Finn, I am lovin that vernier caliper.  Accurate to within .05 mm, sweeeeet.

Your stack height is .020" (0.5 mm) more than mine.  That explains some of your problems.  All these small variations combine to have a significant effect.  That .020" increase in stack height decreases your pressure disk travel by roughly 27% of what is required.  Was the wave washer assembly in the stack when you measured the stack height?

I love your machine work on the pressure disk and sleeve hub.  Your solution for holding the pressure disk in your 3-jaw is clever.  Nice job.

Your input shaft bore is pretty ugly.  I don't know how an expandable ream will work on that hardened shaft.  This is what a normal shaft looks like.  The bore is .485" (12.32 mm).  As you can see, surface finish is very smooth.  You are already .003" over that.  After you finish reaming it's gonna be way oversize, and it might still need some honing to improve the finish.  

The groove in the push piece is .100" wide.  You may need to open that up a bit.  Maybe widen it to .110" or .120".  Given the sliding application, you may need to do a little trial and error fitup.

Mike,

Lots of usefull input as usual.
I have left out the so called wave washer from all my work up to now. I am still debating with myself, should I just do as yourself and at least also Dave, and put those 2 washers in, and miss most of the friction from the outher face of the narrow friction disk, or should I do the scientific thing, omit them, and experience the lousy clutch operation that demonstrates the need for them.

Still does not at all make any sense to  what they can possibly benefit, or the mechanism involved in making them work to the benefit of the clutch  engagement.

Yes, perhaps a good idea to skim a couple millimeters off the sleeve hub to benefit the nut engaging the shaft.

Btw. regarding the hardness of the shaft, I tested it with a file, as I always do when contemplating "going at" a potentially hardened workpiece with HSS tooling. The shaft is not hardened inside the hole: not a surprise!

Shafts like these are not hardened throughout. If they were, they would be prone to splinter during shock loads. Instead high strength and ductility is needed, how do they do it?

They make the shaft from a steel type formulated for case hardening. This means that the steel is alloyed with chrome and molybdenum, but has low carbon content, below 0.3%C or thereabouts. It is the carbon content that makes it possible to harden the steel.

So they machine the shaft to final dimensions where no particularly fine surface finish is needed, but leave 0.2mm where grinding will be needed after quench hardening. They leave the diameter a couple of mm thicker in places where no surface hardness is desired. This will be turned off later.
Unhardenable areas can also be created by covering the part partly by for example copper, you probably still remember those beautifull copper plated conrods on the A7?

After this, the shaft is submerged in a special salt solution which is heated to some 500-600 degrees centigrade, and this allows carbon from the salt to diffuse into the outher layers of the steel. It is the iron portion of the steel it enters. The iron molecules are organised in a cubic structure, meaning that there is an iron molecule in the corner of each cube. The carbon molecules then wander into this lattice, so that it is situated on one of the faces of the cube. In this state, the material is called cubic-face oriented, this is the normal state at elevated temperatures. And the percentage of carbon will be above 0.9% possibly 1.2%
When the carbon has entered into a debth of around a millimeters deep, the shaft is taken out of the salt bath, and allowed to cool slowly. During this slow cool down period, the carbon molecules wander into the center of the iron cubes, and the material is now cubic-center-oriented, which is the norm at room temberature.

It is now still relatively soft, and surprisingly nice to machine, if this should be desired. For example, if there are areas of the part that should be left unhardened, it is now time to turn away the layer with high carbon content.

The hardening process can take place now, by heating the shaft to red hot, and quenching it in oil or water. During the heat up, the carbon moleculed wander back into the face-oriented position, and during the quench, they cannot return to cubic center orientation, so the stresses caused by the carbon molecules being trapped outside their normal position inside the iron cubic structure is causing the hardness.

It is now needed to anneal the material, to avoid cracks to form, you can say it is a calibration of the position of carbon in the lattice that is taking place. The shaft is heated to a couple houndred centigrade, some of the hardness is lost, and much ductility is regained.

Finally the part goes to the grinding machines to produce the fit and finish for the gears to mate to.

In the case of my shaft, apparently the hole was either shielded in the salt bath, or it was drilled afterwards. But they either forgot the reamer, or they used a too large drill, rendering the reamer inefficient it being too small for the bore.

So I do not worry too much, the adjusteble reamer will produce a superiour surface, I am confident about that.

When you ream and polish the input shaft, you want to make sure that chips and abrasive debris don't migrate into the shaft.  One thing that will help is to feed compressed air into the trans oil supply.  You can do that by removing the special orifice and blowing compressed air into the feed hole. You should blow the air continuously during the reaming and polishing.

The hole made by the reamer turned out to be 12.35mm, so probably I made an error measuring it earlier. A pinkie finger inserted into it confirmed that the surface finish is A1, something that the pictures don't seem to convey, but trust this old toolmaker.
The nut overhangs the shaft by 0.15mm, so I see no urgent reason to trim the hub down. Clutch is good to go, with so called "Wave Washer" and all. It will be mounted with stock springs, since my left hand hurts too much with the DR springs in it.

So is the DR650 cam, here at TDC

But I want to talk about the induction system. This picture holds a lot of information.
Here in Denmark, it is near impossible to source a plastic (or metal for that matter), tube elbow unless it is either 50mm or 75mm PVC or PolyPropylene. I went with the 75mm PP elbow.
To join a 64mm carburettor to a 75mm elbow, you have to source a hose in the form of a truncated cone, not easy. So I made my own.
On the picture in white, you see a paper template. I used half of the template to mark out copper sheet, 1mm thick. From this sheet, I made the mandrell shown. I also cut 1mm EPDM rubber using the same template.  (I have a lot left over from a roofing project). Wrapped it around the mandrell one turn, then gluing it with isocyanoacrylate glue as I progressed the second turn. This produced the black hose shown, which fits great.
What You also see is the multicutter saw which is invaluable for cutting the filter case. I don't know how I could have done without it. First plug the hole with a piece of wood, and use a circular saw to make the round hole, then start gouging away with the multicutter.