Clutch Won't Disengage

[Patcon]

If the clutch plate is slightly off center then the transmission input shaft is not centered and has an interference fit with the pilot bushing. When using a centering tool, sometimes you need to lift it slightly to counteract gravity.

[cgsheen1]

Damn gravity...

[adivin]

21 minutes ago, cgsheen1 said:

Damn gravity...

Yea, it's really weighing me down!

[adivin]

Breakthrough I hope...while waiting for a new collar to come in, I decided to adjust the slave cylinder to what I thought was an extreme amount.  I desperately didn't want to drop the tranny again.  The rod is now tight against the fork and there is zero play in the cylinder, BUT low and behold the clutch disengages.  The car rolls forward while in gear with the clutch in.  I hope the clutch doesn't slip now.  I need to find where the sweet spot is.  Taking out the clearance and backing the nut 1.5 turns per the FSM is too much and the clutch won't disengage from there.  I have no way of measuring a 2mm gap (FSM) from the bearing plate springs.  Trial and error?  I guess this adjustment is ok as long as the clutch doesn't slip?

[Zed Head]

There's no real "sweet spot" to find.  Pressure cannot be maintained on the clutch fork once the pedal is released because the fluid will return to the reservoir.  The beauty of the hydraulic system.  In other words when you make the rod longer once it touches the fork, (edit) and the fork is touching the pressure plate fingers, you're just using up potential travel if you extend it further. 

There's no reason for the clutch to slip.  If it is releasing fully you should be fine.  Good luck.

 

Edited June 3, 2022 by Zed Head

[adivin]

55 minutes ago, Zed Head said:

There's no real "sweet spot" to find.  Pressure cannot be maintained on the clutch fork once the pedal is released because the fluid will return to the reservoir.  The beauty of the hydraulic system.  In other words when you make the rod longer once it touches the fork, (edit) and the fork is touching the pressure plate fingers, you're just using up potential travel if you extend it further. 

There's no reason for the clutch to slip.  If it is releasing fully you should be fine.  Good luck.

 

What I'm trying to say is that with this adjustment, I don't have 2mm of clearance\travel between the bearing and the PP fingers.  The clutch fork is tight against the PP even when the clutch pedal is not depressed.  I am supposing I need to back off the adjustment nut to find the point at which the clutch still disengages when pressed, but yet the bearing is not up against the PP when the clutch is released.

[Mark Maras]

 Don't sweat the 2mm clearance. The important thing is there is enough clearance between the release bearing and the pressure plate fingers that the bearing doesn't spin with the pressure plate when the clutch is released.

[Zed Head]

It's interesting that when Nissan went to the self-adjusting operating (slave) cylinder that they put a very light weight spring in the cylinder to take up the play.  Which means that the gap gets reduced to zero, but with no significant force.  I wonder if that has something to do with the noise that people often hear, that many have assumed is the countershaft bearing.  Maybe it's the clutch fork rubbing on the throwout bearing.

A person would have to hear the noise, open the hood and reach down to the cylinder and pull the rod back to be sure, I'd guess. Or get a helper to do it.  Just a thought I had when looking at how the self-adjuster works.  There is no 2 mm gap.

 

[Zed Head]

Here's 1976.  Just bolt it up and bleed it.

[Zed Head]

2 hours ago, adivin said:

What I'm trying to say is that with this adjustment, I don't have 2mm of clearance\travel between the bearing and the PP fingers.  The clutch fork is tight against the PP even when the clutch pedal is not depressed.  I am supposing I need to back off the adjustment nut to find the point at which the clutch still disengages when pressed, but yet the bearing is not up against the PP when the clutch is released.

Are you following the instructions exactly?  The 1.5 turns?

[Zed Head]

Never mind.  That wouldn't work.

 

Edited June 4, 2022 by Zed Head

[adivin]

1 hour ago, Zed Head said:

Are you following the instructions exactly?  The 1.5 turns?

I tried this initially but the clutch wouldn't disengage. I finally adjusted the crap out of it (my last pic) and the clutch disengages but I have no gap between bearing and plate.  I need to adjust it where the clutch still disengages and where the bearing is not up against the plate all the time.  I guess this is just trial and error.