Brake Fluid

[ChargerRTguy]

Hello everybody, I just got done rebuilding my brakes. It has 11" heavy duty drum brakes, what type of fluid do you recommend ? Thanks.......

 

[oxytousc]

I am planning on using DOT 5 silicon fluid in my car. I know some guys hate it, but since I have an entirely brand new system from the hoses to the master cylinder, I figured it wouldn't be a problem. Wanted to avoid a paint catastrophe using the other stuff.

 

[1moreproject]

I'm going with silicone next time. I don't want to have to clean up another mess like this. Conventional brake fluid, moisture, and aluminum pistons don't mix. I plan to flush the lines with isopropyl alcohol as I've read that this is the best way to purge the old fluid.

 

[Cranky]

Wow onemore, how long what that in service/leaking? Glycol-based fluids come in Dot 3,4 and 5.1 with each having a higher boiling point but they do absorb moisture and need to be changed every few years but hardly no one does that. The silicone does not attract moisture.
The big differences are:

• Silicone, when sucked through a leaking vacuum booster into an engine, burns to form silica sand and quickly wears down an engine's internal parts. Glycol burns harmlessly.
• Silicone affects rubber brake components' “elastomers” differently than glycol and may not be compatible.
• Silicone will not mix with water; glycol will.
• Silicone will not lift paint; glycol will.
• Silicone contamination in your shop will cause fisheyes in future paint jobs; glycol will not.

There's a lot of info on the net on how to convert to silicone and a total rebuild of the system using compatible parts for silicone is the only way to fly if you are going to use it.

 

[1moreproject]

The car sat for about 10 years, in a garage the entire time. It probably wouldn't have done this, had it been driven from time to time. This is an extreme case, but it seems I always see some moisture related corrosion in wheel cylinders so I figure the silicone is worth a try. I think most replacement elastomers used these days will handle the silicone fluid.

 

[b5rt]

The mid 60's and earlier systems have a problem with the silicone fluid ruining the hydraulic brake light switch, located on the master cylinder. Later systems obviously have the switch located on the pedal so it's not an issue.

I've used silicone in a half dozen cars now. Never an issue with compatibility. Some will say that residual moisture left in a system will gather in one spot, usually a low spot in a line, and cause the line to rust. I can see this being an issue because moisture won't mix with the silicone fluid. To combat this possibility, I simply bleed the brakes every 3 years or so to flush whatever moisture may be left in the system. The good news is you don't have to worry about the fluid ruining your painted surfaces and it won't attract any new moisture into the system.

 

[1moreproject]

Hmmm, the distribution block/safety switch (on dual master cylinder models) has a couple o-rings in it. I never considered those, hope they'll be okay.

 

[bluefury]

Fresh system....?

Hello everybody, I just got done rebuilding my brakes. It has 11" heavy duty drum brakes, what type of fluid do you recommend ? Thanks.......



Dot 5...............

 

[zrxkawboy]

I use DOT 5 in my old cars and recommend it. I've never "rebuilt" a system to switch over; I just suck as much old fluid as possible out of the MC, fill it with DOT 5, and bleed it til I see purple at each wheel. No problems!

 

[Revhendo]

I use DOT 5 in my old cars and recommend it. I've never "rebuilt" a system to switch over; I just suck as much old fluid as possible out of the MC, fill it with DOT 5, and bleed it til I see purple at each wheel. No problems!

Smart boy. I can vouch for this one also. Bleed 'em till you see purple. Never had a problem with that evil mixing rumour. The different fluids may not mix, but they won't attack each other or anything else in the universe, either. The main reason behind that is that it is mandated that way. Can't have Al Bundy putting the wrong stuff in his brown Dart by accident and crashing into Marcie's house.

 

[zrxkawboy]

can't have al bundy putting the wrong stuff in his brown dart by accident and crashing into marcie's house.

LOL! Al Bundy rules!

 

[scotts74birds]

Rev..I love your analogy!