Chaincases

Hi John - They did fit a Matchless alloy primary chain-case set-up to the Atlas engine unit on the G15, N15, P11 hybrids in the mid sixties.  So yes it is feasible.  It would probably be best to get hold of a pair of Matchless G9 , G11 or G12 cases as they are often available.  Good luck, Howard  

A NOC  member came to the SNOC event at the Hayes village fair last year with a Dominator 99 to which he had adapted a Commando chain-case. I wrote about it in an article for Roadholder. The Atlas engine that was used in the P11, N15CS series of bikes had a different drive side crankcase to accept the alloy AMC chain-case. 

Yes John - I should have said that a bit of alloy welding and light machining will be necessary to mate the Matchless inner chaincase to your Dommie crankcaes.  Similarly the outer may need some work to fit with your Dommie footrests.   Cheers, Howard 

Hi John

I’m the person Anthony referred to in his post.

I have 1956 model 99 which I fitted a commando chaincase.

In my situation the pillars supporting the commando alternator have been cut back to allow the dynamo crank and drive sprocket to function. No other mods to the chaincase were required.

I have left the engine in its vertical position but it has meant moving it back slightly in the frame necessitating larger front engine plates and an extended head steady.

The crankcase was drilled and tapped to except fixings that matched the position of those in the commando chaincase.

Hope this helps

Mike
 

The Commando case is very much shorter than the Dommie one, SO you either move the engine back or move the gearbox forward, with the latter it messes up the stand spring as well so there is quite a few minor snags to overcome, best of luck........

You have to wonder if the long alternator (or dynamo) case from a rigid Triumph could be adapted.  

It was popular enough on Tritons.

For what its worth I fitted non alternator Royal Enfield chain cases to my single motor, in this case I needed the engine and gearbox to be closer to fit in a Rickman frame. It was surprisingly easy and has the advantage of letting you fix the gearbox position and use a primary chain tensioner as well as getting rid of most of the leaks! All I had to do was make a spacer to push the inner case a bit further outwards and re drill the 3 holes in the case to attach it to the studs in the crank case.
I think the later RE cases were longer. 
Dan