as some of you know i'm running a 4agze attached to a toyota 5speed.

recently i replaced the clutch master cylinder due to a bung seal. the change went smoothly i adjusted the rod length to match the old one and i've been driving with the new one for a month no probs.

yesterday things started to feel different. the engagement point felt much further from the floor, in fact nearly at the top of the pedal travel.

today on the way home i started getting slippage with the pedal fully released in 4th gear.

i'm figuring all is ok at the master cyl. end??? so i started thinking about the slave cyl. i read some info that said that hydro's aren't adjustable and some others that said if there are nuts on the end of the rod you can adjust.

I just had a look and can't see any way of adjusting. am i on the right track here?? what next??

The majority of hydralic clutch slave cylinders don't have any adjustment.
The major adjustments for a hydralic setup is the pivot ball inside the bellhousing or as you've played with, the pedal adjustment. The pedal adjustment is just for setting clearance of rod to master, not making adjustments to the amount of travel or anything.
It's possible that this was maybe slightly over adjusted and there has been slight pressure being applied to the clutch the whole time. This would lessen the clamping load.
Is the pedal firm immediately right from the top?

yes it is now but there was about 10mm of travel immediately after the master was changed.

Speak to someone with a bit more knowledge than me (!!) but I'm thinking it's the diaphragm fingers gone.
Does the pedal feel king of springy?
If so I'm sticking with clutch plate diaphragm fingers.
It's worth giving it a bleed first just to make sure it hasn't got an air bubble in the fluid for some reason. Is the reservoir full or empty now?

cheers shoota. pedal is not springy just firm. resevoir is full and hasn't shifted 1ml since i filled it

The fluid level should drop. As the clutch plate wears the slave cylinder moves further forward in its bore. this obviously creates a cavity behind it that needs to be replaced by fluid, hence lowering the level.
Get under the car and get someone to activate the pedal. You may be able to see something funny while you're under there.
Also check the rubber boot that the clutch fork goes through into the box, just to make sure it isn't jamming the clutch forks travel.
If all that looks ok, if the clutch slave is easily accessible, whip it off and pull it apart just to confirm everything is ok. There's a possibility that the piston could be stuck in the bore, holding pressure on.
While the slave is out and the fork boot off, see if you can use a folding telescopic mirror and torch (shine torch onto mirror to reflect into the box) to see if you can see the clutch diaphragm fingers.
Other than that, without being there, I can't think of anything else!

had a look under there this arvo as my son pressed the pedal - nothing untoward. so, if you look into the resevoir as the pedal is depressed you should see a notable drop in the fluid level? and the fluid should return on release.

Yes, that's right. It should not rise when the pedal is depressed.

Many hydraulic clutch setups have minimal adjustment.

But the Datsun 1200 has full adjustment:
* Adjustable Pedal travel
* Adjustable master cylinder rod
* Adjustable slave cylinder

So you cannot always go by common wisdom. Datsun 1200 LHD uses a hydraulic clutch setup.

The fluid won't drop much when you push the pedal down. As the piston moves forward in the bore it covers the hole that goes to the reservoir. It might fluctuate a tiny bit but not much.
If it looks like the clutch fork is trvelling it's full travel forwards AND back then it's looking more and more like a clutch plate issue.

how much toe clearance do u have jason ? , that is all u can adjust on a hydraulic system

if the pedal doesn't engage until right at the top & u have slippage in 4th gear , well those symptoms to me reading it over the internet without driving the car tell me the clutch is #OOPS#ed mate.