Brake Fluid Contamination

[bc45]

You can get brake fluid test strips at auto parts store. There are 2 types one that mesures moister content and one that mesures copper content. You just dip it in and the tip changes color and you match it up on the guide on the bottle. There is also electronic testers that messure the moister content but cost a lot more. But like others have said you should change it every 2 years.

 

[kemo]

You must also remember that the moisture in DOT 5 doesn't mix with the brake fluid, it settles at the lowest point which would be the calipers. You can mix DOT 3 & 4 but do not mix anything with DOT 5
kemo

 

[Crocker]

I would like to add that when you flush your fluid also change out the cover and gasket , the composite that the covers are made from do not hold up well over time ,on my 07 and 08 HDs all covers and gaskets have been changed , It would seem that the covers is where the point of entry for mosture is occuring,the fluid and vapors eat the stock covers up fast. I would assume though if I maintaned the torque requirements on the covers more often this would not happen .

 

[bobwire]

i don't think you can mix 3 and 4, 4 will soften brake lines designed only for dot 3.............bw

ignore my previous post, i got my #s backward. it should be dot 3 will soften brake lines designed for dot 4.....................bw

 

[TQuentin1]

I would like to add that when you flush your fluid also change out the cover and gasket , the composite that the covers are made from do not hold up well over time ,on my 07 and 08 HDs all covers and gaskets have been changed , It would seem that the covers is where the point of entry for mosture is occuring,the fluid and vapors eat the stock covers up fast. I would assume though if I maintaned the torque requirements on the covers more often this would not happen .

Remember Boyle's Law. Air HAS to be able to get into the system to allow the fluid to go down as the pads wear and more fluid is required out in the caliper and lines. So you do NOT want your reservoirs to be completely air tight. Unfortunately, this "breathing" of the reservoirs means that humidity WILL get into your reservoir and be absorbed by your brake fluid if it is hydroscopic. So. Flush and bleed your brake system at the beginning of every season!!

TQ

 

[Hoople]

Man-O-Man,,, I just realized I have not done anything to the brakes on my cage in over 5 years. Not Good!... Purchased it in 2005 so flushing the system is now the next thing to do! ASAP

The bike just turned 15 months old so that is coming soon.

 

[kemo]

I just Googled DOT 3 & 4 and you can mix them. I just wanted to comfirm what I had stated. YOU CAN NOT MIX DOT 5 with anything else.
kemo

 

[dhorne]

I believe you can mix 3 , 4 and 5.1 they are compatable but do not mix Dot 5 with any of them

 

[NEWHD74FAN]

What Smitty & Kemo said is true...Ethylene Glycol based Dot 3, 4 & 5.1 are compatible, and yes will attack paint. The number relates only to the boiling point temperature...the DOT 3 was for old drum brakes (remember those?), DOT 4 & 5.1 came later as disc brake fluid temperatures began to soar as more swept area and need to prevent overheating came to pass.

DOT 5 is silicone based not compatible with any other type fluid and has no substitute. It does not mix with moisture, in fact it allows the water to settle where it can do damage, though it will not harm paint, Being inert it contaminates by not mixing with anything (kinda like Teflon) and really does not degrade in the environment par se' just lets all contaminents float around in that slurry. Haven't really figured out how to get rid of it other than bottling it and putting with hazardous waste collection...do not put in storm drains or trash!

 

[bobwire]

kemo, i may have been misunderstood. what i meant to say was dot 3 will degrade some brake lines. maybe hd has lines that handle eather one. that's not universal though, i paid the price on a car (m-b) that i had..............bw