brake fluid

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dartley

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Hi folks,

I know this topic has been covered before, but all I want here is a poll. It goes without saying that ya'll can post whatever info you want, but all I am asking for is a poll of who uses dot 3/4 non-silicon brake fluid and who uses silicon.

My front calipers (regular single piston stock Mopar issue) got replaced recently because I don't drive the car that much and they apparently started dragging. So I am re-considering silicon fluid.

So, if you don't mind - who all of you uses which? Thanks!
 
Regular old DOT3 here. I used silicone in my old Vettes due to caliper problems inherant with old Vettes, but I never did like the feel of the brake pedal.

George
 
I ran silicone in my ebody for over 10 years and never changed it. Parts still
looked good and no rust.

I did read a SAE posting a year or so back about how silicone needs to be
purged out every 4 years to keep pedal feel and keep contaminants for
doing any damage to the system. I like it and when I redo my entire system
next year I will go with the silicone. FWIW
 
As an ASE certefied brake guy I like silicone. If only because it doesn't gather contaminants. All modern manufacturers recommend you replace DOT3 every 2 years because it will gather moisture (hence the reason the bottle says don't leave around opened) and contaminants and break down (no pun intended.) I've had customers come into the shops I've worked at with almost no pedal but the brakes are good. They've boiled off the moisture on the monster hills here in the Finger Lakes area of New York (7-12% grades) and had complete brake fade. After a cool down, the brakes come back and after replacing the fluid they're on their way. (What would really help is if they learned to frickin' drive on the frickin' hills, but I digress...)
Around here it's an almost given on Mopars of all years with disk/drum set up that if you replace the front pads you're also going to replace the rear wheel cylinders. Silicone keeps that from happening. So chalk up another for silicone.
 
idrift said:
I ran silicone in my ebody for over 10 years and never changed it. Parts still
looked good and no rust.

I did read a SAE posting a year or so back about how silicone needs to be
purged out every 4 years to keep pedal feel and keep contaminants for
doing any damage to the system. I like it and when I redo my entire system
next year I will go with the silicone. FWIW
Click to expand...
I have to agree but be shour your brake hoses are good .
 
1 for non-sil
4 for sil

What's that about the brake hoses and silicone? Not heard that before (or don't remember anyway ;-)
 
1 car with silicone,1 with dot 3.

Guess which one has the paint lifted under the master cylinder all the
way down the firewall!

Dot 5 only here from now on.
 
Not sure on this one. Since silicone does not absorb moisture (non-hygroscopic), any moisture in the system would corrode the internals. I would think this would be good for stainless lines and calipers. When they rebuild Corvette calipers they are usually with S/S sleeves.

I like Motul 600 DOT 4, that has an exceptionally high boiling point.
 
3 non-sil
5 - sil

It's the corrosion I am fleeing from, Pete. Since I don't drive it much, as you know. I do know about the non-absorptive nature of silicon; that if there is moisture in the system it can pool. But I think that if I just really bleed them out good I should be able to replace with silicone.

To all: http://www.moparaction.com/Tech/quest/BINDER_JUICE.html
 
The one thing you really need to be aware of when it comes to silicone brake fluids is they outgas. Unlike a DOT 3 or 4 which have a propensity to absorb water, Silicone brake fluids like air, and what happens when you drive over the mountains...........the air in the fluid out gasses due to the different atmopheric pressures and VOLA you have air in your brakes and pedals that may go to the floorboards.
 
5 non-sil
6 - sil

luvbeer35 - this one I'd never heard before. I would think that Rick would have mentioned this if it were any real concern; wouldn't you?

Actually, it's pretty clear you wouldn't ;-)
 
I use DOT 5 Silicone in my 65 Barracuda and my 76 Warlock both spend time at 12,000 ft elavations. I would not use anything else in an older vehicle. Check Richard Erinberg's articles about disc brake conversions.
 
5 non-sil
7 - sil

76 WARLOCK - yes, I posted the link above too.
 
luvbeer35 said:
The one thing you really need to be aware of when it comes to silicone brake fluids is they outgas. Unlike a DOT 3 or 4 which have a propensity to absorb water, Silicone brake fluids like air, and what happens when you drive over the mountains...........the air in the fluid out gasses due to the different atmopheric pressures and VOLA you have air in your brakes and pedals that may go to the floorboards.
Click to expand...

There is some truth to this. The military will not spec dot 5 for exactly this
reason. In the SAE tech article I mentioned above, air was the main reason,
in reference to microscopic bubbles, that they wanted you to bleed out your
brakes completely every 4 years max. I have never ever heard of the amount
of air you mentioned gathering in silicone fluid unless is was not stored
correctly or shaken before it was used.

In any event, my car sits quite a bit (working on that one) and I try to
bleed them out every couple of years anyway.

On a scary note, my father worked at Chrysler for over 30 years and told
me a story of a guy on the brake line that got fluid in his eyes and it
blinded him, yikes. Something other than paint to worry about!
 
Dot #5 here. My old 70 Duster with kh 4-piston calipers had to be torn down evry spring out of winter storage. No problems with dot 5.
 
I did find this article which has some of the info i had mentioned in a previous post.

SILICONE BASE BRAKE FLUID (SBBF)
The U.S. DOT defines silicone brake fluid as that which consists of no less than 70 percent of adiorgano polysiloxane by weight. Silicone-based fluids are regarded as DOT 5 fluids. They are highly compressible and can give the driver the feeling of a spongy pedal. The higher the brake system temperature, the more the compressibility of the fluid--increasing the feeling of a spongy pedal. Silicone-based fluids are non-hydroscopic, meaning that they will not absorb or mix with water. When water is present in the brake system, it will create a water/fluid/water/fluid situation. Because water boils at approximately 212 degrees F, the ability of the brake system to operate correctly decreases, and the steam created from boiling water adds air to the system. It is important to remember that water may be present in any brake system. Therefore, silicone brake fluid lacks the ability to deal with moisture and will dramatically decrease a brake systems performance. Silicone brake fluid has a number of strengths and drawbacks.

Strengths:
1) It has a high boiling point since it does not absorb water. Therefore, there's no so-called wet boiling point.

2) Doesn't absorb moisture.

3) Doesn't remove paint.

4) The viscosity is more stable over the extremes of temperature.

5) With the exception of some formulations used in external boots, silicone brake fluid is compatible with all standard brake components.

Drawbacks:1) It's hard to pour without entraining air bubbles--hence an application will generally have a softer, spongier pedal feel.

2) It doesn't absorb water, so any water already in the system accu-mulates in the lowest point of the system and stays there, causing rust.

3) Glycol fluids begin to compress near their boiling points, whereas silicone fluids begin to compress at around 300-350 degrees Fahrenheit.

4) Additives in the fluid can vaporize at comparatively moderate temperature, increasing the spongy feel.

5) Silicone fluids expand significantly when hot.

6) Silicone fluid is functionally incompatible with systems that have held glycol-based fluids for any length of time, requiring flushing and seal replacement (there are counter opinions on this, which state that the modern silicone formulations are in fact compatible with only a flushing, rather than a complete reseal). The actual DOT specification requires chemical compatibility, so as far as that goes, the two fluids won't cause reactions if used in the same system, but they certainly won't mix, either.
 
Silicone X1. Completely brand new brake system and new paint.
 
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