LemansBlue68

Is anyone out there using silicone brake fluid (dot 5) rather than the conventional fliud(dot3)? I've heard the following but haven't verified this myself:

Pros:
-Doesn't absorb water so keeps lines, calipers and seals in good condition for a long time
-Doesn't attack paint if some spills on your paint job.
-Doesn't require changing as often as conventional fluid (due to 1st point listed above)

Cons:
-Hard to bleed system free of air
-Is more compressible so brake pedal is more "spongy"
-Has lower boiling point so shouldn't be used in extreme driving conditions.
-More expensive

Is the silicone fluid worth the effort and expense? My car will not be driven as a daily driver. Mostly a fair weather/weekend car. Anybody using this stuff?

Wrencher

We ran it in our entire fleet with the resulting problems you mentioned. Lots of complaints, so we switched back to DOT3. Personally, I only run Ford DOT4 in all my cars. I don't know why it's better, but in the SCCA production cars I was involved with, that product held up the best under extreme conditions and literally everyone used it.

I have heard good things about the Redline fluid as well.

Hans

GDaina

using it since 2001 in my 68, and for teh life of me, can't understand why everyone says the brakes feel mushy. Bleed ing teh system wasn't bad....I first ran thepwer bleeder to get the fluid going, then it was time for gravity bleeding and tapping the calipers with a hammer...Once all the air bubbles were eliminated, the peddle was and still is rock solid.

COMMANDER370

My 80 has beeensetting up since 92 with silicone fluid.once i got car started,still had good pedal and i converted system in 85.old fluid was rusty and caused calipers to leak,so i went ahead and changed complete system.my understanding is regular fluid absorbs moisture and living in louisiana humidity is a problem.

70vert

I just made the switch to silicon when I did a complete overhaul of the entire system. The difference in compressiblity is very small; unless you have a calibrated foot there is no way you will feel the difference. I didn't have any bleeding problems; I did use a vaccum bleeder. The benifits of silicon are really long term so right now I have piece of mind that my breaks are near maintenence free.

gkull

I'm with Gdaina on not spongy. I also use a vacuum bleeder. To purge out the old sucked it all dry and cracked all the bleeds and manually compressed all of the pistons to squirt out all the old. Then I filled the system with solvent and did a regular four wheel brake bleed. I let it sit over night and repurged the whole system before flushing with denatured alki.

Then adding silicone and vacuum bleeding the whole thing again. DOT 3 or 4 is incompatable with silicone so it needs to be as clean as posible.

What a pure waste of time!

I had to replace a couple of calipers and rotors. So I'm using the best stuff I have found now. "Valvoline Synthetic dot 4 - with a 500 degree boiling point"

Wrencher - It's now what the SCCA crowd is using. I put in a couple hundred miles worth of laps last Friday without a brake problem other than the pads were low enough that they needed replacing.

NHvette

... so you went to silicone .... now back to DOT4 ? Why go back again ?

CF6873

I put silicone fluid in the 68 in 1991 and have had no problems since. I autocross 3-4 times a year and average 2000 miles a year. I don't have power brakes. They are not spongyand it stops pretty good for an old car.

Craig :cheers:

632C2

I've had silicone brake fluid in my '67 for a couple of years now. Absolutely no problems whatsoever.

Steve

MEAN72

I have used silicon brake fluid for over eight years with no problems. My car sits a lot and I use silicone because it is less prone to absorb moisture. I really don't see much difference in it, however. :) :) :)

DP77Vette

Had it in approx. 15 years, NEVER a problem!! Nothing you stated as cons have been a prob.. Just don't mix it with DOT 3 or 4. I did mess up one time and added DOT 4 to top it off and realized it the next day. All I had to do was remove the fluid from the master cyl. and refill with silicone. The other never got to the lines, it just sat on top.

:yesnod:
:seeya

Paul Borowski

Another "con" would be the silicone vapors entering the fiberglass strands and then "bubbling" the paint. Ever see a midyear, which has it's m/c close to the hood, with paint bubbles all around this area??? Silicone vapors can "wick up" into the fiberglass strands :yesnod: Personally, not one of my cars will ever see a drop of that **** :yesnod:

GDaina

Can't say I've ever seen that on a midyear, and I know a few who use silicone...

71coupe

I use the regular stuff that absorbs water. I change it every 2 years. Silicone will give you problems because it doesn't absorb water.

:beatdeadhorse:

GDaina

Eh? :skep: :leaving:

pacabada

Go silicone and stop worrying. It's been in my 69 for 13 years. Granted only have 3400 miles but no problems. BUT your system MUST be entirely clean of DOT 3 before converting over.


[Modified by pacabada, 5:27 AM 5/5/2004]

Wrencher

Thanks for the update George. When I got out of racing the synthetic DOT4's were just showing up. No one used silicone 'cause of heat/air/feel problems.

Go with what works. I change mine once a year, so moisture is not an issue. If your 'gonna let it sit, yea, silicone is probably an option and will save your calipers and MC, but I'd still change it.

Hans

Barry's70LT1

I've had DOT5 for over 10 years.
As others have stated, no problems at all. I have not had any problems with my brakes in 10 years. Nothing to fix.

Sorry Paul, my paint is still on my hood.
And that is the original lacquer paint as well. 30+ years.

Barry

71coupe

What happens when you mix water with oil? It doesn't mix & the oil settles above the water. In a brake system with silicone fluid, the water will sink all of the way to the wheels.
Reg brake fluid absorbs water and prevents this from happening by keeping the water is suspension where it won't do any damage.





[Modified by 71coupe, 1:00 AM 5/5/2004]

gkull

Hans & 71coupe You both have the wrong idea! :cheers: You just always have to have enough speed and stomp on the brakes to keep any water boiled out of your system! :smash: :LOL

I think it really comes down to how often do you do maint. work. How many people change their oil in the tranny and rear end. Or power steering........

Hey I alway's have fun! and my old car is paid for :thumbs: