Superior Engineering's Superfles Radius Arms

[Peter Connan]

The castor correction can be done relatively simply on the superflex arm by changing the location of the middle bush, maybe you would consider castor correction bushes on the right radius arm then you only need to fabricate the one arm.

Adrian my feeling is that the easiest way to correct castor is with the thin plates joining the superflex arm with the original axle mounting points.

Why not fit the additional bush in both arms and keep the load paths symmetrical? With one stiff and one less stiff arm, the lion's share of the torque reaction (braking, acceleration) will be borne by one arm only.

Gerrit the guys who developed it sometimes run with one standard arm and one modified arm, therefore the system can work unbalanced. I will try it first with two superflex arms using standard bushes, in order to get the maximum advantage, but if there is too much axle twist under braking, I will fabricate one or two stiffer bushes in order to limit this, at the expense of flexural freedom.

[Gerrit Loubser]

The distance between the rubber bushes on the patrol is 240mm whereas this distance is 165mm on the range rover and 186mm on the land cruiser. Clearly this greater separation is why flex at the front of patrols is not as good as either the range rover or land cruiser.

Not necessarily. The rubber stiffness also comes into play, so it is possible that the Patrol, Cruiser and Land Rover all have similar front axle roll stiffness, despite having different bush separation distances. In my opinion there is not a huge difference in front end flex between the three (some of the Cruiser guys actually reckon that the Patrol has a bit more front end flex than their steeds).

Basically the superflex arm moves the two bushes on the passenger side closer together (100mm) which reduces the stiffness of the front suspension.
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There are still only two rubber bushes on the superflex arm, the front connection is essentiall pinned and does not offer any movement.

I misunderstood how the Superflex arm works. Thanks for clarifying

You will also notice from the picture that the standard bushes are essentially parallel with the ground whereas the superflex bushes are almost vertical, I think this helps apply more leverage on the bushes which assists the flexing.

I doubt that this makes a difference. Essentially a moment has to be reacted by two forces working in opposite directions and separated a certain distance from one another, so the only relevant parameter is how far they are separated from one another. Their direction is immaterial.

Because both bushes on the superflex arm are still equally radially spaced on the axle there will be differential traction or braking forces introduced into the axle.

Not sure if you meant to say that there will not be differental traction or braking forces introduced. The amount of traction or braking moment reacted by the flexible Superflex arm will be less than that reacted by the stiffer arm. This is an inescapably consequence of having two possible load paths of different stiffness; the stiffer one always carries more load.

The Superflex arms themselves would probably not have any problem with this, but the durability of the mounting plates on the axle might be affected. Then again, reducing the front axle roll stiffness would tend to reduce the forces transmitted to the axle when the bushes wind up during flexing, so it is an open question whether one would end up ahead or not. Having a symmetrical system would still be preferable from the point of view of engineering purity and this would allow the use of stiffer and hence probably more durable bushes for a given axle roll stiffness. These stiffer bushes would probably also allow the most accurate axle location, something that might be benficial to on-highway handling.

The unequal torque reaction forces might also induce slight body roll under acceleration or braking, but I doubt that this would be very cleary perceptible.