Mercedes W09 wheel, Autodromo Hermanos Rodriguez, 2018

Mercedes’ rear wheel holes ruled legal by stewards

2018 Mexican Grand Prix

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Mercedes have received a boost ahead of the Mexican Grand Prix after the stewards confirmed their contentious rear wheel hub design is legal.

The team requested an official clarification whether the spacers in their wheel design conformed to the regulations. The design was introduced several races, but questions over the legality of the holes in the wheel prompted Mercedes to seal them ahead of the last race in Austin.

The team suffered its first defeat for five races as its drivers struggled to manage their tyre temperatures in the United States Grand Prix. This prompted claims the rear wheel design had made a significant contribution to their car performance.

Doubts over the design’s legality centred on whether its holes served an aerodynamic function, and therefore might be considered an illegal moveable aerodynamic device, or were purely for heat transfer, making them legal.

Referring to the opinion of the FIA’s technical department, the stewards confirmed that “should Mercedes run the part as described in the correspondence between Mercedes and the FIA’s Technical Department, the stewards would consider this part to be in conformity with the regulations, but only with respect to the points raised in Mercedes request.”

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Stewards’ ruling on Mercedes’ rear wheel

The stewards received a written request by Mercedes Benz Grand Prix, Ltd, operating as Mercedes-AMG Petronas Motorsports (“Mercedes”) to settle a matter, as is provided for in the International Sporting Code’s Art 11.9 “Authority of the Stewards”, specifically Art 11.9.2.b which states that “They may settle any matter which may arise during an Event, subject to the right of appeal provided for in the Code.”

Art 12.8.1 of the Technical Regulations permits “spacers on the inboard mounting face of identical specification on all wheels for the same axle.” Mercedes runs such a spacer on their rear heelsand in order to reduce the heat flow across the junction between the axle and the wheel, they have added a number of small holes and grooves for cooling. Following the 2018 race in Japan, understanding that this scheme was in question, Mercedes requested clarification from the FIA’s Technical Department, as to whether this arrangement violated Art 3.8 of the Technical Regulations, which says in part “any specific part of the car influencing its aerodynamic performance must remain immobile in relation to the sprung part of the car.” The question therefore, was whether the air passing through these holes and grooves violated this provision.

The FIA’s Technical Department provided advice to the team, which in part confirmed that in the opinion of the Technical Department, that the configuration of the part in question would be in compliance with the Technical Regulations.

As with all advice given to the teams by the FIA’s Technical Department, the teams are reminded in those documents that they are “Advisory in nature and do not constitute Technical Regulations. it is for the Stewards, and ultimately the FIA International Court of Appeal, to offer binding interpretations of the Technical Regulations.“

Thus Mercedes requests:
“A) Confirmation from the Stewards of the interpretation of Article 3.8 of the Regulations as set out in the FIA’s Clarification and so the legality of the Part; or
“B) details of all changes required to the Clarification such that certainty surrounding the correct interpretation of Article 3.8 is achieved.”

The Stewards find that:
1. Our jurisdiction extends solely to this Event, and therefore decline to make a generalised interpretation of Art. 3.8. Further, we agree with the FIA Technical Department’s position that this would have to be addressed on a case by case basis, taking into account, at least, the specific points in the FIA Technical Department’s document of the 16th of October, 2018.
2. The FIA’s Clarification and acceptance of the part specifically states that it is limited to the part presented by Mercedes in their submission to the FIA and that alternative design options would have to be considered separately.
3. The opinion of the FIA Technical Department is correct when they state:
“Regarding the legality of the holes in the spacer:
“1. To determine whether the holes have an aerodynamic influence, one has to consider their size, shape and function. Small holes will tend to have primarily a cooling function, and while we can at times consider cooling to be an aspect of aerodynamic performance, we feel that cooling of very localized areas (as in your design) can be acceptable.
“2. The spacer is specifically part of the wheel assembly (as mentioned in Article 12.8.1), so provided its main function is that of a spacer, we feel that having some localized bleeding of the flow for cooling can be acceptable. The fact the spacer rotates is inherent in its function, in much the same way that the wheel rim spokes rotate.

