Master Cylinder? Slave Cylinder? Clutch? how to diagnose?

[banguin2]

Having issues shifting in all gears and based on previous experience (had similar issues on my miata) it seems like a hydraulic issue rather than a failed clutch but wanted some input.

• 2014
• 56,000 miles
• owned for about a month
• lots of little issues to fix, but loving it otherwise
• was shifting with no problems yesterday and let a friend (hasnt driven manual for a while) and there werent any major "events" while he was driving (one slight grind, and started in 2nd a few times), but after I starting driving again I had trouble getting into any of the gears...
• pedal is soft. Have to push it all the way to the floor and even still it struggles sometimes to disengage.
• Easier to shift while parked
• clutch/brake fluid was extremely dirty(I think this is a sign of failed seals in either of the cylinders?)
• rear brakes were down to metal and fronts are on their last leg
• Fluid was still full and cant find any visible leaks
• flushed out the dirty fluid and didnt help

so I wouldnt expect a clutch failure to happen so abruptly and it seems the clutches on these are fairly robust and it seems others have had issues with both cylinders. I REALLY hope its not the slave as it is inside the transmission so my next move is to try replacing the master since it is easier, but wanted to know if others have had similar symptoms and what it ended up being.

Also, is there any way to tell between a master and slave cylinder failure without just replacing one of them?

Any help would be incredible

 

[PunkST]

Get new pads and rotors. They all share the same reservior. The pads being shot has lowered the fluid level. Not that is should cause an issue. A bad slave would go straight to the floor or require several pumps to get good clutch action. A bad master would leave you stuck in a gear ( or neutral) and have fluid leaking down the clutch pedal arm.

 

[banguin2]

Thanks @PunkST ya definitely planning to get new pads and rotors, just wasn’t sure if it would contribute to the problem since fluid is shared.

also, update I replaced the master this afternoon and it doesn’t seem to have helped... dang :/ Not totally confident it was perfectly bled though so may need to play with that more.

per your Master cylinder criteria above though. I wasn’t Totally stuck in gear/neutral, but kinda had to force It in and out and/or wait for rpms to hit about 2500 for it to drop in. Also no visible leaking at master even after inspecting during removal

for slave criteria, it does go to the floor I guess, though there is still some pressure and it doesn’t stick on the floor as others have mentioned with the slave

so my only other guesses now are

1. still air in the line. Small chance but can try bleeding again
2. Bad slave. Would need to pull tranny(I am a mechanical engineer and whoever designed this should be punished)
3. Bad clutch??? Doesn’t seem like it should be though. Has anyone gone through a clutch that fast?
4. Any other ideas???
   
   If I do have to pull the tranny, anything else I should do while I’m there from a reliability standpoint? Almost seems like I should replace the clutch whether bad or not. Isn’t there a bearing that can go bad in there?

 

[Rhinoserious]

ChrisFix's video of a clutch replacement ends up showing you several parts that would good for replacement while you're in there.

 

[M_illy7one8]

[mention]banguin2 [/mention] did you ever fix this issue??


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[banguin2]

[mention]banguin2 [/mention] did you ever fix this issue??


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just pulled the transmission and the clutch and flywheel are toast . previous owner must have abused it to fail at 56,000. I love driving this car, but the number of things wrong at this mileage is pretty astounding. My miata i just sold was at 165000 on the original clutch and i hadn't changed brakes since owning it @ 100k despite aggressive driving. i'm just waiting to get this all fixed only to have an engine or transmission fail on me.


have others had to replace flywheels? my mechanic tells me you can't re-surface a dual mass? Has anyone resurfaced successfully? Any good aftermarket options?

 

[PunkST]

Your mechanic is correct. You cant resurface a dual mass. Having just done the clutch on my GF's gti it operates better with a single. Yes its noisy. But its much more solid.

 

[PunkST]

Btw Whoosh motorsports has a few single mass flywheels and some other clutch kits. Id hit him up first for a fun streetable option.

 

[banguin2]

Just reinstalled everything. New clutch, new flywheel, new bolts, new slave cylinder, new master cylinder, new brake pads(EBC redstuff), new rotors. Got it all together, bled the system (2 man pumping the pedal) and had pressure, then started the engine and after a few pumps the pedal lost pressure and brake fluid is leaking from the bell housing....

How on earth does a brand new slave fail like that. Anyone else had this? Time to pull the trans. Again.

 

[Ford ST]

You're not the first person this has happened to I would say these slave cylinders do not like the manual bleed method. In the Ford manual the preferred method is reverse bleed.

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[kivnul]

Im on my 2nd slave and it is leaking. Its very slow and isnt getting worse so I am just waiting for the day it fails.

 

[banguin2]

You're not the first person this has happened to I would say these slave cylinders do not like the manual bleed method. In the Ford manual the preferred method is reverse bleed.

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Any idea who? I couldn’t find any threads on it. That’s just insane that the master can create enough pressure to pop the slave. So you fill it with pressure from the bleeder valve then?

 

[banguin2]

Im on my 2nd slave and it is leaking. Its very slow and isnt getting worse so I am just waiting for the day it fails.

That sucks! How long did your first one last, and when did your second start leaking? I’m wondering if there is some external factor that causes them to fail.

 

[banguin2]

Btw Whoosh motorsports has a few single mass flywheels and some other clutch kits. Id hit him up first for a fun streetable option.

Also, thanks. I did end up going with the OEM as I could get it quicker, though I’m sure a single would have been good

 

[kivnul]

That sucks! How long did your first one last, and when did your second start leaking? I’m wondering if there is some external factor that causes them to fail.

1st one was fine actually, I replaced it, clutch & flywheel while I was replacing the differential. Figured might as well while I already had it apart.

