Brake fluid

watchman

watchman

Club Member
Anyone in here got an 03 vrod and know what brake fluid harley used back then on the front for the 4 piston calipers too many variations come up on google and i am using a set of the calipers on my build 🤔🤷🏻‍♂️
 
If it was me and a fresh clean system, I'd go with 5 and then have no risk to your finishes. I don't think fluid is seal specific, but happy to learn differently. I like the idea that 5 isn't hydroscopic.
 
continually being told how Brake fluid is Hydroscopic { like its some kind of weird wizardry or witchcraft}
and that it easily becomes ineffective with water contamination. this may be so , but how is any water going to get into a completely sealed system anyway, its not open to atmosphere !
a warning light just came up on my car saying brake fluid change required, because of either mileage or a period of two years. Why no contaminents or moisture has got in there. B.M.W quoted me £400 to change the fluid . I replied with ive never changed fluid just for the sake of it on any other car ive ever had before, I think its just a main dealer scam whether H.D or any other make
 
My 1980 Sportster came new with Dot 5 brake fluid. I was told by the supplying dealer, Oxford Motorcycle Engineers not to mix 5 with other fluids as it could damage seals.
 
Ron said:
My 1980 Sportster came new with Dot 5 brake fluid. I was told by the supplying dealer, Oxford Motorcycle Engineers not to mix 5 with other fluids as it could damage seals.
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Dot 5 is Silicone based, Dot 3, 4 and 5.1 are Glycol based fluids. Mixing Dot 5 with any of the others will not only damage the seals it turns the Fluid into a Mush. Any second hand Caliper or Master Cylinder, if it is not known what fluid was being used, should be stripped completely and the seals replaced before use. Dot 5 usually has a Purple colour to the Fluid, the others tend to be Yellow.
As said elsewhere, Dot 5 does not harm paintwork and, handily, can be used to polish paintwork, chrome, cables and tyres. :encouragement:
Dot 3, 4, and 5.1 can be mixed with each other.
 
Spice said:
continually being told how Brake fluid is Hydroscopic { like its some kind of weird wizardry or witchcraft}
and that it easily becomes ineffective with water contamination. this may be so , but how is any water going to get into a completely sealed system anyway, its not open to atmosphere !
a warning light just came up on my car saying brake fluid change required, because of either mileage or a period of two years. Why no contaminents or moisture has got in there. B.M.W quoted me £400 to change the fluid . I replied with ive never changed fluid just for the sake of it on any other car ive ever had before, I think its just a main dealer scam whether H.D or any other make
Click to expand...
Not sure if Harleys have a totally sealed Brake System but Cars usually have a breather hole in the Master Cylinder Cap where moisture gets into the Brake Fluid.
 
There is a hole in the master cylinder lid but there is a membrane gasket ( if that's the correct name) under it so the fluid is sealed from the atmosphere.
 
Ron said:
There is a hole in the master cylinder lid but there is a membrane gasket ( if that's the correct name) under it so the fluid is sealed from the atmosphere.
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Sealed until you take the cap off to refill or check. I’ve used 5 in some of my old brits just to protect the finishes if leaks happen.
 
I have never understood why Dot 5 Brake Fluid was not used more by Car and Bike manufacturers. Dot 5 has a higher boiling point than the Glycol based Fluids. It doesn't absorb water so lasts indefinitely. It doesn't harm paintwork, Chrome etc. It is not that much more expensive than the alternatives. Seems strange to me. scratch_head
 
"Silicone fluid doesn't have or need glycol fluid's visual mechanism for tracking moisture pollution; i.e. it doesn't darken."
Almost, it goes from purple to brown PDQ.
The two do NOT mix, I had terrible problems with corrosion in the front master cylinder due to the PO being an idiot, the alloy parts grew crystals which jammed the piston and caliper.
The seals are not bothered what the fluid is, as long as they have not been soaked in the wrong one first.
This is some of the stuff that came out and emphasizes the lack of compatibility.

IMG_2998.jpg
 
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