280z Auto to 5 Speed swap-- Clutch pedal height

[sboy79]

3 hours ago, Namerow said:

These three photos may provide some additional insights

This is nuts!  A 3/16” change at the master cylinder rod made a 2” difference in pedal height for me so these different length parts DEFINITELY matter. 

Edited May 5 by sboy79

[Captain Obvious]

10 hours ago, sboy79 said:

I can sum up the clutch adjustment like this. The threaded master cylinder rod is only used for adjusting pedal height. The only problem you can have with pedal height is if the pedal is too low. With a low pedal you may not have enough swing of the pedal to completely disengage the clutch making for tough shifts.

So how I understand it a clutch pedal engaging too low is most likely a misadjusted slave cylinder (too much free play) which could be exasperated by a low clutch pedal (not enough swing of the pedal)

Couple comments about the above... First comment is that the info you posted above (while all true) does not apply to what grannyknot is experiencing. He is experiencing a clutch engagement at too HIGH of a pedal position, not at too low of a pedal position. Granny is not running out of clutch throw, and in fact he's asking how he could effectively get LESS slave movement, not more.

Other comment is I don't agree with the description of the use of the master adjusting rod. The rod is not supposed to adjust the pedal height... It's supposed to ACCOUNT for it. The up-stop bumper is supposed to set the pedal height and then the master rod length should be adjusted such that the holes in the clevis line up with the hole in the pedal. In other words... Set the pedal height first using the bumper, and then adjust the push rod length to account for the hole positions. Rod length should not set pedal height.

Does that make sense?

[Captain Obvious]

12 hours ago, grannyknot said:

And now that I look at my own pic of the slave I think if I adjust the pivot ball backward toward the slave cylinder that should make it engage later?

I agree. Moving the pivot ball towards the slave body should make it engage / disengage closer to the floor.

So... A related question... What ID master and slave are you using? I think the masters are all 5/8, but I think slaves are available in 11/16 and 3/4. I think you should be running 11/16, but maybe you could change to 3/4 if you can't get satisfaction using just the adjustment on slave rod length.

[Captain Obvious]

9 hours ago, sboy79 said:

This is nuts!  A 3/16” change at the master cylinder rod made a 2” difference in pedal height for me so these different length parts DEFINITELY matter. 

Haha! Geometry!!    

It sounds like you have plenty of pedal height now!!  

[sboy79]

11 hours ago, Captain Obvious said:

Set the pedal height first using the bumper, and then adjust the push rod length to account for the hole positions.

Absolutely. I should have been clearer there. What you wouldn’t want to do is set the pedal height without adjusting the master cylinder rod too or you might have a situation where you’re riding the clutch a little all the time. 

[Captain Obvious]

Right. At the top of the pedal stroke, you need to assure that the master cylinder returns to it's "at rest" position where the plunger is not pushed in at all. There is a valve inside the master that needs to be actuated when you let the clutch pedal up. If you have things adjusted with the rod too long, you run the risk of having that valve not open when you take your foot off the clutch.

You can also cause a clutch riding situation by having the push rod on the slave adjusted too long, but that is strictly mechanical and isn't caused by a hydraulic situation, just simple mechanical.

So for clutch adjustment... 

1) Set the pedal height with the master disconnected.
2) Adjust the master rod length such that the holes line up for the clevis pin and install the pin.
3) Adjust the slave rod to get engagement where it feels right.

I'm no clutch expert, but after being inside a couple different master cylinders and understanding how they work, that's what I do.

[sboy79]

2 hours ago, Captain Obvious said:

1) Set the pedal height with the master disconnected.
2) Adjust the master rod length such that the holes line up for the clevis pin and install the pin.
3) Adjust the slave rod to get engagement where it feels right.

This is the best summation FTW