Been having some issues with my clutch grinding into reverse and the old 1st to reverse wasn’t helping. Also felt the pedal was a bit softer than usual. I have had the car for two years now and have never had any clutch related issues until recently. Only thing I really have done was changed the transmission fluid 6 months ago.

My pedal engages almost at the floor and is how it has been since owning it. Checked for leaks and didn’t see any. Fluid was pretty dark so I changed the fluid in the reservoir but introduced some air and ended up having to bleed the system. Got it working decent for about 20 minutes or so and but now it’s giving me issues getting into first and reverse is almost more difficult.

I’m guessing there still may be some air in the lines so that’s my next plan but am wondering if I should be making some adjustment to the slave cylinder. It is the threaded one and was planning on lengthening it a couple turns to start. Having trouble figuring out exactly how to do this and if it is ok for it yo be resting directly against the lever or if it needs to have a small gap for play.

anyhow if someone has some advice on my next steps and adjustments I should be making before replacing everything I would appreciate it.

Sorry just did some more research and I see I’m missing the slave cylinder return spring. I see the fork has a hole where it should go but the slave cylinder does not so guessing it’s from a newer car. Should I be trying to purchase a 71-72 slave cylinder and spring or is this something guys are commonly doing without issue?

I put a newer self adjusting clutch slave on my '72. That was 2015, so far so good...no problems.

I think it was a Beck/Arnley like this one. You can use your old rod for the hole in the fork.

https://www.autozone.com/p/beck-arnley-clutch-slave-cylinder-072-1191/502681?searchText=clutch%20slave%20cylinder

Edited July 30Jul 30 by siteunseen

I bled the clutch again and worked good for a couple minutes but then went soft. Went underneath and found a small puddle leaking from the boot in the slave cylinder. Guessing that was the problem all along.

Would it be best to try to find the correct 11/16 bore slave cylinder for this car??

11/16" = 0.6875 inches = 17.5 mm. I think that that's all that's out there.

The self-adjusting slave cylinders have a spring inside. No need for the external spring. Nissan improved the system. Maybe a PO already used a newer cylinder. You'll need to swap rods like site said though, unless you change the clutch fork.

https://www.rockauto.com/en/catalog/nissan,1971,240z,2.4l+l6,1209158,transmission-manual,clutch+slave+cylinder,2044

p.s. if you put your car info in the signature box and save it it will show up under each of your posts. It's under Account Settings.

https://www.classiczcars.com/settings/signature/

Edited July 31Jul 31 by Zed Head
Left out a 7.

Actually, there is some weirdness out there. 3/4" does not equal 0.690". Not sure if the 3/4 molded in to the cylinder is its size or something else.

Edited July 31Jul 31 by Zed Head
. > /

That’s what was curious. The 72 I believe is suppose to have one that is 11/16. Most I find when searching for a replacement are 3/4. Which is the size that was on mine already. I was worried that this was causing my shifting issues as the rod was only travelling roughly 10mm. That being said mine was also on the fritz.

Looking further I think that you asked a good question. I'd never really thought of it before, and even now assumed that you would just want to match the master and slave bore sizes, that they would be the same. But that is not the case, see specs below for 1976.

Add on to that that the 240Z's had a taller pressure plate and maybe it is important to match the specs on all of those components. Pressure plate, master, and slave. Many people put later model pressure plates on their L24's.

It deserves some study. Notice that image I pasted above has the 1976 style slave cylinder non-adjustable rod.

1976. Not the same! -

It gets weirder. 1970. 5/8". 0.625". Matching master and operator.

What the hell is happening! My world makes no sense! We might have discovered the source of decades of clutch problems.

1972. New sizes.

I went to Nissan today and they said the original part number is 30620-28502 and that part number 30620-v2800 replaces it at a price of $170.19 Canadian.

I’d install the aftermarket 3/4 on the car and give it a shot. I think you’ll find that it will work. My two cents.