Jeremy,
When springs (or torsion bars) are loaded, they take a 'set' in that direction. Torsion bars are different to most coil springs in that the load can be reversed, so that when a torsion bar is subjected to (say) an anti-clockwise twist and then it is reversed, it is likely to settle again by an amount equal to twice the 'set'. For this reason, Mr Douglas colour coded the torsion bars so that they could be identified as either LH or RH, very necessary if a bar was being swapped from one machine to another, but if you swapped the torsion bars side for side on the same machine, the worst they would do is settle equally and need to be re-adjusted for ride height. The big problem occurs when replacing just one bar that is not identified, as this bar could then settle and create excessive loads on the opposite bar.
Whilst we are on the subject of suspension - have you looked at the front forks? Mr Douglas provided 2 options for front fork springs - a parallel (heavy duty) spring and a lighter duty tapered spring. Now the tapered spring is effectively a multi-rate spring, and Mr Douglas shows it fitted in the forks large diameter upwards - I think this is wrong, as it is normal practice to fit multi-rate springs with the strong end taking the shock load (to prevent the weak end becoming coil bound - a major cause of springs breaking). In recent years, quite a few Mark series machines have suffered spring breakage - could it be due to incorrect fitting of the spring? I have always inverted my springs - and had no problems - even on my Comp which has 'bottomed' the front forks many many times!!
Regards,
Eddie.
