Clutch Won't Dis-engage
 

Today I went to take my Miata out and it shifted really hard into reverse. It took me a bit of force to get it in gear, but after that it seemed fine. I hadn't driven my miata in a few days , so I figured maybe the transmission wasn't lubricated as well as usual since it had been sitting. Then tonight I went to go cruise again with some Miata Buddies and again it shifted hard. As I drove it, the harder and harder it got to shift. I was out for probably around 30 minutes and wasn't driving it real hard, more just cruising and it got progressively worse. Now my clutch pedal has a lot of play in it and the clutch doesn't start to dis-engage until the pedal is almost all the way in. As I drove it home it got worse and worse really fast to the point where is is barely even working, when I put the clutch in it barely does anything. I checked the fluid and there appeared to be plenty in there, however it did look really dirty...almost black, it was kindov dark though, so that might be why. My first notion is the clutch master cylinder...my car has 145K miles on it by the way...any help would be greatly appreciated

If you look on this page: http://bellsouthpwp.net/P/o/PopVII/C...%20Rebuild.htm ... should tell everything you need to know on checking an/or replacing any of the components.

Think the first step in any event is to go ahead and just bleed out the system and change the Dot 3. Will need a helper for a few minutes to work the pedal while you work the bleeder valve. Contains instructions for bleeding, tools needed, as well as pictorial on doing it.

From 14 years of tech sessions plus several visiting Miatas we worked on still have not come across a bad master yet. Not saying it can't happen though. I did make a special tool to completely isolate the master for checking. When editing the page again will show the tool and instructions for its use.

Pop is pretty much my hero.

Pop is everybody's hero:bowdown:

Well - I'm bettin on the "MASTER CYLINDER" going south on you.
We all think POP is the greatest thing since ICE CREAM, but I have seen them go out many times. Especially on my motorcycle.
I replaced mine on LOLA not a year ago - The slave was fine, but the master had taken a dump.

I gentleman's bet you that it's the "SLAVE CYLINDER."

slave.

See Poll and Vote

If it was the slave guys, then he would not be maintaining fluid in the reservoir. He would be constantly refilling or "topping up" the reservoir.
I think he said:
"APPEARED" seems to be the "gray area"

To be sure that the slave is "OK", then of course he needs to pull back the little ruubber boot down on the slave plunger to check for leakage!

Another vote for the slave. Rebuild kits are pretty cheap.

I don't want to see your "POLE" Bruce :gay:

Possibly Slave
 

Well guyz I just picked up the slave cylinder rebuild kit at my local parts store. I jacked up the car this morning and pulled the wheel off to look at the slave cylinder and there appears to be a fresh fluid around the rubber boot, but there also appears to be some on the line that is coming down into the boot, so it might be a leak up above. I'm going to try rebuilding it first and see if that takes care of it, if not I'll go from there. I'm just heading out to my garage now with my rebuild kit, a can of dot 3 brake fluid, and a 1/4" diameter hose, wish me luck

Don't fully agree with either statement. Could have an air bubble in the system. If the slave has been installed for a length of time have some fluid in the boot. Curious how many posters found a little dribble in the boot, then just ran out and replaced the unit?

Tried to condense the pages down to what I thought was important. Some things deleted was part of the background reasoning and tried to go directly to the point. Each time you push on the clutch pedal a small amount of air and dust is drawn into the reservoir thru the vented cap. Dot 3 is hygroscoping and absorbs moisture from the air and the dust dirties the fluid. 2-3 % is not uncommon during the year. Water is heavier than the Dot-3 and settles to the lowest point being the cast iron slave bore. Nice.

The master isolation tool I made is merely a short hunk of fluid line (with coupler) that replaces the hydraulic line. Used an old self tapping schrader valve from my refrigeration tools. Open the valve to bleed the master then close it and see how well the pedal holds pressure.

Again the first step to take would be to bleed the system and see if any additional repairs are needed. Would run about $2.50 for a small container of Dot-3, and a few minutes of borrowing a helper's foot.

I only bet on sure wins .. like checker and chess games.

I followed Pop VII's instructions and went ahead and bleed the system first. This seems to have taken care of the problem for now. I decided to hold off on the rebuild until it gives me more trouble, plus I was getting hungry as I haven't had lunch yet. My car is shifting now the same way as it was when I got it. Now when I purchased the car I noticed that when I put it into gear that the idle would drop a little bit, even if the clutch was all the way in. I have had my Miata for around six months I think and I hadn't noticed it getting worse until yesterday. Now that I have bleed the system it is back to how it was when I bought it(dropping idle a tiny bit when I put it in gear), not sure if the two problems are related. Unless the problems are un-related, I would guess that I will be tearing into it again b4 too long to do the rebuild.
Thanks for the help Pop VII

The Resolution
 

Well, after bleeding the lines, things were good for a couple of days, but soon the problem was back. Last night myself and another miata buddy who has rebuilt his before, removed mine and rebuilt it. There was a lot of fluid in the plunger and after putting in the rebuilt slave cylinder, the pedal was far more stiff than it has ever been the entire time I have owned the vehicle. So, it was the slave cylinder after all.

Notes:
Even though it was a bad slave cylinder, the dot 3 level in the master cylinder never fluctuated or went low.

The hole in the bleeder valve plug was plugged up, so I used some brake cleaner and canned air to get it un plugged, I also used brake cleaner on the slave cylinder and it cleaned it right up back to new, and had many years of grime on it. The piston didn't want to come out, so I used some canned air and stuck the nozzle in the bleeder valve hole to get it t pop out.

Pop VII rocks!!!

Tell us what we've won! :bigtu:

First, I apologize for resurrecting a dinosaur, but, hopefully, someone can explain this to me.

If the slave is bad, shouldn't the fluid be pushed out past the rubber seal of the piston?
And, if no fluid is leaking and the fluid level remains the same, wouldn't it be the case of master being at fault?

Not always. Did you do a more in-depth search for slave cylinders? You'd see that many failures do not result in fluid leaking from the slave. It doesn't always mean it can't be a bad master though. Just start with the cheap one (slave) and if it doesn't work, well, the next logical step is the master. But before checking the master, verify the soft clutch line isn't fuct. I'm sure there had to be a few threads since 2006 that explain this better. At least you admitted the bump, meaning you did some searching.

No soft line here. Braided, recently replaced. Master is recent, so is the slave.
ATE gold in the system. Flushed with Motive power bleeder