Today's puzzle - A7SS s'arm frame

[MG]

Hi there!

I've just been out on the A7 and during a coffee break I was (once again) wondering about the frame.
The bike has matching numbers and was first registered here in Austria in April 1955, with the original paperwork still present today. The numbers appear to be original and not messed with.
Nevertheless, the frame has the Goldie-type rod operated rear brake (QD crinkle hub), as supposed to be for 1955, but on the rhs, there is the cable bracket for the rear brake, which would only make sense for the Ariel hubs with crossover shaft used a year later. I have added a picture (sorry for the quality, cell phone pic), looks very original to me.
So I am wondering, why would they bother to put it there? The bike was registered with a sidecar, which would be mounted on the rhs here on the continent. Maybe has something to do with that? Different rear hub, or maybe for the brake on the sidecar?
Any other theories?

Cheers, Markus

P.S.: I know the frame should be dark green for 1955, but I couldn't live with that colour, so opted for satin black powder coating.

[manosound]

Markus,

Very interesting. Also,  interesting to note solid s'arm spindle.  Assuming the numbers are correct,  I wonder if the frame was part of a run-up for '56 production,  though,  you would think if they could put on the correct spindle brackets they could have left off the cable anchor. Have a look around the spindle brackets to see if there are any signs of modificatoin to get to the smaller hole. If so,  it could have been a really slick job of number modification.  Do the papers list the frame number?   Mine is registered by engine number only.    Perhaps you've confirmed matching with the BSAOC,  which would lead back to my first guess or one of the possibilities you've named (Ariel hubs or sidecar)  of which I have no clue.

The reason this is interesting to me is because I modified a '62 frame to become a " '55" but kept the hollow spindle.  It' too long a story for thumb typing.

Richard L.

[MG]

The numbers are correct, the engine and frame number are both documented in the original paperwork. I haven't asked the OC for confirmation, since I have the original 1955 registration documents, so I have no reason for doubt there. The frame number starts with CA7.
The spindle brackets had the larger holes for the hollow spindle, had to weld small rings in there to reduce the diameter. But the frame also has the mounting hole/tube for the brake arm pivot on the lhs (like the Goldies). So it is sort of a combination of '55 and '56 type. April '55 appears to be a bit early for a run-up version though.
I had the frame bead blasted to the bare metal, and there was absolutely no sign of any modification to the frame number, no grinding or welding marks, etc. And the number looks absolutely authentic in size, position and font style. So I actully doubt it has been "modified", if it really was, then whoever did it did a great job making it look absolutely original.
I was wondering, whether they maybe could have used a rod operated rear brake in combination with a crossover-shaft and cable for the sidecar on the rhs?
Otoh, thinking back to when I got it, the frame had been heavily messed with by the PO, who wanted to build a chopper. So he thought it was a good idea to cut the tank and seat mounting brackets off, and who knows what else he had planned to do with it. Fortunately I rescued the poor thing and brought all the boxes with bits and pieces to a good new home.  
Probably the cable bracket is one of his chop mods and I should have removed it in the first place.
Sometimes the simplest explanation most likely is the correct one.... 

[trevinoz]

Markus,
                As the frame had large swinging arm spindle holes, I would guess that at some time in the past someone had fitted a later swinging arm and wheel and modified the frame to suit. Have a look at the weld on the cable bracket. If it is electric, it is definitely a modification. CA7 and early EA7 frames are oxy welded.
On the subject of sidecars, the CA7 frame was never intended for sidecar fitting. The lug in the left rear loop was not fitted to the swinging arm frames until probably 1957 on the EA7 frame.

  Trev.

[MG]

I suppose you are right, Trev. I can't tell any difference between the weld seams on the cable bracket and the other ones around the frame, but could have been oxy-acetylene welded as well of course. The bike has had a hard and wild life, the last registration dates back to 1989, that makes over 30 years of continuous (ab)use.