Lowe explains extra wheel tethers for 2011

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The number of wheel tethers on F1 cars will be doubled next year in a bid to improve safety.

McLaren engineering director Paddy Lowe, who is a member of the Technical Working Group, explained why the steps had been taken in response to recent accidents:

Tethers are a great concern to us. We had the tragic incident last year with Henry Surtees [in Formula Two]. And we also see wheels coming off Formula 1 cars rather more often than we’d like. The tethers are working, but they’re not reliable enough.

We maybe see one, two or three wheels detaching within a season. This year a wheel came off Alonso’s car in Monaco and there was one this weekend gone when Liuzzi crashed.

We discussed that at the Technical Working Group. One of our tasks in the TWG is to constantly improve safety. It’s through rules introduced by the TWG over 20 to 30 years that Formula 1 has become safer.

What we have agreed to do for next year and is now in the published rules is to introduce a second tether on every corner. Rather than each tether being 100% reliable what we’ve found is that when they don’t work it’s because they’ve been cut for some reason due to the particular nature of the accident.

Our thinking is that if you put two tethers on each corner that are run independently, so fully redundant – one in, say, the top wishbone and one in the bottom wishbone – then we’re going to drastically improve the probability that one or both tethers survive in an accident.
Paddy Lowe

Speaking in the Vodafone McLaren Mercedes phone-in, he added that the tethers were not being added this year because it was necessary to add extra connection points on the chassis for them.

Read more: F1 2011 Season

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Keith Collantine
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33 comments on “Lowe explains extra wheel tethers for 2011”

  1. The problem is that you can’t make the tethers infinitely strong because, even if it were possible, all that would happen is that an accident would tear out a corner of the car instead. At the front especially, that could easily be worse for the driver than having a wheel fly off.

    1. Well maybe, but as Lowe explained they’re not making them stronger, they’re just adding more of them, so that shouldn’t be an issue

      1. It depends. He might be talking about different things:

        – Multiple tethers of same strength as existing ones fixed to different locations (overall tether strength increased)

        – Multiple tethers of same strength as existing fixed to same locations (overall tether strength increased)

        – Multiple tethers of same strength as existing fixed to same locations but only act once existing set has failed (overall tether strength the same but with back-up)

        – Multiple tethers of fraction of strength of existing fixed to same locations giving same strength but multiple load paths (overall tether strength the same but rather pointless!!)


        1. the quotes above are quite clear, an ADDITIONAL tether, FULLY independant, and therefore redundancy built in.

          Your post sounds like you didn’t even read the article…

        2. Erm, try reading the article mate. It’s option one.

        3. I know, serious brain fade. I knew that that this post was pointless and redundant as soon as I came back on….! Sorry for the wasteful use of pixels!

    2. As was said at the time of the Surtees accident – you can make the tethers infinitely strong but they’ll be useless if attached to a block of cheese! :-)

    3. But that’s very unlikely to happen. The suspension will give way so the wheel WILL come off the car, what the tether does is prevent it flying off down the road etc as it will just flap about beside the car…

  2. These tethers, are they made into the suspension? So within the suspension arm itself, the tether is inside, sandwiched between the carbon fibre?

    1. Shaun Field
      28th July 2010, 12:43

      As far as I know, the suspension arms are hollow, and the tethers run though them (I stand to be corrected, please)

      1. damonsmedley
        28th July 2010, 17:49

        I would have thought that if that was the case there would be a lot more breakages.

        when they don’t work it’s because they’ve been cut for some reason…

        Being contained within a solid structure such as a suspension arm I’d have believed that the jagged and sharp edges generated by the suspension arm itself breaking would be enough to slice right through the tether. I have always been curious as to where the tethers are hidden and I still remain bewildered by the topic. I have often found myself staring at pictures of suspension assembly looking for the tethers! Does anyone know what they are made of? Whatever it is; it is pretty strong!

  3. This is good news and a sensible decision. Watching how close Liuzzi’s wheel came to hitting Glock (I think it was) was awful.

  4. Good news. We all know after the events of last summer how dangerous flying parts are. When Henry Surtees was killed last year it was only from a glancing blow; imagine then what could have happened had Glock hit Liuzzi’s wheel head on at speed on Saturday…

    Also, I get the impression some car’s seem to disintegrate and shed wheels far easier than others. In the past I remember Sauber’s often lost wheels even in small crashes. Now it seems to be Force India- think back not to just to Hockenheim but also to Sutil at Shanghai and Liuzzi at Interlagos in 2009 (and I have a nagging feeling there was another similar incident last year which I’ve forgotten!)

