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Discussion Starter · #1 ·
Finally got round to sorting out the chain alignment.

The S4*R SSS models rely on the axial location of the swing arm to establish and maintain chain alignment. The manual calls for a minimum 1.8mm shim thickness on the swinging arm pivot between the left hand engine case and the swing arm, any axial play is taken up by shimming between the right hand engine case and the swing arm, shims are available in 1.8, 0.2 and 0.1 mm thickness, this reflects the precision required for chain alignment rather than wheel alignment which is also affected by the axial position of the swing arm.

The front sprocket is located axially by a keeper plate that engages into a slot in the shaft, there is a fair amount of ‘slop’ in this mounting arrangement

My S4R has exhibited abnormal front sprocket wear since new, the pictures below indicate excessive wear on the inside face of the sprocket, in the first pic, the sprocket has done about 4k in the second, 600.

The wear pattern indicates a misalignment between the sprocket and the chain, in addition wear on one side only of the keeper plate teeth suggest that the sprocket is axially loaded (by the misalignment) during operation, illustrated below.

I rigged up a straight edge located to the outside face of the rear sprocket, this indicated that the rear sprocket was displaced to the right a distance of 2mm .

Since neither the font or rear sprocket have provision for adjusting the axial position, the only recourse is by displacing the swing arm to the right, replacing the 1.8mm shim with one of 0.1mm (to eliminate aluminium to aluminium contact), reduced the error to 1.7mm.

A further 0.2mm will be obtained by grinding the outside face of the front sprocket flush, the Afam sprocket shown below has a 0.2mm raised center boss, the keeper plate locates on this boss, displacing the actual centerline of the sprocket teeth by that amount. The OEM sprocket is by contrast completely flat. Note the absence of wear on the outside of the sprocket face

This does of course mean that the rear wheel has be displaced 1.7mm off of the centerline (if it was ever on it in the first place) I doubt whether this will have any perceivable affect on the handling. John Hacket (of JHP) told me he has never seen a Ducati with its wheels perfectly in line.
At some later date I intend to get the wheel alignment checked.
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