Fading hydraulic brakes.

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SteveD
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Location: Melbourne, Oz.

Fading hydraulic brakes.

Post by SteveD » Tue Dec 26, 2017 5:01 am

How often do you flush your brake fluids?

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Victoria, S.E.Oz.


1982 R100RSR100RS supergallery. https://boxerboy81.smugmug.com/
2006 K1200R.

barryh
Posts: 483
Joined: Fri Oct 01, 2010 12:30 pm

Re: Fading hydraulic brakes.

Post by barryh » Tue Dec 26, 2017 9:44 am

Every 2 years but to honest more out of concern for corrosion protection than the lowered boiling point of the fluid. I doubt my brakes get anywhere near hot enough in my normal riding for it to be a concern.

One thing I learnt recently that makes brake fluid change an absolute breeze and totally fool proof is gravity bleeding. Just open up the bleed nipple and let the fluid flow through a short tube. Gravity bleeding works well on a bike because of the relatively high head of fluid and short system length offering low resistance. As long as the master cylinder is kept topped up there is zero chance of introducing air.
barry
Cheshire
England

Wobbly
Posts: 165
Joined: Mon Aug 07, 2017 8:48 pm

Re: Fading hydraulic brakes.

Post by Wobbly » Tue Dec 26, 2017 12:56 pm

Minor correction.... DOT3, DOT4 and DOT5.1 brake fluids are "Hygroscopic"...
After 20 years as a professional bike mechanic and 30 years as an engineer I know just enough to be dangerous !

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Zombie Master
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Joined: Sun Aug 22, 2010 12:21 am
Location: Vancouver Island BC Canada

Re: Fading hydraulic brakes.

Post by Zombie Master » Tue Dec 26, 2017 5:16 pm

barryh wrote:
Tue Dec 26, 2017 9:44 am


One thing I learnt recently that makes brake fluid change an absolute breeze and totally fool proof is gravity bleeding. Just open up the bleed nipple and let the fluid flow through a short tube. Gravity bleeding works well on a bike because of the relatively high head of fluid and short system length offering low resistance. As long as the master cylinder is kept topped up there is zero chance of introducing air.
Interesting. So you just let the fluid drip out, and refill before the reservoir empties? Do you repeat more than once to get a flush? I can see where this might be less wear on the master seals.

I've hear so many having problems with bleeding brakes. I've rarely had an issue with it.
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barryh
Posts: 483
Joined: Fri Oct 01, 2010 12:30 pm

Re: Fading hydraulic brakes.

Post by barryh » Wed Dec 27, 2017 5:32 am

I refill 2 or 3 times. Gravity bleeding is no different in principle to pressure bleeding just the pressure is lower at approx. 1 psi. The advent of DOT 4 LV makes it an easier proposition due to the lower cold temperature viscosity. Most cars with ABS now specify this type of fluid so I first did a gravity bleed on my car. The fluid flows much better on a bike though whether Dot 4 LV or ordinary DOT 4 is used.
barry
Cheshire
England

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