Saturday, 22 January 2011

Assembly of Rear Suspension

The wishbones were all fitted with the 'weld marks' to the rear of the car. You would then expect the damper/spring to just bolt on between the chassis and the upper wish bone. If only it were that easy. The manufacturing tolerances or the design of the chassis jig don't allow this. Only after disassembly and reassembly in different sequences did I get it all to fit together. In the end I fitted the two wishbones to the upright, but not to the chassis. Then the damper/spring was fitted. Followed by the upper wishbone to chassis and finally the lower wishbone to chassis.

If you look sideways on you will see that the damper/spring fits, but only at a slight angle. In this view you can also see the spacer/crush tube that had to be cut to length and fitted between the two mounting lugs on the top of the upright.

Before fitting all the washers and nuts I followed Jim Dudley's guidance for setting up the rear suspension geometry (camber). To do this the shorter front dampers were installed on the rear (yes more disassembly and reassembly). The shorter front dampers allow the suspesion to hang in the position it will be in when the weight is on the wheels. With the car level on the floor a 1 metre length of square tube was clamped vertically to the upright and then a 900mm spirit level used to determine +1 degrees camber from the vertical. Using the small angle approximation it was detemined that a delflection of 13.5mm was required. This is for road use, more camber would be needed for track use. The rose joints on the lower wishbones were screwed in and out until the required deflection was maintained.

With the rear dampers/springs refitted all nyloc nuts and washers were fitted. Washers were fitted either side of the lower wishbone rosejoints. The nuts were kept loose and will be fully tightened when the cars weight is on the wheels.

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