Swelling in master cylinders could be more of a problem and in some cases brake lock-ups from stuck master cylinders have been reported. DOT-5 fluid is being used in more new cars every year. In these cars, the non-metallic and rubber parts are formulated and manufactured specifically for use with DOT 5 fluid. From actual hydraulic performance characteristics including the boiling point, DOT 3, DOT 4 and DOT 5 are all satisfactory for normal passenger car and light truck use.
The difference is D OT All polyethylene glycol fluids including 5. Basically, DOT Think of DOT So where do we go from here? These incompatibility issues can be hard to predict, observe and detect. In some cases discoloration of the purple appearing DOT 5 fluid can indicate deterioration or contamination. The safest bet for vintage cars at this writing seems to be DOT-4 LMA low moisture activity its formulation is consistent with vintage rubber parts and professes to absorb less moisture than our old reliable DOT 3.
These substances were used prior to brake fluid regulations were established, and the DOT 2 standard provides for oil-based brake fluid. Glycol-based brake fluids were the next to appear, and the DOT 3, 4, and 5. In the United States, these three basic types of brake fluid are broken down further based on a number of specifications that are dictated by the US Department of Transportation. It has the lowest wet and dry boiling points of all the brake fluids.
DOT 3, 4, and 5. The correct type of brake fluid is typically indicated on the reservoir or cap. The boiling points of these fluids varies, with DOT 5. The viscosity of glycol-based brake fluids follows the same pattern, with DOT 5.
All glycol-based brake fluids are somewhat hygroscopic, which means that they tend to absorb water from the atmosphere. It also has a higher boiling point than either DOT 3 or 4 fluid, and the same viscosity and boiling point as DOT 5 fluid. Although DOT 5 brake fluid has a number of positive factors going for it, its compressibility can suffer if it absorbs too much air. In some cases, repeated bleeding can remove more air as it works its way out of solution. Brake fluid works by transmitting hydraulic pressure from a brake master cylinder to slave cylinders that are located at each wheel.
When a brake pedal is pressed, it actuates a master cylinder push rod, which may or may not be assisted by a power brake booster. This push rod then causes the brake master cylinder to generate hydraulic pressure, which is transmitted through a closed system via metal brake lines. Brake fluid transmits hydraulic pressure from a master cylinder to multiple slave cylinders.
In drum brakes, the hydraulic pressure generated by the master cylinder causes wheel cylinders to push brake shoes against brake drums. In disc brakes, the pressure is used by brake calipers to pinch brake discs between brake pads. In order to perform this function, brake fluid has to possess a number of vital characteristics, including:.
Ive been reading and other than dot 5 they all seem to be interchangeable to an extent, the extent being that it will lower the grade of say dot 5. If im wrong please tell me but Ive come to the understanding that it wont affect my brakes if I were to change over to 5. Why complicate matters? Scruffy West Tennessee. If you want to use 5 instead of old fashioned 3 or 4, flush the system with denatured alcohol, then add the 5 and bleed as normal. Dot 5 silicone is great for normal motoring, not for track use.
Does not work well with ABS or servo boosters. Dot 5. Some older rubber parts , made for Dot 3, do not tolerate Dot 4 or 5.
If your changing everything don't worry. DOT 5. DOT 3, 4, 5. Yea I learned that, replaced brakes with 5. Please dont misunderstand Iwas never considering using dot 5 I was talking about 4 and 5. When the DOT rating refers to dry boiling point it means brand new brake fluid right out of the container.
Brake fluid becomes wet when it's been in the lines for a while and has managed to absorb 3. It takes about two years for any DOT brake fluid to reach the point where it has absorbed that much water. At that point you are going to want to have it replaced by way of a brake fluid flush. If you allow your brake fluid to continue absorbing water beyond 3.
The lower the boiling point of your brake fluid, the less effective it will be. Boiling brake fluid creates air pockets which diminish or completely eliminate the ability of your brakes to actually stop your car from moving. If it gets bad enough, you'll find that you are unable to stop in an emergency which could lead to some serious accidents and even death. That's why knowing the DOT rating of your brake fluid is important, as well as knowing when it was changed last and when it needs to be changed again.
As we have seen, DOT 5 brake fluid has one of the highest boiling points of all the fluids available. DOT 5 brake fluid is a silicon-based fluid. This was developed to be used in cars where moisture was definitely going to be prevalent and unavoidable. That means things like high performance vehicles and military vehicles. It has a very high boiling point, but it also has more compressibility than the glycol ether-based fluids. You can usually tell DOT5 brake fluid at a glance because it will be a purple colour unlike the other brake fluids.
The advantage of the silicon based DOT5 fluid is that it absorbs no moisture whatsoever, unlike the glycol-based fluids. Because it is also chemically inert it won't react with other chemicals in your braking system, nor will it even react to your car's paint which the glycol-based fluids will.
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