DOT Brake Fluid

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I will be flushing the Brake fluid in my 1991 Ford Bronco soon and I wanted to use a fluid with a higher boiling point then DOT 3. While looking up Brake fluid I found mention of a DOT 5.1 fluid. I know that DOT 5 is silicone based and is not compatible with any other DOT brake fluid. I was planning on just going with DOT 4 but Everything that I can find says that DOT 5.1 is glycol-based so putting that in my system is no big deal. And I don't have a ABS system so I have no need for DOT 4 LV. I'm now wondering about DOT 5.1 and I'm wondering if their are any things I should worry about before switching? If nobody has any experience with this I'm happy to be the Guinea pig.
 
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Just for fun I pushed my brakes with hi speed stops I would never make then measured the rotor temperatures, they came in at 200F 210F, lower then I thought, with normal stop and goe driving, I was down to 160F! The bigger issue is regular brake fluid changes since the fluid is very hydroscopic and wants to suck moisture out of the air and corrode the lines and calipers from the inside. For years on older car brake jobs, I saw lots of corrosion pitting in wheel cylinder bores and black crud that was actually rubber piston ring material that wore off and went into the fluid! So old fluid is capable of corrosion damage even when not immediately exposed to air! Very old brake fluid is often black and may even have visible metallic bits in it! The boiling point is something that's far less of a problem then scaremonger suppliers want you to believe!
 

blupupher

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Yup, DOT5.1 came out partially for the compatibility with older fluids. Kind of a waste as a top off fluid, but since you are doing a flush, 5.1 is a great choice. It is what I am putting in my bike's clutch and brake fluid when I flush it.
 
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Originally Posted By: i_hate_autofraud
Just for fun I pushed my brakes with hi speed stops I would never make then measured the rotor temperatures, they came in at 200F 210F, lower then I thought, with normal stop and goe driving, I was down to 160F! The bigger issue is regular brake fluid changes since the fluid is very hydroscopic and wants to suck moisture out of the air and corrode the lines and calipers from the inside. For years on older car brake jobs, I saw lots of corrosion pitting in wheel cylinder bores and black crud that was actually rubber piston ring material that wore off and went into the fluid! So old fluid is capable of corrosion damage even when not immediately exposed to air! Very old brake fluid is often black and may even have visible metallic bits in it! The boiling point is something that's far less of a problem then scaremonger suppliers want you to believe!
For Dot 4, it's more hydroscopic than regular Dot 3. Most manufacturers that use it recommended 2 or 3 year brake flushes. You can go for much longer on Dot 3 without changing it. Not sure if 5.1 is worse. You don't really need a fluid with a high boiling temperature if you're not going to get it up to that temperature.
 
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Why do you think DOT-3 offers insufficient boiling point for a 1991 Ford Bronco? Do you use it for extreme applications?
 

Skitter302

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Originally Posted By: ArcticDriver
Why do you think DOT-3 offers insufficient boiling point for a 1991 Ford Bronco? Do you use it for extreme applications?
Correct, My use is above normal and is very performance related. No proof if I exceed DOT3 Specs but I want to upgread and just wanted to confirm flud compatibility before I gel'd up my system.
 

Skitter302

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Originally Posted By: slacktide_bitog
You can use DOT 5.1 with no worries smile I use it in my car.
Thanks for the Feed Back!
 
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Originally Posted By: Skitter302
Originally Posted By: ArcticDriver
Why do you think DOT-3 offers insufficient boiling point for a 1991 Ford Bronco? Do you use it for extreme applications?
Correct, My use is above normal and is very performance related. No proof if I exceed DOT3 Specs but I want to upgread and just wanted to confirm flud compatibility before I gel'd up my system.
Understandable. grin
 
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Originally Posted By: demarpaint
So there's no benefit in using a Dot 4 brake fluid in a Dot 3 application?
There are benefits and drawbacks. Higher boiling point, but more hydroscopic than Dot 3. Cost is higher and needs more frequent flushing. So if you need it, be prepared to pay for it.
 

Skitter302

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Originally Posted By: Wolf359
... There are benefits and drawbacks. Higher boiling point, but more hydroscopic than Dot 3. Cost is higher and needs more frequent flushing. So if you need it, be prepared to pay for it.
I'd use DOT 4 but they don't sell the good blue stuff any more and all I can find is TYP200.
 
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Originally Posted By: Wolf359
Originally Posted By: demarpaint
So there's no benefit in using a Dot 4 brake fluid in a Dot 3 application?
There are benefits and drawbacks. Higher boiling point, but more hydroscopic than Dot 3. Cost is higher and needs more frequent flushing. So if you need it, be prepared to pay for it.
I was planning on changing the brake fluid in my Jeep it was done two years ago this month. I need front brakes, and a tire rotation so the timing is perfect. I saw it on sale somewhere for about $1 a quart more than the DOT 3 fluid. I can't see myself letting it go past three years. The plus I thought was a slightly higher boiling point of the fluid, now I'm second guessing myself.
 
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