Recently, a friend had his brakes fail going downhill from Lake Isabella to Bakersfield. No crash, but seriously scared him. After cooling down, things were OK again. This is typical brake fluid boiling. His brake fluid was regular Pep Boys DOT 3, about 4 years old.

He was unaware that brake fluid absorbs moisture and should be replaced every one to two years. The moisture absorbed into the fluid not only lowers the boiling temperature, but also allows rust to form, further compromising braking. Some shops can test your fluid, either with a refractometer or by a tester that actually boils a bit of your fluid..There is also a strip that you dip in your fluid and compare color. About 55 cents apiece. http://www.phxsyss.com/products.asp

Here is a good link on testing and changing frequency: http://www.misco.com/change.php

And another: http://www.babcox.com/editorial/bf/bf40142.htm

Here is a good link with general info: http://www.motocrossactionmag.com/readridingtips.asp?id=106

I use ATE Type 200 and ATE Super Blue fluid, alternating each time. The Super Blue is (surprise!) blue, and the 200 is golden. The color change in the clear bleed hose tells me when the new fluid has reached the wheel cylinders. One of the reasons I like the ATE is it comes in metal cans, which absorb less moisture from the air. I fill a partial can with marbles to exclude air before storing. I do not trust any brake fluid from a plastic bottle unless it is dated. Even HDPE is too permeable for something as serious as brake fluid unless it is fresh-dated.

Here is a good link with test figures on different fluids: http://brickboard.com/FAQ/700-900/BrakeFluidComparison.htm

And another: http://www.motocrossactionmag.com/readridingtips.asp?id=106

http://www.stoptech.com/whitepapers/brakefluid1a.htm





At the minimum, you should also know what is inside your wheel cylinders on drum brakes. If they have not been opened up and inspected, you are taking a gamble. There can be rust, pitting, scoring, or grooved cups. Any of these can allow the introduction of air into the system, whether you know it or not. I got driv crazy once by this.

Thanks Bill for this important information. Over on rv.net there has been recent discussion about runnaway coaches on grades and just the thought scares me to death. Before I go on my next long trip I will have mine checked.


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I have been told by my neighbor, an “expert”, that motorcycle break fluid has a higher boiling point and is hence more desirable to use in motor homes. He also claims to have spend $80,000 on a SOB class C he owns, addons included.

As I recall he quoted a boiling point of 600 degrees, sounds less than plausible. Does anyone have experience using motorcycle “racing” break fluid?

Now he did stop dead in his track when he saw the Barth and said, "Wow a Barth, my parents always told me this was the best motor home. Can I look inside?". Clearly he is not a complete fool.

Thanks for the great advise. Information like this is worth a lot. Little hard to place a value on being safe. This web site is worth tons, thanks for being here for us Bill. Dennis

quote:

Originally posted by timnlana:
I have been told by my neighbor, an “expert”, that motorcycle break fluid has a higher boiling point and is hence more desirable to use in motor homes.

Tim, brake fluid is all over the map. Some motorcycle shops sell Motul 600, which is very good, but absorbs moisture faster than I am comfortable with. I would rely on independent testing rather than which shop sells it.

My motorcycle road racing experience predates disk brakes, so I can't offer any experience-based advice. I push my Ducati pretty hard now and then, and have never smelled the brakes (unlike my MHs). My gut feeling is that motorcycle disks are out in the open, so they don't stress the fluid too much.

BTW, Ford sells a hi temp fluid that is highly rated for boiling point, but is reported to absorb moisture more rapidly than some others.




[This message has been edited by bill h (edited August 06, 2005).]

I have some super blue racing fluid dot 4 that has a dry boiling point of 536 degrees. I use that in all my cars.

paul schuster