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Old 02-18-2017, 01:03 AM   #1
mang0
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Squishy brakes

So I'm having trouble with the brakes on the 08 600RR. When I purchased the bike, the front brake was basically non existent.

1) Bled / replaced all fluid, fluid coming from both calipers was gross. Brakes were a lot better, but then became squishy again over a few weeks.

2) Bled again... same thing happened again. To the point that the brake lever would hit the bar when pulled (so basically no pressure).

3) Rebuilt master cylinder. Brakes have been good for a few weeks.... but it's getting a bit squishier now.

So now I'm thinking either brake lines or calipers. There are no visible leaks anywhere, but air is somehow getting into the system. When I rebuilt the master cylinder, the bleed coming from the left caliper still had some dirty-ish fluid. Any ideas what the next step should be? Replace lines? They're already aftermarket (steel braided) from the previous owner.

Thoughts? Thanks in advance!
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Old 02-18-2017, 02:03 AM   #2
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Better pads, and steel braided lines. Also try a phoenix system that pushes brake fluid from the caliper to the reservoir at the MC. It helps prevent air bubbles getting trapped.

I am installing hot pink steel braided lines on the CBR this weekend. I will tell you if I can achieve the same feel after the install.
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Old 02-18-2017, 02:10 AM   #3
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Check around the bleed nipples. Some people tend to go all super torque on them and damage either the nipple itself or the sealing surface in the hole.

How are the caliper pistons? Lots of crud built up on them? Seals might be bad if they are nasty and corroded.

The lines probably aren't the problem.

Try zip tying the lever back over night and see if the brakes firm up. All the air will rise and bleed past the piston if you hold the lever back.
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Old 02-18-2017, 04:49 PM   #4
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Quote:
Originally Posted by Miruri View Post
Better pads, and steel braided lines. Also try a phoenix system that pushes brake fluid from the caliper to the reservoir at the MC. It helps prevent air bubbles getting trapped.

I am installing hot pink steel braided lines on the CBR this weekend. I will tell you if I can achieve the same feel after the install.
Have a pretty new set of EBC double sintered pads. Lines are already aftermarket steel braided.

Quote:
Originally Posted by zrx12dan View Post
Check around the bleed nipples. Some people tend to go all super torque on them and damage either the nipple itself or the sealing surface in the hole.

How are the caliper pistons? Lots of crud built up on them? Seals might be bad if they are nasty and corroded.

The lines probably aren't the problem.

Try zip tying the lever back over night and see if the brakes firm up. All the air will rise and bleed past the piston if you hold the lever back.
Hmm. I'll look at the bleed nipples. I did notice that some of the nuts were a bit misshapen, so that could be a problem. I was planning on doing a complete brake clean job, so I'll check the seals on the calipers as well.

I've been zip-tying the lever overnight each time I bleed the brakes. It does firm up overnight and stays firm, but will eventually start feeling squishy again after a few weeks. I was thinking about trying reverse bleeding the brakes as well, but it just seems to me like there is some sort of air leak in the system.
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Old 02-18-2017, 05:31 PM   #5
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Well I was able to achieve relatively the same feel. The Phoenix brake kit helped a lot. All I did after the lines and reservoir were filled was prime the master cylinder and bleed through the fluid built up in the reservoir till I felt confident in the pressure. One thing I noticed was my right caliper held a bubble till I bled it. Until I did so I had no pressure at all lever . The cbr is never going to have super firm brakes, that's part of its charm they give you that "feel" which makes trail braking very smooth.


Pics just because I'm proud of my work. I am sorry you still are struggling with your brakes. Who knew hot pink would match?
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Old 02-18-2017, 06:22 PM   #6
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Are you capable of bleeding at the banjo? If so, do that then down to the calipers again.
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Old 02-19-2017, 01:55 PM   #7
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Quote:
Originally Posted by Gixxerguy855 View Post
Are you capable of bleeding at the banjo? If so, do that then down to the calipers again.
There's a master cylinder bleed port (if that's what you mean). I've been doing all three. The right/left calipers and the nipple at the master cylinder.
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Old 02-19-2017, 04:43 PM   #8
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I had the same problem on my 06 ZX6R. I rebuilt the master cylinder, new ebc HH pads, steel braided lines... none of those fixed the squishy lever feel until i replaced the rotors... once i replaced those with arashi ebay rotors and rebled the system, it was the firmest/best feeling i had on that bike (Yes i had ebay rotors, but yes i tracked on them and they were perfectly fine)
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Old 02-19-2017, 09:18 PM   #9
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Quote:
Originally Posted by pelinors714 View Post
I had the same problem on my 06 ZX6R. I rebuilt the master cylinder, new ebc HH pads, steel braided lines... none of those fixed the squishy lever feel until i replaced the rotors... once i replaced those with arashi ebay rotors and rebled the system, it was the firmest/best feeling i had on that bike (Yes i had ebay rotors, but yes i tracked on them and they were perfectly fine)
Totally forgot this rotors are an awesome suggestion!
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Old 02-19-2017, 09:39 PM   #10
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Some things on brake calipers/lines/MC:

