Brake fluid question

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Oct 15, 2015 | 06:52 PM

#31

RANGER73

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From: Beyond Fucital

I could be wrong, and probably am. But if I was going to flush the lines, I wouldn't put DOT5 back in.
I've heard that DOT5 because of its silicone base attracts moisture and should be changed every few years.
Can anyone confirm this?

Oct 16, 2015 | 08:39 AM

#32

jhsellers

Cruiser

Joined: May 2015

Posts: 139

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From: North Ga.

Moisture in brake fluid

Ranger,

I think all brake fluids are hygroscopic - meaning they will absorb moisture. That's why it's a good idea to completely flush and change the fluid every couple years or so. Leaving fluid in the system long term will cause the steel parts to corrode and/or rust from the moisture.

I would want to stick with the fluid type shown on the master cylinder cover - seals may also be different with the various types of fluid (DOT3, 4, 5, etc.) and switching types could have detrimental effect to seals.

Just my 2-cents,
John

Oct 16, 2015 | 09:41 AM

#33

splattttttt

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Joined: Jul 2014

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From: MASS_hole

Synthetic lubes are known to be safer on seals than petrolium based lubes in general and lasts longer so I tend to trust them. But I will never tell anyone not to use organic lubes. To each his own

Dec 30, 2015 | 11:54 AM

#34

InTheWinda1

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From: FL

dot 5

Quote:

Originally Posted by olongapo1

Mrbongo,

Your 01 Heritage came from the factory with a DOT 5 brake system.

I'm guessing that the labels on top of your reservoirs are missing. DOT 5 is a synthetic fluid. As Ranger73 pointed out, if any amount of DOT 4 and 5 are mixed together a chemical reaction will occur turning the fluid into a gel. Serious Safety Issue! Some manufactures add a purple dye to their DOT 5 however this dye will break down over time preventing identification by looking at the color of the fluid in the reservoir.

If your brake system is stock factory, it requires DOT 5. If your brake system has been modified (Aftermarket) it is imperative that you determine and use the correct fluid. I once saw a bike with a stock rear brake system = DOT 5, and a modified front brake system = DOT 4.

Dot 5 is know as silicone , least wise that's what in printed on bottle.

Dec 30, 2015 | 12:19 PM

#35

Uncle Larry

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Joined: Jan 2011

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From: Michigan 15 Minutes East Of Hell

Quote:

Originally Posted by RANGER73

Totally the opposite. DOT 5 is NOT HYGROSCOPIC

https://en.wikipedia.org/wiki/Hygroscopy

Dot 5 can be used in all systems ( with the exception of ABS ... the ABS cycles so quickly that it can aerate and cause bubbles ) provided the system is cleaned and flushed ( usually with alcohol ).

There are some limitations to DOT 5.

http://www.stoptech.com/technical-su...rs/brake-fluid

Dec 30, 2015 | 05:26 PM

#36

InTheWinda1

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From: FL

Quote:

Originally Posted by Uncle Larry

dot 5 = sure U can use it , but Harley does not put it in any bikes any longer , I think for more reasons besides , does not work well with ABS brakes.

Dec 30, 2015 | 06:56 PM

#37

dennyo

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From: Jamestown, CA

One thing is Nice bout 5 is it won't hurt Paint.

Dec 30, 2015 | 07:07 PM

#38

Uncle Larry

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Joined: Jan 2011

Posts: 157,474

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From: Michigan 15 Minutes East Of Hell

Quote:

Originally Posted by InTheWinda1

dot 5 = sure U can use it , but Harley does not put it in any bikes any longer , I think for more reasons besides , does not work well with ABS brakes.

does not work well with ABS brakes .... I think that's what I said :>)