Edmunds dealer partner, Bayway Leasing, is now offering transparent lease deals via these forums. Click here to see the latest vehicles!
Lug Nut Issues
bonnie_rick
Member Posts: 115
in the News and Views Conferences' Over-tightened
Wheel Lug Nuts (Topic #291).
Catch up and come back here to continue!
Bonnie Rick
Town Hall Community Manager, edmunds.com
Wheel Lug Nuts (Topic #291).
Catch up and come back here to continue!
Bonnie Rick
Town Hall Community Manager, edmunds.com
Tagged:
0
This discussion has been closed.
Comments
Using an impact wrench will grossly overtighten lug nuts and lead to damaged alloy wheels, warped brake rotors and stripped lugs/nuts. Also, if you ever want to change a tire using hand tools, forget it! In extreme cases, the overtightening can stretch the lugs and lead to breakage and the wheel will fall off while you are driving.
I have dealt with this improper practice for many years and want to take a crack at trying to stop it. Most people are unaware of the problem. The next time you have tire work done, watch the mechanic. He will remove and replace your wheels with a compressed air powered tool called an impact wrench. He may tell you he will use a torque wrench or torque stick to correctly torque the nuts when he is done, but he typically does so AFTER he has already overtightened the nuts with the impact wrench. Obviously, the mechanic just doesn't understand that the torque wrench doesn't unloosen nuts that are already too tight.
If you do some of your own work and have a torque wrench, set the wrench to the ft lbs recommended for your wheel nuts (see owners manual, typically 80 ft lbs for a car) and try to remove the nuts. Keep increasing the setting until the nuts first start to come loose. Read the torque. That is the torque at which they were tightened to the last time the wheels were installed. I find that the tire shops will typically tighten to 120 to 200 ft lbs, that's way too much. Caution, if you do this test, don't remove all the nuts if the weight of the car is still on the wheel or it will come off! Retighten each nut to the proper torque.
I am trying to influence industry groups to better educate tire mechanics. I may also approach NHTSA and similar safety groups. What I need are your comments and stories here in this topic.
So, let's here the horror stories, comments, suggestions, etc.
Are you torqued off? Did some lug give you a wrenching feeling? Are you tire-d of this practice?
I believe that if you use a click-type torque wrench to loosen the bolts, you'll mess up its calibration. Someone said this here earlier.
Perhaps there may be some slight affect on calibration (my instructions do not say such a thing) but we are talking a small amount. For general use, being +/- 5% is sure much better than being way off the mark. Most torque specs are in a +/- 10% range, i.e. 65-80 ft lbs, so I wouldn't worry about affecting the calibration unless you were wanting to keep your click type wrench within extreme accuracy. And if you did, you would sent it out regularly for recalibration.
So I contend that you can go ahead and use a click type torque wrench to check torque by unloosening a nut, provided that it is designed to be bi-directional.
Incidently, I finally did this yesterday after 2 weeks of neglect since I got my new tires. I feel much better now.
PS Part of the super-high reading you get is gonna be due to the pre-load effect of the rim; like a lock washer.
Tomorrow (or soon, at any rate), I'll try to find out how tight torque bars and impact guns really get lugnuts. The experiment will be conducted on Volvos and Toyotas. If I haven't posted results by Saturday, please remind me, and I'll do my best to get something up by Monday evening.
I work as a quality technician for a company that manufactures hydraulic pump and motors. We have over one hundred snap-on torque wrenches to keep calibrated on 6-9 month intervals. The "click" type wrenches are designed to torque both clockwise and counterclockwise but are not designed to break fasteners loose. I quote from the snap-on catalog:
"Use of torque wrenches to break fasteners loose may cause overload." To be safe, I would use a breaker bar to loosen the lug nuts.
Snap-0n certifies accuracy on it's click type wrenches is +/- 4% CW and +/- 6% CCW of any setting within the upper 80% of scale.
I have seen wrenches out of calibration by as much as 20% due to miss use.
Note to C13 reply: I have never experienced an unusually high reading due to the starting torque. I can tighten a lug nut to 80 ft lbs and come back a day, week or year later and it will click at setting of 80 and untighten at a setting of 85. It would have to be rusted or corroded on for there to be much more starting drag. And I am talking about overtightening to 150 to 200 ft lbs here. There is no way that the starting drag upon unloosening can cause a nut tightened to 80 to require 150 ft lbs to untighten.
As to checking torque on front wheels only, I would recommend that it be checked on all wheels. You can warp drum brakes, too. And many cars have disks on the rear. Besides, overtightening can lead to stripped threads, broken lugs, alloy wheel damage or a wheel that can't be removed by hand tools in the event of a flat tire on the road.