Any idea who? I couldn’t find any threads on it. That’s just insane that the master can create enough pressure to pop the slave. So you fill it with pressure from the bleeder valve then?

Edit: Step number copied/pasted fine but don't show up properly when posted.

Clutch System Bleeding

WARNING: Before beginning any service procedure in this section, refer to Safety Warnings in section 100-00 General Information. Failure to follow this instruction may result in serious personal injury.

• Refer to: Health and Safety Precautions (100-00 General Information, Description and Operation).
  Refer to: Brake and Clutch Systems Health and Safety Precautions (100-00 General Information, Description and Operation).

• NOTE: Make sure that the brake fluid level does not drop below the MIN mark.

• If equipped.

• Install the following items:
  • General Equipment : Brake/Clutch System Pressure Bleeder/Filler
• 
  
  
  • 
    
  • If equipped.
  • Refer to: Specifications (206-00 Brake System - General Information, Specifications).
    General Equipment : Brake/Clutch System Pressure Bleeder/Filler
• 
  
  • If equipped.
• 
  
  • Remove the following items:
• General Equipment : Brake/Clutch System Pressure Bleeder/Filler
  
  
  
  • If equipped.
• 
  
  • In order to remove any small amounts of trapped air remaining in the system, operate the clutch pedal 5 times, using the full clutch pedal travel.
• 
  
  • NOTICE: Make sure that fluid level is to the MAX mark.
    Material : Motorcraft® DOT 4 LV High Performance Motor Vehicle Brake Fluid/PM-20(WSS-M6C65-A2) (ISO 4925 Class 6)
• 
  
  • Start the engine.
• • Check the operation of the clutch. If reverse gear engagement is excessively noisy, operate the clutch pedal 5 times, using the full clutch pedal travel.
• 
  
  • After waiting approximately 30 seconds, check the operation of the clutch again. If reverse gear engagement is still excessively noisy, repeat the bleeding procedure.

 

[banguin2]

@kivnul thanks for the info. Ya mine wasn’t technically having issues either, just replaced it to be safe. Glad that worked out so well. Did you have issues even bleeding with the method in the manual? Did you see leaking immediately?

 

[kivnul]

@kivnul thanks for the info. Ya mine wasn’t technically having issues either, just replaced it to be safe. Glad that worked out so well. Did you have issues even bleeding with the method in the manual? Did you see leaking immediately?

I actually had a shop in Seattle do the work, so I cant verify their bleeding method. The clutch had weird 'popping' behavior on pedal release that went away after a few hundred miles. The leaking took about a year to start.

 

[Redty]

Just reinstalled everything. New clutch, new flywheel, new bolts, new slave cylinder, new master cylinder, new brake pads(EBC redstuff), new rotors. Got it all together, bled the system (2 man pumping the pedal) and had pressure, then started the engine and after a few pumps the pedal lost pressure and brake fluid is leaking from the bell housing....

How on earth does a brand new slave fail like that. Anyone else had this? Time to pull the trans. Again.

So what was the final verdict? Please report your experience and issues in the Transmission/Drivetraing thread on Slave Cylinder and any other hydraulic part damages or issues, any heat related issues?

 

[Legend]

Having issues shifting in all gears and based on previous experience (had similar issues on my miata) it seems like a hydraulic issue rather than a failed clutch but wanted some input.

• 2014
• 56,000 miles
• owned for about a month
• lots of little issues to fix, but loving it otherwise
• was shifting with no problems yesterday and let a friend (hasnt driven manual for a while) and there werent any major "events" while he was driving (one slight grind, and started in 2nd a few times), but after I starting driving again I had trouble getting into any of the gears...
• pedal is soft. Have to push it all the way to the floor and even still it struggles sometimes to disengage.
• Easier to shift while parked
• clutch/brake fluid was extremely dirty(I think this is a sign of failed seals in either of the cylinders?)
• rear brakes were down to metal and fronts are on their last leg
• Fluid was still full and cant find any visible leaks
• flushed out the dirty fluid and didnt help

so I wouldnt expect a clutch failure to happen so abruptly and it seems the clutches on these are fairly robust and it seems others have had issues with both cylinders. I REALLY hope its not the slave as it is inside the transmission so my next move is to try replacing the master since it is easier, but wanted to know if others have had similar symptoms and what it ended up being.

Also, is there any way to tell between a master and slave cylinder failure without just replacing one of them?

Any help would be incredible

Hey, new member from the good ole UK here.
Having purchased my st 3 mk 7 from a car supermarket, the day after I noticed that the clutch was sticking to the floor but only when using first gear.
As the car was still in warranty the car dealership I bought it from has accepted to pay for any repairs.
Having had a diagnostic test at a local mechanic it looks like it could cost well over a grand in pounds sterling for a master cylinder plus a clutch and slave cylinder. The car has only done 23k miles so I'm not sure why there's an issue with the clutch unless the previous owner frequently abused the car at every opportunity.
Anybody else have any issues regarding the clutch?

 

[CarGuy]

Hey, new member from the good ole UK here.
Having purchased my st 3 mk 7 from a car supermarket, the day after I noticed that the clutch was sticking to the floor but only when using first gear.
As the car was still in warranty the car dealership I bought it from has accepted to pay for any repairs.
Having had a diagnostic test at a local mechanic it looks like it could cost well over a grand in pounds sterling for a master cylinder plus a clutch and slave cylinder. The car has only done 23k miles so I'm not sure why there's an issue with the clutch unless the previous owner frequently abused the car at every opportunity.
Anybody else have any issues regarding the clutch?

The clutches in these cars are strong unless abused.

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