clutch sticking after aggressive driving
 

It has been mentioned a few times before but i dont think anyone diagnosed the cause of the problem. it's basically when the clutch pedal goes soft and sticks to the bottom and you have to actually lift the pedal upwards with your foot. this problem seems to occur after aggressive driving like repeated drag racing or driving on the track probably due to heat build up in the clutch. last sunday i was on the track and even though you only upshift and downshift once in the entire lap, i did get the sticking clutch after a prolonged session of driving. i had to lift it up with my foot. i pulled into the pits and the problem went away, but i left the track right after that.

so, has there been any progress in identifying this problem or a remedy? is it the slave cylinder? or the pressure plate?

I would start with the easiest thing first which is bleeding the clutch. Takes 2 people but the process is the same as bleeding a brake system. The bleeder screw is attached to the transmission on the drivers side. Replace with a high temp DOT4 fluid.

this would be my first inclination as well.

why would that help? i mean, if the fluid is boiling and bubbling, the clutch would not disengage easily. but that's not the issue. it disengages fine, it just doesn't rebound as easily and sticks in the disengaged position. as far as i know only mechanical springs engage the clutch and the fluid is irrelevant.

I've tracked my car 6 times in hot weather with no clutch issues.

Because the clutch uses a CSC (rather than a fork) the system is entirely hydraulic. I haven't pulled it apart but I imagine the CSC assembly contains a return spring so that the fluid is pushed back out of the assembly and force returned to the master cylinder. So if you are overheating the CSC you may be fatiguing the spring, or you have a defective CSC. In the interest of cheapness, the CSC body is mostly plastic and so isn't the most durable piece in the vehicle. Like Spearfish I haven't encountered this on the track yet, even in high heat.

Definitly sounds like you have either a fluid boiling proplem or air in the fluid system.

Get the best clutch fluid you can find and bleed the system.

i took mine back to the dealer the moment it happened. they had to replace the clutch release bearing and something else. hasn't happened since and my dealer was kind enough to put me in a rental for the duration of the repair.

Pharmacist, any update?

no, clutch is working fine. i havent been to the track since then. i'll see what happens next time i go to the track.

USMCASA, did your clutch stick only during aggressive driving like on a track or on normal use?

So.... I had a very similar problem... except mine never returned to normal. Took it to the shop hoping they could just bleed the line but no such luck. Their diagnosis: Slave cylinder weak and pressure plate fingers warped/worn. edit: from looking at the invoice it looks like they replaced the entire clutch assy and the slave cylinder... the service adviser I was dealing with didn't seem like he knew what was going on so getting information out of him was like pulling teeth and the info was suspect.... the guy that handled the long block replacement was great though.

On a side note... My clutch had always felt a little weird. It wasn't exactly smooth and as the clutch pedal was depressed you could feel some kind of rotational knocking.

My clutch feels smoother now and the knocking has went away.

^ Throw out bearing noise. I'm assuming yours is still new so the noise is not as noticeable, but give it a few months and it'll come back. It is quite normal.

Clutch sticking... is this the same feeling under super cold temps?

no. under cold temperatures everything feels sluggish, like the clutch, steering wheel, even lcd displays. that's normal and caused by excessive viscosity of the fluids due to low temp. in my case, i was on the track, so temp was at least normal if not more. and the clutch pedal was not sluggish, it was completely stuck. it didn't rebound on its own at all and i had to pull it up with my foot. it only happened once after a long drive on the track, but i left the track right after and it didn't happen again. another member here also had a similar problem while drag racing his car. haven't seen any updates from him about a cause or solution to the problem.

I had the exact problem on the track 10 days ago. It was towards the end of the day, on a track where you shift maybe 5 times per lap. I was going to overtake somebody and clutch in to goto 4th gear and bam...stuck to the ground. Long story short I let it cool down for 25 minutes and it was okay. Now it is important to note it was getting progressively "slushier" as the day went by, and this happened when I ran two consecutive 20 minute sessions.

I'm probably going to bleed the fluid with a Dot4 before my next session next weekend.

Side note: I used to have a 2006 Infiniti G35 manual coupe. Maybe once a month or so the same thing would happen to me on the street, mainly if I was going around 15mph coming up to a light to take a RH turn. I would be rolling up 15mph, have clearance, put it in 2nd and give it gas as I let out the clutch quickly and it would get sucked to the floor. Happened to me maybe 5 times over the year I had it.

No... not talking about throwout bearing noise or gear lash noise.... I'm talking about a physical knocking sensation felt in the pedal when the clutch was disengaged (pedal depressed). That is not normal and indicative of a problem.

That was a separate issue that was resolved with the clutch assembly getting replaced. My clutch now feels better than it ever has in this car. Engagement is also smoother.

I think the issue of the clutch sticking to the floor after aggression stems from the slave cylinder, unfortunately. Seems like I'm not the only one that has had to have the slave cylinder replaced.

http://www.the370z.com/nissan-370z-g...ck-clutch.html