Landracing Forum
Tech Information => Technical Discussion => Topic started by: Saltfever on October 01, 2013, 02:35:58 PM
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I want to move my master cylinders inside the cockpit. Does anybody know of a non-flammable brake fluid?
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Saltfever, I don't think anyone makes a non -flammable brake fluid for racing. The best I have found was the AP PRF 660 which has a higher boiling point and is mainly used on carbon on carbon brakes. One big thing to keep in mind when you use it is it cant be mixed with other types of brake fluid and the system needs to be thoroughly flushed before using it. If you don't use the plastic cups (will melt very quickly) and stay with a good reservoir, (steel or aluminum) you should be fine. On the Firebird all the cylinders are inside the car mounted to pedal box and the reservoirs are remotely mounted inside the car also just above where the radio would sit.. Tony
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Mr Google *may* be your friend http://www.clearcoproducts.com/pdf/specialty/NP-dot-5-brake-fluid.pdf (http://www.clearcoproducts.com/pdf/specialty/NP-dot-5-brake-fluid.pdf) among other results. I've heard that silicone brake fluid can make for a spongy pedal since it's more compressible, but that's just "stuff overheard in the hall"
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I want to move my master cylinders inside the cockpit. Does anybody know of a non-flammable brake fluid?
Commercial aircraft since at least 1957 have used a fluid known as "skydrol".
It means all surfaces exposed to it need special primers. When we worked with it, we needed special
composition boots that wouldn't dissolve from the stuff.
Check it out, you most likely will not be happy with what you find.
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Welcome back Tony. I hope the new venture is going well. I’m looking forward to many more of your build postings. Also, you make an excellent point about avoiding plastic master cylinders and going with all metal construction. I’m starting to feel better about this.
Roy, one of the features listed in the DOT 5 silicone specification from the link you gave indicates the fluid is non-flammable. It also has a few mil and SAE specs which is somewhat of a reassurance.
Tanks, Roy and Tony for the reply and help.
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Commercial aircraft since at least 1957 have used a fluid known as "skydrol". . . . Check it out, you most likely will not be happy with what you find.
Ah yes, Tex, I remember that stuff well. Marine Air Wing . . . one of the most miserable fluids I ever worked with.
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Can't say I have ever heard of a brake fluid fire & I'm not aware of any race governing bodies addressing this issue. There are a mile of race cars with cylinders in the drivers compartment. :?
Sid.
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KBT, who ever heard of an antifreeze fire... :-o
Hopefully we all won't have to go to Skydrol... if the fire is bad enough to set your 3 oz of brake fluid on fire... that contribution to the fire is not going to make much difference.
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If the brake fluid worries you, tee off a nozzle from your fire system and have it aimed towards the interior reservoir. I have two nozzles at my feel and one aimed at my hands.
Of course this suggestion comes from a guy that sells fire systems! :)
BR
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Don't use skydrol, it will remove paint and anything plastic, a little spot on your finger and you rub your eye will make you wish you never bought it. Requires special seals as well. It's a nasty hydraulic fluid and used for aircraft systems.
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I'll be changing over to DOT-5. Thanks to all for the input.
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I'll be changing over to DOT-5. Thanks to all for the input.
DOT-5 did not work well for me at altitudes above 2500 feet.
I use DOT-3.
Don
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Wow, Salty . . that is interesting! DOT-5 is silicon based and is OEM on a few high end cars. I'm sure there are few Corvettes running around Denver and other high places. In addition it is not hygroscopic and will not absorb water. What is not to like about it?
Could you please expand a little more on the problems you had with it. Thanx.
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Saltfever, I would use the fluid with highest rating for boiling point. The majority of the brakes we use is for minor stopping, but when we do need them in an emergency the heat will be an issue and fluid will start to boil. I have heard from a very reliable source that in at least one emergency instance calipers have melted from the heat on the salt. Tony
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Hi Tony<
That link posted by Roy in reply #2 gives some good information.(thanks roygoodwin) Silicon has the highest boiling point I am aware of. Also, since silicon won't absorb water that "wet" boiling point is interesting! I wonder about that "wet" number.
from the link . . .DOT 5 Silicone Brake Fluid provides corrosion protection and lubrication of the brake system components. In addition, it has a higher dry boiling point (260C) and wet boiling point (180C) than conventional glycol-based brake fluids.
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Wow, Salty . . that is interesting! DOT-5 is silicon based and is OEM on a few high end cars. I'm sure there are few Corvettes running around Denver and other high places. In addition it is not hygroscopic and will not absorb water. What is not to like about it?
Could you please expand a little more on the problems you had with it. Thanx.
Saltfever, the DOT-5 made the pedal spongy at altitude.
A little research indicated that this is not uncommon.
I was just trying to save you some trouble, maybe your results will be better than mine.
Has anyone tried DOT-5.1?
Don (not Salty)
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Newer synthetic ester brake fluid DOT 3, 4, and 5.1 have higher boiling points now than they used to years ago. Some DOT 4 and 5.1 have higher boiling points than silicone DOT 5.
All brake fluid systems attract moisture. Synthetic ester brake fluid is made to absorb the moisture and not allow pooling until the absorption point is reached. Silicone fluid will not absorb moisture so pooling begins immediately with collection in low points. Water boils at 212 degrees slightly higher under pressure and slightly lower at altitude. All types of brake fluid needs to be flushed every two years to eliminate moisture.
The micro air bubbles in silicone fluid cause the spongy pedal feel and cannot be blead out.
Geo
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Thanks Don and Geo. I see that DOT 5.1 has the same or higher boiling temps as DOT-5.