VERY Dark/Dirty Clutch Fluid??? Cause?? Fix??

[San Diego Busa]

Hey Guys

Got a mostly stock 2011. Just hit 12k miles. Bike is ridden fairly hard in canyons.

From day one, i noticed the clutch fluid darker then the brake fluid, not by much, just kept getting darker and darker.

Finished a ride today and checked it, its almost a dark charcoal gray and cant even see the little round thing inside.

Im of course gonna flush it out and put in new fluid, but what would cause this? Indicator of a serious problem?

Been riding 20+ years so im not doing anything weird with the clutch or anything. I do wheelie a bit, usually slip the clutch for it.

Ideas?
THanks

 

[mikelr]

From what I have seen on my past bikes it is quite normal for this to happen, you have a lot more fluid being pushed through the line (back and fourth) then you get on the brake circuit, the black from the stock rubber line (assume you have stock line) tends to break down a bit and darken up the fluid.

 

[San Diego Busa]

From what I have seen on my past bikes it is quite normal for this to happen, you have a lot more fluid being pushed through the line (back and fourth) then you get on the brake circuit, the black from the stock rubber line (assume you have stock line) tends to break down a bit and darken up the fluid.

OK thanks. Ill just flush it and see what happens

 

[Freechance]

Just flushing might help for a while but will not solve the problem..
Your clutch slave cylinder is dirty..and needs cleaned out..all the oil and stuff from the chain gets in that cylinder and turn the fluid dark..
Keeping a clean chain helps .there are several post about it on here..

 

[mikelr]

Just flushing might help for a while but will not solve the problem..
Your clutch slave cylinder is dirty..and needs cleaned out..all the oil and stuff from the chain gets in that cylinder and turn the fluid dark..
Keeping a clean chain helps .there are several post about it on here..

Explain to me how the oil from your chain gets into a sealed hydraulic system???

 

[Freechance]

Well the back of that slave cylinder is open and stuff gets in it..and that piston moves back and forth picking up dirt or whatever is on the slave cylinder walls..which makes the clutch fluid dark..
U can reach up in there with your finger without taking anything apart..u will be surprised how much stuff collects in there..

 

[dadofthree]

Mines dark too. Getting ready to change chain and sprockets. I'll clean that area up real good and then change the fluid out. 30K miles.

 

[tonyj]

Clutch fluid darken up is normal. I just flushed mine, as it was charcoal gray. I also removed the sprocket cover and WOW it was nasty up in there. Got it all nice and clean now. I use Silkolene Pro Lube for my chain. I love that stuff. very clean and doesn't flick off or gather dirt/ dust that much.

 

[QWKENAF]

Good to see I wasn't the only one. Was wondering why it would get dark after running new fluid through. Good info.

 

[lankeeyankee]

Noticed mine tonight when I was doing a front brake job and flushing out the brake fluid. I am not really concerned with it though until I loose hydraulic clutch pressure which hasnt been effected yet.

 

[Freechance]

Ya that will help cleaning that slave cylinder out..if u only change the fluid it will be dark again and kinda wasted your time..plus it also helps that slave cylinder from going bad..all those rock dirt particles can scratch the walls of the slave cylinder housing and it will start to leak..
They make a thing called a sand seal that covers the back of the slave cylinder i guess that would help..but i havent had any luck finding one..

 

[Superzuki]

I believe it's from the engine heat. Mine uses the same fluid as the brake master cylinder, but the brake fluid doesn't get as near to the engine heat as the clutch line. I just change it out more often.

 

[San Diego Busa]

Thanks Guys!

I flushed all the fluid, and definitely learned something, YUP, was dirty as hell back there near the slave, cleaned it all out!

Thanks for the tips!

Kevin

 

[ccapse]

My bike mechanic told me that the darkening of the fluid is due to the movement of the Master cylinder piston rubbing the inside of the alloy bore of the master cylinder. Over time the small amount of dust/residue produced by the internal rubbing builds up and colours the fluid. If there was muck getting inside your slave cylinder it would also be leaking. Brake fluid doesn't suffer from this so much because there is far less movement of the Brake master cylinder piston each time you apply the brakes when compared to the full stroke of the clutch Master Cylinder piston each and every time you change gear. Changing of the fluid is all that is required. Also note the ratio of Master cylinder stroke to slave cylinder stroke is about 6/7.5 to 1, depending on Gen 1/2 so the actual movement of the slave cylinder piston is much less than the Master cylinder piston.

 

[jellyrug]

Ya that will help cleaning that slave cylinder out..if u only change the fluid it will be dark again and kinda wasted your time..plus it also helps that slave cylinder from going bad..all those rock dirt particles can scratch the walls of the slave cylinder housing and it will start to leak..
They make a thing called a sand seal that covers the back of the slave cylinder i guess that would help..but i havent had any luck finding one..

Just looked at this in the parts manual (24 in the schematic), can't see how chain dirt could get in there, and then work its way all the way up to the master cyclinder. Is this on a Gen II? What am I missing?

 

[FALQN]

Last week I noticed my clutch fluid was starting to get darker. Due to this thread I pulled off the sprocket cover to investigate and clean the area. I did have a build up of gunk on the motor, around the sprocket but there was nothing on the clutch slave cylinder. It was clean as a whistle. It would appear that the darkening of the fluid is from within the system, as mentioned earlier by "ccapse". BTW I have a 2012 with 3900 miles on it.
FALQN

 

[1busa]

When I swapped out my rubber lines for SS i noticed my fluids were really dark.....did a full flush of all the lines and used Motul fluid and havent had any problems since

 

[Gixx1300R]

Try D.O.T 5 brake fluid, gotta flush the D.O.T 4 completely

 

[lankeeyankee]

Just looked at this in the parts manual (24 in the schematic), can't see how chain dirt could get in there, and then work its way all the way up to the master cyclinder. Is this on a Gen II? What am I missing?

View attachment 252648

It cant... use logic... if dirt could get in dont you think the high pressure of the fluid would pizz out in a stream... Some just write things that they think and are not always accurate information.

 

[jellyrug]

It cant... use logic... if dirt could get in dont you think the high pressure of the fluid would pizz out in a stream... Some just write things that they think and are not always accurate information.

LOL, you sure know how to call a spade a spade bro!!!