At one stage I fitted a double adult Canterbury sidecar (not a Carmobile) to my 1957 VH. With 4 adults on board (we were students at the time, so a little lighter than more mature adults) the bike would not go up something like a 1 in 8 without the passengers dismounting. This was with a 22T engine sprocket. But the original green lining alloy hub brakes were no problem going down a similar hill.
I didn't like the sidecar when fitted and sold it as soon as I could, replacing it with a Watsonian Monza which I did like, very much.
If you fit a double adult sidecar to the Square and want to take 4 adults about in it, you will need to come down quite a bit on the engine sprocket. I have both 22T and 23T Sq 4 sprockets available in my autojumble box should you need them.
36 4G, 37 VH, 54 KH(A), 75 Healey 1000/4, 52/53 ex ISDT KHA (project).
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.