Topic: Brake fluid maintenance?

[mycb750k6]

Researching DOT 3 I found the following on Wikipedia which says DOT 3 absorbs so much water it should be replaced every couple of years to avoid corrosion plus is toxic if you get it on you. Is this realistic?

http://en.wikipedia.org/wiki/Brake_fluid

Service and maintenance

Most automotive professionals agree that glycol based brake fluid, (DOT 3, DOT 4, DOT 5.1) should be flushed, or changed, every 1-2 years.[1] Many manufacturers also require periodic fluid changes to ensure reliability and safety. Once installed, moisture diffuses into the fluid through brake hoses and rubber seals and eventually the fluid will have to be replaced when the water content becomes too high. Electronic testers and test strips are commercially available to measure moisture content. The corrosion inhibitors also degrade over time. New fluid should always be stored in a sealed container to avoid moisture intrusion. DOT 5 is silicone fluid and the above does not apply. Ideally, silicone fluid should be used only to fill non-ABS systems that haven't been previously filled with glycol based fluid. Any system that has used glycol based fluid will contain moisture, glycol fluid disperses the moisture throughout the system and contains corrosion inhibitors. Silicone fluid doesn't allow moisture to enter the system, but doesn't disperse any that is already there either. A system filled from dry with silicone fluid, does not require the fluid to be changed at intervals, only when the system has been disturbed for a component repair or renewal. The United States armed forces have standardized on silicone brake fluid since the 1990s.

Brake fluid is not considered a "top up" fluid. If it is low, there is usually a problem. Brake fluid level in the master cylinder will drop as the linings (pads or shoes) wear and the calipers or wheel cylinders extend further to compensate. This added fluid may need to be removed when renewing pads or shoes. Overspill from pushing back pistons should be avoided, because glycol (but not silicone) fluid, will lift or strip paints and other coatings on contact. Brake fluid level may also be low because of a leak, which could result in a loss of hydraulic pressure and consequently, a significant loss of braking ability. Modern cars have split hydraulic circuits to ensure against total hydraulic failure. As a general rule, brake fluids with different DOT ratings should not be mixed, although all DOT fluid is compatible, (this is part of the DOT specification). This is because it will dilute and reduce the properties of the higher specification DOT fluid, or in the case of mixing of glycol with silicone fluid may cause corrosion due to trapped moisture.

Brake fluid can be dangerous as it is toxic and highly flammable.

[MCRider]

That's pretty much all true, old news.  As a practical matter, who changes their fluid every 2 years? In my 96 Aerostar, I just had the second changeout and the mechanic looked at me funny when I asked for it.  Like I'm the first guy ever asked.

It does improve the pedal/lever feel.

And yes its nasty stuff.

Careful or you'll get something similar to an "oil thread" going here.  

[rhos1355]

I would change my brake fluid every 2 years on my bike as well as on our cars. With the cars, I drop all the fluids; coolant, engine oil, gearbox oil at the same time. I dunno if it does my machines any good, but I sleep well.

[MCRider]

I would change my brake fluid every 2 years on my bike as well as on our cars. With the cars, I drop all the fluids; coolant, engine oil, gearbox oil at the same time. I dunno if it does my machines any good, but I sleep well.

Its an excellent thing to do. I'm just thinking in my sphere of influence who do I know that has ever had their brake fluid changed?

Nobody.  And that's not a good thing, I'm just saying... 

[mycb750k6]

Well thanks for that and I don't mean to start an unnecessary thread especially if it's old news but I'm rebuilding my front brakes per another thread and want to understand all that's involved and I like to share if relevant. I've ordered all my parts, finally got the circlip out of the master cylinder and made the MC nice N purdy (see pic), but I emailed and PM's the guy on here with the colorful stainless brake hoses but no response. Maybe he's on vacation.

[gregk]

You only have to rebuild one brake system that has been neglected before you start changing the fluid on a regular basis.  The process takes no time at all and your investment is minimal.

greg

[bucky katt]

it was part of the winter storage process at the dealership i worked at.

[MCRider]

Well thanks for that and I don't mean to start an unnecessary thread especially if it's old news but I'm rebuilding my front brakes per another thread and want to understand all that's involved and I like to share if relevant. I've ordered all my parts, finally got the circlip out of the master cylinder and made the MC nice N purdy (see pic), but I emailed and PM's the guy on here with the colorful stainless brake hoses but no response. Maybe he's on vacation.

No problem. I didn't mean to imply it was unnecessary thread, just that the information is not new, in case you thought it might be.

Never hurts to revisit these issues and for some its still the first time around.

If you want to really get a discussion sparked, tell the forum you're going to use DOT 5.0 (silicone) (not 5.1). 5.0 does not hurt paint or person (I think) and can be used if your system is virgin. Sounds like yours is. Look it up on Wicki. It doesn't absorb water, but that means the water will pool somewhere and you still need to change it. Some say this condition may be worse than with the DOT3.0, etc.

Can never mix the non-sili with the sili. So its irrevocable. I've read that auto restorers prefer it.

I've used it for extended periods with no problems, WTHDIK?   

[Johnie]

Good thread for a reminder for us. I actually change mine on my 750's a couple times during the riding season when I first got them. They were not leaking but I got some crud out so I just did it a few times to clean out everything that was in there from sitting all those years. Can you imagine my KO sat for 17 years. I opened the brake resevoir and it was like honeycomb in there. I figured I may as well clean up the bowl and fill it to see if it works.  Filled, bled the heck out of it and the brakes works like new. Has been 3 years now and works great. So yes, it is a good idea and very inexpensive to do it.