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Discussion Starter · #1 ·
I've bled brakes many times. I know how to do it. On my '07 I just upgraded my brakes lines to Galfer SS lines. Of course I had to completely re-fill the brake lines. I filled them up, did the bleed, and... the brakes are just kinda' mushy. They work fine, but I think a tiny bit mushier than they were before the upgrade. Yesterday I did a "reverse bleed" again on both front calipers, since I think that does a better job of getting out any air bubbles. Pushed a few syringes of fluid up from the bottom. And they still fill mushy.

If someone just hopped on my bike and rode they probably wouldn't think anything. But I thought there would be some bit of improvement in the firmness of the brakes, not slightly less.

Any thoughts on what I could be doing wrong here? Something with the banjo bolts? Do little curves in SS lines trap air more? Maybe this is as good as it gets, but I think my brakes have regressed.
 

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How long has it been since you did it? I changed my brake fluid using a vacuum bleader last year. After changing I had to let it sit in the garage for a day (with a zip tie pulling the brake lever in) and allow the few tiny bubbles of air to work up, there's always a possibility there's just a little air trapped in there somewhere. I'm assuming you replaced all the washers (inner and outer) on the banjo bolts and made sure they were all clean and tight?
 

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How long has it been since you did it? I changed my brake fluid using a vacuum bleader last year. After changing I had to let it sit in the garage for a day (with a zip tie pulling the brake lever in) and allow the few tiny bubbles of air to work up, there's always a possibility there's just a little air trapped in there somewhere. I'm assuming you replaced all the washers (inner and outer) on the banjo bolts and made sure they were all clean and tight?
Can you share some info about how to do that? I need to do so and learn myself.
 

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Can you share some info about how to do that? I need to do so and learn myself.
I used a hand pump vacuum brake bleader, you can find them at any auto parts store I think I paid $10-15 for mine. The bleeder will be a closed system, the hose attaches to the bleeder nipple on the brake caliper and has a container built into it or a discharge hose that goes into a container. Have your bike level, at least the reservoir needs to be level, connect the hose to the bleeder valve, remove the reservoir cap and top it off. Loosen the bleeder (only need to crack it, 1/4-1/2 turn typically) pump until the reservoir is almost empty but don't let it go below the bottom of the reservoir, top off reservoir and repeat until you're getting new brake fluid and no bubbles in the hose of the pump (buy clear tubing if it doesn't come with it so you can see it). Don't forget to close the bleeder valve on the caliper before you remove the tubing. Always start with the caliper that is the farthest from the lever. After you do the first one move to the other and repeat the process. Its the same process for the rear brake. I always use a new unopened bottle of brake fluid, temperature fluctuations create moisture in an open container (even with the cap on, once the seal is broken I use what I need I throw the rest away or use it in a car, motorcycle systems are a lot smaller and more susceptible performance problems from minor things) and moisture is what makes brake fluid need replaced (it compresses different then oil).

After you're all done use something to hold down rear brake and use a zip tie or similar to pull the lever closed and leave it like that overnight. Having the brake fluid under pressure will make any small bubbles want to creep up the hoses to the reservoir. Since your bike sat with the brakes on all night double check that you have no leaks at the bleeders, the caliper pistons, or the hose connections. You can also do the leak test prior to replacing the fluid, then if you need to fix any leaks you can do that first then fill with new fluid and bleed.

Having a second person to monitor and fill the reservoir will make it go a little faster, but it's easy to do by yourself.

Look on YouTube if you need more understanding, there's plenty of videos or there on it. It's a really simple job to do, but if it's done wrong it can have bad affects.

Happy riding!
 

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Good stuff bud. I've heard of people using a backwards system where they were actually pushing the fluid into the system from the calipers eliminating chance of air getting in, and pushing away any crud away from calipers instead of possibly pulling stuff into them potentially clogging them. Does that make sense? Also it was on an 4 wheeled vehicle, and traditional rubber lines not SS lines.
Thank you for sharing your knowledge and especially your effort. That was lengthy suggesting you really give a **** about answering that. I really appreciate that myself.
 

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Good stuff bud. I've heard of people using a backwards system where they were actually pushing the fluid into the system from the calipers eliminating chance of air getting in, and pushing away any crud away from calipers instead of possibly pulling stuff into them potentially clogging them. Does that make sense? Also it was on an 4 wheeled vehicle, and traditional rubber lines not SS lines.
Thank you for sharing your knowledge and especially your effort. That was lengthy suggesting you really give a **** about answering that. I really appreciate that myself.
They call it reverse bleeding, I've seen posts about doing it on bikes also. I thought about doing it last summer when I changed my fluid, but I've never done it that way and had done it the way I described above before so I went with what I knew.
 

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I have similar complaints and following other posts on the forum led me to plan a master cylinder rebuild at some point. $50 in seals and a bit of time and the feel should improve if everything I read is true.
 

