An Idiot and His Torque Wrench
Sunday September 9, 2007
We get a lot of letters about a lot of problems here at Auto Repair central. Most are either easy to solve or hopeless, with not much in between. But this one had me, not because of an obvious solution or lack of one, but just because it was funny:
Hi, I had my truck in for repairs. The repairs required a torque wrench. When I was watching it appeared that the torques being applied by the mechanic seemed to be substantially higher than those recommended. He said, "Oh, that's because my torque wrench is out 10lbs." Needless to say, the repairs became a problem again shortly after they were "repaired."Terry, without knowing exactly what repairs were made, there's no way to get any kind of answer here. But it's safe to say that not many repairs will "go bad" just because they are over-torqued by 5 or 10 percent. Some jobs do require very specific torque adjustments, but not many. The real laugh is on your mechanic. Anyone who claims to run a shop but uses a broken torque wrench for anything besides a fish club should be out of business. If you're still using that shop, check your head for bumps, maybe he caught your blind side with that bum wrench.
I spoke to a different mechanic and he told me that a torque wrench is not "just out 10 lbs". When a torque wrench is out, the amount it is out will vary depending on how much pressure is applied and that anyone knowing the wrench is out should not be using to do precision work. Is this true? Is there a manual or authoritative source of written proof of this that I can take back and show the mechanic? (I somehow don't think he'll take my email seriously) He is refusing to deal with the repairs again.
Thank you, Terry H.
photo CC licensed by Fuschia Foot
Comments
There is a way to check a torque wrench for accuracy. There is a tool called a torque wrench tester. I don’t know of anyone that actually owns one of these testers since they cost between $2000 and $5000. And if anyone had that kind of money to spend, they wouldn’t have the resources to bring the wrench back to specs.
If the wrench is a major brand, Snapon, Mac, Proto and so on, you can always contact someone at the company and they will set you up to send the wrench back and have it recalibrated. You have to weigh that cost against the cost of a new wrench though…
I’m hoping the mechanic in question doesn’t own the shop. But that would make me wonder why the shop hasn’t fired him for using a faulty tool and talking about it to a customer…
I carry my torque wrench in the car, equipped with the socket that fits the lug nuts. It is one with micrometer setting of torque and is conveniently long to remove any tight nut. And when replacing the wheel I generally use two intermediate settings before the final setting.
It is much better than any OEM supplied lug wrench. Perhaps the new Bugatti has one in its kit, but for cars that ordinary people buy this is a great assurance that the nuts are tight.
duke
Check out your Snapon Tool Dealer and you will find a torque wrench tester mounted to his wall. If the wrench is not accurate it will have to be sent out for calibration. The dealer will check any torque wrench for free.
Also as a former business owner, I would cringe at the obvious law suit.(small claims or not). A comment like “my wrench is broken” will surely go against you.
All licensed repair shops should have a source for getting their torque wrenches recalibrated and I am sure the time frame would not be greater than one-year and the wrench should have the calibration date on it. Of course these are “shoulds” and probably not reality.
Most good mechanics are going to have a fairly accurate feel but in a court of law that feel will not gain much support generally. It is completly amazing to me the number of professional shops that use an impact wrench to tighten lugnuts and have not enough sense to check the torque. Using the same air-pressure to tighten that they used to break and remove will absolutely result in folks loosing lugbolts. Still it is tough to win a case against them after any amount of time.
The mechanic that tells anyone the wrench was “off” is very likely in a shade tree shop. How many times are you going to have the opportunity to watch a mechanic torque anything? Not in my shop;…but rest assured it will be properly torqued; — just that you are not going to be watching the process. I can think of at least ten good reasons why a customer should not be anywhere near the work area.