Deconstructing Formula 1: The front suspension

When we see major visual changes to Formula 1 cars, it's normally because of FIA regulation changes.

The last comprehensive bout of changes came for 2009, and they were fairly dramatic. The rules required a redesign of all the major aerodynamic surfaces - front wing, rear wing, sidepods, engine cover and diffuser to name but a few.

But something that has been changing quietly in the background over the last five or six years is the front-suspension linkage. This style, angled upwards to the chassis wishbones, has now been adopted by all the teams. Some have gone more extreme than others, but all are following the same concept.

I have always believed that suspension geometry is vital in getting the best from the tyres and, in turn, the car. Yes, aerodynamics are without doubt the overall defining factor when it comes to lap time, but that performance is only transmitted to the track surface through the tyre contact patch.

For me, getting consistency and minimising tyre degradation over a run is all down to how kind your suspension geometry is to the tyre contact patch.

Compare and contrast: Ferrari's 2004 (top) and 2011 front suspension lay-outs © LAT

If we look back at the Ferrari F2004 - one of the best F1 cars of the past decade - it now looks like a simple, conventional car. The front suspension is conventional, with an upper and lower wishbone and pushrod driver damper/spring unit. The geometry would have been normal in that it would have had good control over the force centre, some camber change when the suspension went into bump, and as a result good lateral control over the movement of the tyre contact patch.

Let's take a step forward seven years, and look at what the teams have got and why they've got it.

FERRARI

The angled wishbones from the upright/wheel assembly to the chassis open up many opportunities for development, but all of them are aerodynamic and offer nothing positive to the mechanical package.

Comparing the old with the new, there is a considerable difference in the suspension philosophy, but actually the Ferrari is probably the car that has the least-extreme suspension geometry.

Red Bull's 2011 front suspension lay-out © LAT

RED BULL

When it comes to wishbone angle, Red Bull has pushed the limits to the maximum. Where the wishbone pickups meet up with the chassis, it looks like the RB7 is running with quite a lot of anti-dive. This helps support the car under braking, making it less aerodynamically pitch-sensitive. With the top wishbone mounted as high as possible within the wheel, it leaves no room at this height for the steering arm.

So, like most other teams, Red Bull has a steering trackrod and steering arm that is mounted lower than the top wishbone. If you compare front-wheel to rear-wheel vertical angle, we can see that the RB7 is also running a lot of front camber.

McLaren 2011 © LAT

MCLAREN

A bit different from the others: the top and bottom wishbone are closer to each other, which allows the trackrod to be in line with the top wishbone. The lower linkage consists of two separate members as opposed to an 'A'-frame wishbone - it's quite tricky to work out the geometry of this, but with the rear leg being as low as possible it helps increase the stiffness of this component under braking.

Like Ferrari, the McLaren is not quite so extreme as far as wishbone angle is concerned.

Renault 2011 © LAT

RENAULT

The suspension is very neat, and like McLaren's the steering and wishbone are in line. But Renault has gone a different route in incorporating the front trackrod into the lower-wishbone leading edge, which puts fewer mechanical components in the airstream. But by having the trackrod in front of the lower wishbone it increases the cord length of the assembly, giving the team more power over controlling the airflow wake off the trailing edge of the front wing.

Comparing front wheel to rear wheel, the Renault runs a lot less front camber than the Red Bull.

Mercedes 2011 © LAT

MERCEDES

The wishbone angle is less extreme than the others, and the car also has a fairly shallow lower-wishbone-to-pushrod angle. This reduces the ratio of wheel movement to inner-pushrod-end movement, making it more difficult to get a reasonable mechanical ratio on the rocker that operates the spring/damper unit. If this ratio is poor, it leads to an increase in the pushrod loads, and more problems with stiction in the rocker-mounting assemblies.

The tyres are running with a lot of front camber, and the left-front - with its inner-shoulder blisters - shows what happens when you exceed the tyre's working parameters.

So why do the teams push design parameters to - and sometimes past - the limits?

With aerodynamics defining 99.999 per cent of the performance of a current Formula 1 car, getting that little extra is the challenge for every team. Having a higher chassis reduces the blockage behind the front wing, meaning it will work that little bit more efficiently. The higher chassis will also allow better airflow management by way of larger, more aggressive, turning vanes mounted underneath to improve the performance of the airflow to the leading edge of the underfloor. This is very important, as these two areas are responsible for the total amount of front downforce.

More importantly, there is a huge vortex set up where the FIA-defined symmetrical centre section of the front wing joins the downforce-producing flap components. This vortex then goes under the lower-front wishbone and, aided by the bargeboards, goes around the leading edge of the sidepods and down the side of the underfloor, helping with the performance of the diffuser among other things.

If the lower wishbone is too low, this vortex will be broken up and it will lose its structure, rendering it useless. Details such as this are the small differences between a good car and a not-so-good car, but as with anything it all comes at the expense of something else - in this case a suspension geometry that may just give the tyre an easier life. And we all hope an easier life will hopefully turn out to be a longer life.

Giancarlo Fisichella finished third in the 1997 Canadian Grand Prix © LAT

As a side story, at the 1997 Canadian Grand Prix we had a rear-tyre-blistering problem with both our Jordans in Friday practice. In the evening I sat down with the Goodyear tyre engineer and discussed this problem. The tyres had what was called ply-steer coming from the construction of the carcass of the tyre. Goodyear always mounted the rear tyres in such a way that the ply-steer from the left and right tyres forced against each other, and after thinking about it for a while I asked them to mount them with the ply-steer force working the other way.

They were against it to begin with, but to keep me from spitting my dummy they did it, and on Saturday - which turned out to be hotter - we had no blistering problems, even though most other teams did. Needless to say the Goodyear tyre fitters were very busy all through Saturday, swapping everyone else's tyres. We went on to finish third with Giancarlo Fisichella, so all in all a good weekend.