Primary case

[Paul Slootheer]

Hmm... These are cases from a rigid KH Twin, the inner cases look quite diff. then yours.

[Leejm]

I see there is step in the back of the inner case. So that's not it. I looked on draganfly the cap is the right through the years and models. So I don't know why my cap doesn't fit.

[Vincent.vanGinneke]

The outside one is o.k. for a rigid frame model (1938-1954)
This is the long type, you can reconize it by the hole where the footrest hanger goes through.
Later cases are shorter as the footrests come from underneath the engine (also completely different frame btw..)
The inside one you have got butchered, the part where it sits against the engine has been grinded of.
Not much use I am afraid , find another one....

second thought; as the twin engine is wider the rear case has a step in it to get things in line.
looks like someone tried to alter a single engine rear case into a twin rear case by slimming down the backside.

[Leejm]

Case with cap. You can the hole it should go in is smaller. I will just have to look for another set. Thank you to you both.Lee

[Simon.Gardiner]

That inner looks a bit weird in detail - it's very different from any I've seen around the oil-drip (to the back) for the secondary chain (look at the cast-in trough just below the screw-lug at the inside/back of Paul's KH).
The inners for the twins have a 'step' to accommodate the wider crankcases, singles don't (as Vincent has said), so that difference is to be expected.
However, the footrest hanger doesn't always go through the middle of the hole, it just has to go through. And I'm hot sure what the question is about a brake pedal stop unless it's a difference between your '48 and my '51, where the chaincase doesn't have anything to do with the brake pedal.
I think it's possible that that other things have caps that aren't dissimilar to the Ariel one but are different sizes (I think I might have one somewhere myself...)
If you get stuck you should be able to make up a spacer from thick sheet (might not have to be that thick, maybe 3/16 inch) to go between the crankcase and the front of the chaincase inner. My swing-arm bike ran for many years with a hand-hewn alloy plate between a single crankcase and an FH chaincase inner, it was fine even though the plate I used wasn't really anywhere near thick enough....

SG

[Leejm]

Thanks to all, I just look for another set of cases and cap.

[Steven.Carter]

Would these help?

http://www.ebay.co.uk/itm/Ariel-singles ... Sw8-tWYvyU

[Leejm]

They would! I keep my eye on them.

[bruce.carrad]

I think you have swinging arm case (the curve in the top looks wrong to me) that has been modified by welding a hole for a footrest mount. The correct case should be 19 1/2"Long for a rigid NH I believe. What does your case measure? Trust this is some help.

[Leejm]

Cheers Bruce. I've got myself another set of cases should be here anytime soon. So this should sort out the issues. Lee