VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Brake Fluid ??

Howdy !!

I was wondering if any one knows which brake fluid to us in my 41, special deluxe -??

Thanks Mike

My best friend and fellow Chevy Club member who 'helps' me do my brakes (translation: I hold the tools, etc.) is pretty dang fussy about brake systems and he just uses any 'familiar' brand of dot 3. We checked into silicone quite a bit and decided against it. Hope this helps! Bill.

Brake fluids can be broken down to two different types of automobile brake fluid - DOT3 and DOT5. These fluids should NEVER be mixed together.

DOT3 is the old standard brake fluid that has been in use for many, many years and would be compatible with what was used in your car, when it was manufactured. The major problem with this fluid is, it absorbs water from the atmosphere and can cause dilution of the brake fluid, as well as internal rusting of brake lines and cylinders. On 'normal', cars that are driven every day, the heat produced from normal brake useage gets rid of the water and there usually isn't any problems from using DOT3. If you open a can of brake fluid to add to the system, you should not save the unused portion due to it also becomming contaminated in storage.

DOT5 is a silicone-based product which does not attract & absorb moisture in the air. To use DOT5 in a system previously filled with DOT3 (or vice-versa), the entire brake system must be flushed and all rubber components replaced with NEW (NOT NOS) parts, otherwise it's possible to experience catostrophic failure.
I had numerous problems with DOT3 brake fluid, including a wheel cylinder failure while I was headed for a "T" intersection, and switched all my collector cars to DOT5 about 12 years ago and have never had any other problems and I drive them approx 2k miles each, per year. I'm sure this will open up a can of worms and stories about DOT5 failure will be presented, but from my experience, if the system is prepared correctly and with care, DOT5 is an excellent choice for cars that are stored for long periods. I've also never experieced any difference with braking performance between DOT3 & DOT5 fluids.

I'm guessing you have a recently acquired car and don't know what's been used in the past. It's usually impossible to tell exactly what the fluid in the system is by looking at it, since there's normally some discoloration. My suggestion, if you're not sure what's in the car now, would be to drain, flush & rebuild the system with whatever product you choose to use or to send a sample to a lab to verify which you have.

Sorry to be so long winded, but brakes are the MOST important part of your car, IMO !

-Bob

Thanks to Bob & Bill.... as always your there when I need you.

Much appreciated
Mike

If your not sure when the brakes were last serviced and to be sure the hydralic system is "safe" I would recommend overhauling the master and wheel cylinders and replacing the hoses.

With either fluid I would recommend bleeding out and refilling the system-evry 3 years with Dot 3 and every 5 years with Dot 5.

I have Dot 3 in two of my cars and Dot 5 in two-have had no problems with either.