WGREGT Posted February 10, 2015 Share Posted February 10, 2015 Any idea what would cause clutch fluid to turn black (like oil. Really dark.) within a couple hundred miles after changing it? The bike has steel braided lines, and I know the fluid will turn dark if it gets mixed with air or water over time, but I don't think that's happening. Everything is tight from what I see. I haven't checked the clutch plates, but it shifts fine. This has happened over the last 5-10k miles actually. I swap it, and it goes black again within a couple tanks of gas. The bike is a non-VFR, but that shouldn't matter really. Thoughts on where to start looking? Link to comment Share on other sites More sharing options...
Member Contributer MarkDetroit Posted February 10, 2015 Member Contributer Share Posted February 10, 2015 Sounds like the brake fluid you are using (assume dot 4) is not happy with some of the "rubber" materials. It's a simple system so either the master cylinder piston seal, the hose, or the slave cylinder O-ring. I'd guess one of the elastomers is getting soft & deteriorating. It's definitely worth a look. Possibly someone used an incorrect fluid in the past and that caused softening. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted February 10, 2015 Share Posted February 10, 2015 i would say the slave cylinder and or master need a rebuild. for what its worth, my fluid is doing the same thing right now. Link to comment Share on other sites More sharing options...
WGREGT Posted February 10, 2015 Author Share Posted February 10, 2015 I put a master cyclinder rebuild kit in it a couple thousand miles ago. Honed the bore as well. Did not do the slave cylinder though. Mabye that's up next. Good ideas. Link to comment Share on other sites More sharing options...
WGREGT Posted February 10, 2015 Author Share Posted February 10, 2015 Looked up my slave cylinder parts. Should I only replace the rubber seal, or should I do the spring (not sure how that would cause an issue with the fluid being dark) and the piston/cup as well? Link to comment Share on other sites More sharing options...
Member Contributer Lorne Posted February 10, 2015 Member Contributer Share Posted February 10, 2015 Fwiw, my VTR1000F did this within weeks of buying it new. Never did figure out the cause but it certainly was due to wear or age. Link to comment Share on other sites More sharing options...
WGREGT Posted February 10, 2015 Author Share Posted February 10, 2015 Did you do anything to track it down? Or live with it? Link to comment Share on other sites More sharing options...
Guest Posted February 10, 2015 Share Posted February 10, 2015 I am thinking calipers. Since we don't know the are or model of the bike, we just have to guess. The calipers is were the heat is created. If there is moisture in the lines the heat and moisture will start to eat away the aluminum. Link to comment Share on other sites More sharing options...
WGREGT Posted February 10, 2015 Author Share Posted February 10, 2015 Oh...the bike is a ZX10 Ninja. Eat away the AL? I don't have any AL eaten away anywhere.... Link to comment Share on other sites More sharing options...
Guest Posted February 10, 2015 Share Posted February 10, 2015 Really? So you have had the calipers taken a part and the insides were shiny and new? I find that odd. Brake fluid is an extremely harsh chemical. Link to comment Share on other sites More sharing options...
Tamworth Posted February 10, 2015 Share Posted February 10, 2015 I am thinking calipers. Since we don't know the are or model of the bike, we just have to guess. The calipers is were the heat is created. If there is moisture in the lines the heat and moisture will start to eat away the aluminum. I don't think calipers or overly high temperatures are an issue with the clutch hydraulic system. Link to comment Share on other sites More sharing options...
Member Contributer MarkDetroit Posted February 10, 2015 Member Contributer Share Posted February 10, 2015 Looked up my slave cylinder parts. Should I only replace the rubber seal, or should I do the spring (not sure how that would cause an issue with the fluid being dark) and the piston/cup as well? IMO you should only need to replace the seal. The clutch stroke is really long by comparison to what a disc brake / caliper would have to do. Logically the clutch seal should wear more than brake piston seals. Link to comment Share on other sites More sharing options...
Member Contributer expvet Posted February 10, 2015 Member Contributer Share Posted February 10, 2015 I did mine this summer and replaced all of the components, which are not that expensive. I've had rebuild experiences where the higher pressure of a new seal causes almost worn seals to begin to leak. It's a bummer to have to reopen a part you had diassembled a few days ago, especially when it involves draining and bleeding. As the saying goes, do it right, do it once. Link to comment Share on other sites More sharing options...
