What an asshole...

[Matt Tobias]

Driving my 65 cal looker home from work one day with my K8 Street Eliminatord IDAd 2276 just singing in the background the light changes up ahead of me.  I apply the brakes and when the car doesnt start to slow down I realize something is wrong.  I press down harder on the brake pedal and the rear brakes completely lock up!  So unfortunately for me and everyone else around me I am now sliding towards the intersection with no control over the car.  Luckily all of the witnesses to this event have their wits about them and have decided not to break the yellow light ahead of me   As I enter the intersection I decide I only have one choice of action as to not completely run the now red light.  I drop the Dragfast into 2nd gear, turn the wheel to the right and just slam the pedal to the floor.  You can imagine the reaction of that decision.  The rear of the car slung itself perfectly out to the left, I straightened the wheel and shot into my lane with unbelievable precision, grabbed 3rd and got the hell out of there.  The fluidity of it continues to me amaze me to this day.  You would have thought that I planned to do it.  The only drivers face that I got a look at had a look on it that said perfectly- What an asshole!

After I got home I found out that my dual circuit master cylinder had lost pressure on the front brakes, leaving me with nothing but rear brakes!
I only run dual circuit masters now!

[glenn]

Lucky no one got hurt.

Good save.

[Neil Davies]

I had a brake failure in my beetle many years ago, and drove home just using the handbrake, about 10 miles of country lanes. Thing is, I didn't want to  be an asshole and worry my girlfriend at the time, as she was set in the passenger seat...

[hotrodsurplus]

I only run dual circuit masters now!

That's all fine and well but how often do you flush your brake fluid? Remember, it's hygroscopic (absorbs water). And water contains oxygen. And oxygen oxidizes metal and rubber. Almost all brake failures can be attributed to oxidized seals and/or bores.

It's a good idea to flush the system at least every two years. Most of my cars run single-circuit cylinders and the only system failure I ever had was in my T0y0ta pickup. And until that point that was the only vehicle that never got the posh treatment--I figured the more modern system wouldn't be so susceptible. I think differently now.

Any brake fluid that's marginally darker than the stuff in the can does more harm than good.

[Matt Tobias]

I only run dual circuit masters now!

That's all fine and well but how often do you flush your brake fluid? Remember, it's hygroscopic (absorbs water). And water contains oxygen. And oxygen oxidizes metal and rubber. Almost all brake failures can be attributed to oxidized seals and/or bores.

It's a good idea to flush the system at least every two years. Most of my cars run single-circuit cylinders and the only system failure I ever had was in my T0y0ta pickup. And until that point that was the only vehicle that never got the posh treatment--I figured the more modern system wouldn't be so susceptible. I think differently now.

Any brake fluid that's marginally darker than the stuff in the can does more harm than good.

The fluid in the system was only a year old, and I hadnt had any leaks whatsoever.  I dont have that car anymore but on the one Im building now Im going to start fresh with silicone brake fluid, as thats all I use in the motorcycles I build and havent had any problem with it. 

[RichardinNZ]

I did have a problem with Silicone in my early Type 3....it made the rubber seal on the reservoir swell.  As a result air couldn't get into the top of the reservoir as the hole in the rubber seal closed.  Changed to a later cap and all was OK.

[hotrodsurplus]

I initially didn't want to respond to your intent to use silicone for fear of sounding like a wet blanket but I think it's in your best interests to know exactly what you're getting into if you convert a car to DOT 5 (silicone). Like Richard I've been down this path and had some issues with silicone brake fluid.

DOT 5 gels if exposed to DOT 3 or 4. So you have to replace any rubber in the system. Not a big deal if building a car from scratch but it's an expensive conversion on an existing car. Plus you have to purge the lines with acetone, lacquer thinner, or brake cleaner and compressed air.

Prepare to pressure-bleed the brakes to get a decent pedal. When I built a car in about 1991 one of the techs at the shop my dad ran talked me into silicone.  I bled it by the conventional method: pumping several times, holding, and releasing. The pedal felt spongy.

I borrowed a friend's vacuum bleeder but that was no better. I gravity-bled the system overnight (cobbled up a feed to the reservoir, ran a hose from each bleeder to a jar with a little fluid in it, cracked the bleeders, and let it sit overnight). If it was any better I couldn't tell.

Finally I had to modify a spare cap so we could use the shop's pressure bleeder to purge the system. The pedal finally got firm. I could successfully pump-release bleed the system if I removed a wheel cylinder but if I removed anything remotely close to the master cylinder I had to go through the pressure bleeding misery all over. Frustrated, I disassembled and cleaned the entire system, filled it with DOT 3, and never considered running silicone ever again.

