Clutch Hydraulics Issue

[GeoffM]

Hi everyone,
While getting the roadster back on the road, I noticed the clutch pedal didn’t engage, so I did a gravity bleed. I noticed that the fluid was completely black and even after exchanging a whole can of dot3, the pedal hasn’t changed.
Also, after the pedal was depressed a few times and the fluid in the master circulated, it’s completely black again. I’m guessing the seals have deteriorated for…reasons?

Anyway, both master and slave are new-ish. Should I buy kits and rebuild them or change them out outright…again?

Thanks for any advice.

[redroadster]

Dot 3 ,4,Brake fluid eats rubber ..slowly
The seal was dipped in brake fluid then assembled if it's old stock it's been working on the rubber for yrs
Dot 5 silicon fluid doesn't deteriate rubber BUT , If a tad of the old fluid mixes with it , it reacts to form a RTV adhesive and ruins even the lines .

[drieseck]

Buy the kits, you'll be fine. In my experience, however, the hose was deteriorating and the culprit it was being "eaten" also. So if the components are newish, might consider it first, or with the re-build..

[GeoffM]

Thanks…the hose is new-ish but I guess you never know with NOS parts. I fired the parts cannon.

Could a tight fork adjustment cause the same issue?

[Habitat.pat]

I bought a new hose , master & slave cylinder a couple years ago but didn’t get the fluid into for over a year. My fluid turned dark almost immediately. Turned out the “NEW” hose was over 15 years old! I’ve replaced the hose but haven’t filled the system, waiting on other parts but expect the fluid will not be dark.

Peace, Pat

[Solex68]

I'm not sure why but it's common to see the clutch master cylinder reservoirs typically have the fluid turn dark. I've replaced both master and slave and experienced the same. I have even turkey basted the black fluid out and refilled it, but its fluid is still darker than the brake's reservoir's fluid.

[DAC21]

Not much that can be done about the piston cylinder cups, but I guess the one rubber bit that can be taken out of the equation is to go to a stainless clutch hose and see what happens?? NOS Rebuild kits for Clutch Master / Slave could be 40+ years old well before Dot 4 came out. Maybe stick with Dot 3 if you rebuilt with old kits?

[GeoffM]

Good ideas everyone.
I might get the local shop to make up a hose for me when I swap out the cylinders and see if the hose or the cylinders are the source of the black rubber staining the fluid. The hose I have is NOS that I replaced 10 years ago. I haven’t considered that a collapsed hose could be why the slave isn’t actuating.
I guess when I replace all three items…I’ll inevitably fix the issue anyway…whatever it was.

[spyder]

I replaces the clutch hose with the Gates braided lines and the black went away.

[DAC21]

I replaces the clutch hose with the Gates braided lines and the black went away.

Do you know the P/N?

TIA

[zippy67roadster]

I carry a full clutch hydraulic kit that includes the clutch master, slave cylinder and new spring and a stainless steel braided hose for the slave cylinder. You can buy them as a kit or only the parts you need. you can find them at sincitydatsuns.com

[GeoffM]

Thanks

[spyder]

I replaces the clutch hose with the Gates braided lines and the black went away.

Do you know the P/N?

TIA

I picked it up in a pack that had all the brake plus the clutch hose so, sorry no.