The lug nuts were probably over-tightened by the shop, but if you waited 8 months to check the lug nut torque, it would normally take more force to move the nut after it has been sitting there and the wheels had gone through many heating and cooling cycles.
By the way, do you have steel or alloy wheels?
Tire rotation should be a fairly straightforward project, especially on a car with small light wheels like a Camry. I'm not sure why it was such a big deal. Because most people are not all that comfortable working with star and torque wrenches they are usually better off paying the tire shop the pittance they usually ask to do the job.
Did you have a question?
yes, but when you do it yourself, you know it's done right.
So do I, sometimes, but it co$ts. Sure, I could take it to the gas station down the street, but there are only a few shops that I really trust to do a good job. Usually the kind of things that I don't address myself are NVH issues, vibrations, etc. and the typical mechanic will just tell you he doesn't feel anything and charge you an hour's labor. Sad but true. The ones that DO take you seriously are $90/hr. or more. So I only take my car in when I really don't know what's wrong with it and/or it's something just too ambitious to tackle myself. (I figure, if someone doesn't notice that the steering wheel is shaking back and forth a half an inch at speed, do I really want him rotating my tires or changing my oil.)
If they're really good ones, sure!
nate
It seems to be more critical on sporty or sports cars that have low unsprung weight to begin with. A Porsche or BMW is very intolerant of any wheel imbalance so I ASSume that improper torquing would also potentially cause issues.
Speaking of which, I need to get the summer wheels/tires for my 944 over to my friend's garage so we can check them with a dial indicator before the weather gets too nice... see my complaint above about not being able to find a garage that takes NVH/vibration problems seriously...
nate
It seems to be more critical on sporty or sports cars that have low unsprung weight to begin with. A Porsche or BMW is very intolerant of any wheel imbalance so I ASSume that improper torquing would also potentially cause issues.
Speaking of which, I need to get the summer wheels/tires for my 944 over to my friend's garage so we can check them with a dial indicator before the weather gets too nice... see my complaint above about not being able to find a garage that takes NVH/vibration problems seriously...
nate
***************** NVH is tough to diagnose because it is difficult to check stuff under the car at highway speeds. Our office had a nice setup for chasing down NVH problems - a 2 axle chassis dynamometer which allowed you to "drive" the car at the speed where the problem occurred, and multiple microphones and sensors that could be placed near suspect components and hooked up to an ocilloscope. Look at the frequency and amplitude of the vibration, compare it with the RPM of various components, and then put the dial indicator on the component.
I don't think lug nut torque is going to effect balance too much as long as they are even and not loose. The "weights" are still in the same place. If balance is a problem, just needs a more precise balancing job.. Preferably on the car, if it's critical. I think most these days do it off the car. Usually that's good enough for most cars, but some hard cases might do better with an on the car balance. Tires themselves can cause that too if there are tread, belt, problems, etc. They would have to be really loose to be an issue, or very unbalanced as far as the torque of the various nuts, and even then, I don't think it would amount to much as long as none are loose and causing the wheel to slightly wobble on the hub, or actually distorting the wheel, which I would think would take some pretty serious torque unbalance considering the nuts are towards the center of the wheel. Most torque them fairly evenly whichever method they use. Course, I assume no mechanical problems that might cause vibration, shimmy, etc..
The issue with uneven/overtorquing is that it can result in warped brake rotors. Like I said, cars with low unsprung weight - they often have lightweight aluminum hubs, one-use-only rotors, etc. and there's less mass between the hubs and the chassis to damp out vibes.
nate
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In answer to your question, they are the car's factory wheels, so they're steel wheels on steel hubs.
I don't think 8 months should have allowed the phenomenon of embedment to result in a torque reading of greater than 120 foot-pounds if the dealer's technician had properly tightened the lugs to 76 foot-pounds. I waited 9 months between my
2 self-done tire rotations (not 8 months, but 9 months), and the torque reading last week was somewhere between 76 and 90 foot-pounds on the two wheels I tested. In other words, in my test with the torque wrench set at 76, the wrench clicked. And when I set the wrench to 90, the lugs rotated quite a bit in the tightening direction. So I think the tech at my dealer just tightened the lugs too much because he wasn't using a proper torque wrench :-)
The correct lug nut torque varies depending the stud size, and some vehicles can require well over 100 foot-pounds of torque, with 90 being fairly common. My guess is that the tech was incorrectly shooting for 90 and went over a little, resulting in the 120 foot-pounds later.
Yep, over torquing can warp rotors.. That's why I never use an impact to tighten lug nuts. I might start the nut with one, but I'll torque it by hand to fully tighten it. But I don't have an impact here at the house, so I rarely use one for changing tires here. I have to do it the old fashioned way.. : ( I get my tires from Discount Tires, and they are real close too. So all my rotates, I let them do it. And they don't tighten with impacts.. I'll stand out in front of the door watching them to make sure they don't. :/
I don't trust the quickie lube places to get the job done right.
Once, I drove off with an oil leak due to the fact that they forgot to put a drain plug gasket on. Fortunately, I caught it before I lost all the oil.
Then, they stopped doing changes on my Porsche. I guess the corporate folks didn't want to pay for expensive screw-ups. So I do that one myself. Before they stopped doing these, I'd keep an eye on them. Once, it took the guy about 5 minutes of looking around before he admitted he couldn't find the oil fill (clearly labeled 'OEL'*). Then, they try to fill the engine through the screened cup under the cap. That'll take all day. Take the screen out and pour the oil in!
I took one of the Landcruisers in for a complete lube check once and spend
15 minutes listening to the guy in the grease pit grumble about having to remove skid plates to access the transfer case. That's a reasonable amount of time for the job. But more often than not, they come up from underneath the truck with a dirty sample after a few minutes, recommending a lube change. I'm pretty sure they haven't actually gotten to the fill plug that quickly, so its a con job.
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