soft clutch pedal

[merkyworks]

Having issues with my clutch pedal and could use some help.

When I push on the pedal the very first 1/2"-3/4" feels soft/mushy then I get to the engagement point and the pedal pressure feels normal. When letting the clutch out the engagement point is in the same place but right after the pedal pressure is so soft I can't feel the pedal at all but the pedal returns to the very top like normal.
When on the highway turning 3K rpm I have done 4th/5th gear pulls and the rpm's rise steady and don't spike so I don't think the clutch is slipping. I'm also able to shift into all gears like normal. Did I some how get air in the clutch line and it needs to be bled or is this a sign my clutch master cylinder is bad?

 

[Catmonkey]

Hard to say. I've noticed that if my car sits a while, the clutch pedal doesn't fell that responsive and I have a metal clutch line that shouldn't be expanding. Has the clutch hydraulic system ever been opened on your car? I don't think you could get air in the system unless you changed the clutch line or opened the line between the slave and the master cylinder. You'd have to be very low on brake fuild to have run the system dry to push air into the slave with the master cylinder. Pretty sure your clutch would be unresponsive at that point.

 

[RedVenom48]

What kind of clutch and line? There really is no flush per say, the factory slave and line have no bleeder valve built in. Did you have any recent clutch work done? Pumping the cluctch pedal a bit might help if there is air trapped in there. If you havent flushed your brake fluid, that would be a good place to start. Unclip your clutch line from the slave and let drip with new brake fluid in till you get clear fluid coming out. Reattach and pump clutch pedal until you feel pressure again.

My OEM clutch is worn and the engament point is literally right at the top of travel. Ill be going through this myself soon when i put in my RXT.

 

[merkyworks]

Bought the car used at 12K miles but everything was stock so I'm confident the clutch and line are OEM. I have put 7K miles on it and never experienced this issue until a couple days ago. I have never had the clutch worked on or anything like that, also I have not noticed any dip spots on garage floor to indicate leaking. Car is daily driven so at most it will sit for a day or two unused. Will check the brake fluid level this evening but the brakes haven't felt soft or different than normal.

 

[merkyworks]

Got home and checked brake fluid level. So I'm going to assume my fluid shouldn't look like used motor oil, how does the fluid get to be this bad with only 19K miles?
View attachment 76771

Also I don't do any HPDE or anything like that.

 

[centerforce]

Got home and checked brake fluid level. So I'm going to assume my fluid shouldn't look like used motor oil, how does the fluid get to be this bad with only 19K miles?
View attachment 76771

Also I don't do any HPDE or anything like that.

The fluid becomes contaminated from clutch dust working past the slave cylinders seal and into the system. Over time, this will cause the mushy pedal symptom you are describing and poor disengagement of the clutch.

Do a good thorough bleed of the system until that fluid is crystal clear, and the proper pedal feel should be restored. Let us know if this works for you!

 

[merkyworks]

The fluid becomes contaminated from clutch dust working past the slave cylinders seal and into the system. Over time, this will cause the mushy pedal symptom you are describing and poor disengagement of the clutch.

Do a good thorough bleed of the system until that fluid is crystal clear, and the proper pedal feel should be restored. Let us know if this works for you!

I was going to do a full brake bleed with a Motive power bleeder but wasn't sure if just that would also replace the clutch fluid. Do I need to separately bleed the clutch line that goes from the firewall to the transmission? If so what is the best way to do this, should I just unhook the line at the transmission and let it drip till fluid is clear? Thanks

 

[centerforce]

I was going to do a full brake bleed with a Motive power bleeder but wasn't sure if just that would also replace the clutch fluid. Do I need to separately bleed the clutch line that goes from the firewall to the transmission? If so what is the best way to do this, should I just unhook the line at the transmission and let it drip till fluid is clear? Thanks

That is one way to do it, although a little more of a hassle. Most times you are able to get a good bleed on the system by using a mityvac on the master and dont need to get under the car and disconnect anything.