Speaking of misuse, I've seen torque wrenches used as hammers. Also, the manager at that same shop (not an automotive shop) would very firmly chastise an employee who didn't use a torque wrench when he was supposed to, but the wrenches were all set at different values for the same task (like it matters, once it's been used to hammer). I asked the manager what they should be set at and he had no idea what I was talking about.
Just a little story I like to bore people with. Has nothing to do with the present subject.
I bought my 3/8 Snap-on clicker at a pawn shop. Very new-looking, in a case. I guess I need to get it calibrated though.
I tried testing a 7-series Volvo with aluminum wheels today, and you know, C13 is right. There is just too much pre-load on the lug nuts to get an accurate indication of how tight they are (if you're backing them off with a torque wrench). I could try to start at 80 lbs. and work my way up in 10lb. increments until I got the nut to tighten some more, but that would do more harm that good--I wouldn't want to strip the studs or damage the wheels. I really couldn't come up with an adequate way of measuring just how tight the nuts were, coming off or going on! So, I began to think about why lug nuts need to be torqued properly.
Lugnuts need to be torqued properly for several reasons. First, they need to be torqued uniformly, so that the brake rotors, as they heat up, won't become warped. Second, they need to be torqued properly so that the holes in the wheels won't be totally chewed up. Different rims will require different torque specs. Steel rims can generally stand a greater amount of torque, and aluminum/alloy rims require less torque. I think that if the nuts are torqued properly, then a person changing his/her tires should be able to undo the nuts with a standard tire iron.
I will keep on looking into this.
Wow, I was right about something mechanical. Now I feel better about typing on this lop-sided desk. I swear I measured carefully and used a square and everything. I blame my tools.
geo:
That's an interesting question. I can't imagine that there could be a problem with Loctite, the right one, whichever one it is. That's probably got enough anti-seize but also some 'glue', so to speak. I probably wouldn't risk using plain anti-seize on lugs. My racing buddies safety wire everything, though I guess that wouldn't be too practical.
I wonder if anybody's tried 2 nuts per lug (the first one is not capped, obviously), the second one to lock the first? Then there are those clips, like on a motorcycle axle. Some vandal used to keep pulling my front axle clip out on my old Yammie. Never caught him. Had to carry spares. May he suffer eternal torment.
Often lubricant is not recommended on fasteners that are torqued because the lubricant gives you a false reading or in the case of aluminum, might allow you to overtorque before you realize what you've done.
On many cars over many years, I have always been able to use a torque wrench to tighten the nuts to the proper torque and come back immediately, a week later or a year later and use the progressive torque setting to measure how tight the torque was. I just did that with my new car. I had torqued the lugs to 80 ft lbs. A week later I set the wrench to 75 and it clicked before the nut unloosened. At 80 some nuts would loosen, some would click the wrench. At 85, all nuts would unloosen.
I just can't imagine a nut being tightened to 80 requiring twice that to unloosen due to pre-load.
A lug and nut in good order should be easy to tighten by hand until the nut hits the wheel. If it is hard to turn, the threads have been damaged by improper handling (over torque, cross-threading). Cleaning up with a wire brush, or better yet, a thread file, can help. Even a messed up thread only ads 1 to 5 ft lbs of drag. You can verify that by using a dial-type torque wrench to install the nut. It is also important to make sure the surfaces where the nut and wheel make contact are clean and smooth. If not, smooth them gently with a file or crocus cloth. Manufacturers warn against oil on the treads, but say anti-seize is okay. Not loctite to hold the bolt in place, but anti-seize to prevent corrosion or rust, though I have never seen a nut rusted in place.
Though all of this conversation is interesting, the main point of this topic is the issue of mechanics grossly overtorqueing lug nuts to the point of damage, warping, lug stretching/breaking, etc. What we need to do is prevent the problem at the source. Demand that all tire work is done with hand tools and that nuts are torqued tight with an accurate torque wrench. It's your car.
You made some very good points in that last post. Next time I rotate my tires I will apply a little anti-seize compound to make them tighten smoother.
My daughter has a 98 Pontiac Grand Prix GT. She took it in for service yesterday to have the wheels aligned and an oil change. I told her to stop over after she picked up the car and I would check the torque on her lug nuts. First off they did a poor job of alignment because they only did the front end. The torque varied to loosen the lug nuts from 60 ft lbs on the left side to 200 ft lbs on the right. The right side varied in itself from 100-200 ft lbs! If that don't warp a rotor, nothing will. I told her to ask the service department if they torqued to the proper spec. They told her that they did and used a torque bar. I'm not sure what they are calling a torque bar but apparently it's a poor method. I also checked the rears while I was at it and found them to be 120-130 ft lbs but more uniform.
To top it off, I checked the air pressure in the tires and sure enough, 42 psi in every one. The book calls for 30 psi in the Goodyear Eagles on the Pontiac and on my Intrigue also.
