C3 Brake Fluid

[Art Ives]

I have pondering over what brake fluid to use in my restoration project, silicon or DOT 3. The system is new with stainless sleeves for calipers and master cylinder. All lines have been replaced. I plan to drive the car a little but also want to show it. Based on the experience of others what fluid would be recommended? Art Ives

[Jack H.]

Re: C3 Brake Fluid

Check the archieves searching on DOT5, Etc. There's been a LOT of prior discussion on this. Basically, there are pros and cons to both of the brake fluids. Most stay with basic DOT3, especially if they intend to drive the car extensively and do cross country trips where they expect to change altitude....

[Jim T.]

Re: C3 Brake Fluid

I switched over to silicone in my 68 and 70 16-18 years ago. Still like it because silicone does not absorb water causing problems. DOT3 should be changed about every couple years acoording to some and it is additional work that I don't have to do on the 68 and 70. The 68 has manual and the 70 has power brakes. The 70's braking performance is really great with the power brakes.

[Duke W.]

Re: C3 Brake Fluid

If the calipers and master cylinder were assembled with DOT 3 fluid, then you've already made the decision. If you decide to use silicone fluid, you'll have to disassemble and clean everything with denatured alcohol to remove all traces of glycol fluid, then assemble everything with silicone fluid.

Duke

[Dick W.]

Re: C3 Brake Fluid

Just because that you use silicone, it does not eliminate the moisture problems. DOT 3 is hydroscopic (has an affinity for moisture). Silicone will not mix with water, but the moisture is trapped in pockets. These pockets over a period of time can corrode steel parts just like DOT 3. If anyone is interested I will dig up the technical paper on brake fluids. It was either a SAE paper or ATA Maintenance Council presentation some years ago.

Yes Ethel, there ain't no free lunch!

[Jim T.]

Re: C3 Brake Fluid

Dick what mileage/time interval would you recommend for a change of silicone fluid to remove the moisture?

[Terry M.]

Re: C3 Brake Fluid

I've have had DOT 5 in my Corvette for close to 20 years, and never gave a thought to flushing it. I can't believe there is any way for moisture to get into a DOT 5 system (unless one does some really unlikely things to add water to the system).
Dick I would be interested in those papers. I have a collection of SAE and DuPont papers regarding DOT 5 fluid tests, one of which writes about rubber brake lines submerged in water as a test. Subsequent fluid testing showed major absorption by polyglycol fluids, but no measurable absorption by the DOT5.

[Dick W.]

Re: C3 Brake Fluid

I will try to find it. I am not sure if it was an ATA Maintenance Council or SAE paper. There was a lot of controversy (sound familiar?) concerning the use of Silicone in commercial vehicles.