Pete, Don't pay too much attention to Norton's cut and paste parts list illustrations. They often vaguely altered existing pictures with an artist's brush to reflect production changes.

I have a small collection of 1930s parts books and also an inner case here, waiting to fit. I'll take some scans and photos tomorrow.

As Dave Horror says, the WD chaincase certainly has the front mounting position. Some of the parts number changes related to such things as the use of a welded instead of rolled edge etc.

Any post-1935 open cradle frame inner chaincase should fit (although the Model 50 was odd, I believe) - They do turn up.

Hi Pete, Looking at your picture again, I can't actually see much of a problem with your inner case that adjusting the mounting holes won't cure, unless I'm missing something on the small picture. The only thing you're missing are the 2 circular plates that go each side of the gearbox shaft hole. This slides with the shaft when you adjust the primary chain. That should be easy to make. A good way of joining them together is drill 4 small holes through each and weld in the holes, like a spot weld.

Pete, I've followed in your footsteps with the parts books and I'm puzzled too. It certainly seems that the WD16H and Big 4 used the 3410 inner case which appears in the undated book with the blue cover. I've always assumed it was 1933 - 35.

The later green book which refers to 'subsequent to 1936' looks to me to have been applicable for the 1937 model year (i.e. September 1936 onwards production).

The first WD models were delivered earlier in 1936 so may have stuck with the original chaincase. The change of part number may not have been related to dimensions but maybe just to oil sealing arrangements or similar.

I once borrowed a case that had a welded on flange rather than a one-piece pressing. I used it as a model as the cover I had seemed to have lost its pressed depression around the crank boss.



I don't think that the case you have there is from a post-war model as I had an idea that the mounting positions were different for the cradle frames. This looks to me to be for an open diamond frame.

What I don't understand about it is the raised panel around the crankshaft boss which is going to move the case outwards. I can't see how this won't give clearance problems behind the clutch. Your inner would seem to suit an engine with narrower crankcases ?

I'm not sure that I've ever seen a case with a long top rear fixing such as shown in the early parts book. I believe that there is always a front mounting hole present (and the screw and washer are listed in the book). It's simply a poor illustration... maybe from an even earlier book.

The inner below is one that I thought was right for the WD16H and is intended to replace my repaired original, but I won't know until I can compare them.





The outer case ought to be the same as your 1936 civilian model, I believe. This is mine :-



Good luck and let me know how you get on. I may be able to source a rough inner case out here in Belgium but there would be the problem of getting it to the UK quickly.

Thanks guys, your input very much appreciated. That photo of my inner case against the bike probably looks better than it is Dave. In reality, with the crankcase hole aligned and the fixing bolt in place, the footrest spindle is a good 1/2" low in the case and the gearbox shaft, set up with a newish 74 link chain, is hard against one end of the case slot. Since my original posting a friend has sent me a photo of the inner case off his 1956 ES2, apart from my missing slider disks this is identical to the one I have.

Rick's astute observation that the pre-war and WD Parts Lists include the 5/16" fixing bolt even if the corresponding image of the inner casing shows no hole to put it through certainly shows that one shouldn't believe all one sees in a Parts List. As regards dates, I also have original copies of both the blue (1933-35 ?) and the green (1936-38 ?) pre-war parts lists, in addition to the dates "subsequent to" referred to on page 2 of each, my copy of the later edition also has a Norton sticker on the inside referring to a 10% price increase after 1st September 1937.

I hadn't got as far as thinking about that raised panel around the crankcase opening screwing up the fit of the clutch basket, but you are spot on Rick, it's a non-starter. The photos of your inner case are especially useful, at least I now know what I need to be looking for and am sure I will find something nearer to home.