WHY THE HELL DOES CLUTCH FLUID KEEP TURNING DARK?

[OB_valklex]

This is my first bike which I have this problem. I replaced the dark fluid at 600 miles with brand-new synthetic. Now at 1,800 is dark again. I haven't touched the brake fluids, and they are still clear. On all my other bikes the fluid on both the brakes and clutch start turning dark at the same time.
Does anybody have an explanation why does this happen?

 

[RedBull]

 

[Kiwi Rider]

Hmmmmm . . . only one answer to a 19 year old thread, and even then it's not a relevant answer to the question.
Odd . . . very odd.

 

[Kiwi Rider]

Alright,alright, ok, I'll play your silly game Red, I can't resist, here goes . . .
So . . . . think about how many times you pull your clutch in and then release it compared to your front brake.
what, like maybe 10 times more? 20 times more? A lot more anyway.
The clutch fluid goes darker sooner than the brake fluid because it's moving back and forth in the hose so much more often than the brake fluid.
That is why.
Hope you are still watching for notifications after 19 years lol.
How did I do Red?
All good?

 

[WuzzaCBXRider]

Alright,alright, ok, I'll play your silly game Red, I can't resist, here goes . . .
So . . . . think about how many times you pull your clutch in and then release it compared to your front brake.
what, like maybe 10 times more? 20 times more? A lot more anyway.
The clutch fluid goes darker sooner than the brake fluid because it's moving back and forth in the hose so much more often than the brake fluid.
That is why.
Hope you are still watching for notifications after 19 years lol.
How did I do Red?
All good?

But, why would the simple movement of the fluid contribute to its change in color? Doesn’t heat or pressure play a part?

 

[Jbaby1969]

This is the best answer I could find to this ancient mystery!

What Brake Fluid Should & Should Definitely Not Look Like – Adam's Auto Advice

www.adamsautoadvice.com

 

[Kiwi Rider]

But, why would the simple movement of the fluid contribute to its change in color? Doesn’t heat or pressure play a part?

I was informed years ago by senior mechanics I worked under that the fluid goes dark mostly due to the rubber hoses the fluid travels through shedding particles at a microscopic level into the fluid.
These particles then sit inert in the fluid and give the appearance of 'dirty' fluid.
I've noticed when I've had braided hoses the fluid appears ro stay 'cleaner' for a lot longer I put this down to the fact the fluid is no longer in rubber hoses but in the teflon or PTFE material.
Remember too, that the piston in the m/cyl also has black seals that wear as they move in the m/cyl bore, and these will also shed fine material into the fluid.

 

[Bumblebee]

@RedBull went on a fishing trip and caught some old wise fish.....

 

[Mr Brown]

@RedBull went on a fishing trip and caught some old wise fish.....

Quick, throw it back before it teaches us something....

 

[Bumblebee]

Quick, throw it back before it teaches us something....

Or bites us...

 

[SSGT_B]

Did you mix in the pie additive?

 

[Jbaby1969]

In my own defense I checked the date on the first post and waited for others to bite before I commented!

@RedBull -0

Me-1 (not counting all the other times he got me!)

 

[Kiwi Rider]

Y’all gotta realise, it was a catch, teach, and release scenario.
Besides, Red is fishing illegally in foreign waters but the old fish are onto his game lol.

 

[WuzzaCBXRider]

I was informed years ago by senior mechanics I worked under that the fluid goes dark mostly due to the rubber hoses the fluid travels through shedding particles at a microscopic level into the fluid.
These particles then sit inert in the fluid and give the appearance of 'dirty' fluid.
I've noticed when I've had braided hoses the fluid appears ro stay 'cleaner' for a lot longer I put this down to the fact the fluid is no longer in rubber hoses but in the teflon or PTFE material.
Remember too, that the piston in the m/cyl also has black seals that wear as they move in the m/cyl bore, and these will also shed fine material into the fluid.

Hmm, thanks, never thought of the rubber hose deterioration as I’ve always changed to Galfer braided SS brake and clutch lines. Never liked the flex of rubber hoses.

 

[c10]

Temputure slave cylinder attached to engine, line crossing over heated engine. Slowly cooks fluid making it dark.
Zrx engine same issue on clutch fluid as same design as hayabusa, and many other models.

 

[Kiwi Rider]

Temputure slave cylinder attached to engine, line crossing over heated engine. Slowly cooks fluid making it dark.
Zrx engine same issue on clutch fluid as same design as hayabusa, and many other models.

Yes, temperature is also a contributing factor,
but does anyone here have this 'dark fluid' issue when using braided teflon/PTFE hoses?
I've personally never had a braided brake hose so I have no experience in this to speak from . . '
would be keen to hear from those who do use braided clutch hoses

 

[WuzzaCBXRider]

These are what I have on the Busa and what I had on the CBXs.

Brake Lines, Clutch Lines | Galfer Performance Motorcycle Braking Systems

galferusa.com

 

[c10]

Yes, temperature is also a contributing factor,
but does anyone here have this 'dark fluid' issue when using braided teflon/PTFE hoses?
I've personally never had a braided brake hose so I have no experience in this to speak from . . '
would be keen to hear from those who do use braided clutch hoses

yes on Hayabusa , ZRX , ZX11D , ZZR1200 . All use same design .

 

[Kiwi Rider]

yes on Hayabusa , ZRX , ZX11D , ZZR1200 . All use same design .

Thanks Bryan, very interested to know that.
Obviously the constant high heating temps to the fluid (from the engine) are discoloring the fluid.
I had no idea of how much this has an effect in relation to the rubber hose particles discoloration, but this gives me more insight into this issue.
Brake fluid is not at a constant high temp, temps fluctuate depending on the riding conditions (lots of corners, long straights,) so will not dirty up as quickly.