Break Fluids

[Clem Z.]

Re: Brake Fluids....Silicon NOT

i think the color change come from the release agent they use when the mold the rubber parts in brake system. i notice this happens very quickly on my dirt bikes and quads because they have a transparent master cylinder and you can see the fluid turn dark in just one days riding. i never remove the cap from any of my master cylinders and i even have tags on them not to open when they do the state safety inspections. i have had a few cars go over 100,000 miles and never changed the brake fluid and never had a leaking wheel cylinder or calipher. just lucky i guess but my thinking is why look for trouble.

[Clem Z.]

PS

there must be a good reason the auto companies do not use silicone fluid as a factory fill. some one out there must be still employed by the big 3 could check this out.

[Craig S.]

Re: Brake Fluids

Thx Duke....I will do that...Craig

[Terry M.]

Re: Brake Fluids....Silicon NOT *TL*

Can't do that Jim, I have had DOT 5 in my 1970 Corvette for over 20 years. I do, however, have DOT 3 in the Caprice - want to go against the SEO brakes on that barge? You would have the weight advantage.

[Terry M.]

Re: PS *TL*

Clem,
DOT 5 is specifically prohibited with anti-lock brake systems. That rules it out for many modern vehicles.

[Duke W.]

Re: PS

I've heard that, but what's the technical reasoning behind the prohibition of DOT in ABS systems?

Duke

[bruce11495]

Opinions or guess!!

Hey Duke....Doesn't take you long to put someone down. If silicon was so damn good, why don't you use it when you race? Furthermore what racing series or major manufacturer does? Nascar, F1, WOO, CART, GM, Ford, Honda? I don't have any degrees in engineering or have I ever worked for GM. I have problems understanding computers, their lingo and how to make them work. But my 72 Vette would stop just as good as the as the C4s when I raced!!!
I guess I'm the only guy who doesn't believe in it..............

[Duke W.]

Re: Opinions or guess!!

??? Who am I putting down??? I have silicone fluid in my SWC, but it's the only car where I completely disassembled the brake system and started from scratch with everything clean and dry. Assembled the m/c and wheel cylinders with silicone fluid and filled and bled the system with silicone fluid.

I use DOT 4 in my other cars and change it every two years because it's easier to do the bienniel maintanance than competely rebuild perfectly functioning brake systems.

...got any experience or research to offer on silicone fluid?

Duke

[Terry M.]

Re: PS *TL*

Duke,
I believe the prohibition on DOT 5 with ABS is due to the difference in viscosity between DOT 3/4/5.1 and DOT 5, but I have not seen a reason in writing from any authority. This is strictly my opinion. If I find an authoritative reason I'll let you know.

[Terry M.]

[John H.]

Re: Brake Fluids....Silicon NOT

Several reasons why you don't see DOT5 silicone fluid as factory fill:

1. Cost - DOT5 is much more expensive than glycol fluid, with no specific advantage to justify the cost (most daily-driver cars NEVER see a flush/bleed or fluid change, and go to the crusher with the same fluid they left the assembly plant with).

2. Standards - glycol fluid has been the industry (worldwide) standard for 75 years, all brake components are designed for absolute reliability using glycol fluids, and there is no interest in developing a second design standard to further complicate the design, manufacture, or long-term in-service reliability issues related to use of a "different" brake fluid chemistry.

3. ABS - the ABS system uses high-frequency solenoid-driven hydraulic valving to modulate brake application under ABS-activated conditions, and fluid agitation from these valves causes air entrainment problems with DOT5 fluids (makes many more smaller air bubbles from fewer larger air bubbles), which is a disaster, as it causes more compressibility and the smaller (almost microscopic)entrained air bubbles are nearly impossible to remove, as they "cling" to the walls of component surfaces. Most racing brake systems also use ABS these days, and racers use very costly synthetic (not silicone) brake fluids like Motul 600 and others that are formulated for high boiling points and very frequent fluid changes (like after every track event).

4. Liability - There is no desire to generate a situation where the factory fill brake fluid is incompatible with aftermarket service fluids when that situation can result in a deterioration of brake system performance or reliability. All the "Warning" labels in the world on master cylinders to identify the need for a specific/different type of fluid for brake system maintenance/service in the field wouldn't stop the flood of product liability lawsuits that would result from Bubba adding or bleeding with the "wrong" brake fluid.

There are other reasons as well, but this covers the high points.

[Calvin M.]

Re: Brake Fluids....Silicon NOT

Hi All -
FWIW I've been using silicone in my 72 and 57 with no problems. I went to silicone for its anti-corrosion benefits and have been pleased.
Cal

[Clem Z.]

Re: Brake Fluids....Silicon NOT

john after your reason #1 why do people use silicone fluid? is it monkey see monkey do?

[Joe L.]

Re: Brake Fluids

Ray------

Two things I'll add to this discussion:

1) When we describe silicone brake fluid as "DOT 5", keep in mind that the "DOT" refers to "Department of Transportation". This means that the fluid meets a rigorous, government-established standard for automotive brake applications. It's not necessarily approved for ALL automotive brake applications (e.g. ABS), but it IS approved for automotive brake applications. It's not as if we're talking about some "snake-oil" that marketers claim is the "be all". DOT 5 silicone fluid is used in some military applications, as well;

2) one BIG, BIG advantage of silicone fluid that's not been discussed: did you ever spill any glycol ester-based brake fluid on automotive paint? Do this just ONE time and you'll fully appreciate one of the non-brake related qualities of DOT 5 silicone. Of course, everyone says that you just need to be careful with DOT 3 or 4. Believe me, being as CAREFUL AS YOU CAN BE, accidents do happen. I'm VERY careful and it happended to me once-upon-a-time. It was NOT a pretty sight. Fortunately, the car was in need of a re-paint, anyway. Have it happen on a recently painted Corvette with a paint job costing $7,000 to $10,000 and one ABSOLUTELY WILL understand the benefit of DOT 5 silicone fluid-----even if DOT 5 is not quite up to the performance standards of DOT3 or 4.

[John D.]

I used silicone *NM*