Norbar: avoid wheel nut overtightening
Drivers with flat tyres are being left stranded at the roadside due to overtightened wheel nuts that cannot be removed, according to Norbar Torque Tools.
The company says it is issuing the warning as the result of increasing anecdotal evidence that too many wheel nuts are being tightened by professional tyre replacement operators using more than a single click of a torque wrench as it reaches the required load, or are being tightened using power tools such as impact guns with no torque capability at all.
“Overtightening risks bolt failure, but it can also leave motorists stranded at the roadside unable to perform basic wheel replacement procedures in an emergency,” said Norbar Torque Tools.
“That second or third well-meant click with a torque wrench when wheels are replaced, can result in the nut being at a torque nearly 15 per cent more than the recommended level in the vehicle manual. These can then be very difficult to remove at a later date, risk damage to threads or could snap the wheel bolt.”
The problem is exacerbated by wheel and tyre replacement operators using impact power tools to tighten wheel nuts because they are faster, adds the firm.
“Too often power tools are being used that have no torque setting capability and the nuts are therefore overtightened to a point that drivers cannot remove them,” said the company.
“After only a few weeks of normal driving with the wheel nuts exposed to wet weather, dirty roads and even salt, the torque that will need to be applied to undo the nut – the break-off torque – will be significantly higher than the torque originally applied to the nut.”
Norbar’s advice to drivers is to insist on good torque practice when wheels or tyres are being replaced.
“If a tyre replacement operative is using a power tool, drivers should insist that the correct torque is applied using a calibrated torque wrench. What’s more, if the tyre replacement operative tightens the nut beyond one click ask them to do it again. One click is enough.”
