Ive often wondered,, (brake fluid)

Topic: Ive often wondered,, (brake fluid) (Read 2785 times) previous topic - next topic

Ive often wondered,, (brake fluid)

April 26, 2005, 09:30:57 PM

Since Dextron III can be fairly universal and could be used as power steering pump fluid,,(mind you ive used tranny fluid for ps fluid going on several years now)
why could'nt the brake system be drained and blown out of all fluid and dextron III used? Its not corrosive and we all know how much of a plus that is.

Re: Ive often wondered,, (brake fluid)

Reply #1 – April 26, 2005, 09:36:23 PM

I dunno that it could stand up to the temp requirements of brake fluid.

Re: Ive often wondered,, (brake fluid)

Reply #2 – April 27, 2005, 12:09:45 PM

I was intrigued at this question and tried to do some research on it. None of the searches I did came up with a comparison of hydraulic fluids to silicon brake fluids. Only differences I saw were that silicon brake fluid absorbs moisture. Why? No clue. I would think a fluid that doesnt would be desireable.

Silicon brake fluid has a very light viscosity. It allows the seals of a brake cylinder or caliper to retract when pressure is released. Thus allowing the brake pad to move away from the braking surface and reduce wear.

I also believe that no matter the temperature, silicon brake fluid maintains its viscosity. Dexron III would lose viscosity the warmer it gets.

Not much help, but certainly an interesting question. One way to look at it is: If it was a good idea, someone would have done it already. But I tend to stick with what works.

Re: Ive often wondered,, (brake fluid)

Reply #3 – April 27, 2005, 01:59:26 PM

You'd boil that ATF right out of the system......

Re: Ive often wondered,, (brake fluid)

Reply #4 – April 27, 2005, 02:52:32 PM

Quote from: armyguy298

Only differences I saw were that silicon brake fluid absorbs moisture. Why? No clue. I would think a fluid that doesnt would be desireable.

Silicone (DOT 5) fluid does not absorb moisture. Glycol (DOT3,4.5.1) based fluid does. DOT 5's boiling point does not decrease as moisture enters the system. The downside is that moisture can gather at low points and corrode the system. Also, if moisture enters at the caliper seals, that fluid now has a boiling point of 212 deg, much lower than DOT 3,4,5.1 fluid with moisture contamination. DOT 5 fluid also has poor compressibility characteristics that change with temperature and foaming issues. For a daily driver, none of this really matters, but DOT 5 does not belong in vehicles going to OT or HPDEs.

Re: Ive often wondered,, (brake fluid)

Reply #5 – April 27, 2005, 06:21:07 PM

Here's a real big reason to never put Dexron III (or any other transmission or hydraulic fluid) into your brake system: You will completely, utterly and royally bone your complete brake system. Master cyclinder, proportioning valve, calipers, wheel cylinders and rubber hoses - every one of 'em would be screwed ON CONTACT!

The rubber that is in a brake system is a special kind of rubber that is not compatible with petroleum based oils. Tranny fluid will soak into the rubber components, causing them to swell to several times their normal size. This would cause all of your components to seize up, and your hoses to swell shut. You would not even be able to get the cap back on the master cylinder once you took it off. And there is no repairing any of it. All of it would have to go, and your steel lines would have to be thoroughly flushed.

Never, ever let any petroleum-based (or synthetic petroleum-based) fluids anywhere near your brake system!!!!!

Re: Ive often wondered,, (brake fluid)

Reply #6 – April 27, 2005, 06:25:52 PM

Agreed!

Re: Ive often wondered,, (brake fluid)

Reply #7 – April 27, 2005, 07:41:43 PM

Much like the morons who accidently put used motor oil (or something else) in, to top up the MC.

Re: Ive often wondered,, (brake fluid)

Reply #8 – April 27, 2005, 08:49:47 PM

Quote from: Thunder Chicken

Never, ever let any petroleum-based (or synthetic petroleum-based) fluids anywhere near your brake system!!!!!

So how bad of a thing is it that my tranny line blew and soaked my brake hoses a few days ago? should I expect to have to replace them soon or what? (if you look closely you can see the sheared off sway bar mount on the drivers frame :disappoin ) this was two days after I replaced the 4-piece drivers coil, been spending a lot of time under there lately

Re: Ive often wondered,, (brake fluid)

Reply #9 – April 27, 2005, 09:24:50 PM

Quote from: tbirdscott

So how bad of a thing is it that my tranny line blew and soaked my brake hoses a few days ago? should I expect to have to replace them soon or what? (if you look closely you can see the sheared off sway bar mount on the drivers frame :disappoin ) this was two days after I replaced the 4-piece drivers coil, been spending a lot of time under there lately

Oil on the outside, while not particularly good, is not particularly bad either. The outside of a brake line is made from a different rubber than the inside

Re: Ive often wondered,, (brake fluid)

Reply #10 – April 27, 2005, 10:30:49 PM

good ta know! thanks

Re: Ive often wondered,, (brake fluid)

Reply #11 – April 27, 2005, 10:38:36 PM

Ill buy into the whole swelling of seals and stuff cause that makes sense.

the issue about the fluid getting too hot,, makes me wonder... Its not like the tranny fluid never gets hot cause it does and infact requires routing to the radiator for a cooldown.

Re: Ive often wondered,, (brake fluid)

Reply #12 – April 28, 2005, 12:29:35 AM

Quote from: jcassity

Ill buy into the whole swelling of seals and stuff cause that makes sense.

the issue about the fluid getting too hot,, makes me wonder... Its not like the tranny fluid never gets hot cause it does and infact requires routing to the radiator for a cooldown.

The seal swelling is the major factor...didn't think about it while I was at work.

The trans fluid never really gets as hot as a brake system can..esp when driven hard.... The std petrolium fluids aren't made to work at much over 230* for very long. Brake fluid on track cars can get to 500*+...I've seen guyshiznit the track with uprated pads and such and forget to uprate the fluid to a high-temp version...then they wonder where their brakes go after several hot laps.

Anyway...yeah, use brake fluid for brakes :hick:

Re: Ive often wondered,, (brake fluid)

Reply #13 – April 28, 2005, 03:59:17 AM

Tranny fluid must be the ketchup of fluids. Use it on about anything. What next? Replace your coolant with it?

Re: Ive often wondered,, (brake fluid)

Reply #14 – May 01, 2005, 03:49:30 PM

i still dont understand how brake fluid gets hot for prolonged times. Sure the caliper gets hot and transfers the heat but ive never ever noticed my brake fluid resivoir boiling over or my brake lines being hot to the touch, or the fluid in the resivoir being hot either

btw,, i needed about 3/4 of a qt of oil the other day and all i had was tranny fluid. I dumped that in there to get the oil to the full mark. been like that for a few hundered miles so far and actually ran quieter. Not suggesting anyone do this,, i just dont really care what i do to experiment on my "own" stuff.