brake oil kz650

Hello All,

I just bought a brake repair kit for my kz650B1 from 77.
I was wondering what type of brake oil I should buy. Does it matter, or can I just use any kind?

Take care,

Jan
Brussels

Dot 3 is the recommended fluid, but if you want to do some reading here are a couple articles.

Wikipedia

How Stuff Works

Fluid Debate

I think they write these articles to confuse us,,, :laugh: :laugh: :laugh:
Ride safe

DOT-3 works perfectly fine for street use and is the recommended brake fluid. DOT-4 also works and is compatible with DOT-3. DOT-5 is not recommended as it is not compatible with DOT-3 or DOT 4 and, because it is not hygroscopic, moisture entering the brake system tends to "puddle" at the bottom of the system (in the calipers) and cause corrosion. Which ever (3 or 4) fluid you buy, get a name brand and get it at a high volume auto supply store. That way you don't need to worry about it having sat on a shelf for years absorbing moisture. Also, for the same reason, don't use fluid that's been opened before sitting in your garage. Plan on changing fluid every 2 years and your brake system will stay like new, but buy fresh fluid each time. Ed

650ed wrote:

DOT-3 works perfectly fine for street use and is the recommended brake fluid. DOT-4 also works and is compatible with DOT-3. DOT-5 is not recommended as it is not compatible with DOT-3 or DOT 4 and, because it is not hygroscopic, moisture entering the brake system tends to "puddle" at the bottom of the system (in the calipers) and cause corrosion. Which ever (3 or 4) fluid you buy, get a name brand and get it at a high volume auto supply store. That way you don't need to worry about it having sat on a shelf for years absorbing moisture. Also, for the same reason, don't use fluid that's been opened before sitting in your garage. Plan on changing fluid every 2 years and your brake system will stay like new, but buy fresh fluid each time. Ed

I use dot 5 and have had great results with it, you do need to clean the system out first ,dot 5 does not absorb water and it will not eat your paint if you spill it, a friend put it in his bike about 4 years ago,and has never had any issues

Regardless of type brake fluid, I was happy to learn that "flushing" the brakes to re-new the same type fluid does not itself require bleeding air from the system.

Just suck "most" of the old fluid from the reservoir without exposing the ports, add fresh fluid, and use the caliper bleed valve in the normal manner to pump fresh fluid through the system. Repeat if necessary to assure new fluid expelled from caliper bleed valve.

Don't allow the reservoir to become empty on pain of incurring a real air bleed necessity.

Maybe everybody else in the world but me already knew this before -- but I had been hesitant to do routine brake fluid flushing because of erroneously believing the lines had to be completely drained before adding new fluid with attendant pita air bleeding procedure.

Cheers!

Post edited by: Patton, at: 2007/09/23 13:51

"a friend put it in his bike about 4 years ago, and has never had any issues"

The issue is that because DOT-5 fluid does not absorb water the water that enters the brake system collects at the lowest point in the brake system (water being heavier than brake fluid) rather than simply being absorbed evenly within the brake fluid (this in unavoidable unless you live in a climate with 0% humidity). As a result, the higher concentration of water in these areas can lead to corrosion, and you are unlikely to notice this until the damage is done. DOT 3 & 4 fluid absorb the water evenly throughout the fluid so there is no single place in the system with a high concentration of water. Racers like DOT 5 because of the higher boiling point (not an issue on a street bike with stock brake systems) but real race bikes have the fluid changed much more frequently than street bikes so puddling is much less of an issue. I've been using DOT-3 in my '77 KZ650 for 30 years, changing fluid every 2 years, with no problems at all, and I've been known to run my bike pretty hard through the twistys with no brake fade. I suspect the above facts are part of the reason manufacturers don't recommend DOT 5. I agree that DOT-5 is less harmful to paint, but why would anyone put brake fluid on paint anyway? I'm glad your friend has had luck with DOT 5, and I hope you do as well, but having used DOT 3 in the same bike for 30+ years has made a believer out of me. Ed

So, with Dot5 fluid just flushing the system out wouldn't remove the water because it would sit at the bottom of the caliper, or whatever the lowest point is in the system. You would either have to disassemble the caliper or at least remove it and turn it upside down to get the water out. Am I correct on this???
Ride safe

Just for info, I put dot5 in all my bikes a long, long time ago. Like around 1985 and my brakes work just fine. Never a problem, and I'm kind of shameful in my change interval, which is never.

"So, with Dot5 fluid just flushing the system out wouldn't remove the water...."

That's a good question. I don't know if that would be a problem as flushing the fluid out might push any water with it, but you're right, depending on the internal shape of the caliper and the method of flushing, there could be a pocket of water left behind. It seems to me that using DOT 3 or 4 eliminates that risk. Other than the fact that DOT 5 is less damaging if spilled on paint, I don't see any practical advantage to it that offsets the potential problems. Ed

650ed wrote:

"So, with Dot5 fluid just flushing the system out wouldn't remove the water...."

That's a good question. I don't know if that would be a problem as flushing the fluid out might push any water with it, but you're right, depending on the internal shape of the caliper and the method of flushing, there could be a pocket of water left behind. It seems to me that using DOT 3 or 4 eliminates that risk. Other than the fact that DOT 5 is less damaging if spilled on paint, I don't see any practical advantage to it that offsets the potential problems. Ed

The dot 5 does not absorb water so how are you going to get it in the system,
I have taken apart a front brake caliper that had dot 5 in it and it was as clean as it was when rebuilt, no rust no trash.

I had Dot 5 put in my front and back systems in the 80s.
My bike sat stored for all of the 90s (10+ years) and in 2004, when she came out of storage, my brakes still worked great, and never siezed or anything.

I have since rebuilt the rear (just cleaning and new seals), adding a GSXR master cylinder and resevoir, as that is what the GSXR system uses.

"The dot 5 does not absorb water so how are you going to get it in the system"

Condensation. The screw-on brake reservoir caps are not air tight. In fact, they are deliberately vented. Take a look at the threads inside the caps and (assuming your caps are like mine) you will find a channel cut perpendicularly through the threads that permits air to be exchanged between the reservoir and the atmosphere. I don't know if the later rectanglular type reservoirs are vented or not. I found that the round ones are vented when I built a pressure bleeder adapter for my bike. I had to plug the vent in my home-made adapter to get the reservoir to hold pressure. By the way, I've never had to rebuild or replace seals in any of my brake components. Ed