Tech Analysis | How the MCL39 'risky' front suspension unlocked even more performance

McLaren ran their car for the very first time at Silverstone for the 200 km shakedown and it was already possible to admire some major changes in some crucial areas of the car, among all the front suspension. Despite having adopted the pull-rod scheme since the beginning of the ground-effect regulations in 2022, the Woking based team completely changed the arrangements of the arms (both upper and lower wishbone), of the pull-rod and the steering arm as well, to get a benefit from an aerodynamic point of view. 

As the car hit the track in Bahrain, it was possible to appreciate a massive level of anti-dive between the front and rear arm of the upper wishbone on the front suspension. To explain why anti-dive is adopted on F1 cars, it’s important to know that breaking causes load to be transferred from the back of the car to the front, normally causing the nose to dive as the additional load compresses the springs. 

The principle behind the anti-dive geometry is very simple: front suspension pivots are inclined in such a way that they counterbalance the dive forces (the two black arrows directed to the top in the figure below). In this figure, it’s possible to appreciate how the wishbone pivots have been inclined so they converge to the rear. The two red lines drawn through the upper and lower bearings are parallel and this is mainly done to generate an anticlockwise moment that balances the clockwise moment caused by the dive under braking.  

The exasperation of this concept, as seen on the Papaya car, has two reasons: 

• The first is for aerodynamic puroposes: as it’s possible to appreciate in the drawing below, the yellow dotted line and arrow highlight the big height difference between the rear and front arm of the upper wishbone. The engineers, in fact, placed the rear arm very low and far behind, almost aligned with the inlet of Venturi channels. As a direct consequence of this choice, the airflow is pushed up to feed the cooling inlet, increasing the amount of air that cools the PU components. 
• Secondly, this design maintains the aerodynamic platform much more stable: generally speaking, the pull-rod scheme helps maintaining the platform much more stable than the push-rod, particularly on this generation of cars. As seen during the last two seasons, in fact, those cars that adopted a pull-rod front suspension seemed to perform very well through high-speed, thanks to the steady platform, while struggled a little bit more at slow speeds (like the RB19 or RB20). For McLaren in particular, this scheme provides a great advantage, as it allows the engineers to adopt slightly softer set-ups (in terms of springs and dampers), allowing the MCL39  to behave very well also on bumpy surfaces and at slow speeds, while still being able to extract a lot of downforce form the Venturi channels (that are kept at a beneficial height from the ground by the suspension system). 

Particularly significant were Red Bull’s director Pierre Waché words about this suspension layout: “The McLaren is very interesting. […]Their front suspension is very interesting, but also very risky from our point of view. It will be very interesting to see if they can make it work.”

These words are the proof that the new suspension can lead to big performance gains if McLaren can get it to work properly. The French engineer, in fact, hints that the problems with this suspension design could be caused by the difficulty of setting it up, which could perhaps arise on more difficult circuits. McLaren’s idea was quite innovative and, for what was seen during testing, they managed to set it up correctly. 

Thanks to everything said above, the MCL39 behaved very well during testing, being very balanced both during the qualifying simulation as well as in the long runs, where it looked extremely gentle on tyres and fast on every compound. As seen during last season, the car seems to still suffer a little bit the hot temperature and rear-limited circuits like Bahrain, but the progress is sizeable. 

During testing, McLaren even tried some different rear and beam wing specs for the first few races of the season: during the first afternoon with Norris, they tested a low downforce rear wing matched with a single-element beam wing. As it’s possible to appreciate in the drawing below, the rear wing version they tried is characterised by a  a very tiny spoon in the central part of the airflow to generate a bit of downforce in this area, while the profile has a smaller (almost flat) inclination as it continues towards the endplates, to minimize the drag produced and increase the top speed. Furthermore, as regards the single beam wing element used, it has a curvilinear trend of the trailing edge, with a smaller chord at two attachments to the endplate and to the rear impact structure. This design’s main goal it to convey the flow coming from the engine cover to the rear, producing some downforce while having a good top speed.

The following day, McLaren tested a double-element beam wing matched with the spoon medium downforce rear wing that best suited the Bahrain International Circuit. As it’s possible to appreciate in the drawing below, the rear wing kept was the same, but while the first beam wing version was the singe-element one described above (right portion of the drawing), the new version fit on Norris’ car was characterised by a second profile (left portion of the drawing), almost horizontal that contributed in increasing the pressure in the area between the two elements, slightly increasing the downforce generated compared to the single-element version (red arrows). 

All these tests done by McLaren were proof that the team felt comfortable of their car’s potential and were conscious to have a little gap to the first of their rivals. This encouraged them to make all the runs and comparisons necessary to really understand how different rear wing and beam wing specs worked and to make the better choice for the first few races of the season. 

In conclusion, for what it was possible to appreciate from the outside, the MCL39 looked the quickest and most complete car of the field during testing, being very versatile in every kind of corner, in different atmospheric conditions and with different compounds. This sets the tone for the beginning of the season, where the team led by Andrea Stella should be the main protagonist.