Inclined twin shock-frame mounts?

[brunocrossley]

Not strictly a GS thing I know, but I'm currently building a special from a twin shock RS, and would like to mount the upper ends of the rear shocks directly to the frame in the style of the older PD bikes.
Are the units inclined toward the centre line of the bike, or are they mounted parallel to each other. I've looked at lots of photos and the upper mounts appear to fasten directly to the main frame loop just below where the subframe brackets would normally be. Is that correct? Are the brackets in line with the frame tubes or are they offset outward?
On my 78 R100RS the upper shock mounts seem to be 15-20mm closer together than the standard lower mounts on the swinging arm and bevel box casing if the upper mounts were centred on the frame tubes. Or perhaps I've measured something wrong?

Alternativly do the lower mounts need to be moved inward? What about clearance between the tyre and the springs? Will the inclined shock idea only work with extended swinging arms?

Thanks
Mark

 

[sycomoto]

just looked at camille

when mounted straight onto the frame the mounts on the swingarm have to be offset to the outside due to the frame being wider than the swingarm. make sure the shocks are inline because the force has to be straight up and down on the shock, they can be canted forward as the swingarm moves in an arc but they won't work well if the force is angled inwards unless you let the shocks float on some form of rod end or spherical bearing.

hope this makes sense