Hence for the above reasons, we consider the spacer geometry you have adopted to be permissible, although we would reserve [the] right to judge alternative geometries, and to change this view if (for example) the spacer were to grow beyond its primary function (that of a spacer) and if the holes were to become big enough to have a more significant aerodynamic effect.”

Therefore, the Stewards confirm that should Mercedes run the part as described in the correspondence between Mercedes and the FIA’s Technical Department, the Stewards would consider this part to be in conformity with the regulations, but only with respect to the points raised in Mercedes request.

Competitors are reminded that they have the right to appeal the decisions of the Stewards (with the exception of those referred to in Article 12.2.4 of the FIA International Sporting Code), in accordance with Article 15 of the FIA International Sporting Code and Article 9.1.1 of the FIA Judicial and Disciplinary Rules, within the applicable time limits.

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Keith Collantine
Lifelong motor sport fan Keith set up RaceFans in 2005 - when it was originally called F1 Fanatic. Having previously worked as a motoring...

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  • 36 comments on “Mercedes’ rear wheel holes ruled legal by stewards”

    1. Good news. This gives Hamilton the chance to win the title on the podium.

      1. @blackmamba
        Unless Vettel goes for a slice of Hamilton’s tyres at the start.

        1. Or if the moon falls on him.

    2. If it doesn’t diminish the structural integrity of the wheel, then it’s legal. No reasonable person would call that aerodynamic.

      1. @zapski: Good thing F1 is filled with reasonable team principals… oh…wait.

      2. That depends. The red bull version was indeed similar and was an aero aid. Merc have clearly managed to make this in a way that is not benefiting the aero.

        1. @Lee1 It’s not that it benefits aero, it’s about whether it’s primary function is to aid aero performance or that any boost in aero performance is just a side-effect. Both Red Bull’s blown axles and Mercedes FRIC Suspension (among other developments) were explicitly designed to improve the aero performance of the car, so therefore contravened the rules.

          The FIA state in the ruling that there may well be an aero effect (including a better overall aero platform because the car can run faster for longer, generating more downforce) but the primary intention of the design is to manage thermals, so it’s legal.

          1. This is not how it works. You can’t just claim that the intention was to manage thermals and then automatically something that increases aero benefits becomes legal… If so then Red Bull would have simply claimed that their design helped with heat dissipation…

            Merc will have to have proven that there is negligible aero benefit to their solution.

            1. “1. To determine whether the holes have an aerodynamic influence, one has to consider their size, shape and function. Small holes will tend to have primarily a cooling function, and while we can at times consider cooling to be an aspect of aerodynamic performance, we feel that cooling of very localized areas (as in your design) can be acceptable.

              Hence for the above reasons, we consider the spacer geometry you have adopted to be permissible, although we would reserve [the] right to judge alternative geometries, and to change this view if (for example) the spacer were to grow beyond its primary function (that of a spacer) and if the holes were to become big enough to have a more significant aerodynamic effect.

              I didn’t say that the team could just ‘claim’ it, they had to functionally prove it – which was fairly obvious with the design and explanation of how the wheels would work.

            2. It clearly was not obvious, otherwise the other teams would not have protested and also Merc would not have felt that they needed to change it for Austin in case they were subsequently disqualified…

            3. Lee1 – Maybe he means it was obvious to the stewards when it was explained to them. And perhaps other teams are more likely to protest when they don’t understand…

    3. So modifying the hub is allowed mid-season ?
      Certainly sets a precedent then.

      They should design the rear wheel as a fan to suck air out from underneath the car, kinda like the BT46 but much less efficient and only working on the straights. I guess you’d have to design the rear tightly around the rearwheels, with the new 18″ rims that’d be possible….

      anyone have access to F1 in schools F1 VWT -software to test this :) ?