Rebuild kits are cool but sometimes its cheaper to find a used MC either on Ebay or CL for cheap. I bought a used CBR MC from a dude in San Diego for $40 and it worked perfect. He upgraded to a different one and didn't need the old MC anymore. Maybe easier and cheaper than a rebuild kit.

Make sure your bleed nipples are on tight, but don't over tighten or you will ruin the nipple, or worse, the threads on the calipers themselves. Read somewhere that Teflon tape helps, and while it does a great job sealing air out, that gets shredded fairly easily and I do not want Teflon floating around in my Caliper/lines/MC. Improbable, but not impossible.

I have an aftermarket Brembo caliper on my current bike, and while I was installing it, noticed that on the Brembo caliper, they have fashioned the bleed valve rubber cover in a way that the retaining ring portion of it presses against the threads in the caliper, which seals air out. Basically, it acts and an Oring. on other rubber caps, the ring portion just kind of held the cap onto the caliper rather than actually seal air out of the system.

You may have already checked, but go through the brake system again, at any connection point, to see if oil is leaking. Places to lose pressure are going to be bleed nipples, banjo bolts, crush washers, and the normal wear and tear parts inside the MC.

Invest in a vacuum pump for bleeding brakes. The old fashioned way sucks. Also, with a pump, you can reverse bleed a system if your MC has a bleed nipple.

Two of you guys mentioned replacing rotors/pads. I have never had squishy lever feeling from bad pads/rotors, only air in the system. I would think bad pads/rotors would only result in bad braking power, not actually having a squishy feel to the lever?

Beginning to think more and more it one or more of the bleed nipples leaking in air?
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Old 02-20-2017, 12:57 AM   #11
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Quote:
Originally Posted by kojiiro View Post
Some things on brake calipers/lines/MC:

Rebuild kits are cool but sometimes its cheaper to find a used MC either on Ebay or CL for cheap. I bought a used CBR MC from a dude in San Diego for $40 and it worked perfect. He upgraded to a different one and didn't need the old MC anymore. Maybe easier and cheaper than a rebuild kit.

Make sure your bleed nipples are on tight, but don't over tighten or you will ruin the nipple, or worse, the threads on the calipers themselves. Read somewhere that Teflon tape helps, and while it does a great job sealing air out, that gets shredded fairly easily and I do not want Teflon floating around in my Caliper/lines/MC. Improbable, but not impossible.

I have an aftermarket Brembo caliper on my current bike, and while I was installing it, noticed that on the Brembo caliper, they have fashioned the bleed valve rubber cover in a way that the retaining ring portion of it presses against the threads in the caliper, which seals air out. Basically, it acts and an Oring. on other rubber caps, the ring portion just kind of held the cap onto the caliper rather than actually seal air out of the system.

You may have already checked, but go through the brake system again, at any connection point, to see if oil is leaking. Places to lose pressure are going to be bleed nipples, banjo bolts, crush washers, and the normal wear and tear parts inside the MC.

Invest in a vacuum pump for bleeding brakes. The old fashioned way sucks. Also, with a pump, you can reverse bleed a system if your MC has a bleed nipple.

Two of you guys mentioned replacing rotors/pads. I have never had squishy lever feeling from bad pads/rotors, only air in the system. I would think bad pads/rotors would only result in bad braking power, not actually having a squishy feel to the lever?

Beginning to think more and more it one or more of the bleed nipples leaking in air?
Yeah, I was actually thinking that as well. I haven't seen any fluid leaking around the nipples, but I was planning on grabbing a set of speed bleeders, so I'll get to change em out anyway.

I re-bled the brakes again and zip-tied that lever overnight and the brake feels good now. Going to see how long it takes to go back to being squishy. Next up is to take the calipers off / remove pistons and check seals.
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