Quote:
Originally Posted by BBQCYCLEWERKES
Dot 5 fluid if you have disc brakes on your vehicle.
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Not exactly good advice.
Quote:
Originally Posted by Tommy
Stu,
You really need to know what fluid is currently in your system before adding anything. Read this article: click here. You can cause some real problems by mixing dissimilar brake fluids, and DOT 5 is very different from DOT 3 & 4. |
This is pretty good advice. It's probably a glycol based fluid. That's pretty much the standard, and I would think a pro builder would use that. But, I would call and find out.
Quote:
Originally Posted by ACademic
Not to pick on this post, but that is really bad advice. Disc brakes have been around since the '60's and they didn't have DOT 5 back then.  |
Disc or drum use the same type of fluid, doesn't really matter. But very few vehicles use silicone based 5.
Quote:
Originally Posted by BBQCYCLEWERKES
not to get defensive either, but SPF 1950 wasn't around in the 60's. Common practice from 2000 and up was that disc brakes used dot 5 and hyd. slave cylinders used dot 3.
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I would have to disagree with that, too. Every car I've ever owned has used glycol based. And I'v owned 5-6 that were built after 2000.
Harley used to use silicone in their brake systems. But even they have switched over to glycol. My '06 Dyna uses glycol; the owners manual calls for DoT 3. But both of my '97's used silicone 5.
Quote:
Originally Posted by Mark IV
Actually, there are some valid reasons NOT to use silcone brake fluid. A high quality DOT 4 is sufficent. While Glycol based fluids do absorb water, silcone does not. That is not an advantage in cars that are well maintained as the glycol holds the moisture to be flushed out when changed as a high performance car should be. The silicone allows the water to gather in your caliper bores and corrode. Many people who have gone silicone are surprised to find corrosion, "I thought silcone didn't absorb water?" they say. They are right, it does not absorb water, but moisture will still enter the system and find its way to the lowest point in your brake system. Good old DOT 4 holds the water in suspension to be flushed away.....
Use a brand name high temp DOT 4 fluid for the street. Racing fluid is made to be changed often as racers do. Regardless, something like an SPF is worth a brake flush every three years or more often.
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This is very true. Silicone is hydrophobic, and glycol is hydrophylic. Water is also heavier than most glycol brake fluid. So all the water ends up in the caliper. Once there, under hard use it heats up and turns to steam. Then you lose your brakes.
You cannot mix silicone and glycole - they clot.
silicone fluids tend to be a bit mushy, too. Not sure why that is, but they appear to be slightly compressable. I never noticed it on my Harley, and I'v never used it in a car.
The only differance between 3 and 4 is the dry boiling point. Once they get "wet", they're pretty close to the same. For street use, 3 or for will work fine. For track use, step up to a high temp fluid like Wilwood or Motul.
About the only advantage to silicone is that it won't eat paint as quickly as glycol. If you're building a show car, 5 might be a good choice. If you do use 5, make sure you flush it regularly. My Harley's got fresh fluid every year.