Any head steady which prevents movement in the vertical plane will transmit vibration. The isolastics work because of the clearance between the ptfe thrust washers and the fixed end caps on the iso tube and iso bolt. Clearance needs to be kept to a minimum to minimise movement of the rear wheel in relation to the frame centre line in the horizontal plane. Any head steady using the rod end linkages only allow movement in an arc (albeit a small arc) so therefore will transmit vibration.
It's apparent on this forum a handling/frame question can't go unanswered without somebody mentioning 'the hinge'. The only hinge on any Commando is on the Mk3's seat.
The actual cause of leading some people to think there is a 'hinge' inherent in the Commando's design, is actually the swing-arm axis out of perpendicular in the vertical and/or horizontal plane to the steering head axis.
When this is the case, as the suspension moves up and down e.g at speed, leaning over through a bumpy corner, the rear wheel centre-line in relation to the frame centre-line will be constantly moving to and fro giving very similar symptoms to worn swing-arm bearings.
This is the number one problem with Commando's which don't handle through bends - as well as those which weave in a straight line.
