Brake and clutch fluid

[VegasDan]

Just wanted to post something I couldn’t find on the forum
Awhile back I posted I was getting less clutch lever once the bike warmed up
I had removed the aftermarket levers that I bought the bike with and installed the factory levers
I thought there was something wrong with the factory clutch lever
I reinstalled the aftermarket lever as it would adjust further out than the oem
No one told me that old fluid especially old fluid with condensation in it would cause the brake or clutch to have less pressure once the fluid warmed up
I read the boiling point changes
So I flushed out the old and in with the new
I had to reinstall the factory levers it changed the pressure back to normal and now the aftermarket clutch lever is too far out even on the closest setting; what a difference
Change your brake and clutch fluid every two years
I had no idea that it really made that much of a difference
You can ruin your gears if you don’t, especially down shifting with old fluid
I’m just saying lol

 

[DreamV4]

This is interesting. I didn't know brake fluid could boil.

 

[Pighuntingpuppy]

This is interesting. I didn't know brake fluid could boil.

DOT 3 vs DOT 4 vs DOT 5

DOT 3 is first on the list and it is a poly glycol-based fluid. The minimum dry boiling point for DOT 3 fluid is 401-degrees Fahrenheit and it has a minimum wet boiling point of 284-degrees Fahrenheit.

DOT 4 brake fluids must have a minimum dry boiling point of 230°C and a minimum wet boiling point of 155°C.

DOT 5 is a brake fluid for hydraulic brake and clutch systems with a boiling point of at least 260 °C and an extremely high wet boiling point of at least 180 °C.

You can mix DOT 3 and DOT 4. Not advisable but both can be mixed. You cannot mix DOT 3 or DOT 4 with DOT 5.

DOT 5

260 °C (500 °F)

180 °C (35

 

[Fire-medic]

DOT 3 vs DOT 4 vs DOT 5

DOT 3 is first on the list and it is a poly glycol-based fluid. The minimum dry boiling point for DOT 3 fluid is 401-degrees Fahrenheit and it has a minimum wet boiling point of 284-degrees Fahrenheit.

DOT 4 brake fluids must have a minimum dry boiling point of 230°C and a minimum wet boiling point of 155°C.

DOT 5 is a brake fluid for hydraulic brake and clutch systems with a boiling point of at least 260 °C and an extremely high wet boiling point of at least 180 °C.

You can mix DOT 3 and DOT 4. Not advisable but both can be mixed. You cannot mix DOT 3 or DOT 4 with DOT 5.

DOT 5

260 °C (500 °F)

180 °C (35

pighuntingpuppy said:
"You can mix DOT 3 and DOT 4. Not advisable but both can be mixed. You cannot mix DOT 3 or DOT 4 with DOT 5."

Technically, that's true, about mixing DOT 3 DOT 4 and DOT 5, however, you can achieve the use of a higher boiling point and preserve the use of glycol based brake fluid by using DOT 5.1, which is compatible with DOT 3 and DOT 4.

About 'not advisable (to be mixed),' other than the different boiling points, there isn't any other reason I can think-of why they cannot be mixed, while respecting the differences as mentioned above.

 

[Pighuntingpuppy]

Technically, that's true, however, you can achieve the use of a higher boiling point and preserve the use of glycol based brake fluid by using DOT 5.1, which is compatible with DOT 3 and DOT 4.

You're right, I forgot about DOT 5.1. I know of it. Never seen it in person. Vehicles that request DOT 5 get the silicone stuff.

 

[DreamV4]

DOT 5.1, which is compatible with DOT 3 and DOT 4.

don't know about 5.1 fluid, but 5 kills seals for 3 and 4 and vise versa. It was a big problem, when Haley switched from 5 to 4 around year 2000(?)

 

[MaxMidnight]

Change your brake and clutch fluid every two years

Yep, or to put it another way, read the service schedule...

The reduction in boiling point referred to above is because glycol based fluid is hygroscopic i.e. it attracts water. It is usually more of an issue with braking systems which can generate more heat under extreme use. As the steam is compressible it is this which causes the pedal or lever to travel further and in extreme conditions lose the function of the system.
Additionally the water content can, over time, also cause internal corrosion to the metal components.

Any moisture that accumulates in Dot 5 (silicon based) fluid will not be absorbed but tends to pool at the lowest point of the system. This may cause more localised corrosion or if this happens to be at the caliper piston area brake fade.

 

[Parminio]

I'll just leave this here:

 

[sdt354]

I alcohol flushed and went to Dot 5 on my rear brakes three years ago. Mostly because 5 is kinder to paint. I'll do the same this winter to my front breaks and clutch, when I switch out my masters.

 

[DreamV4]

I alcohol flushed and went to Dot 5 on my rear brakes three years ago. Mostly because 5 is kinder to paint. I'll do the same this winter to my front breaks and clutch, when I switch out my masters.

Did you search if it is safe for seals?

 

[Radioguylogs]

I alcohol flushed and went to Dot 5 on my rear brakes three years ago. Mostly because 5 is kinder to paint. I'll do the same this winter to my front breaks and clutch, when I switch out my masters.

The clutch slave was leaking on my Gen 1 when I bought it from a dealership. It looked like the dealership had put kit into the slave without smoothing the corroded bore. They used DOT 5 in their replcement, perhaps becasuse the paint under the engine was all goofed up.

I rebuit the slave and clutch master properly, but completely cleaning out the DOT 5 was impossible. Nothing dissolves it. I decided I'd better continue with DOT 5 in the clutch.

I didn't want the brakes and the clutch to be fifferent fluids, so I disassembld the entire brake systems and cleaned them thoroughly with alcohol. Then I filled everything with DOT 5.

It's been about 5 years, and I am very happy with DOT 5 so far. That's good, because I think there is no going back.

 

[sdt354]

Did you search if it is safe for seals?

I took my chances, and it worked out ok.