long post warning
Originally Posted by
Lee Schierer
It has nothing to do with rotors warping as the wheel does not connect to the rotor.
That's incorrect. in older vehicles the front hubs where the rotor and hub assembly while most now days have a hub with a separate rotor that is sandwiched between the wheel (rim) and hub. When I worked on automobiles (moved on the semi trucks and so forth) if you EVER called Bendix or Wagner brake helpline for tech assistance one of if not the first question they always ask was "did you TORQUE the wheel nuts?" Argument for uniform clamping between the wheel (rim) and hub minimizes warping of the rotor.
Another point regarding impact usage is most reputable shops use what are called torque sticks that are varying sized and diameter sockets with built in extensions that will limit maximum torque from impact usage. If you take a smaller diameter and/or longer length shaft it will absorb a good deal of the impact hammering force and you get these in different torque limits. If you have ever tried removing a tight bolt or nut with a extension and couldn't but could remove the extension or use a shorter one and then could you will understand how they work. Back in those days when I installed wheels back after doing brake work or tire replacement I used a TORQUE WRENCH to tighten the wheel nuts.
This is common place even with big trucks now - torqueing the wheel nuts, and ever TA truck stop also prints out on the invoice and tells the driver/ customer that the wheel nuts MUST BE retorqed within a specific amount of time. This is largely due to liability on their part. Or anyone who installs wheels actually. If a wheel runs off - especially a steer tire and causes a accident or injury/death the legal liability is HUGH.
Steel wheels are just as likely as the "mag" wheels to do this. There are established guidelines for installing wheels back on semi trucks that have the tech use a special wire brush on a power drill/driver that will clean the threads of any debris and rust. The brake drum is also cleaned on the area the wheels contact and the wheel(s) and also cleaned in the contact area to ensure there is a clean surface with no rust or dirt/mud or peeling paint etc. that will prevent all mating surfaces from DIRECT contact. Then a couple of drops of oil are sprayed on the wheel nut washer and they are installed in a cress-cross pattern that has the nuts tightened opposite the one just tightened to give even clamping around the wheels. They are torqued using a torque wrench that is designed specifically for tightening truck wheel nuts, in that the handle breaks away in the middle (not depending on a audible "click" as background noise in a truck shop likely would be too loud to hear that). I understand I am speaking about trucks here as that is what I have worked on over 20 years, but wheels run off cars from improper installation. Everyone that works on them for a living is technically a "pro" yet, many will run the nuts up with a impact with no torque stick and swear to you they are so good that they can "feel" the right torque and everything will be good. I have removed tires and wheels from cars that the previous "pro" tightened so tight the studs were stretched and the threads no longer matched. Some twisted the studs off - trying to REMOVE the nuts. Some work to a higher standard than others, yet both are "pro's". The time to torque them is when they are installed. Torque sticks are industry accepted way to do it without the extra time to have someone physically use a torque wrench on every nut.
I worked at Waste Management for 8 years as a tech, then supervisor and I can tell you we had wheels run off occasionally even when we did everything right. We also used plastic pointers on the wheel nuts called wheel checks that where installed on the nuts after torqueing them that gave a visual indicator a nut had worked loose. We also were required to bring every unit back in the shop the next day and retorque ANY/ALL wheels that had been disturbed the previous day. Brake work or tire replacement and so on. Yet there were still wheels that came off. I saw pictures of dual wheels that came loose and came off trucks that hit cars traveling down the road, that hit houses and went through walls.
Things are much more complicated now a day than they use to be in years gone by. More vehicles on the roads, more lawyers, more "professionals" working on everything that are not properly trained often enough, or they are properly trained and for whatever reason don't do the work properly. A great deal of this is CYA, but if you have saw ONE time the consequences of failure it is the best preventative measure left that everyone can do.
Sorry about long post
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