Brake fluid recommendations to save paint

[njsteve]

After repainting the power brake booster on my Hemicar for the unpteenth time (all hemi master cylinders tend to weep out the rear seal over time), does anyone have any recommendations for a brake fluid that does not eat paint? Is silicone brake fluid still a viable replacement? Thanks, NJSteve

[Seattle Sam]

Silicone brake fluid (DOT 5) doesn't eat paint and doesn't absorb water. You have to be sure not to mix it with DOT 3 or DOT 4..

Here are some notes on it
http://www.team.net/sol/tech/dot5.html

Military procedure for converting to "BFS" (brake fluid, silicone)
https://www.logsa.army.mil/etms/data/A/048941.pdf

-Sam

[PxTx]

I did a car with DOT 5 fluid and the pedal effort increased, not sure why?

FYI, brake fluid is designed to absorb moisture in the system. You could have higher maintenance with DOT 5 depending on the amount of moisture that may collect in the brake system.

[Seattle Sam]

I don't mean to be disrespectful, but..

If the system is full of brake fluid, and all the air bubbles are bled out of it, then I believe the only way to get moisture into the system is if the brake fluid absorbs it and carries it around the system?? So if DOT 5 doesn't absorb moisture, then the system should be safe from moisture-based corrosion internally.

I think... ...please enlighten me if I am wrong!
-Sam

[JoeG]

Brake fluid in principal was designed to absorb moisture and to move it around to Avoid Corrosion in the lines etc.--Unfotunately, moisture has a funny way of getting into places it's not supposed to be thru diffusion ,infiltration, sweating due to differences in temps even at a microscopic level---ANYWAY----They say Dot 5 is improved---MY experience with the early Dot 5 was leaking due to softing of rubber,but they are right it doesn't hurt the paint,but make sure you THOROUGHLY bleed all the air out,because Dot5 is very reluctant to give up it's air .

[MosportGreen66]

Also guys - DOT 5 (silicon) brake fluid is only good for your car if it is specified in owners manual -- otherwise it does not necessarily do any good for your car that DOT 3 or 4 will do. Check out your owners manual.

-Dan

[Seattle Sam]

Thanks Joe.

Here is more info I found on the web:

DOT 3, 4, 5, and 5.1 Q&A
AAA Article on mfr's recommendations
Rodding Round Table


I think I'll go change out my brake fluid...

-Sam

[JoeG]

Good web info Sam----------------

[WILMASBOYL78]

I've been using the silicone brake fluid in my resto cars to prevent damage to finished components. You have to make sure all your connections are really tight. For high dollar vehicles the advantages are worth the extra effort.