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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Chris grew up in, under, and around cars, but took the long way around to becoming an automotive writer. After a career in technology consulting and a trip through business school, Chris began writing about the automotive industry as a way to reconnect with his passion and get behind the wheel of a new car every week. He focuses on taking complex industry stories and making them digestible by any reader. Just don’t expect him to stay away from high-mileage Porsches.
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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.
Well played!
"Nuts!" General Anthony McAuliffe
There is a typo in the NHTSA recall notice, and I would like a refund of my taxes.