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Discussion Starter · #10 ·
Thanks for all of the comments. Just an update:

Because I was installing new brake lines, the system was dry. For the first time for me, I used a new hand pump vacuum system. I thought it would be easy and fast. And yeah, it was fast -- but I noticed the fluid coming out was gushing out super fast, tumbling and swirling, and a ton of air mixed in. It seemed very... turbulent. I think filling up a bone dry system with this caused a lot of bubbles, and maybe micro bubbles, to get trapped in the lines. Today I did another another big reverse bleed -- pushed over 1/2 a small bottle through both front lines. I also tried tapping on the lines and everything to "free up" any bubbles. And the brakes are much better now. I really do think the "gush" of the super fast hand pump caused a bunch of tiny bubbles to get trapped in the system, and it has taken a while for them to get worked out -- between a few extra reverse bleeds, and clamping the brake lever down overnight a few times.

I was just looking at this video about filling up a dry system, and he specifically says a traditional bleed to fill up the system is slow and inefficient, and I think he might be right..
 

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Thanks for all of the comments. Just an update:

Because I was installing new brake lines, the system was dry. For the first time for me, I used a new hand pump vacuum system. I thought it would be easy and fast. And yeah, it was fast -- but I noticed the fluid coming out was gushing out super fast, tumbling and swirling, and a ton of air mixed in. It seemed very... turbulent. I think filling up a bone dry system with this caused a lot of bubbles, and maybe micro bubbles, to get trapped in the lines. Today I did another another big reverse bleed -- pushed over 1/2 a small bottle through both front lines. I also tried tapping on the lines and everything to "free up" any bubbles. And the brakes are much better now. I really do think the "gush" of the super fast hand pump caused a bunch of tiny bubbles to get trapped in the system, and it has taken a while for them to get worked out -- between a few extra reverse bleeds, and clamping the brake lever down overnight a few times.

I was just looking at this video about filling up a dry system, and he specifically says a traditional bleed to fill up the system is slow and inefficient, and I think he might be right..
Good to know. I'll be changing over to braided lines in a few months, I'll try and learn from your aggravation. 😆
 

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best way to fill empty lines is with gravity. just crack the bleeders on both calipers and pipe them into bottles, then fill the reservoir. as it drains through just keep filling the reservoir. it'll fill slowly and most of the air will work out. after it's filled i like to push fluid back up from the calipers into the reservoir as that's the way the air wants to go anyway. from there it's usually perfect.

i avoid vacuum bleeders.
 

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Thanks for all of the comments. Just an update:

I think filling up a bone dry system with this caused a lot of bubbles, and maybe micro bubbles, to get trapped in the lines. Today I did another another big reverse bleed -- pushed over 1/2 a small bottle through both front lines. I also tried tapping on the lines and everything to "free up" any bubbles. And the brakes are much better now. I really do think the "gush" of the super fast hand pump caused a bunch of tiny bubbles to get trapped in the system, and it has taken a while for them to get worked out -- between a few extra reverse bleeds, and clamping the brake lever down overnight a few times...
When you poured in fluid to the "bone dry" system, did you have the bleeder valve cracked open to allow air pressure to escape?
 

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One common cause of issues is opening bleeder too much. This lets air in through the gap in threads. Open just barely enough for fluid to flow, usually about 1/4-turn is all you need. See this thread about fighting against physics.

 

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One common cause of issues is opening bleeder too much. This lets air in through the gap in threads. Open just barely enough for fluid to flow, usually about 1/4-turn is all you need. See this thread about fighting against physics.

Now that is good to know
 

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Now that is good to know
I was going to point you to my thread too. :)
I was in your exact position although with an 06.
What seemed to work for me in the end was a combination of raising the calipers and removing/rotating the master.

Sounds silly but being an 07 I assume you have a different master. You havent forgotten to bleed via the bleed nipple at the master have you? When I was researching a fix for mine I came across a few people who seem to have forgetten/not be aware the master has a bleed nipple.
 

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Just fixed CB500F for friend. Poor guy had super-mushy brakes after paying shop to replace just brake-pads. I found these issues:

1. anti-vibration shim installed on wrong-end of calipers, not touching pads at all

2. sliding-pins between caliper & bracket not lubed. So caliper wasn't self-centering and pushing on one pad only

3. pistons wasn't retracted into caliper before installing new pads. They expanded pads by wedging screwdriver in between pads. Broke centre of one of pads.

4. piss-poor job of bleeding. Fluid was all grey and cloudy. Probably just poured in tiny bit of new fluid and kept most of old stuff.

I fixed it by just putting caliper higher than master, making sure MC was full of fluid at all time and did ol' fashioned open-squeeze-close-release routine. Only needed about 10-squeezes to get all bubbles out and now lever-action's firm as rock!
 

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BTW - I put set of Galfer G1375 sintered ceramic pads on my '07 before heading out Chuckwalla this weekend. Worked amazing! Much better than factory-pads which gets overheated and causes me to run wide on corner entrances. While this track isn't hard on brakes like say... Laguna Seca or Thunderhill, it's still enough to require better-than-stock pads. Highly recommend them.

 
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