Desmo Wing Mirrors - Correct Or Best Sizes? / How to Fit

[whyperion]

Having sourced a new(well used) mirror head at the car show on Sunday I found that fitting into the arm I had was not quite so straightforward.

890276 being the patent number of the smaller 'rectangular' mirror. This seems to comprise rubber or plastic (white plastic with lugs on in my case) insert, mirror glass which just falls and fits into the chromed metal backing. Inside the backing there is also a circular disc of paper - what is that for - should it fit over the bolt? The bolt itself seems to pass either through a metal then rubber cup, or a plastic cup, to give flush sitting in the recess in the backing part.
To the rear external another rubber cup and metal cup sit against the backing head, the bolt passes through the D shape aperture in the mirror arm and thence held but an internal tooth lockwasher and chromed headed nut.

Trying to get enough length on the bolt for the nut to actually catch in, and then tighten up without merely rotating the bolt was a bit tricky, and I might have gone overboard on the number of metal and rubber cups (or not?).

Additionally the direction of face of the plastic glass retainer was / is confusing, in the end I settled for the plain side of the plastic against the glass and the side with pips on it fitting into the head frame recess.

Of course I also have one spare mirror to dissassemble (the arm cracked years ago ), Now trying to undo the nut is being a bit tricky as all the bolt wants to do is rotate - I guess taking mirror glass out and holding bolt with pliers is way forward.

I also have what I would call a 'later' Desmo, its just a bit bigger than the one that looks correct on the 1960 car, having the numbers 132, e11 and 1002 embossed on the back plate and nothing around the external raised sides hole. I have a feeling this came off either the traveller pile of bits, or even a old hillman husky we had.

Anyone know if there was a reason or time given change to a larger mirror, ( as the ones on the 1960 have never been that brilliant at giving a decent large rear-view at best of times ( when I had a van I got the largest pair of mirrors I could find on the wings - I don't like the aftermarket clip/screw on door frames , and the ones that screw into the doorskin are a bit drastic- though again I had a set on another van.

*Edit* Just opened up the larger one, pips are face down on glass, and the paper disc is at the wide end which a coiled spring rests against ( no spring in the one I bought - should I fit one from my spares pile ?) Having taken it apart, can I get the plastic back in again!!?

[whyperion]

Just about, I note minorparts have replacment glass at £10.95 (unipart NOS). which makes my £5 charity donation look a good buy for me.