1. seabee

    seabee FABO Gold Member FABO Gold Member

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    Hi Gang. Going to be replacing the brake lines and flush/bleed the system and was wondering what are your thoughts on which Brake fluid and any pro tips? As always, thank you in advance.
     
  2. 69B-Cuda

    69B-Cuda Well-Known Member

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    I run dot 3 in my daily drivers... if it is going to sit over the winter, I wold put silicone fluid in it.
     
  3. dartman340ta

    dartman340ta Well-Known Member

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    simple dot 5 , run about a gt through it your good to go .
     
  4. 66fs

    66fs FABO Gold Member FABO Gold Member

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    DOT 5, won't absorb moisture and won't ruin that beautiful paint.
     
  5. slantsixdan

    slantsixdan =..=

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    I suggest not using silicone-based (DOT 5) fluid. Its non-hygroscopic nature (i.e., its not absorbing water) is not definitely a good thing. Moisture gets into the brake hydraulic system -- it will happen with normal usage and/or changes in ambient temperature and humidity. Ordinary brake fluid is designed to absorb and assimilate a fair amount of moisture without causing substantial corrosion problems. With silicone fluid, the water will accumulate in slugs at the lowest points of the system...and stay there, where it will aggressively corrode whatever it's touching. This is not an improvement.

    Furthermore, it is difficult to get all the air out of silicone brake fluid, so it is difficult to get a good, firm pedal.

    There is an enormous range of conventional non-silicone brake fluids on the market. You can get whatever properties you want (e.g., high boiling point) without having to go to a silicone-based fluid.

    And as if that weren't enough, the cost and effort difference between regular and silicone fluid is such that you can flush the system with conventional fluid every two years or so (which is about the right interval) for a long time before you equal the cost of just one silicone fluid changeover.

    Shop carefully. All silicone fluid is "DOT 5". The highest spec category for non-silicone fluids is "DOT 5.1".

    DOT 3 (original fill), DOT 4, and DOT 5.1 fluids are all intermixable.

    DOT 5 (silicone fluid) cannot be mixed with DOT 3, 4, or 5.1.

    Really, it is not necessary to spend big money on exotic brake fluids. Use a good brand of DOT 3 or DOT 4 (I have tended to use Castrol LMA DOT 4 when I can find it) and flush the system every two years and you'll be in fine shape.
     
  6. dustermaniac

    dustermaniac Senior Member

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    Sorry if I am hijacking this thread and I do not mean to but I have a question regarding brake fluid. Is there any difference in brake fluids in regards to heat generated by the braking system? My car does not have any brake fluid leaking but I notice if I take the car on a long trip that when I get back I notice that sometimes it almost seems as though the brake fluid is evaporating or maybe burning off? because my Master Cylinder is down a little on the front fluid side. The lines and Master and rotors and pads drums and rear wheel cylinders are all recently replaced and like I said there appears to be no leaking when the car is parked. Is there any brake fluid that stands up better under high temperatures? Dot 3, 4, 5, 5.1??????
     
  7. 66fs

    66fs FABO Gold Member FABO Gold Member

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    Having 4 "A" bodys with silicone DOT 5 brake fluid I have yet to see any of the problems outlined above. The non-hygroscopic nature (i.e., its not absorbing water) does just the opposite of what you conclude above. I had to check when I had Stainless Steel rebuild the KH calipers on the 68 Barracuda and they were done in 1992, still no problems. As for the difficulty getting all the air out of silicone brake fluid, "so it is difficult to get a good, firm pedal", all 4 cars are manual disc brakes, 2 KH and 2 73 up BBP systems, all have rock solid pedals. As always, one should do your homework, and make your own decisions. There is a lot of misinformation out there as well as pluses and minuses. Use what works best for your intended usage.
     
  8. 66fs

    66fs FABO Gold Member FABO Gold Member

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    I doubt the fluid is evaporating or maybe burning off. If you can not see any seeping out of the top cover or anywhere else I'd suspect the master cylinder. Was it New or rebuilt?
     
  9. oneway71

    oneway71 Well-Known Member

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    I just had a brake class at the local college and the instructors and book suggested not using DOT 5 for the reasons that /6dan stated above. They even stated that the MFG's are going away from it.

    I personally have no experience with it; I justed wanted to let you know what is being taught at the college level.
     
  10. 66fs

    66fs FABO Gold Member FABO Gold Member

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    The problem is we typically split hairs. There is no right or wrong answer on many questions. I have cars with both types. All High milage and up to 18 years of flawless service on either. Manufacturers have not used DOT 5 that I am aware of. It was originally developed for the Military. I made my decision to use it when I completely do a brake system and am starting from scratch and will continue to do so.
     
  11. davescuda

    davescuda FABO Gold Member FABO Gold Member

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    i been using dot 5 for 10 years plus. never had a problem. i switch to dot 5 because i was using dot 3 and my master cylinder leaked out the rear seal and pealed all my paint off my fire wall, around and under my master cylinder. what a mess. i will never use dot 3 again. i have 5 a bodies all dot 5
     
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