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Motorcycle brakes

This is a discussion on Motorcycle brakes within the Technical forums, part of the Caferacer.net Forums category; Should brakes be getting stiffer as you ride? It's been happening to me and I'm a bit worried that it's going to lock up. It'll ...

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  1. #1
    Junior Member Monsier_Mom's Avatar
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    Motorcycle brakes

    Should brakes be getting stiffer as you ride? It's been happening to me and I'm a bit worried that it's going to lock up. It'll get stiff and then drag the brakes. I stop for a bit and then the brakes go back to it's original stiffness. I changed my handlebars so now my brakes lines have more slack. Could that be a reason?

    Sent from my Moto Z (2) using Tapatalk

  2. #2
    Senior Member woodsman's Avatar
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    Sounds like what might happen if the fluid in the lines is getting heated.

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    Senior Member TrialsRider's Avatar
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    Hydraulic brakes? Change your brake fluid it's hygroscopic meaning it absorbs water from the atmosphere. It only takes ~4% water content to be useless. Water boils at a lower temperature then brake fluid, brakes get hot, the water boils and makes steam inside your brake system :| (you just built the worlds smallest steam engine) Brakes drag because of expansion in the fluid and that promotes even more heat which amplifies the problem.
    Bleed the brakes off and the problem temporarily goes away until the next time the water gets hot.
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    Junior Member Monsier_Mom's Avatar
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    Now that I think about it, I did use dot 3. I'll just bleed the brakes completely and use dot 4. Ugh so much to do this weekend.

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    Senior Member TrialsRider's Avatar
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    Either way you probably have water in it:


    Water boils at 100 degrees C

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    Senior Member Geeto67's Avatar
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    Not sure what bike you have (pro tip: when you ask a tech question, ALWAYS include year, make, and model) but while you are in there you might as well inspect the caliper piston and grease any brake pad slides you might have.

    Also take a guitar string and clean out the return hole in the master cylinder.

    To me it sounds not like a "heating" problem but a "retraction" problem - your caliper is sticking because everything is dry, or the piston has corrosion on it and isn't retracting as quickly.
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  8. #7
    Senior Member Cyorg's Avatar
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    Quote Originally Posted by Monsier_Mom View Post
    Should brakes be getting stiffer as you ride? It's been happening to me and I'm a bit worried that it's going to lock up. It'll get stiff and then drag the brakes. I stop for a bit and then the brakes go back to it's original stiffness. I changed my handlebars so now my brakes lines have more slack. Could that be a reason?

    Sent from my Moto Z (2) using Tapatalk

    Although you likely need a fluid flush, you will probably find that the piston in the caliper is either gummed up or corroded and it not returning properly when you release the brake. It generally gets worse as you ride. You need to take the caliper apart, clean it out and check it for pitting. It may survive with a cleaning and new seals etc, or it may need a new piston, or you may have to toss it and get a new one. No offence, but if you are asking about cable slack, you need to be very cautious about brake work and if you are going to do it yourself, have someone who knows how to do it look over your shoulder.
    Last edited by Cyorg; 04-18-2019 at 09:10 AM.
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  9. #8
    Senior Member Cyorg's Avatar
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    Geeto can type faster than me.


    ps

    If you do go inside there, this stuff works well with the rubber bits and won't do funny things when exposed to brake fluid..... although exposing it to brake fluid shouldn't be an issue, because you are using a very small amount. I use this stuff for the bits inside the calliper. There are better things to use on external bits like caliber pins.

    You can search around and find a smaller container for less...or its possible if you buy a rebuild kit, it will come with enough of this stuff. So you can order the kit first and wait and see if it comes with the proper grease.

    +1 on the guitar string.

    https://www.ebay.com/p/4-Oz-100-Pure...oot/1389852637
    Last edited by Cyorg; 04-18-2019 at 09:21 AM.
    "Non urinat in ventum"

  10. #9
    Junior Member Monsier_Mom's Avatar
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    Quote Originally Posted by TrialsRider View Post
    Hydraulic brakes? Change your brake fluid it's hygroscopic meaning it absorbs water from the atmosphere. It only takes ~4% water content to be useless. Water boils at a lower temperature then brake fluid, brakes get hot, the water boils and makes steam inside your brake system :| (you just built the worlds smallest steam engine) Brakes drag because of expansion in the fluid and that promotes even more heat which amplifies the problem.
    Bleed the brakes off and the problem temporarily goes away until the next time the water gets hot.
    Thanks. How can water get into it? This started happening once I swapped handlebars.

    Sent from my Moto Z (2) using Tapatalk

  11. #10
    Junior Member Monsier_Mom's Avatar
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    Quote Originally Posted by Cyorg View Post
    Although you likely need a fluid flush, you will probably find that the piston in the caliper is either gummed up or corroded and it not returning properly when you release the brake. It generally gets worse as you ride. You need to take the caliper apart, clean it out and check it for pitting. It may survive with a cleaning and new seals etc, or it may need a new piston, or you may have to toss it and get a new one. No offence, but if you are asking about cable slack, you need to be very cautious about brake work and if you are going to do it yourself, have someone who knows how to do it look over your shoulder.
    I changed my handlebars to super sport ones and now I have a longer hose that loops around a bit more. Is there no chance of he hoses bending and causing the brakes fluid to not return?


    Sent from my Moto Z (2) using Tapatalk

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