McLaren Recalls Arturas Equipped With the Wrong Kind of Nuts

Chris Teague
by Chris Teague
mclaren recalls arturas equipped with the wrong kind of nuts

We’ve been hearing of recalls impacting hundreds of thousands of vehicles in recent weeks, but supercar manufacturers don’t have that kind of scale. McLaren recently issued a recall, and the number of vehicles involved and the component triggering the whole mess is tiny.


The British automaker recalled 164 of the brand-new Artura for a potentially faulty nut on the car’s high-pressure fuel pipes. McLaren said affected cars use cold-formed nuts, which can loosen from their connection on the direct-injection fuel pump “in particular during dynamic driving maneuvers commonly associated with track running.”


The rolled threads on cold-formed nuts have a lower residual torque than is needed to secure them. Some Arturas were built with fully machined nuts, which McLaren said do not have the problem. McLaren’s fix for the recall involves replacing high-pressure fuel pipes that have cold-formed nuts with new high-pressure pipes with fully-machined nuts. 


McLaren isn’t the only supercar maker with small-scale recalls in 2022. Lamborghini recalled nine units of the Countach last month over the possibility that its rear glass panels could loosen and detach. Ferrari issued what might be the largest recall of the group, including nearly every vehicle it had sold since 2005. The Italian company recalled more than 23,000 cars for risk of brake failure. 

[Image: McLaren]

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  • SCE to AUX SCE to AUX on Dec 22, 2022

    As a mechanical engineer, the recall of the nuts is fascinating. Fastener torque performance is a game of thousandths (or sub-thousandths) of an inch.


    It is possible that both nuts (cold-formed and machined) actually met the default dimensional tolerance for this type of fastener, but evidently they perform differently enough under extreme sustained vibrations that a superior manufacturing method (with tighter controls) was needed.


    A cold-formed part is cheaper but won't have the crisp threadform of a machined part. The machined part can accept a higher tightening torque, and it's possible they even upgraded the material spec so the new parts don't strip.


    I'm a bit surprised that the mitigation is so extensive, and couldn't be accomplished with the application of some red Loctite 277 threadlocker or similar. But if the solution includes higher installation torque to effect a seal, threadlocker wouldn't be enough.

    • Bullnuke Bullnuke on Dec 22, 2022

      I also am fascinated with threaded fasteners in general. It's a lot more than finding a "goodenuff" bolt/stud/nut to fit an application. During my younger days I remember the large hold-down studs for a reactor vessel cover being hollow to allow an electric heater to be inserted. These studs were then heated to the proper temperature and pre-stretched using an overhead crane with a precision scale to set the required stretch of the stud. The large nut was then threaded down on the stud to basically hand-tight into place on the vessel cover. The overhead crane tension was then released, the heater removed, a plug inserted into the heater well in the stud. The fastener was then considered properly torqued to hold the vessel cover in place. Watching this all those years ago has made me somewhat vigilant when using threaded fasteners since that time. The Kindly Old Gentleman is still in the background of my brain...



  • FreedMike FreedMike on Dec 22, 2022

    Well played!

  • Azfelix Azfelix on Dec 22, 2022

    "Nuts!" General Anthony McAuliffe

  • ToolGuy ToolGuy on Dec 23, 2022

    There is a typo in the NHTSA recall notice, and I would like a refund of my taxes.

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