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can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: rnch ()
Date: March 11, 2012 03:26PM

in the same master brake cylinder/brake system?

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: MattNall ()
Date: March 11, 2012 03:31PM

NO!!





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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: vairmech ()
Date: March 11, 2012 03:44PM

AHHHH! anything that says DOT 3-4 can be mixed.

You cannot mix silicone and any other brake fluid.

When you say synthetic, what do you mean? Silicone?

I have DOT 4 that is synthetic.

Ken Hand
CORSA Central Division Director
CORSA Treasurer
248 613 8586
[www.corvairmechanic.com]
vairmech@aol.com

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: Richard M ()
Date: March 11, 2012 03:45PM

RNCH, you said "synthetic" correct. I am assuming you do not mean "silicone".
Dot 3 & 4 brake fluids can be mixed whether it is "synthetic" or not as long as it is DOT 3 or 4. DOT 5 is "silicone" it should not be mixed with any kind of brake fluid but DOT 5.

Richard
Gulf Coast Auto Parts
Sarasota FL

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: MattNall ()
Date: March 11, 2012 03:51PM

God catch Richard... I was thinking Sillycone as wellmoody smiley





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Somewhere between Sea Mountain and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: Swifster ()
Date: March 11, 2012 03:55PM

You'll have to completely flush the old DOT 3 before replacing with DOT 4. BUT, Ford sold a Heavy Duty brake fluid that is DOT 3. The part number was C6AZ-19542-AA. I ran a Suzuki Swift GTi in SCCA ITB racing and because I didn't want to rebuild my entire brake system (rubber parts) that had known only DOT 3 since birth, I put this fluid in while flushing out the old fluid. At that time I had also installed a set of Raybestos Super Stops for pads. Between the two, it knocked 4 seconds a lap off of my lap times from my first race. Since then, I think it now comes in a plastic bottle vs the big can it used to come in, and it's dirt cheap.

If you are rebuilding the entire system with a new master cylinder and new wheels cylinders, then I would use DOT 4. If you are looking for better braking performance, by some high performance shoes. This will make far more of a difference than DOT 4.

Here's the other end. It doesn't matter if you are using 3 or 4, you should be flushing out the old fluid every year. This is true even on a daily driver. I'm hard on my brakes, and the fluid turns black from heat and contaminates. I have a Ranger and the first time I took it in, I wanted the brake fluid flushed. The idiot behind the service desk said I didn't need to have it done ever. I have it done on my cars every 30,000 miles along with every other fluid. I didn't have to replace any parts in the brake system other than pads and rotors until 260,000 miles.

***EDIT - Some of the DOT 4 at the time I was racing had silicone. It was also expen$ive. The newer stuff can be mixed***

Tom Allen
Lakeland, FL
Just Another Day in Paradise



1964 Studebaker Daytona - 289 4BBL, 4-Speed, A/C



Edited 1 time(s). Last edit at 03/11/2012 03:58PM by Swifster.

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: 66vairman ()
Date: March 11, 2012 04:07PM

Swifster is correct. There is NO substitute for regularly changing brake fluid.

Even back in the old days the race guys changed silicone brake fluid often.

With the Vair drum brakes there is ZERO advantage using DOT 4.

In fact some of the replacement master cylinders specify DOT 3!!!!

Some DOT 4 fluids are NOT compatible with the DOT 3 spec brake components - so you're taking your chances with DOT 4.

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: rnch ()
Date: March 11, 2012 04:42PM

Quoting from the label:

"SuperTech Synthetic Brake Fluid DOT-3"

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: jjohnsonjo ()
Date: March 11, 2012 07:10PM

[www.performanceonline.com]

Here is what I use in my motorhome. Don't need to be cooking fluid while driving that thing in the mountains. Overkill for normal Vair, but you racing guys may be interested.

J.O.

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: Swifster ()
Date: March 11, 2012 07:28PM

The important numbers are the Dry and wet boiling points. The Raybestos is 550/284. It's the same as the newer Ford fluid. It would work fine,

Tom Allen
Lakeland, FL
Just Another Day in Paradise



1964 Studebaker Daytona - 289 4BBL, 4-Speed, A/C

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: metalman ()
Date: March 14, 2012 08:19AM

What I remember from class, you cannot use DOT 5 in a 3/4 system, and vise versa. Dot 5 (synthetic) will make the seals swell in a 3/4 system i.e. damage them.

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Re: can regular brake fluid and synthetic brake fluid be "mixed"
Posted by: corventure Dave ()
Date: March 14, 2012 03:04PM

DOT 5 is Silicone brake fluid.


Corventure Dave

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