Dot 5 Fluid and CSSB Warning

[Ed D.]

Re: Dot 5 Fluid and CSSB Warning

Have DOT 5 in my 72 since 1985. Have the original master cylinder, which has never been rebuilt. Replaced the calipers in 85, which is when I changed to DOT 5. Still have those calipers on the car and have never been rebuilt. Car has been driven to many Regionals and 7 Nationals, and got Sam Foltz distance Award. No leaks and the fluid is clear, with no rust in master cylinder. Cant comment on new type rubber or new DOT 5 formula
Ed

[Paul S.]

Re: Dot 5 Fluid and CSSB Warning

I cannot speak to incompatibility but only my personal experience from 2013 with DOT5 and a totally new brake system (other than rotors) that I purchased from CSSB to convert my standard disk brake 67 to power disk brakes. I could never get the right front caliper to quit seeping brake fluid where the rubber hose screws into the caliper--and yes I had new copper crush washers, tightened, re-tightened, etc..and the master cylinder also bought from CSSB was leaking out the rear. After CSSB (which also sold me the DOT5) replaced the caliper and MC once including paying the shipping to return the bad parts, they said send us all the calipers and MC, we'll cover the shipping (which is quite a bit due to the weight), and we'll give you your money back.

I started over with LoneStar and used DOT 4--no issues and the DOT 4 was so much easier to bleed the air out of because I could use my motive powerbleeder. I could not get the air out of the DOT 5 with the motive powerbleeder and had to have a friend help me doing it the old fashioned two man way.

I would have loved to be able to make DOT 5 work and have to tell you the sheer aggravation factor of trying and failing, was enough to last me a lifetime. Truly, I can flush out brake fluid at three year intervals from now until the day I die, with far less hassle.

It would not surprise me that my experience and others, contribute to the label you now see on CSSB's MC. Maybe you will have better luck than I. If not, you might be doing it on your own dime. Not sure I'd fuss with DOT 5 any longer.

[Patrick B.]

Re: Dot 5 Fluid and CSSB Warning

If you use a power bleeder with silicon brake fluid, it should be the type that has a bladder to separate the pressurized air from the brake fluid. It is possible for silicon fluid to "absorb" pressurized air, preventing a firm pedal. Perhaps that contributed to Paul's frustration.

[Jeff J.]

Re: Dot 5 Fluid and CSSB Warning

Jim (& Larry)-
I am not confused. I understand the difference between DOT 5 (silicone) and DOT 5.1 (polydimethylsiloxane) based fluid (reference 2nd paragraph in my previous post). Although, in trying to ferret out the issue, I'd thought that perhaps the vendors (or their customers) were confused and created the seal swelling material incompatibility problem by mixing the two fluids in the same brake systems. However, my discussions with Lone Star Caliper suggests mixing is not the issue. They separately ran tests with a wide variety of silicone brake fluid sources.

I don't normally like to provide specific company names in public forum discussions, I spoke with representatives from Stainless Steel Brakes Corp (SSBC), Corvette Central ("Gus") and Lone Star Caliper ("Brad" or "Ken"). As info, Lone Star Caliper along with SSBC were some of the pioneers in SS sleeving and rebuilding brake calipers. LSC now performs rebuilding for retail vendors including Corvette Central for a wide variety of automotive hydraulic equipment including power steering ram cylinders and control valve assemblies. I'd encourage you to speak with them directly if you are trying to make a decision on brake fluid type.

I also have a '66 which I converted to SSBC silicone brake fluid 17 years ago when I did a frame off on the car. I have also not had any problems with my '66 which is why I'm trying to determine if this is a real problem or not. Evidently, this is a relatively new phenomenon which started about 3 or 4 years ago (even though the referenced EPA notice dates back to 2009).

After additional discussions it seems the import - export nature of silicone brake fluid may be resulting in substandard fluids entering the silicone fluid market. An analogy would be when bolts marked as Grade 8 but not tested enter the US and are sold as Grade 8 bolts when they do not perform as Grade 8 bolts. From discussions I've had, I think fluids that are sourced, blended and quality controlled in the US are less likely to result in incompatibility problems such as seal swelling.

I'll continue to research the issue and will post any new info once I make a decision for my '72 brake overhaul.

[Ronald L.]

[Jeff B.]

Re: Dot 5 Fluid and CSSB Warning

I think the entire thing is BS, and is basically a way for CSSB avoid dealing with other issues that using DOT 5 may create. In my experience Dot 5 simply does not damage the rubber. It can make the pedal more spongy because it holds more air, but that is a different issue and is manageable if you want to use DOT 5. The only time I have ever heard of a (real) problem with the seals ended up being caused by a person using a petroleum based solvent to clean the system before switching to DOT 5 - which will kill the seals in short order. I think these kind of mistakes are what starts the rumors about problems with DOT 5. When I questioned CSSB about their test results they put me in touch with the guy that apparently conducted the test. I have to tell you he was a total flake and did not answer ANY of my questions head on. His responses were completely non-sequitur and he essentially wore me down with nonsense until I gave up.

[Jim L.]

Re: Dot 5 Fluid and CSSB Warning

There still is something fishy and lacking Engineering102 test data

And this is right at the heart of the matter.... there hasn't been any good science behind the hand-wringing and the what-ifs.