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techtalk:ref:wheels03 [2020/05/29 02:51]
hippysmack [Mixing Brake Fluids]
techtalk:ref:wheels03 [2020/05/29 02:54]
hippysmack [DOT 5]
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   * The change to Dot 5 brake fluid was made with HD production motorcycles in September of 1976 ((HD Service Letter M-28)). It is of silicone chemistry and not being water miscible, it must rely on the silicone (with some corrosion inhibitors) as a barrier film to control corrosion. Water is not absorbed by silicone as in the case of DOT 3-4-5.1 fluids, and will remain as a separate globule sinking to the lowest point in the brake system, since it is more dense. ((http://​importnut.net/​brakefluid.htm))   * The change to Dot 5 brake fluid was made with HD production motorcycles in September of 1976 ((HD Service Letter M-28)). It is of silicone chemistry and not being water miscible, it must rely on the silicone (with some corrosion inhibitors) as a barrier film to control corrosion. Water is not absorbed by silicone as in the case of DOT 3-4-5.1 fluids, and will remain as a separate globule sinking to the lowest point in the brake system, since it is more dense. ((http://​importnut.net/​brakefluid.htm))
   * When using Dot 3 brake fluid, the brake system should be drained, flushed, and refilled with new brake fluid every year to eliminate any contamination such as sludge. This yearly service was eliminated when D.O.T.-5 silicone fluid was used instead and with improved performance. ((HD Service Bulletin #M712 dated June 16, 1977 pg 1))   * When using Dot 3 brake fluid, the brake system should be drained, flushed, and refilled with new brake fluid every year to eliminate any contamination such as sludge. This yearly service was eliminated when D.O.T.-5 silicone fluid was used instead and with improved performance. ((HD Service Bulletin #M712 dated June 16, 1977 pg 1))
-  * Silicone brake fluid reduces corrosion, will not degrade the "​rubber"​ components, and sludge will not form in the system. It will not absorb water, does not attack painted parts, and has a higher boiling point than conventional brake fluid. When stored under normal conditions it has unlimited shelf life. However, it is somewhat harder to bleed brakes with Dot 5 because of its viscosity. ((HD Service Bulletin #M712 dated June 16, 1977 pg 1))+  * HD changed to DOT 5 brake fluid in production models in September of 1976. \\ Silicone brake fluid reduces corrosion, will not degrade the "​rubber"​ components, and sludge will not form in the system. It will not absorb water, does not attack painted parts, and has a higher boiling point than conventional brake fluid. When stored under normal conditions it has unlimited shelf life. However, it is somewhat harder to bleed brakes with Dot 5 because of its viscosity. ((HD Service Bulletin #M712 dated June 16, 1977 pg 1))
   *  Dot 5 in its pure state offers a higher boiling point (500F) however if water got into the system, and a big globule found its way into a caliper, the water would start to boil at 212F causing a vapor lock condition (possible brake failure). DOT 3 fluid with 3% water content would still exhibit a boiling point of 300F. Silicone fluids also exhibit a 3 times greater propensity to dissolve air and other gasses which can lead to a "​spongy pedal" and reduced braking at high altitudes. ((http://​importnut.net/​brakefluid.htm))   *  Dot 5 in its pure state offers a higher boiling point (500F) however if water got into the system, and a big globule found its way into a caliper, the water would start to boil at 212F causing a vapor lock condition (possible brake failure). DOT 3 fluid with 3% water content would still exhibit a boiling point of 300F. Silicone fluids also exhibit a 3 times greater propensity to dissolve air and other gasses which can lead to a "​spongy pedal" and reduced braking at high altitudes. ((http://​importnut.net/​brakefluid.htm))