SCORES of drivers are being left stranded at the roadside thanks to overtightened wheel nuts.
Experts have urged motorists to demand “just one click” when their tyres are being replaced, or risk not being able to remove them at all.
It is becoming increasingly common for professionals to use more than a single click of a torque as it reaches the required load, according to specialists at Norbar Torque Tools.
Some are even using power tools with no torque capability at all – which is potentially dangerous and could cost drivers hundreds of pounds.
It could leave people unable to perform basic wheel replacement procedures, which might be vital in an emergency.
And if stuck, drivers may have to call for help which can come at a serious cost.
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To ensure people don’t get caught out, experts advise motorists keep a close eye on the work being done on their vehicles.
And if they spot the following at a garage or MOT センター, they should speak up immediately.
Norbar Torque Tools marketing manager Julian Bremner-Smith said: “Overtightening risks bolt failure, but it can also leave motorists stranded at the roadside unable to perform basic wheel replacement procedures in an emergency.
“That second or third well-meant click with a torque wrench when tyres are replaced at a garage or MOT centre can result in the nut being at a torque nearly 15 per cent more than the recommended level in the vehicle manual and very difficult to remove at a later date.”
He said that the problem is worsened by tyre replacement operators using power tools to tighten wheel nuts because it’s faster.
“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,” Julian added.
The break-off torque – or the power needed to loosen the wheel nut – would then likely be much greater than the original torque applied.
“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 most likely be nearer 50 per cent more than the torque originally applied to the nut,” 彼が追加した.
例えば, a フォード Focus has a wheel nut torque setting of 135 NS∙m.
If it is tightened to 150 NS∙m – above the recommended torque – it will likely have a break-off torque of about 225 NS∙m after just a few weeks of driving.
“This is something very few drivers will be able to apply with the typically short wheel brace supplied as standard with most modern cars,” Julian said.
His advice is for motorists to insist on good torque practice when tyres are being replaced – and to avoid power tools at all costs.
彼が追加した: “If the tyre replacement operative tightens the nut beyond one click ask them to do it again. One click is enough.
“And if a tyre replacement operative is using a power tool, drivers should insist that the correct torque is applied using a calibrated torque wrench.”