PAS adjust weight of steering
Discussion
Like the title says is there an easy way of making the steering a bit heavier and more feelsome on a car with overly light steering. I am discounting changing the rack as too expensive and with the tyres and suspension already fairly optimised. What I am thinking is would changing the pulley on the PAS pump make a difference?
No.
Most traditional hydraulic PAS systems work by generating the same pressure in each side of the rack. As you turn the wheel, a valve near the pinion disturbs the balance of the pressures so that one side "wins" and the rack gets pushed away from the side with the higher pressure. If you reduce the pressure coming out of the pump with a pressure reducing valve, the balance of pressures is still the same - just lower on both sides of the rack. The result is that you don't get enough fluid flow rate to fill the rack when you move it quickly so if you had to swerve, the steering would suddenly go very heavy until the fluid caught up. If you make the pump turn slower by putting a smaller pulley on it, the same thing will happen - it won't be able to flow enough fluid through the rack in a fast swerve.
As far as I'm aware, the only way would be to change the diameter of the torsion bar inside the valve block which governs the balance between the pressures in each half of the rack but this is a very difficult job without pretty advanced machining facilities. Similarly, removing the assistance altogether would make it (quite a lot) heavier but would probably feel pretty horrible as there would be "play" in the rack pinion valve without any fluid in it. It might also be dangerous as the pinion might not be strong enough to withstand the extra torque.
Most traditional hydraulic PAS systems work by generating the same pressure in each side of the rack. As you turn the wheel, a valve near the pinion disturbs the balance of the pressures so that one side "wins" and the rack gets pushed away from the side with the higher pressure. If you reduce the pressure coming out of the pump with a pressure reducing valve, the balance of pressures is still the same - just lower on both sides of the rack. The result is that you don't get enough fluid flow rate to fill the rack when you move it quickly so if you had to swerve, the steering would suddenly go very heavy until the fluid caught up. If you make the pump turn slower by putting a smaller pulley on it, the same thing will happen - it won't be able to flow enough fluid through the rack in a fast swerve.
As far as I'm aware, the only way would be to change the diameter of the torsion bar inside the valve block which governs the balance between the pressures in each half of the rack but this is a very difficult job without pretty advanced machining facilities. Similarly, removing the assistance altogether would make it (quite a lot) heavier but would probably feel pretty horrible as there would be "play" in the rack pinion valve without any fluid in it. It might also be dangerous as the pinion might not be strong enough to withstand the extra torque.
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