Replacing Clutch master cylinder and Slave cylinder?
 

Hey guys I have a RJM clutch master cylinder that I have been wanting to install. I called up a mechanic to install it and he told me that I should replace the slave cylinder at the same time or else it will fail shortly after I replace the CMC. Other than inconsistent engagement points, I dont have any symptoms of a bad CSC so im kind of hesitant to replace the CMC now because I know how much money it will cost to replace the CSC if it does go. Im thinking the mechanic was trying to get me to pay for a bigger job because he told me he wouldnt change just the CMC. How many of you have changed the CMC without changing the CSC and if so did the CSC fail shortly after?

You've got a good mechanic... On these cars both are commonly changed together and changing one usually leads the other to failure (in the context of the OEM parts...not the upgraded parts). Not sure what the failure mechanism is - perhaps they are so fragile they don't survive being drained to dry?

If you aren't having any issues with clutch hydraulics I would leave it alone until such time that something fails, or you are dropping the tranny to replace/upgrade your clutch... then replace both with the upgraded items. Just my :twocents:

I changed to the RJM master with the stock csc. No issues. I eventually replaced it when i did the clutch but if you read the description about the RJM master, it's supposed to save the csc by not over pressuring it.

Not sure I'd call that a good mechanic if he's refusing work unless you pay for a bigger job. He can give you the pros/cons then ask if you still want to proceed.

Bottom line, what ever you decide the RJM master is a tremendous improvement.

Your mechanic is wrong. CMC replacement does not increase the probability of CSC failure. I replaced my master cylinder twice in the first 50K miles, and never had any issues with the CSC. I did ultimately replace the CSC, but it was done as a preventative measure, not because it failed.

If you replace the slave, best practice is to replace the master at the same time because dirty seals in the master can allow contaminants into the system even after a fresh bleed. Contaminants in the clutch fluid will definitely increase the probability of failure in the slave.

If your current clutch fluid is black or really dark then I wouldn't install the new master without doing a new slave.

No point in installing a new master to have it deal with contaminated brake fluid and wear the seals out.

Leave it alone until you're ready to do a clutch & flywheel, of which I would highly recommend ZSpeed. I love my stage 3.

Going by what I've read about the 370Z's clutch hydraulics - especially the failure rate of CSCs - I'd replace both the CMC and CSC. And give serious thought to replacing the piping, also. It seems the whole system is prone to failure. I'd upgrade the fluid, too (several threads exist on that subject). Frequent fluids flushes seem to help a lot. YMMV.