Clutch pressure

[pope_face]

Alright, this question may be a little finicky, but hopefully someone can help me out with it... I need to know one of the following:

 

What are the inner sizes of the clutch master and slave cylinders? Or, rather than actual sizes, what is the diameter and displacement of both? Also, how much pressure does the clutch plate require to fully disengage?

 

Or, what is the diameter of the clutch slave cylinder, and what is the PSI required to fully disengage the clutch?

 

Or, if nobody knows the above, then what is the pressure required to fully depress the clutch pedal? I'd prefer to know the pressure exerted on the clutch master cylinder piston itself, but if someone knows how much is required on the actual pedal then I'll take that.

 

I don't care whether the answer comes in metric or imperial or both, and I don't really care which one of the above is answered. I'm looking specifically for information for the KA-E or KA-DE with a 5-speed manual transmission, or a J13 with the 4-speed, but if you've got info on the L or Z-Series engines I'll take that.

[datzenmike]

Clutch master diameter... 0.625" or 5/8"

 

(this was easy, it says so on the outside of the cylinder)

[pope_face]

Oh, well that was easy... I'm assuming that's for the L-Series, correct?

 

Assuming 1" of piston travel, and assuming my math is correct, then...

 

1(3.14159[(0.625/2)^2]) = 0.3068 cubic inches of displacement...

 

Is that right? I can't tell if that's dead on or way off...

 

Now I just need the slave cylinder diameter and the clutch pressure...

[DanielC]

My slave cylinder piston diameter, 3/4. This is on a 1970 PL-521. that I swapped a 5 speed into many years ago.

[LenRobertson]

I know there were at least two different diameter slave cylinders for L series. When my '79 200SX slave started leaking, I was going to put a kit I bought in a spare slave (likely '72 510) I had, as the spare bore was less corroded. I was surprised the two were not the same diameter, so I rebuilt the original cylinder. At the time, I wondered if installing the different diameter cylinder would have any effect on the clutch action, but since I went with the original, I never found out. I don't recall the different diameters. I can check later today.

 

A friend who is a mechanic has mentioned to me a few times over the years that clutch rebuild shops can test pressure plates to see if they still meet original specs. From this, I assume they have lists of pressure specs.

[hang_510]

My slave cylinder piston diameter, 3/4.

 

all the slaves ive done on a 510 w/any tranny has been 3/4".

my clutch MC is currently 3/4"

[LenRobertson]

From 1979 200SX factory shop manual - clutch master cylinder dia. 5/8".

Clutch slave cylinder dia. 11/16".

 

I looked at the slave on the dogleg trans. from '78 510 - it has 11/16" cast on the body.

 

The slave that I think is '72 510 has 3/4" cast on the body.

[pope_face]

Alright, so it sounds like the general consensus is:

 

Master cylinder: 10/16", 12/16"

 

Slave cylinder: 11/16", 12/16"

 

I suppose it makes the most sense for the MC to have the smaller bore, so I'm assuming the options are:

 

A) MC: 10/16", SC 11/16"

 

B) MC: 10/16", SC 12/16"

 

C) MC/SC: 12/16"

 

Does it make sense for both the master and slave cylinders to have the same diameter?