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The Tech Page

There are tons of really good tech articles out there.
Hopefully i will find some of them soon and get them in here!

The Brake Fluid Argument

OK. Here's the situation. The other day i was discussing (read Arguing) with a friend of mine.
Since he is an avid formula Ford racer i should have shut up and listened. No sir, not me!
In the past i have tried to use DOT 5 brake fliud whenever possible. Many people have
recommended it to me because of its performance values (which remain undetermined). It also has no
adverse effect on expensive paint jobs. Bonus! From what i had been told the only bad thing about
the silicone based fluid was the price.
Not so, according to "Ford Boy"!When converting from a standard DOT 3 or 4 based system it
is very important to flush every component thouroughly. The two fluids form a thick jelly when mixed. A very small amount of the DOT 3 or 4 can render the brakes useless. This part i knew (don't ask how!) However, according to my guru, another set back (which i did not know about) to DOT 5 is its thermal coefficient of expansion."Never even thought about it", I say.
Should Have! Last year i was driving my rabbit down from the local ski hill. I was speeding, at times getting up to about 180 kilometers an hour. Come to a corner and the four piston willwood calipers grab the 12" rotors, car slows down really fast! The rotors must have been red hot by the bottom of the 15 Km. road, (but thats ok because polymatrix D pads are race stuff and work best on hot rotors). At the bottom of the hill i noticed that my pedal was a good bid stiffer, but never thought about it... Until now! What was happening? Thermal expansion! If the road was a few miles longer the pedal may have become much stiffer, and could have caused the brakes to lock. Not cool.
For racing use, the most economical fluid to use is a good DOT 4. You can spend $100 a liter for willwood stuff, but who knows if the benefits will offset the cost. DOT 4 is about a quarter the price of the DOT 5 and doesn't have the same expansion problem. It has been known to boil, but only under extreme situations. If you spill some on your paint, it's toast, but nothing is perfect.
Right now i am waiting for some technical data on both types of fluid, as well as the willwood stuff for comparison. I will add some stuff as soon as it gets here.