6R (comes with reservoir and res bracket) in perfect working order. Good luck getting this figured out. You don't want to take malfunctioning braking systems lightly.

 

[Freebird]

oh snap! I think I may have figured it out! Riding to and from the stunt show in Denver today was about 4hrs or so and I didn't realize it until I parked the bike in the garage. Say I brake then left off some (not completely) then apply the brake again, that is when the lever keeps getting softer. So if I don't return it the lever to it's original position it will just keep getting softer until I do. It appears the lever snaps back all the way but I think sometimes if I left off the brake lever softly it may not go all the way back thus causing it to be soft when I re-apply the brake cause it never returned to its full position. Errrr...so I how do I fix this?

I would try this first before digging into the MC.
I would swap back to stock levers and see if it resolves it. If so you know the levers are the culprit. I feel the aftermarket levers are the culprit due to a little bit different ratio of fluid volume they apply and my be causing a conflict with the stock MC. In other words the aftermarket levers may not be 100 percent compatible with the MC. If you swap back to the stock levers and the fade is gone you will have your answer.

I recall you did not have an issue until you changed the levers and the brake lines.

 

[J10]

How would the levers cause the brake system to lose power? I could see if maybe they were interfering with something but it shouldnt be something that comes and goes. The lever is independant of the actual MC. It just pushes the plunger which moves the fluid.
Right? What am I missing

 

[hedz0r]

How would the levers cause the brake system to lose power? I could see if maybe they were interfering with something but it shouldnt be something that comes and goes. The lever is independant of the actual MC. It just pushes the plunger which moves the fluid.
Right? What am I missing

your correct. freebird has some pretty far fetched theory.

now there has been cases of levers machined poorly (chinese levers in most cases) which cause the plunger of the MC to be pushed in when the lever is idle. however that is unrelated to this.

used mc's are cheap, swap it out and see if that fixes it. sounds like your mc is sucking in tiny bits of air.

 

[Freebird]

900 miles ago (I keep records) my mechanic installed Galfer SS front lines and ASV levers. I drove around and had some brake fade so he bleed the entire system going through two reservoirs only producing tiny bubbles. A week later after riding around, hitting bumps, getting the fluid hot on some longer rides it started up again as expected so we did the same thing and very tiny bubbles if any. Last week it started again so I decided to get some speed bleeders, even for the MC, which I installed and instead of using the reg Silkolene stuff I went to the fancy Motul RBF600 factory line to see if it would improve with the higher heat resistance. Took it out for a short 30 test ride today and almost zero fade but on the last two stop signs before I hit my house more brake fade so while it was hot I bleed the entire system and NO bubbles anywhere! What the hell am I supposed to do? Bike only has 11K miles so I doubt it's the MC and even then how would I test it other than seeing if bubbles were coming out? I only mention the levers because before the new lines/levers it all worked great. My wife's new 2011 250R doesn't have these issues when I use it as the control in my experiment...

Another comment he made ...
Say I brake then left off some (not completely) then apply the brake again, that is when the lever keeps getting softer. So if I don't return it the lever to it's original position it will just keep getting softer until I do.

Bold print directly from his 1st post is what makes me feel he should try the stock levers and see if the issue is resolved.

Now if he said he pulls the brake lever and on the initial pull it holds pressure, and it faded gradually back to the bar in say 30 seconds then I would say the MC is the issue cause it clearly is not holding like it should. But that is not what he said.

Just trying to help guys, sorry if I am off base here.

 

[hedz0r]

The mechanic could have also cracked the mc or caliper installing the new SS lines.

I think its a good idea to swap the lever anyways just to rule out part of the equation. However I doubt Thu is the cause.

 

[Freebird]

How would the levers cause the brake system to lose power? I could see if maybe they were interfering with something but it shouldnt be something that comes and goes. The lever is independant of the actual MC. It just pushes the plunger which moves the fluid.
Right? What am I missing

I agree with this also but the comment below he made makes me think the levers are causing the problem.

Say I brake then left off some (not completely) then apply the brake again, that is when the lever keeps getting softer. So if I don't return it the lever to it's original position it will just keep getting softer until I do.


Again I am just trying to help and could be completely wrong. If so .

 

[Freebird]

The mechanic could have also cracked the mc or caliper installing the new SS lines.

I think its a good idea to swap the lever anyways just to rule out part of the equation. However I doubt Thu is the cause.

I totally agree, going back to the stock levers is the easiest way I see to rule out a MC issue. What I would hate to see is him go to the hassle of a MC rebuild and find it does not solve the issue.