I had a similar problem. It wasn't a "heavy duty" clutch or anything, but nonetheless, It no worky. I had the same symptoms, the clutch was not disengaging. I had the tallest thrust bearing carrier already on. I tried moving the pivot, but the thrust bearing carrier came off the end of the shaft before it completely disengaged the clutch.

In the end, I shimmed the thrust bearing forward on the carrier. It *just* disengages. Still pretty notchy and hard to get in gear.

Ok!

Last night i bled the slave cylinder... guess what i found!? The thing was leaking slightly. I still bled it up and it has certainly helped, but no doubt in the coming days it will be back as it was. Today's drive to work was much smoother between gears with no clunking noises!

I'd say you're on the money changing to an SR slave cylinder, so now perhaps try adjusting the master cylinder at the pedal to see if it gives the full movement of the slave.

People use 1600/180B clutch master cylinders all the time to my knowledge, should be fine if you adjust it... didn't notice if you had already.

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'72 Datsun 180B SSS - Z18ET
2001 Holden Commodore Wagon - Ultimate Family Car.

yeah i was kinda happy but now im not so sure.

i did adjust my pedal to full travel with the SR slave in but it sat 2inches above the brake pedal. this is a bit dangerous and annoying.

i tried to find a bigger master cyl but there only seems to be 5/8ths for the datto. someone tell me otherwise please.

will a bigger master cylinder increase the force needed to press the pedal or decrease it? i thought it would make it easier but someone on the phone from a brake shop just told me otherwise.

will no doubt end up going back to the standard clutch

maybe we need to set up a not happy with you clutch support group for ourselves

Just an update....

re-bled the new slave cylinder (properly this time ) and it seemed to be much better straight away. after driving a few kilometers though, it went back to being shite.

did this re bleeding a couple more time and the same thing happend. mmmm.

got a new master cyl and put that in it and it all works a treat now! yay!

diagnosis was a crapped ouyt M/C that perhaps let air in and a little fluid out everytime the pedal was pressed (small dribbles inside the car)

didnt realise it had been this long but i guess the car was off the road for a long time.

anyway the clunky clutch issues are still there and i am now determined to fix them! i thought it was just the heavy duty clutch but after instaling new standard clutch a week ago it is the same notchy feeling especially into 2nd.

i had a re bleed and took it for a spin and it was good for a couple gear changes then notchy again.

got under the car for another rebleed and to suss things out and noticed that the slave cylinder rod is on an angle.

i am guessing that it should not be like this. i dont know why i havent noticed this before.

plus the new 1 week old fluid was dirty already. i think the slave cyl piston is rubbing to hard on one side causing wear on the seal creating dirty fluid and also less usable pressure on the fork?

so i bought a new slave yesterday and i planed to shim the slave by 3-4mm to make the rod behave in a straight manner but that cant be normal either. i think perhaps i was given the wrong fork when i got my engine package. as at the time they gave me a smaller FWD clutch and flywheel which i used to begin with and everything was great. it was only when i changed to a larger rwd flywheel clutch combo that this problem started to happen. although i don't know how many other forks would fit and still operate if they are not the right fork.

by shimming the slave i will be loosing clutch travel slightly which may leave me in the same boat. i dont want to take the gearbox out to fix a wrong fork so maybe i can grind and weld the fork in place for a new hole dip bump thing for the rod to sit in.

its a long shot but does anyone have an sr20 gearbox sitting around with a fork in it that they could measure how far out the fork dimple (where the slave rod sits) sits from the box?

for anyone following this...i just fixed the problem

after trying to re bleed the clutch system many times and different ways still with a standard clutch and everything it was still notchy. i pretty much gave up but realised that now and then i didnt put the clutch pedal in fully and would get a smooth change. this along with the clutch pedal engaging halfway up the travel of the pedal made me try something which i have thought of for a while but never tried till now. i adjusted the pedal so it had less movement. tada! it worked. a smooth gear change from 1st to 2nd and all the rest too. its amazing and a little embarassig that this may have been the cause all along... too much clutch travel.

not sure exactly how that makes notchy gear changes but anyway very happy as the whole car has changed its feel now and is much more joy to drive.

Nice one!
Always good to fix a niggling issue and post how you fixed it!

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1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

i had that problem with my os giken twin plate the clucth was fully disengaged at half pedal but would fully engage at full pedal so we made a stopper up and solved it