I bought into the silicone because it wouldn't harm paint or powder coating. However, more recently i found out what silicone does to a painted surface if you accidentally spill some of it. The guy who painted our Baja does collision repair. He's a by-the-book kind of guy and he suffered some pretty serious fisheye issues on a tank that he sprayed. The overall tank came out fine but he couldn't eliminate the fisheyes in a seam or crevice. He ended up having the tank blasted just to eliminate any risk. A Volkswagen pan is nothing BUT seams and crevices. It makes me shudder to think what spilled DOT 5 would do. 

And as Richard brought up, you also have to consider rubber compatibility with DOT 5. Swelling in a rubber part is an indication of a failure. The swollen seal was obvious but a swollen cup wouldn't necessarily reveal itself. Since automotive brake parts are designed for DOT 3 and 4 you might run into problems.

I find the risks/shortcomings with DOT 3 or 4 much more manageable than DOT 5 (silicone). Cycles designed to run it have compatible seals and cups. Their shorter lines don't trap air to the same extent that cars' longer systems can.

I'd also hesitate to blame the DOT 3 for your system's failure. One of our pickups is 24 years old and has 185,000 miles and it's on its original master cylinder, wheel cylinders, and hoses. I last replaced the wheel cylinders on my Thing in 1997 or 8 and the master cylinder in about 1991. Failures are almost exclusively the result of poor quality or questionable maintenance and DOT 5 won't eliminate either risk. 

I'm not saying you shouldn't run it; I just think you should understand the potential risks and hassles before you make the decision.

[danny gabbard]

Plus silicon brake fluid doe's not like brake switch's for some reason. Or I was one of the few, Had problem with it when I used it on my ghia ,24 years ago ?

[Matt Tobias]

I initially didn't want to respond to your intent to use silicone for fear of sounding like a wet blanket but I think it's in your best interests to know exactly what you're getting into if you convert a car to DOT 5 (silicone).

By all means!  I appreciate the input.  Ive converted 5 motorcycles over from DOT 3 to DOT 5 and have never had a problem.  Everything will be new from master to braided lines to steel lines so Im not worried, I also use a pressure bleeder. 
Sucks you guys have had so many problems, with the success Ive had with it I find it superior to other stuff. 

[Bruce]

Matt, I've been using DOT 5 for 20 years in my car with no troubles and no need to flush the juice all the time.  In another car I had to change the rusty MC every 2 years, so for my current car I decided to use the non-hydroscopic juice.
After 10 years of success, I decided to use DOT 5 in my Mexico Beetle.  I did the conversion when I did the pan swap.  All I did was to flush methanol through the MC, followed by air to dry the methanol.  5 flushes for each component.  Then after assembling the system I poured in the DOT 5.  Bleeding was easy.  Did a gravity bleed for a few hours and all was good.  That was 10 years ago, haven't done anything to the brakes other than adjusting the rear shoes since then.

[mg]

fwiw I like the super blue.
https://www.pegasusautoracing.com/productselection.asp?Product=3326


SILICONE BASED FLUID
http://www.afcoracing.com/tech_pages/fluid.shtml

Fluids containing Silicone are generally used in military type vehicles and because Silicone based fluids will not damage painted surfaces they are also somewhat common in show cars.

Silicone-based fluids are regarded as DOT 5 fluids. They are highly compressible and can give the driver a feeling of a spongy pedal. The higher the brake system temperature the more the compressibility of the fluid and this increases the feeling of a spongy pedal.

Silicone based fluids are non-hydroscopic meaning that they will not absorb or mix with water. When water is present in the brake system it will create a water/fluid/water/fluid situation. Because water boils at approximately 212º F, the ability of the brake system to operate correctly decreases, and the steam created from boiling water adds air to the system. It is important to remember that water may be present in any brake system. Therefore silicone brake fluid lacks the ability to deal with moisture and will dramatically decrease a brake systems performance.

[mg]

Bruce shame on you 10 years with no brake fluid refresh....

That was 10 years ago, haven't done anything to the brakes other than adjusting the rear shoes since then.

[hotrodsurplus]

All good information. One unrelated clarification is that the correct term is hygroscopic. With a G. No, it doesn't sound right or seem to make sense since we know the Greek base for water as hydro but hygro is the Greek base for moisture which is a bit more descriptive of water suspended in a solution.

[/nerdyhairsplitting]

[Bruce]

Bruce shame on you 10 years with no brake fluid refresh....

That was 10 years ago, haven't done anything to the brakes other than adjusting the rear shoes since then.

Mike, that's the Mexican Beetle.  My yellow German Beetle is using 20 year old fluid.  The performance simply does not change over time.  And the fluid remains clear.