Filing holes for the bonnet locks

Next on the agenda was the bonnet and nose cone.  We accurately measured the holes for the front locating dowels. We clamped the bonnet and nose cone together with 3 clamps. Carefully aligning the contours for an accurate fit.  We drilled through the pilot holes for the locating dowels in to the nose cone to transfer and align them.  We separated the bonnet and nose cone and fitted the locating dowels in the bonnet We opened out the dowel locating holes in the nose cone and fitted the rubber grommets.

Then we trial fitted the bonnet and nose cone. Using masking tape we created and transferred the rivnut locations to the nose cone and drilled them out. We bolted the nose cone to the chassis and trial fitted the bonnet. Despite all our efforts the nose cone alignment was below the contour of the bonnet. We put 2mm shims under the nose cone to equalise the nose cone, by compensating for the distance between the top of the rivnut and the body.

Aligning and Fixing Bonnet and Nose Cone

We made several attempts at alignment and though we improved the fit it was not to our satisfaction. The problem we had was, that the insertion of the packing pieces also lifted the bonnet, meaning we needed to adjust the grommet positions. However we notice that when the rear of the bonnet was pressed in to position the front rose up.  We considered an adjustable mechanism so that we could fine-tune the alignment, possibly sliding plates with a locating hole in the middle so that we could adjust the bonnet with the nose cone in situ.  We ran out of time and were getting stale as we mulled over the options

On the way home I realised we were approaching the problem from the wrong end. The idea was not to adjust the grommets but to adjust the dowels.  The theory was that we pack the nose cone up to its correct height and move the dowels correspondingly, to fine tune the alignment.

Bonnet Locks

Finally we got the bonnet and nose cone to align to our satisfaction. After a lot of trial and error we made a couple of 2mm aluminium shims to fit under the nose cone to level it with the bonnet We removed the nose cone grommets to allow the pins to align themselves whilst we adjusted the bonnet and nose cone.  When we refitted the grommets the alignment was good. Measuring the nose cone to attach it to the bottom bracket was not easy. We eventually did it and drilled out the hole.  The nose cone is slightly asymmetric but this can be adjusted at final fitting.  We fitted the bonnet locks. These were new type ones and Westfield provided us with a template for fitting them to the bonnet.  There was no particular difficulty, we just carefully drilled out the holes with a pilot drill and then filed to size