The Stovebolt Site Forums The Shop Area Driveline Correct brake fluid for 53 3100

What is the correct type of brake fluid to use? Type 3 or Type 4? Thank you .

Discussed in the past. I use DOT 5, but it's controversial:

https://www.stovebolt.com/ubbthreads/ubbthreads.php/topics/1366700/dot-3-to-dot-5-brake-fluid.html

DOT 4 is backward compatible with DOT 3.

DOT 5 silicone fluid is superior to all of them but you can't mix it with the glycol based fluid. If you're installing an entirely new brake system with all new components, use DOT 5 if you want to.

Thank you for the answer to my question!

Might want to stay with dot 3, yes dot 4 is compatible with dot 3 but it has different properties for HiPo vehicles on track days, a higher boiling point and needs to be changed significantly more often. Dot 5 is silicone, different animal again
Chuck

I will purchase dot 3;thanks for the info.

Brake fluid in all cars should be flushed /changed every 2 or 3 years regardless of type.

Why?

Brake systems are not perfectly sealed
One important specification for brake fluid is the quantity of absorbed water it can retain while still meeting spec
Brake fluid is designed to absorb the water and allow it to mix so that it won’t collect in the wheel cylinders because that Would boil so fast and lead to dragging brakes which would generate heat to the point of the brake fluid boiling and then total loss of brakes because then the pedal is trying to squish a gas pocket and not solid fluid
There is a video on here posted a short while back of a fancy car fully resto mod and the owner is bragging about how powerful the engine is that he had to Ride the brakes to keep at the speed limit while cruising - totally dumb - and then he loses his brakes and crashed - as expected - because the fluid boiled in the wheels and pushed back the volume of fluid into the master

So when your brake fluid absorbed all that water
You need to replace it
With fresh stuff capable of absorbing new water
Or you die on the long down hill parts of the road
Or the flat parts if you have poor driving habits
-s

2Many Trucks gave a much more elaborate explanation than I was going to give but suffice to say if your brake fluid is brown and not clear/amber, your system is long overdue for a total flush.

This goes for new cars as well.

The master cylinders on our old trucks are open to the atmosphere. There is a tiny hole in the top of the filler cap. That is where the water gets in (humidity in the air).
More modern vehicles have closed brake systems. They have a collapsible accordion-like diaphragm in the filler cap so that as fluid level drops when you push on the brakes, the diaphragm lowers down allowing the master cylinder to push fluid to the wheel cylinders without drawing in humid atmospheric air into the system. Once you release the brake pedal, fluid returns to the master cylinder and the diaphragm returns to the original position.

The fleet I work on rarely gets a fluid flush. Modern vehicles, lifetime expectancy of 10-20 years or close to 200,000 miles. But, these vehicles are inspected regularly and thoroughly. Every 90 days, for some. A flush will occur when the vehicle requires it. But for the life of most of them, it just won't happen. The system stays sealed.


A different story when it comes to the '46 International or '65 Ranchero that are also part of my fleet. In fact, out of the three axles on the '46, I still need to stainless sleeve the slaves on one of them so they last longer than usual. Wheel cylinder leakage used to be a regular occurrence with that truck.


I guess my point is, know your vehicle and maintain it accordingly.


BTW, DOT 3 on 95% of my fleet. Forklifts and EV's think they are more special than the rest of the vehicles.