Modern steering rack?

[sdc]

The feel and weight of the steering is determined by a number of components, key is a torsion bar that sits inside the pinion valve body. This has to be 'wound up' before the hydraulic assistance starts to cut in and provides the initial weighting. The pump characteristics do have an impact but much less so. The valve in the pump does two things, firstly it controls the flow rate from the pump, this can be used to fine tune the feel of the rack, and secondly it is a pressure relief valve, this only comes into effect on full lock (system hissing like mad). When we manufactured the racks for Triumph there were a number of different torsion bar sizes for different customers & applications. In my experience, reconditioned racks often have the wrong torsion bar fitted.

[V Mad]

When we manufactured the racks for Triumph there were a number of different torsion bar sizes for different customers & applications. In my experience, reconditioned racks often have the wrong torsion bar fitted.

Thats very interesting and ties up with my experiences of variation of assistance between racks.

Also interesting is your comment on the pump. If the pressure relief only activates at endstops then that suggest that pump pressure hence assistance would vary with revs.