      1. A precedent set in 1956 by Owen

      2. reasonable chap
        26th October 2018, 8:49

        Why would you want to increase the downforce on the straights? wouldn’t that make the car slower?

      3. @uneedafinn2win It wouldn’t be possible, because designing the wheels to channel air in order to improve aero performance would contravene the ‘moving aero device’ rule as the tyre isn’t a fixed device.

        Mercedes design is to improve their tyre management, so it’s completely unrelated.

    4. ‘Cheese Grater’ rear wheels. Interesting.

      1. Improved surface area = more heat dissipation.

    5. Can anyone give me a layman’s terms description of the difference between Mercedes legal and Red Bulls illegal wheel rims?
      Thanks

      1. The primary function/intent of the Mercedes design is to improve thermal management. The primary function of the Red Bull design was to boost aero performance.

        Because a tyre is a moving component, it would constitute a moving aerodynamic device if it’s design was primarily about improving the aerodynamic performance of the car.

    6. Good news for the Sliver Arrows. Their tyre wear issue is definitely resolved. It will be really tough for Ferrari to catch them in the next 3 races unless Merc mess up their strategies or someone takes them out in the race. Pace wise they are evenly matched. If this handicap is gone, Merc will be really strong in the coming races.

    7. Holy hubcaps Batman! Wheels like a V6 washing machine.
      I find it grimly amusing that any innovation prompts instant complaints from other teams, yet they’ll all cheat if they can get away with it.
      They might as well go all the way at this point and turn it into a spec series. Everyone have the same chassis, buy an engine, and stick on a bodyshell covered in logo stickers.

      1. The ‘complaint’ (clarification) is a logical step. Little point in a number of teams expending vast amounts of resources chasing someone else’s innovation, only for that innovation to be ruled illegal at a later date. This way a ruling is given following clarification request, and teams can then work towards their own solutions if the innovation is considered within the rules.

      2. So, rather let people get away with things 100% of the time than complain about them?

        Let’s just say we’re fortunate you’re not running the sport.

    8. Re: “… or someone takes them out in the race.”

      Alternatively, Merc take themselves out of the race by colliding together. Hamilton ran into Rosberg a few years ago, ruining his own race. (As well as other poor outcomes. )

      1. What on earth are you talking about?

        1. It was a reply to Yellowflash (that didn’t get inserted in the correct sequence / location) who said:

          ” Good news for the Sliver Arrows. Their tyre wear issue is definitely resolved. It will be really tough for Ferrari to catch them in the next 3 races unless Merc mess up their strategies or someone takes them out in the race. Pace wise they are evenly matched. If this handicap is gone, Merc will be really strong in the coming races. “

          1. Ok. Hamilton and Rosberg had clashes on track but they were in an exclusive duel for the WDC until 2016. I’m interested to know which incident you are talking about between HAM and Rosberg though.

            1. He was talking about chances of collisions between Bottas and Hamilton; which Toto will never allow of course :)

      2. True that; but less plausible. Even if Ferrari takes 1-2 in all races and Merc takes 3-4, Ferrari can’t win WCC.

    9. how do they make them? anyone knows?

      1. The basic wheel is forged from one of the two legal alloys, and then the detailing is machined on.

        1. That’s closed die forging and the process was developed by Russia’s institute of Light Alloys.

          I couldn’t tell you for sure if Mercedes use liquid or flow forming, but the smart money would be on liquid.

        2. @sleepywill thank you, I was aware of the forged process, but the details were puzzling me, wasn’t quite sure if machining was the right way to do it, I imagined they were doing it pre-forming with some sort of stamping process.

          Those things are already expensive, with that amount of detailed machined I can only imagine how much it increases costs. Yet it did give them and edge on tyre management

    10. I guess to reduce weight. 1 kg on six G, on most corners, is 6 kg , say 10 corners is 60 kg less on the tyres each round , 20 rounds on a set is 1200 kg less. So reducing the wear on the tyres.

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