Brake Fluid

Over the winter I plan on replacing my brake lines. MC and calipers are in good shape but I want braided brake lines. This brings up the subject of brake fluid. Has the DOT 5 fluid in a DOT 3/4 system argument ever been settled? Would I be better off with a Super DOT 4 or does anyone know where to get DOT 5.1? I have never seen it here in Vermont. (Lots of other things I read about I've never seen here either)

There's nothing wrong with using DOT 5 in your system but NEVER mix DOT 3 or 4 with 5. What happens is when the two types mix they form a concoction that will eat away all the rubber components in your brake system very quickly. :ohmy:

I wouldn't recommend using DOT 5 unless you have totally rebuilt your brake system with new rubber parts that have never been exposed to DOT 3 or 4 fluid. Of course, most people who know will recommend purging the system with alcohol to ensure the old fluid is completely gone before adding the DOT 5, there's nothing wrong with that either but I'm not one to take ANY risks with my brake system.

Now days there are some good DOT 4 fluids with boiling points at or above (in some cases way above) DOT 5 specs.. I'd say look around for this stuff and save yourself the time and the mess of switching to DOT 5.

I'm using Valvoline's super DOT 4 (says Valvoline ABS on the label and comes in the gold container) in my system with excellent results. The boiloing point is at 480 F so it's performance easily rivals that of DOT 5.

I'd say the super DOT 4's are the way to go if you availability is an issue.. like if you ever need fluid while on the road and there's no DOT 5 for sale anywhere near whar you are.

I would have to agree on all points Wicked_Kz has mentioned, particularly, the availability of Dot 5.
You may just want to top up the MC, yet, if it ain't available you can't.

Dot 5 has been out now for at least 6 years, I can't understand why it is not readily available. Must be something we don't know about it! Castneogenic or terrorist friendly?

Regardz

Post edited by: Garn, at: 2005/12/10 16:46

DOT 5 brake fluid has been around since at least 1979, as I converted a 77 KZ1000 to DOT 5 back then

The biggest advantage to DOT 5 is that it's not hygroscopic, it don't absorb moisture like DOT 3 does, so it does not cause corrosion to the brake system.

When was the last time you saw brake fluid boil while riding on the street?

Well, I replaced the original fluid with DOT 5 about 2 or 3 decades ago, I guess it had just come out on ther market. No one knew about not mixing DOT 3 and DOT 5, so we just kept adding it until all the DOT 3 was out of the system as far as we could determine. Then all the maintenance I did after that was bleed and add more fluid whenever I changed brake pads. Then the bike sat under a tarp for 16 years. Guess what. The fluid was crystal clear when I got the bike running again, but naturally I bled since I put new pads on along with having the other necessary repairs performed. Aside from pads, everything else is still the original brake system that came on the bike when I bought it in March of 1973. It still works fine.

Garn wrote:

Dot 5 has been out now for at least 6 years, I can't understand why it not readily available. Must be something we don't know about it! Castneogenic or terrorist friendly?

Wow! 2 odd decades! I still can't see why it has not become more readily available? Is it in all new (2005) motorcycles now? Do they use it in race circles?
Regardz.

Post edited by: KZ_Rage, at: 2006/05/16 12:09

As long as the temp is above 32F and the roads aren't covered with snow or ice the bike gets ridden. The PO replaced the caliper with an OEM one for a reason unknown to me. The master cylinder has been inspected by my local dealer and given a clean bill of health. My reason for wanting to replace the brake line is I believe what is on it is original equipment, it looks pretty ratty, and I have heard the the SS lines give a much better feel to the front brake. Before I started riding the bike the fluid was flushed and then it was flushed again last spring. For the little it costs I think flushing every year is cheap peace of mind. It sounds like there is not great benefit to DOT 5 so I will stick with DOT 4. Thanks greatly to all those who responded. I love this forum!

weve been using dot5 since the early 80s it was really pricey when it came out thats why most people never used it.i dont know much about the scientific stuff all i know is it doesnt seem to have the moisture problems,and i know it doesnt hurt paint!ive used this in many very fast hotrods and bikes,i use it in all of our dumptrucks that we use to pull 20,000 pound backhoes and we have NEVER had brake fade problems even pulling this kind of weight,im not sure about temps but i bet our c-60s,c-70s get a lot hotter than any aluminum brake caliper could handle!the dot5 i use is purple i just top off the system and keep bleeding the brakes till it starts coming out purple with no clear stuff in it.i buy mine at advance auto parts in omaha they usually have small bottles in stock,but can order gallon size jugs for me!hope this helps,happy wrenching!