Rebuild brakes

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zalle
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Re: Rebuild brakes

Post by zalle »

I forgot to ask in the previous post: I'm using the original rubber grommets for these stainless steel hoses, and they are very loose. What can I do? What's the common solution? I know you can order them with fat grommets, but mine (bought 20 years ago) don't have that.

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NobleHops
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Re: Rebuild brakes

Post by NobleHops »

https://spieglerusa.com/rubber-grommet.html

That might work, or a cousin from their site.
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Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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zalle
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Re: Rebuild brakes

Post by zalle »

IMG_20240313_132742.jpg
Ok, so I assembled everything. Painted a couple of parts (including the red dot on the central cylinder).

Back brake is working fine, but I can't bleed the front... The one on the left is already ok, but I'm stuck.
The right one has been open for hours, I've pumped and pumped on the lever, but there is no bubbles coming out, on the deposit, and no oil coming out of the caliper...
Any tricks, suggestions?
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Re: Rebuild brakes

Post by daves79x »

Sounds like you have a bleeder or a line plugged. Did you blow out all the new lines? There is often debris left in the lines after they are made up. The bleeder holes can easily collapse, preventing fluid flow. Also, if your caliper piston is completely pushed in, it will block flow of fluid. You need a little space behind the piston for fluid to flow.

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Re: Rebuild brakes

Post by CBX-tras »

I've seen many of the bleeder screws damaged from previous "ham fisted", so called "mechanics".

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Re: Rebuild brakes

Post by NobleHops »

I’ve had my butt kicked on first fill on those brakes. One “gotcha” that got me once was the priming of the master cylinder. I could push enough fluid to get it out the bleed screw, but never make pressure. Turned out that there was a stubborn air bubble in the master cylinder! So the first thing I do when I am about to bleed is (with the reservoir half full and a bit of containment) fan the brake lever hard and fast several times and watch the reservoir to see if any good sized air bubbles emerge.
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zalle
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Re: Rebuild brakes

Post by zalle »

Master cylinder was clogged... 🧐

I think I got it now. Thanks for the tips guys.

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Re: Rebuild brakes

Post by NobleHops »

Nice work (EDITED) however "clogged" is definitely cause for concern. Clogged how? If there was debris or gooey old brake fluid in there, then the MC needs full disassembly and then entire system needs a good flush. You would be wise to blow compressed air through all the brake lines and the splitter too.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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zalle
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Re: Rebuild brakes

Post by zalle »

The master cylinder was clogged, cleaned the tiny hole with a wire, and it's all good now. With a bit of patience it's not that hard to bleed the front system.

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zalle
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Re: Rebuild brakes

Post by zalle »

NobleHops wrote:
Tue Mar 05, 2024 9:42 pm
https://spieglerusa.com/rubber-grommet.html

That might work, or a cousin from their site.
I found a better option: cut a bit of rubber tube, and it goes between the the hose and the grommet, and it's now pretty tight.

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zalle
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Re: Rebuild brakes

Post by zalle »

Forgot to mention I did one more stupid thing:

Front brake wasn't 100%, the lever wouldn't return completely, so I disassembled it and took it to my mechanic for some help. Turns out I had put the conic rubber, one that goes inside the master cylinder, the other way round...

Brakes were also squeaking, washed everything thoroughly with a lot of brake degreaser, and it's smooth now!!!

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