Author |
Message |
Greg_e
| Posted on Wednesday, March 03, 2010 - 11:14 pm: |
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Tried the search and again nothing but blank pages... What are they thoughts on synthetic DOT3&4 rated brake fluid? I want to change the fluid in both ends and Valvoline 3&4 rated is on sale right now. Or should I just find regular DOT4 fluid and use the 3&4 in my car (which also needs a fluid change). |
Ulynut
| Posted on Thursday, March 04, 2010 - 06:08 am: |
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You can't go wrong with following the manufacturers recommendations. |
Kbaddict
| Posted on Thursday, March 04, 2010 - 12:56 pm: |
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I changed my Xb to a firebolt top triple back about 10 months ago and I had to use a different master cylinder. I've been using the valvoline 3&4 rated this whole time without a problem. |
Sloppy
| Posted on Thursday, March 04, 2010 - 01:07 pm: |
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DOT 3/4 complies with both standards. It will be fine. No reason to purchase anything different. I do NOT recommend DOT 3 in the front caliper if you enjoy being aggressive on the brakes - and that is spoken from experience! |
Greg_e
| Posted on Thursday, March 04, 2010 - 01:24 pm: |
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OK, since the Valvoline is on sale I'll probably go with it then. I was just concerned because the required rating is of course DOT4 and I had never used a mixed rating fluid like this before. Also it has been said that mixing DOT3 and DOT4 fluid is very bad as they can break each other down and or each requires a different rubber compound in the seals (might be true, might not). Since it has DOT4 in it now, there would be some leftover in the lines after the drain so I would never consider DOT3 in a bike. |
Sloppy
| Posted on Thursday, March 04, 2010 - 02:11 pm: |
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It's okay to mix, but only as a forward compatability. A DOT 3 system "should not" use a DOT 4 fluid. But a DOT 4 system "can" use a DOT 3 fluid. And you "can" mix them in a DOT 4 system. "Why" you ask? DOT 4's have an extra chemical in it (I forget what it is - it's been a few years since school) that allows for a higher "dry" boiling point temperatures. This extra chemical has not been tested on older, DOT 3, rubber systems so it "may" not be compatible with it. Likely it will be okay, but the manufacturer has never tested so they don't know. So why even use a DOT 3 fluid over a DOT 4. DOT 3's "typically" hold their boiling point properties over a longer period of time than DOT 4's. In other words, DOT 3's don't need to be changed out as frequently as a DOT 4. DOT 4's should be changed at least every 2 years, depending upon where you ride. I ride year round so I change mine out annually. |
Andymnelson
| Posted on Thursday, March 04, 2010 - 02:14 pm: |
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Typically 3 and 4 are roughly the same. The standard laid out is DOT rated need to have a dry boiling point of at least 401 degrees, and a wet boiling point of at least 284. DOT 4 is 446 and 311. DOT 5 is the one you don't want to mix, as it is silicone based rather than glycol based. So if it says 3 and 4...well that really just means it's 4! I believe that ALL DOT 4 brake fluids are also DOT3 compliant. Just make sure you get one that says 4 and you'll be good to go. |
Azxb9r
| Posted on Thursday, March 04, 2010 - 04:13 pm: |
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Typically 3 and 4 are roughly the same. The standard laid out is DOT rated need to have a dry boiling point of at least 401 degrees, and a wet boiling point of at least 284. DOT 4 is 446 and 311. DOT 5 is the one you don't want to mix, as it is silicone based rather than glycol based. So if it says 3 and 4...well that really just means it's 4! I believe that ALL DOT 4 brake fluids are also DOT3 compliant.
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Blake
| Posted on Thursday, March 04, 2010 - 05:43 pm: |
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Then there's the outrageously confusing DOT5.1. Whoever thought that was a good designation ought to be tortured a bit. |
Blake
| Posted on Thursday, March 04, 2010 - 05:44 pm: |
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Good google hit... http://www.afcoracing.com/tech_pages/fluid.shtml |