Guest Posted February 10, 2015 Share Posted February 10, 2015 My bad... I was reading through this earlier the wording and terminology is terrible... When I did my first reply I was thinking brake fluid and brakes. As I said with the Caliper, The problem is going to stem in the Slave. The DOT4 is overheating in the slave and or the Clutch line is routed to close to the engine. Link to comment Share on other sites More sharing options...
WGREGT Posted February 10, 2015 Author Share Posted February 10, 2015 The line is steel braided, and I haven't moved this position of the line at all. It's been in the same OEM spot for 80+k miles. And this "dark fluid" thing has only been the last 2-3 oil changes. I'll order a slave cylinder seal kit and see how it goes and report back. Thanks for the ideas. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted February 11, 2015 Share Posted February 11, 2015 I am thinking calipers. Since we don't know the are or model of the bike, we just have to guess. The calipers is were the heat is created. If there is moisture in the lines the heat and moisture will start to eat away the aluminum. I don't think calipers or overly high temperatures are an issue with the clutch hydraulic system. Lmfaooooooooo Link to comment Share on other sites More sharing options...
spud786 Posted February 11, 2015 Share Posted February 11, 2015 The line is steel braided, and I haven't moved this position of the line at all. It's been in the same OEM spot for 80+k miles. And this "dark fluid" thing has only been the last 2-3 oil changes. I'll order a slave cylinder seal kit and see how it goes and report back. Thanks for the ideas. Generally, that black is from the internal rubber of your lines is breaking down. It normally can be seen on brand new lines, for a short period of time, the fact your seeing it after 80,000 miles is more detrimental. Braided steel lines is only on the outside, not the inside. Link to comment Share on other sites More sharing options...
WGREGT Posted February 11, 2015 Author Share Posted February 11, 2015 Sounds like it could also be the lines themselves then. Hm. I've never heard of steel braided lines going bad from...age. Interesting. Link to comment Share on other sites More sharing options...
Veefer800Canuck Posted February 11, 2015 Share Posted February 11, 2015 Braided steel brake/clutch lines have teflon inner hoses, not rubber. OEM black non-braided hoses are rubber. So I doubt the line is at fault. Like so: Link to comment Share on other sites More sharing options...
Guest Posted February 11, 2015 Share Posted February 11, 2015 This is the slave kit for that bike. The piston seal is breaking down. Link to comment Share on other sites More sharing options...
WGREGT Posted February 11, 2015 Author Share Posted February 11, 2015 Got it. Ordering today. Thanks again. Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted February 11, 2015 Member Contributer Share Posted February 11, 2015 DOT 3 DOT 4 and DOT 5.1 are Glycol based brake fluids whereas DOT 5are Silicone based... Glycol based fluids are designed to signalmoisture contamination... the fluid will start to turn golden, thenlight brown, indicating that it has absorbed progressively moremoisture. Eventually, if left unchanged beyond the recommended serviceinterval, the fluid will become dark brown, indicating high amounts ofwater absorption and thus badly contaminated fluid... user friendlyGlycol based fluids also reduce the effect of both corrosion andcompressibility because it is not only designed to accept significantamounts of moisture, but even to neutralize it by dispersing thismoisture evenly throughout the system, thus preventing itsconcentration in any one area...Boiling point of Glycol based brake fluidsDOT 3 205 °C (401 °F)DOT 4 230 °C (446 °F)DOT 5.1 270 °C (518 °F)DOT 5 Silicone based fluid will not turn color to signal moisturecontent...Boiling point of Silicone based brake fluidsDOT 5 260 °C (500 °F)If you wish to use the latest in Glycol base fluids then its DOT 5.1 Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted February 12, 2015 Member Contributer Share Posted February 12, 2015 Maybe this is an obvious question but have you started using a new brake fluid brand about the time the discolouration started? Maybe a cheap and easy check would be to refill the system with a different brand. If it happens again then BLS seems to be suggesting you've got a water entry problem, would that be in the reservoir cap? Link to comment Share on other sites More sharing options...
WGREGT Posted February 12, 2015 Author Share Posted February 12, 2015 The fluid has always been DOT4, but if you're asking if the brand changed....hmmm....could be? I don't remember being brand loyal to any brand in the past, so I could have grabbed something different last time. I checked the screws on the upper cap, and they were tight. It's always in a dry garage. I'm in SoCal, so I don't ride in the rain. (I drive the car the one week or so it rains every year.) Link to comment Share on other sites More sharing options...
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