Ariel Owners Motorcycle Club

Paul, are you sure that the outers are the same. I think I wrote it up in Cheval but when I had Rigid 350 trials bike I used a drive sprocket set up from a twin because I didn't have a small enough single sprocket. It was fine for years and then I smashed the outer chaincase and when I tried to put on a spare it would not fit over the larger shock absorber and sprocket. I eventually found one which fitted and strangely it did not have different casting no. It seemed though that the bulge at the front was slightly larger on the one which fitted.

Is this ebay item the correct inner chaincase?
193318526667

Many thanks for the very helpful replies. After reading Paul Jameson's response I looked at another bike in the collection that I am working on, this was a 1938 single NH, which was fully assembled, but the inner case had the step. I dismantled the single and lo and behold, it fitted the Twin perfectly !! Then I tried the case originally fitted to the Twin on the single, and that fitted too ! As Paul mentioned, the outer cases fit both so no problem there. So, with the insight of the club members the problem has been resolved. Apparently whoever had worked on the bikes previously had inadvertently switched the cases. Now all I have to do is work my way through the other 22 bikes that are here. Thanks again.

john.mitchell wrote:Paul, are you sure that the outers are the same. I think I wrote it up in Cheval but when I had Rigid 350 trials bike I used a drive sprocket set up from a twin because I didn't have a small enough single sprocket. It was fine for years and then I smashed the outer chaincase and when I tried to put on a spare it would not fit over the larger shock absorber and sprocket. I eventually found one which fitted and strangely it did not have different casting no. It seemed though that the bulge at the front was slightly larger on the one which fitted.

There has been a recent topic on the facebook page regarding the differing outer cases. Richard Thomasson pointed this out (different size bulge same casting number) and posted a photo (see below) he also said it was in Cheval somewhere?
He said the smaller bulge may be WD. Certainly my WNG has the bigger bulge and is rough casting (typical of WNG cases) but no idea of its vintage. Looking at my collection of original WD images most have seem to be the larger bulge. However this photo does appear to show different sizes but its difficult to be certain. The Ariel on the right looks like an early one i.e. central speedo (changed to right side mount 1941/2) and screw on tank badges. Not too sure about the one on the left.
Cheers
Alan

John and Alan,

You are correct. The twin should have a bigger bulge. My apologies for forgetting this - blame old age and trying to rebuild a Healey which fights back in a particularly dirty manner!

I didn't know the bulge was bigger but the sprocket runs on a larger diameter splined sleeve with a bigger dia. spring, so why not?. I've got some checking to do as well. All grist for the mill. Nev

Hmm - Editor John has forgotten more than I will ever know - but I can't see a difference between single and twin outer cases.
However, I only have early KH's - and the inner is different on the later models.