What in the world is wrong with these guys that are working on our cars? This is just plain incompetence.
geo0791: Most shops, if asked to do an alignment, will only do the front wheels. There is usually not any reason to do a rear-wheel alignment, especially on such a new car. Rear-wheel alignment usually comes into play if there's something wrong with the rear suspension--mechanical defect, accident damage, or other.
Wuh-oh.
Be right back.
Actually, now that I think about it, we just had BOTH front rotors break on the jeep within 3 weeks of each other (about 5 months after the tires were put on.) I wonder if this is a coincidence or not??? The break was weire. If you picture a rotor, it has a raised center where the lugs go through, and a 'lower' level (if it's lying flat) where the brakes ride. Well, the raised center seperated from the lower level perfectly. Hmm, I think I might go buy a rotor and torque the lugs down to 200lbs and do some stress analysis on it to see if this was what broke them...
Most good machinery manuals spec torque values for both clean and dry threads, and clean and lubricated threads. My only problems with lugnuts has been when there was 35% or more difference between the correct value and the one it was torqued to. The charts up here are for clean dry threads, and specific to each vehicle, with stock wheels and nuts.
problem is: on almost full turn of the wheels the
front tires will rub on the inside wheel well. My
question is: will wheel spacers be a good idea ?
I have heard that the spacers will make my lugnuts loosen. Has anyone heard of this or have used spacers ??
#26>It probably doesn't matter which one you use, although if the stud is really, really chewed up, a file may not do you much good. Once you've done that, run the nuts backwards over the lug stud to see how freely they turn. If the stud isn't entirely clean, you'll feel it without messing up the first few threads of the lug nut. This may be impossible if you have closed-end lug nuts!! Good luck!
I did write the manufacturer of my car to complain about the overtightening of my wheel lug nuts. I finally heard back from them today. They agreed 100% with me and said they try to get mechanics to properly torque lug nuts, but it takes constant reminding. Old habits are hard to break.
Three cheers for you!! I wish many more people would join me in expecting reasonable shop practices from tire mechanics. If this was just an isolated problem, I wouldn't give it much thought. But for over 35 years I have dealt with overtightened lug nuts from virtually every shop that his touched my tires. Even when you demand that they use a torque wrench, they don't know how to use it (see my previous posts).
I am open to ideas to do a better job of fighting back. I have written the ASE, but they never replied. I have considered approaching NHTSA, but have been waiting to see what comments I can get in this topic to use as a case statement.
Unfortunately, when Edmunds decided to move the topic from its original place (News & Views?), they renamed it "Lug Nut Issues". My original title was more like "Overtightened Wheel Lug Nuts" and attracted more direct attention to the problem. I wish Edmunds would rename this topic back to the better title, but not freeze it and start another. That often kills the momentum of a discussion.
I can't think of too many other issues regarding lug nuts than the question of overtightening.
Using this method doesn't mean I am any more tolerant of the frequent overtorque bad practices than Vivona. However, because the store with good tire prices may not have good work practices, I took a deep breath several years ago and have since done my own tire rotation. Need to look at brakes, CV joints, and suspension anyway. For new tires, I take only the wheels & old tires to the tire store. This is some hassle but ....as you guys seem to know very well....saves time and money in the long run.
I have thought about bringing just the tires and wheels to the store when I need new tires, but the tire store usually wants the mileage off the vehicle for the tire warranty. I don't know how they would react to me just showing up with wheels and tires. But it is an interesting idea for when I have the wheels balanced.
My experience, over many years and many cars, is that mechanics can often create as many problems as they solve by not following proper shop practice. I have thought about starting a topic in TownHall about that. Ohh, the stories I could tell...
Vivona, it takes a little nerve, but in the new-tire negotiation you can frankly tell the tire dealer about your previous lugnut tragedies and therefore your need to take him the tires & wheels only. Get him to agree on how log the mileage before you sign the order. You will get a strange look and an explanation that his shop never overtorques but, in the end, he will agree because this scheme is reducing his labor.
A small floor jack and a pair of stands will easily fit in your trunk. You could drive to the tire store and remove your own wheels in his parking lot.........
I concur that the installation and removal torques will differ very little unless there are unusual circumstances such as pre-existing thread damage, heavy thread contamination, or long-term rust.
Especially intimidating if you have a camera pouch on your belt like I did... (Though it was just a coincidence, I was taking pictures of some houses I was interested in....)
If that doesn't work, hold a piece of paper against a nut and rub a pencil or crayon across the surface to make a copy of the locking surface. Then take that around to auto parts stores and check out the patterns on the locking nuts they have for sale. You may find a match.
You might also check with tire dealers that sell mag wheels. They may keep a large selection of keys on hand.
I torque my wheel locks to the proper spec and have never had a problem removing them.