Wheel offs – they happen on 18-wheelers, they happen on passenger cars, and the news is always bad. The primary reason for this type of mistake almost always has something to do with lug nuts and/or studs.
As lug nuts are taken off, note immediately if they are difficult to remove. This is the first step in preventing a wheel-off later on. If you encounter a resistant lug nut, remove the stud and inspect each part for damage. The most obvious damage is in the thread area of either part. If either part is damaged, your job is to replace them with new parts designed specifically to properly fit the vehicle on which you are working.
Many dealers use a stud and lug nut rethreader to obtain the best possible fit when the assembly is put back together. And there’s another benefit: it saves time. Still, there are times when replacing the stud is the best course of action.
Lug nuts and studs should be easily removable and reinstalled with no unusual resistance. This is no time to try to jam a dinged lug nut into place. At the same time, be certain that if the wheel is hub centric, it is clean and corrosion-free before you attempt to reinstall the tire/wheel assembly. An over-torqued lug nut is just as dangerous as an under-torqued lug nut, and the entire assembly must be reassembled carefully.
Also be aware of yield point, or the point when a stud has reached its maximum clamping force. Once a lug stud has reached its yield point, torquing the lug nut further will cause the clamping force to diminish, especially if this process has been repeated for a number of years. In other words, the risk of a lug nut backing off can greatly increase. If you have any doubts, throw out the old parts and use new ones.
On occasion you may find a lug nut that just won’t thread its way onto new studs. They may bind halfway down the threads of the lug stud. If it fails to torque down smoothly, toss it in the trash. Lug nuts will elongate depending on use and the type of material used in their manufacture and repeated use, which is why they sometimes won’t reseat properly.
It’s not a complicated process, but being in this business and serving today’s litigious society, who can afford to take a chance? Nobody, that’s who. If you can, ask the customer to watch as this procedure is being completed. Done properly, everyone can relax knowing the job was done and done right.
Safety in Numbers
ET Discount Center in New Jersey does a great job of avoiding wheel-offs. Once the tire/wheel assembly is back on the car and sitting gently on the ground, the primary tech uses a color-coded torque stick to determine that each lug nut has been torqued precisely, according to wheel and vehicle manufacturers.
Next, a second tech follows closely behind and does the exact same thing with another calibrated color-coded torque stick. Then, both techs must sign the work order indicating the double check has been completed before sending the vehicle on its way. “The torque sticks we use are 60 foot pounds to 180 foot pounds,” says Dennis Calaff, general manager of ET Discount Centers.
“Thanks to our two-tech sign off on the work order, we can avoid problems that crop up at least once every few minutes. We are a high volume shop. For example, if the tech on a car is very busy and is interrupted he may only torque three wheels. That’s where the back-up tech comes in. We know our guys change out tires and wheels every day of their lives and we know how used they are to properly torquing the lug nuts. It’s almost like an assembly line, so that’s why we put our backup plan into place. It works and I don’t have to worry about it.
“Of course, we keep the customer in the loop and tell him what we are doing and why,” he says. “Another thing we check to avoid wheel-offs is the wheel size or worn out rim seat. Often customers will put on different wheels than those specified by the vehicle maker. There is no way we’re going to put an incorrect wheel size back on that vehicle and run the risk of a wheel-off,” he says.
Before any of Calaff’s techs even touch a tire/wheel assembly, they must pass through an intentionally “precise and tough” training course he developed himself. “I’ve been in this business for 23 years and concentrate on focus, focus, focus. Once you’ve been changing tires for a few years, any interruption, no matter how small, can interrupt your train of thought. We work exceptionally hard on maintaining focus.
“For example, if you’re working on reinstalling the lug nuts on the right front tire and the customer asks you to check the rotor and caliper, it can be disturbing to the tech who has one more lug nut to go,” he continues. “If he forgets to properly torque that wheel, we’re all in trouble. But if he finishes the job and then approaches the issue of undoing his work before checking the rotor and caliper, we should be okay.”
That is, of course, once the tech retorques the lug nuts and the “cast in stone twin tech rule” is enforced, Calaff says.
“In fact, we play a very serious game in our service bays that pays off. To maintain our focus on what type of vehicle is being serviced and the torque specs we have ‘memorized,’ our guys yell out the torque specs for a specific vehicle. If an Audi rolls in our guys will yell out ‘17-80.’ That means this particular vehicle comes OE with a 17 mm socket and requires 80 foot pounds of torque.”
Commercial Tires
When lug nuts come off a tractor-trailer, the results are far more catastrophic. When this happens at high speeds the threat of a wheel-off to the driver, the cargo and other road users is significant. About this, there simply is no debate.
The core issue here is to address the point at which the wheel nuts come off. For commercial vehicles with standard wheel nuts installed, it is not a case of if the wheel nut will come off, but when.
All wheel nuts, when installed on a new vehicle, are installed according to the vehicle manufacturer’s specified torque setting. This we already know. But here’s what you can do to lessen the chance of a problem.
After the wheel installation, the wheel nut torque level should be rechecked after 50 to 100 miles of operation – and retightened, if necessary, to the recommended torque using the proper tightening sequence. In fact, it is recommended that a torque check is scheduled at 10,000-mile intervals.
However, advancements in technology have led to the design of a wheel nut that reportedly requires no additional retorquing (subsequent to the initial retorque) while in service. The Disc-Lock Safety Wheel Nut for hub-piloted wheels from Disc-Lock is maintenance-free after it has been correctly installed with Technology & Maintenance Council installation guidelines.
The bottom line is to remain constantly aware of new technology that can save you from a courtroom trial and allow your business to move ahead with some of the assurances just mentioned.
