I've replaced the Ami's pedal box today with a later Ami 8 item (thanks Paul!), thinking that would allow me to operate the later model three spring clutch which is in there, bolted to the back of the original M4 engine's flywheel. It still won't work: even with the cable adjusted to the maximum, the travel on the pedal is sufficient only to take up the slack in the actuating arm at the gearbox end. It's not even starting to actually disengage the clutch, as far as I could see crawling around underneath the car with a torch in my gob.
Before I take the engine out to have a closer look, does anyone have any ideas?

The clutch is a secondhand one but there looked to be plenty of meat on it.

The gearbox is a short spline (I think) drum brake box of indeterminate origin.

The flywheel looks very similar to an M28 "heavy" flywheel, but (I assume) is the one off the M4 engine originally in the car, since it had the static bearing graphite clutch bolted to it when I first bought it.

The clutch cable is a new one, intended for a LHD Ami 8.

All help very much appreciated ...

According to Jeroen Cats

"When mating engines and gearboxes there is one thing to look out for. There are 2 types off gearbox input shafts. One has approx 20mm splines, this should be used with the old type 3 finger clutch cover. The other has approx 40mm splines, this should be used with the modern (post 1981) diaphragm clutch cover. The long splines can be usedwith the 3finger clutch but the short splines CAN NOT be used with the diaphragm clutch! Each type of clutch needs it's own type of flywheel. The diaphragm flywheel is nearly flat wit the clutch fitted on top, on 3 finger type the clutch is fitted inside the flywheel."

http://www.cats-citroen.net/citroen_2cv/index.html

Unless you've changed the flywheel it is an m28 heavy flywheel as that's what I had to use. The crank on an m4 has a different pcd and won't fit an m28.

The clutch fork isn't bent is it?

I'm assuming it's gotr the correct release bearing for the clutch fitted?

I fitted a Dyane engine in a disc brake 2CV years ago and didn't know that I needed to swap the release bearing which resulted in a very similar sounding problem to yours..................

I presume the release bearing is correct ... it's the one you gave me with the clutch.

I've had this or a similar problem too - it was the release bearing.

Engine out then, and perhaps a nice new clutch kit from Uncle Roy ... cheers folks.

RT,
just a thought...
If you're unable to adjust the cable enough to operate a worn clutch mechanism, things will be even worse with a new unit.

I'm assuming that you've run the adjusting nuts almost to the top of the threaded section, which is how things normally are with a new unit and cable.
As the driven plate wears, free play at the pedal is lost, so when the nuts are near the lower end of the threaded sleeve, that's usually a good indicator that the clutch is near the end of its life.

ken

( Yesterday and today, I've been working on a car where the driveshaft had come loose from the gearbox output shaft.
Yet another owner who didn't think that a torque wrench was needed when working on cars, but that has cost him a smashed gearbox case, damaged caliper, holed crossbox and thoroughly battered lower metal engine cowling.
Anyway, the point of this tale is that I decided to have a look at the clutch while the engine was out, fitted a new clutch then realised that the relatively new clutch cable had an inner which was too short.
Found a good s/h cable and it's all working fine now. )

Cheers Ken. I think the best thing I can do now is crawl around under it and see if I can tell whether or not the release bearing is actually engaging with the three springs.
The nuts on the cable adjuster are indeed at the very top of the thread. I was wondering if the cable inner is too long relative to the cable outer, and I can certainly get the clutch to work (after a fashion) by sticking a bit of tube over the end of the adjuster. But even then, the pedal is on the floor when the clutch bites and there's a horrible smell of hot clutch lining.
I do have a GSA cable somewhere, which I suppose might be worth trying as it's quite a bit longer than the Ami item and I can route it around the houses a bit, if that'll help. All the fittings are the same, except the threaded adjuster barrel, which is a very slightly different thread. But I must admit, I'm approaching my bafflement threshold ... and I really didn't want to have to take the engine out again!