VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 Brake Fluid

I'm sure it has been discussed here before but my search doesn't help me much. The question I have is can you use Dot 5 on 36 Chevy brakes? If not then what is the proper Brake Fluid? Thanks in advance.

DOT 5 can be used but be aware that it requires flushing the system completely, replacement of all the cylinder cups and can result in air being retained in the system of all is not 100%. Otherwise DOT 3 is the recommended brake fluid and should be replaced every 3-5 years.

I think Chipper meant to say Dot 3 or Dot4. While I have not used Dot 5 I have heard it is a pain to clean the system without complete replacement and then bleeding is another story.
Tony

Yes I meant DOT 3. It is the recommended brake fluid for all the older Chevrolets. Some high performance disc brake systems use DOT 5 due to its higher boiling point.

DOT 3 and DOT 4 brake fluids are very similar and compatible.

Some of the differences are:
- DOT 4 has higher dry and wet boiling points.
- DOT 4 does have a slightly higher tendency to absorb moisture from the air.
- DOT 4 is has a slightly lower viscosity which makes it work better in modern brake systems with ABS and traction control systems.

Chipper’s statements about DOT 5 are correct. It is a silicone based fluid and you have to start with a completely clean brake system. It does tend to absorb air over time so can produce a somewhat soft pedal.

I agree that DOT 3 is great for these older vehicles. Plan to completely flush the system periodically like Chipper recommends.

My preference and practice is to use Valvoline Synthetic DOT 3 & DOT 4 brake fluid. That way I only need one container of brake fluid for all my vehicles. Plus I flush every system at least once every 2 years.

Why in the world would one have to flush the DOT3 out every two years?

Owing to the nature of the Huck mechanism the stinking system will flush itself every two-three months. Even faster than that if you leave it sitting and un-exercised for a week or two.

If the system it's not flushed, what happens to the Dot 3. It is in a closed system so which of the following happens to it:

a. It gets dirty so that it can't flow sufficiently to push through the smallest space in order to activate the wheel cylinder pistons? How does it get that dirty?

b. It gets lumpy? (see above)

c. It gets smelly? How do you know if it ain't seeping out and thus flushing itself.

d. It gets water in it? Seems that would not be harmful owing to the fact that water can/t be compressed. It would only be a very small amount owing the the only place it can get in it through the MC plug. Hmmm.

e. Just something to do? Now there you go! When you live in miserably cold areas then it will give you something to do to get away from the missus for a little spell. You know.

For the record, I never flush none of mine. I noticed the coupe now has a trail of fluid on the inside of the rims and down the tire and going through the continual process of flushing itself. It hadn't been driven for a couple months. I'll just add some to the MC and keep on driving it. There is no cure that I have found or been told about

Best,

Charlie

BTW: The coupes front linings are so soggy they have swelled and stick. They break loose with an audible "Pop" when the powerful 216 is put in low gear and then act normal. The soggy linings will soon burn off. Yeah, right.

BTW2: Think of the brake fluid as the engine oil. On a 216, if you have an oil filter (even a trickle) it will keep the oil clean and you never have to change it. Just check and add periocically. Right?

Charlie,
Your answer "D" is the correct one. Water can migrate into the brake fluid not only past the MC plug but through the hoses and past the covers and cups on the cylinders. There are inhibitors in the fluid to be able to tolerate a little water but when that reaches its capacity to tie-up the water it becomes corrosive and starts eating at the metal in the cylinders. If you flush the brake fluid every 2-5 years (depends on how much the vehicle is driven, temperature and humidity in the environment) the system will remain in good shape. Same for the cooling system. Flushing every 2-5 years will restore the corrosion protection there as well.