Tech analysis: What's behind Mercedes suspension controversy

For while it has been aggressive in bringing aerodynamic developments to its W07, that does not appear to offer the full explanation of the gap it has had over its rivals.

Over recent weeks, however, there has been growing intrigue about suspension developments, with a report in respected German publication Auto Motor und Sport this week suggesting that rivals want F1's rule book tweak to outlaw what Mercedes is doing.

So what is behind this latest controversy? What is Mercedes up to and how has it gone about keeping its edge?

Mercedes W06 front suspension bay

Photo by: Giorgio Piola

FRIC lessons

There was a bit of intrigue around the W06 in Brazil last season when Mercedes began testing suspension components and an 'S' duct solution in preparation for this year.

It highlighted the development direction the team had been on for a number of years and continues to refine, encompassing their learnings when the cars were FRIC enabled.

FRIC was the Front-to-Rear-Inter Connected Suspension that was banned by the FIA in the middle of 2014. It used hydraulic accumulators connecting all four corners of the car to help stabilise it, improving both mechanical and aerodynamic performance.

It's important to say at this stage that FRIC or any hydraulically-controlled suspension currently in operation is not 'active'.

These are passive systems that are tuned to work harmoniously rather than being programmed to react to a particular situation.

The FIA issued a technical directive after the British GP in 2014 insisting that FRIC constituted a breach of the regulations as it helped with the aerodynamics of the car.

However, due to the scope of the systems in place, the governing body said it would turn a blind eye to it being run until 2015 unless a team lodged a protest. All of the teams set about removing their systems from that moment though, in fear results could be changed if a protest was launched at a GP weekend.

Ongoing development

When items like FRIC get banned, teams do not simply turn their backs on such ideas, and the lessons learned from FRIC were applied to fresh development avenues for suspension systems.

Mercedes, which was at the forefront of FRIC, continued to develop hydraulic systems to improve the overall stability of the chassis, be it during braking or cornering. It is something that can be seen by its drivers' ability to ride kerbs and take more aggressive driving lines without adversely affecting tyre life.

Mercedes W07 front suspensions

Photo by: Giorgio Piola

The W07 features a fully hydraulic front end, with the heave or third suspension element the key to understanding how it differs from many of the other teams.

The heave element is placed just behind the rocker assembly (see inset) and helps to control the vertical displacement of the suspension, an arrangement mirrored at the rear of the car.

All of the teams use a third/heave element but only a few have hydraulic units. Renault and Sauber are the other teams that come to mind, although neither is on the complexity level of Mercedes arrangement, likely due to budgetary constraints.

The rest of the field continues to use a spring assisted third/heave damper, although Red Bull and Williams use Belleville springs to fulfil their demands.

The trick behind the design

Mercedes AMG F1 W07 Hybrid front detail

Photo by: Giorgio Piola

Mercedes has had to be particularly aggressive in terms of packaging to accommodate the access needed for adjustments, taking a large wedge out of the upper part of the bulkhead.

Manor MR03B front chassis structure

Photo by: Giorgio Piola

This is done thanks to an allowance in the regulations that came about when Charlie Whiting allowed Manor Racing to run a chassis spacer last year as it adapted the MR03 to conform with the nose transition regulations.

The use of a vanity panel, a leftover from the aesthetic compromise the sport introduced in 2013 to disguise the hideous step nose, is the last piece in the puzzle that allows this packaging and also provides channels for air to flow through the nose to the upper chassis outlet.

Whilst almost every team takes advantage of the retention of the vanity panel to package its suspension components more effectively and gain better access, none has gone to the level that we see Mercedes has gone to.

Red Bull Racing nose assembly

Photo by: Giorgio Piola

It's worth noting though that both Red Bull and McLaren have positioned their rocker arms particularly high, which perhaps wouldn't be possible without the chassis/nose transition and vanity panel rules either.

Tipping Point

The benefits of such a complex suspension system are clear.

One of the largest factors in determining performance is the treatment of tyres. Creating a more stable chassis is clearly going to enhance performance and reduce degradation, but it can also have aero implications too.

A tyre undergoes significant changes in shape throughout a lap depending on the load imparted on it, but if you are able to reduce this you'll make the shape change more predictable.

This can be incredibly helpful to the design team, as it reduces unstable flow structures during transitional phases such as braking and cornering.

It also creates less fluctuation inside the tyre, keeping pressures and temperatures stable: making it easier for the driver to keep the tyre in the operating window.

Mercedes brake heater, carbon casing

Photo by: Giorgio Piola

For this reason Mercedes was widely regarded to have been one of the best at managing tyre temperatures - amid suggestions that it used clever heating of brakes before the start of the race to regulate things.

However, that theory was debunked after the FIA revised its checking procedures on minimum pressures to before tyres were fitted to the cars - and yet Mercedes carried on heating the wheels.

In Hungary, though, it was noted that Mercedes revised its third/heave element once more, likely in response to this procedural change and it has seen them edge away from the opposition once more.

Where to now?

It appears that the chassis trick employed by Mercedes to grant the aggressive packaging has now become a big talking point.

However, despite suggestions it was put up for discussion at the latest meeting of technical directors with the FIA, it is understood it never actually got talked about.

That will not stop any private lobbying though, although a short term change is thought highly unlikely.

With the regulations already beyond the point of no return for next season, it would need a unanimous vote from the teams to change the regulation now, which will not happen.

Mercedes will undoubtedly continue to chase this development and rivals may be forced to follow suit, even if the FIA responds and outlaws the trick for 2018.