Clutch won't disengage at high RPM

[CDX_NSX]

So, I've had this problem since I had my clutch replaced; or at least I think that it's been since then as I don't do it often.

When I get into high RPMs in first gear, the clutch won't disengage and I remain locked into first until the RPMs drop. I'm not certain of the precise point at which it will disengage, but my guess is that it's around 3500-4000 RPM. Once I get out of first, all other gears shift normally regardless of RPM. Sometimes it grinds a little going into second, but I'm not sure if that's just driver error since it isn't consistent. No other gears have any issues.

Any ideas of what might be causing this? Maybe more bleeding is needed?

 

[Old Guy]

Have you checked the operation of the clutch in terms of confirming that you are getting full disengagement of the clutch? Check the operation of the slave cylinder (stroke).

 

[JD Cross]

I believe it takes more energy to disengage a clutch at high rpm.
Your problem suggests you may have a loss of pressure in your hydraulics due to a leak or low fluid.
At lower rpm your system may operate okay.
As Old Guy suggests check your stroke length and while you're at it check your fluid levels and look for leaks in the master and slave cylinders.

 

[CDX_NSX]

Thanks, guys. I'll have a look. I just did a quick check and it appears that I also have about an extra 5mm of pedal free play over spec.

Just to reiterate, this only happens in first gear, where it locks in first until RPMs drop. I can take all other gears to redline and it shifts normally (not to say that I've taken all of the gears to redline )

 

[Old Guy]

If the clutch is dragging, it will be really hard to do the shift from 1st to 2nd. There can be other causes for a clutch dragging; but, I would check the slave cylinder stroke first. Does it grind or is it balky trying to go into reverse? That would be an indication that the clutch is dragging because of the absence of synchros into reverse. If it does not grind or balk going into reverse, then it probably time to look at something else.

 

[CDX_NSX]

No, no issues getting into reverse.

 

[Si Espanol4Yes]

I have the same issue at the current moment. Grinds almost 80% of the time going in to second. 4th gear feels really spongy pulling it in, but no grinds. And reverse gear is balky, with an intermittent racking noise. I just put in a new clutch and had short gears installed. Im taking it in to the dealership to see their response. But intent is to replace the Clutch MC (hands cant get to the two bolts), and do a pedal adjustment, while checking the shim washers on the gear cables from shifter to tranny. Ill let you know more if its anything down these lanes and maybe it'll assist in identifying.

 

[CDX_NSX]

I decided to try to check and adjust my pedal yesterday, and found while there that there is a small leak at the master cylinder. I'm going to have it replaced and try again. Hopefully, that solves it.

The stroke seemed short by about 3/4" to 1", but I also found it tricky to get a precise measurement. I measured multiple times and went with the numbers that were somewhat consistent. I couldn't extend the stroke length by much as the push rod was already close to the end of its thread. Will revisit after changing the master cylinder. Thanks, guys.

 

[RYU]

how about in a non-double clutch pump situation? also, no air in the line i'm assuming?

 

[CDX_NSX]

how about in a non-double clutch pump situation? also, no air in the line i'm assuming?

I mostly double-clutch on downshifts, so the issue is experienced in a normal disengagement method of a single clutch pump. All other upshifts are fine. Just can't get out of 1st at high RPM.

After finding the leak at the master cylinder, air in the lines is certainly a possibility. I'll see if replacing it and bleeding the system solves it.

 

[RYU]

let me know if there's anything I can do to help

 

[CDX_NSX]

let me know if there's anything I can do to help

Thanks, man.