Front Anti Roll Bar Solutions

An excellent Sutton Images picture seen on F1Talks.pl, taken through the aperture on the front of the McLaren has given us a rare chance to see the set up of the front suspension.

(http://www.f1talks.pl/2011/08/25/czwartek-na-spa/?pid=4590).

Typically most teams follow the same set up for the front suspension in terms of the placement of the rockers, torsion bars, dampers anti roll bars and heave elements. As unlike with rear suspension, the raised front end almost dictates a pushrod set up in order to the get the correct installation angle of the pushrod. However the McLaren antiroll bar shows there is some variation in comparison to the norm and also highlights Ferraris similar thinking in this area.

In comparison to my more recent posts, this is not a breakthrough in design, simply a chance to see the teams playing with packaging to achieve similar aims.

Typical front suspension

As an overview of the conventional of the rocker assembly in the attached diagram shows the rockers are operated by the pushrod, a lever formed by the rocker operates each of the suspension elements. Compressing the heave spring and wheel dampers, extending the inerter and twisting the torsion bars.

A typical "U" shaped ARB: Arms connect the torsion bar to the rockers via drop links

Typically teams use a “U” shape anti roll bar (ARB). In this set up the antiroll bar is connected to the rocker via drop links, and then each arm twists the torsion bar when the car is in roll. When the car is in heave (car going up and down, no roll) the ARB simply rotates in its mounts and adds no stiffness to the suspension. Different torsion bars in the anti roll bar create different roll stiffness rates for the suspension. Teams will either switch the entire ARB assembly for a different rate ARB. Red Bull have engineered their ARB for the torsion bar to be removed transversely through the side of the monocoque, in a similar fashion to removing the normal torsion bars.
However McLaren and Ferrari have gone a slightly different route.

Mclarens ARB

McLarens ARB is formed of two blades joined by a drop link

In McLarens case their ARB is a simple blade type arrangement. These blades are splined to each rocker the blades are joined at their ends by bearings and a drop link.

In roll, the blades react against each to create roll stiffness

When in roll the rockers rotate in the same direction, one blade goes down and the other goes up, the stiff drop link transfers these opposing forces and the blades flex. These opposing forces add stiffness to the front suspension in roll.

In heave, the blades move together

In heave the rockers rotate in different directions, both blades move down and the increasing gap between their ends is taken up by the drop link. So the blades do not flex and do not contribute to heave stiffness.
Different thickness blades create different roll stiffness; they must be removed from the rockers and replaced to achieve this.

Ferraris ARB

Ferraris ARB uses two blades joined by an elegant arched guide

Ferrari have used this solution at least since the late nineties, the idea has been seen on older Minardis too. I suspect the idea was taken to Minardi by Gustav Brunner, who may also be the creator of this elegant solution.
Similar to McLaren the roll stiffness is provided by blades splined to the rockers. But the connecting mechanism is instead a single bearing sliding inside an arched guide. Just as with McLaren ARB, when in roll the two ends push against each other to create the reaction force to prevent roll. When in heave the bearing slides through the arc of the guide and no force is passed into the suspension.

Summary
I don’t believe either of these solutions has a compliance benefit over the other. The McLarenFerrari systems may be take up a little less space inside the nose and may weigh a little less. But both will be a little more complex when changing the roll stiffness.

Assemblies

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