Brake rebuilding

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Fojyie
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Brake rebuilding

Post by Fojyie »

Last fall I started my '80 after 16 years off the road. I had to completely rebuild and clean the brakes of dried crud, but quickly found I had leaks from my new seals. I removed them a second time and again they leaked (front and back). The third time I took them apart, I used a dental pick to slowly go through the groves removing hard scale carefully. One caliper looked like it might not hold a seal due to damage, but when I put it back together, they all worked fine. I guess the lesson is to take your time, work slowly and clean every little grove and piece of scale you see out of those groves. Last, I learned that replacing the pads is best done on the bike, not on the bench. I had one heck of time getting the calipers on without parts misaligning, but if you follow the manual for pad replacement it was a piece of cake. I'm just a slow learner I guess.

steve murdoch icoa #5322
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Re: Brake rebuilding

Post by steve murdoch icoa #5322 »

The phrase "practise makes perfect" is bogus.
It should be "practise makes better".
Brass wire wheel on a Dremel worked for me in cleaning the crud out of the grooves.

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NobleHops
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Re: Brake rebuilding

Post by NobleHops »

Yeah, that's exactly what I learned Steve, I thought I had the grooves well cleaned out with my pick, then I tried to the Dremel with the brass wheel and POOF a mini cloud of dried brake fluid crud.

Good on ya Fojyie, I had to do the same, eg do it a couple of times and get it wrong before I felt like I understood what made the difference.

N.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

Fojyie
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Re: Brake rebuilding

Post by Fojyie »

Working on bikes is a humbling process for me. I thought my barnyard mechanics when raised on a farm would suffice, but it takes more. This site is a tremendous help. Thanks again guys. Now I think I need to address a possible warped disc giving me a vibration like a wheel out of balance in the rear. Got to measure it and see if off.

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Kool_Biker
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Re: Brake rebuilding

Post by Kool_Biker »

In my rather limited experience, the final step to bleeding brakes, which always makes a difference to the quality of braking, front or back, is to pump the lever / pedal several times, and without letting go, use a tie wrap in the front or loads of weights in the back, to keep the systems under pressure for ~48 hours.

Nowadays I have made this process part of my brake bleeding routine and works for me ... Does anyone know the mechanics of it? Why this helps?

Cheers, Aris
Aris Hadjiaslanis
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daves79x
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Re: Brake rebuilding

Post by daves79x »

Holding the brake lever in for a period of time allows the small bubbles of air still in the system to bleed out into the master cylinder through the 'bleed' hole. Taking the bike for a ride in a trailer on a bumpy road with the brake lever taped or ty-wrapped will also do wonders.

Dave

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NobleHops
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Re: Brake rebuilding

Post by NobleHops »

Fojyie wrote:Working on bikes is a humbling process for me. I thought my barnyard mechanics when raised on a farm would suffice, but it takes more. This site is a tremendous help. Thanks again guys.
You took the words right out of my mouth there, all around.
Now I think I need to address a possible warped disc giving me a vibration like a wheel out of balance in the rear. Got to measure it and see if off.
Re your potential disk issue, I have had great results sending disks to my new friend Tom Tokarz at Truedisk:

http://www.truedisk.net

Image

As long as there is some thickness to work with, he can make old worn rotors flat and true, for $45 a pop, plus $12 or so Flat Rate USPS shipping. Great service. Call him when you've measured it and know what you're up against and he'll let you know if he can do it too. Great guy.

N.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Kool_Biker
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Re: Brake rebuilding

Post by Kool_Biker »

daves79x wrote:Holding the brake lever in for a period of time allows the small bubbles of air still in the system to bleed out into the master cylinder through the 'bleed' hole.

Dave
Dave, as I understand it, when the brake lever is squeezed tight, the system is under pressure; nothing can come in or out.
Could it be then that the constant high pressure helps / encourages (?) the tiny air bubbles more easily dislodge from their hiding places, move up and combine at the highest point just under the master cylinder, and then, when the lever is released escape as they would through its little bleed hole?
Is it not the moment of actually releasing the lever, that gets rid of the accumulated air? :think:

Aris
Aris Hadjiaslanis
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Rick Pope
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Re: Brake rebuilding

Post by Rick Pope »

Dave may have meant to pull the lever in just a bit, just enough to expose the return hole, but not enough to put pressure in the system. I bleed brakes this way too. Turn the bars to the left to get a little more air out and let it set a few hours.
Rick Pope
Either garage is too small or we have too many bikes. Or Momma's car needs to go outside.

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