Seven years ago I had the clutch master cylinder in my car replaced with the ZR1 master cylinder after my clutch stuck to the floor. This was on GM's dime since my car was still within range of the service bulletin miles/age. At the time I figured that since GM did the work and provided GM parts that I had a 12 month/12,000 mile warranty, so I was going to conduct an experiment and not do the ranger method on the clutch during this period to see if the clutch would stick again, at which time GM would be forced to fix it again on their dime. Now it's seven years later and I just remembered that I was conducting this experiment, and I haven't done the ranger method during this entire time. Despite this, my car is still working just fine, and I haven't had a single problem with the clutch. I do plan on doing the ranger method soon, but wanted to let everyone know that the replacement ZR1 master cylinder really does fix the problem long term.

 

Is your fluid black?

 

Hope this isn't a stupid question, but what is a ranger method?

 

This is what I do. Sorry my video skill isn't the best, so fast forward 15 seconds.

The SRF fluid is important. I had GM fluid in there, and Id get dirty brown fluid within a couple hundred miles. I change that fluid 4 times in a couple months before I switched I switched to SRF. Since going to the SRF, I changed it 3 times in 4 years and the color was barely of yellow.



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I replaced my master cylinder with the ZR1 unit about 2 years ago and did the ranger method. After 2 years and about 10,000 miles the fluid is only slightly off color, but I think that is because you can never get all the old fluid out doing the ranger method.

 

Don't know, I haven't looked at it yet.

 

Found this:

 

Would you happen to remember the part number?

 

I sure don't, and it was so long ago that I might not even have the original receipt anymore.

 

gm # 19331709

 

I do the ranger method at every oil change. No big deal.

I prefer diluting dirty clutch fluid with clean fluid at oil changes.

And yes, I have seen black clutch fluid on a few Corvettes I have bought.

Why take the risk for a few dollars?

On my HPDE car I used the Ranger method after every track day. No question that there was a fluid color change, same with the brake fluid. Better safe than sorry.

Another fluid change that most neglect is the power steering fluid. These cars are ten to fifteen years old - change the power steering fluid.

It is easy knowing a few tricks.

 

I wanted to revisit this thread to update you on what I found today when I had the clutch master and slave flushed by a local shop. The fluid was very black, and was low as well, which I attribute to it having so much clutch dust in it. I was actually forced to get this done as the clutch pedal had stopped returning to its outermost position after shifting, which reminded me yet again about this forgotten experiment. To sum everything up, the clutch lasted 7-1/2 years without doing the ranger method even once, and it only cost me $300 to have a shop flush it for me. Considering how much I would have spent over all of this time if I'd done the ranger method myself once per month as I normally would have, I actually came out ahead in both money and time. At this point I'm not sure that I'll ever do the ranger method again as just waiting and getting it done when needed seems to have worked out just fine. Opinions?

 

Don’t believe it’s so much the amount of time the fluid is in there but rather the amount and type of miles put on the car. I have very little traffic where I live and don’t run a lot of miles during the 6 or 7 months it's out. The clutch fluid looks pretty good so I do the Ranger Method before putting the car away for the winter. Spending 300 bucks for a clutch fluid flush imo be over kill so I’ll just keep doing what I’ve been doing the past 14 years on my 06. I think if you’re more comfortable with having it flushed professionaly then it’s what you should do. FWIW my vette is running about 600 hp and I’ve never had any clutch issues.

 

I have about 108600 miles on my car. It's daily driven, and driven in stop and go traffic both to and from work, which is about a 45 minute drive. It's been my daily driver for the past 6+ years. The car had about 35k miles on it when the master cylinder was replaced. That's 7-1/2 years and 70k miles ago. As I said in my OP, I spent less to have the clutch fluid flushed now than it would have cost me to have done it every month for the past 7-1/2 years since the car is a daily driver.

 

Lets first understand the problem of the old masters, and what the new masters did to upgrade it so solve the problem.

So old master problem as as the fluid get dirty, it slowed down the fluid returning from the slave to the master. Pedal would start to have problems at bottom of stoke coming back up, would get to the half way point up for the assist spring to increase the amount of force to the master piston rod, and the end plunger would be pulled off the end of the rod.

So old plunger to end of rod looks like this, and you can see the plunger end pieces that can get pulled off the end of the rod.


When end plunger pieces gets pulled off, pedal will pull the rod back, but end plunger is down in the bottom of the cylinder doing nothing/ not way to push fluid back to the slave with more pedal pushes,


So its just how the end plunger is secured to the end of the rod that is the update, so it can not be pulled off,

And Gm making the tank black with dot 4 markings, a way to identify if it has been updated.


So updated master solves the end plunger getting pulled off the rod as the fluid gets dirty, but did not solve the problem with slowly lock up of the clutch at higher rpms when the fluid is dirty in the first place.

How the fluid gets dirty, the plunger seal of the slave does not have a outer top lips to push the clutch dust on the forward surface forward, the seal will just run over the dust, and when pressure on slave is releases, the inner bottom lisp on the seal just pulls that clutch dust back into the fluid.


So even with new update slave, still want to keep the fluid clean, so it can return to the master faster, to prevent slightly stalling of the clutch to lock up rapidly during high RPM shifts. If a remote bleeder has not been installed, then ranger method of keeping the fluid clean is the next best think, since getting to the stock slave bleeder to conventional power flush the system is a PITA instead.


The stock slave bleeder nipple tool,


And where is needs to go, to get to the stock slave bleeder to open and close it to do convertial power flushings without a remote bleeder line,

 

As for the LS9 clutch, its a different animal. Hence on it, as the clutch starts to wear out, the pedal will get harder, unlike the other LS clutches that the pedal pressure stays the same though the life of the clutch pressure plate.
What they do share in common, is the dirtier the fluid, the slower the clutch fluid is pushed from the slave back to the master, and all have the same dirty fluid slower clutch lock up problems at high RPM shifts.

https://www.rangeracceleration.com/Clutch_Care.html