by Steve J » Sat Dec 23, 2017 4:53 pm
It's just the distance the torsion arm needs to be pulled forward to allow the pivot pin to be inserted through the lugs on the engine case and the hole in the torsion bar link. Just fit the bush or needle cage bearing into the torsion bar link, and with the rear buffer in the engine resting against the pad on the frame upright, position the link between the two lugs on the frame. Look through the bore of the outer engine lug (LH side of engine), and you will see the link and bush/needle cage bearing partly obscuring the view through the lug. The preload obtained when the pivot pin is fitted will be equivalent to the distance between the inner edge of the hole through the lug (at its forward edge) and the inner bore of the bush/needle cage bearing, again at its forward edge. The easiest way to measure this is with a short steel rule laid flat across the face of the engine lug, and then estimate/read off the distance from the forward edge of the bore through the lug to the forward edge of the bush/needle cage. OK, it's not exact, but you will be able to get a reading to better than 1mm accuracy, which is all that's really needed here.