    1. damonsmedley
      28th July 2010, 18:15

      I think that the tethers for the rear wheels are far less durable than those at the front. Most accidents where the rear takes a considerable knock result in the rear tether/s being broken, such as Alonso in Monaco and Liuzzi in Brazil. I am not even convinced that rear tethers exist, because when I have seen a rear wheel dislodged however not completely detached, it appears to be only held by the not-completely-broken suspension assembly. I wish there was more information available about these sorts of things though… Especially the lack of onboard cameras.

  5. Electrolite
    28th July 2010, 13:03

    When Buemi crashed out one practice and both wheels came off, was that the same as this issue? Or was part of the chassis that came off?

    1. This was in China and he had a broken suspension upright. A new part which obviously wasn’t strong enough. When it exploded it affected both sides of suspension with massive loads causing the tethers to brake along with the whole suspension system itself. No way would a tether hold that!

    2. Charles Carroll
      28th July 2010, 15:19

      The “Buemi Bomb”, as I call it, looked more like the result of a well-placed explosive.

      1. damonsmedley
        28th July 2010, 18:07

        Haha! It was certainly hard to fathom when it happened…

  6. Did the tether fail on Liuzzi’s car, or did the tether tear away from where it was attached to the car?

    1. I can’t say for sure, but given the nature of the accident I would expect that the tether was sheared off by other car parts as the car crashed diagonally into the concrete barrier.

  7. The trouble is, even with an infinite amount of testing, nobody will be able to predict every possible scenario for an accident involving the cars hitting walls etc with such force to send the wheels and bodywork flying.
    That said, we have come a long way in development, and I am impressed in how the cars absorb the forces and still protect the driver (thinking back to Webber landing upside down at speed).
    Its good to know that the TWG is watching what happens and looking for an even safer future.

    1. I don’t think the idea is to have 100% success, which you can never have. You can only decrease probability, and that is exactly what they’re doing here.

  8. Very sensible idea from the TWG to have more than one tether in a different location. Good to see.

  9. Good idea, but when the entire suspension is ripped from the car, tethers attached to that suspension aren’t going prevent the wheel from flying. Somehow they need to be connected to the monocoque.

    1. in that case, there is a possibility that the wheels might hit the driver in the crashed car, as the tethers might need to be considerably longer

  10. fecklessmoron (@)
    28th July 2010, 15:43

    I’m surprised that TWG is making this change so suddenly. It seems that it would be possible for the two tethers to wind themselves around each other and pop off that way.

    However, I fully support their efforts to address the problem before there is an incident.

  11. Th extra tethers they are going to put on each corner need to be longer than the first tethers – that way when a wheel comes off the first tether will attempt to hold it and even though it may fail to achieve this & breaks it will have dissipated a lot of the energy from the flying wheel & in doing so which will give the second longer tether a much better chance of completing the task.

    1. I think the tethers are being broken by other parts of the car that have broken off or on impact with whatever the car hits, I don’t think they’re breaking under tension.

      I think it’s a case of being cut rather than being snapped, although as always this is just how I’ve interpreted what’s been said so feel free to correct me.

  12. Well the car’s are going to weigh a hefty minimum of 640Kg next season so they might as well stick extra safety features on

  13. A good and sensible desicion. When the tethers get cut in several accidents this is a good solution. Lets hope we see no flying wheels in the next years.

  14. You’ve got an upper control arm, a lower control arm, and a spindle where the tire/wheel assembly mounts. The tether, or tethers, should connect to the spindle. I doesn’t get any simpler than that. Anything else is just “**** happens”. I’m sure Massa would’ve appreciated a tether on Barrichello’s rear springs last year, but somewhere you just have to get realistic about how much you can anticipate or accommodate.

  15. They didn’t ask me but I would suggest that as the main reason you need tethers in the first place is because carbon fiber suspension parts, unlike those made out of a metal, shatter at their load limit rather than bend, they should consider modifying the suspensions. Perhaps require one set of control arms on the front suspension be steel or titanium. You avoid the problem that a tether stronger than the bonding point will destroy the monocoque to an extent because the suspension can actually additionally absorb some of energy of the wheel whipping around, post impact, instead of just lying 100m behind the car in 2000 pieces.

  16. In the States we use 3(three) 15,000 lb. Nominal Breaking strength. SWEMS. (Suspension Wheel Energy Management System) wheel tethers at each corner. Working independently to reduce the odds of premature cutting and catastrophic failure.

    Go to this website: http://www.amickracecarrestraints.com


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