Brakes for Grace Slick

[jeepbut]

I have gathered most of the brake parts for Grace and wonder about silicone brake fluid. It seems like the way to go on several levels. Who has used it and what do you think? I am leaving it drum-drum for now (disk and drop axles later) with a 71 F-250 power booster and master cylinder. Yes I have the funny little firewall bracket and a core for the booster($80-120 core charge on the booster). Thanks, Lyman.

[62galxe]

Silicone is expensive and the system needs to have no standard fluid in it. It is paint friendly also. that's my limited knowledge.

[jeepbut]

At Walmart today I found a DOT 4 synthetic. Anybody have experience with this? Paint friendly? My system will be all new, so no old fluid to deal with. I am going with DOT 4 or DOT 5 depending on what info I can from anyone who has used them. Thanks, Lyman.

[Toyz]

Disclaimer: I have not used DOT 5 fluids, and probably will never have any reason to.
There's been some expressed concerns as to DOT 5 silicones used in vacuum brake systems. This is based on silicone supposedly becoming sand when burned, so in the event of leakage into the booster, it might be possible to suck in enough fluid to "sand" engine components. Also, I damn sure don't want any form of silicone around any automotive painting process or area! I usually wholeheartedly try "technological advances"; this is one I choose to avoid.
Glycol based fluids (DOT 3, DOT 4) mix with water, not a good thing in our Gulf Coast environment; silicone (DOT 5) does not absorb water; instead will supposedly push it through the braking system where it supposedly could cause corrosion, again not a good thing.
AFAIK, DOT 4 is still a glycol based fluid, albeit "synthetic", so it appears it may be simply a higher temperature-capable, higher priced type of paint remover . Based on my level of ignorance, DOT 4 would be my choice on a clean system, and probably as a "top-off" fluid also.
Another disclaimer: my opinions are sometimes based solely on "he said she said" information; this is one of those times, so please take them on that basis!
Paul

[bmcgc]

I replaced the entire system on my 66. The orginial DOT3 system worked fine for 47 years, Im guessing the current DOT3 system will work fine for the next 47 years, long after I have checked out.

[Brians1966]

I have used DOT 5 once when I redid the whole brake system on my BOSS 302 some years back. Not only was it expensive, I really did not see or notice any advantage over DOT 3/4 brake fluid.
I have done a complete brake system rebuild on my 66 - using DOT 3/4. Works well
Most Brake Fluids sold today are synthetic base. The DOT ratings equal a specific heat/boil rating with DOT 4 having the highest temp. rating
I used Valvoline brake fluid with my rebuild because of the dual 3/4 rating so if and when I go from drums to disc brakes I wont have any issues with fluid. Also as stated DOT 4 will strip paint as well as DOT 3 does.

[HiBoy63]

I replaced the entire system on my 66. The orginial DOT3 system worked fine for 47 years, Im guessing the current DOT3 system will work fine for the next 47 years, long after I have checked out.

X2 did the same on my 65. I just adjust the breaks at every oil change. I think it would stop on a dime..... well maybe a dollar due to inflation.