Dear Mechanic,
About a couple months ago, I read a column that Click and Clack wrote in which they talked about the dangers of over-tightening lugs or lug bolts. At that time I had just purchased a brand new car, then went out and bought new wheels and summer tires.
I took the advice and bought a “click type” torque wrench at the local auto store. Torqued my wheels to the correct amount stated in the car’s manual with no problems whatsoever.
The tire shop I bought my wheels from said I needed to re-torque the wheels about 150 miles after putting the new wheels on, because they may come loose during that time. Anyhow, I set the torque wrench again, and retightened them, but no “click” sound came from the wrench. The damn wrench had already broke (no clue how) and it was the 2nd time I used it. I immediately felt that I had probably over-torque my wheels big-time, since I kept waiting for the sound that never came. That same day, I went to the local auto shop who let me use their torque wrench, and I loosened the lug bolts, and re-tightened them again to the proper amount of torque. I checked one of them, and it was at about 150lbs, instead of the 88lbs it was supposed to be at. Most likely, they were all overtorqued like that, but are now at the proper amount.
My question is, do you think I caused damage to the lug bolts, or rotors?
If so, what signs do I look for to tell if the lug has weakened from that previous procedure or the rotors may warp in the future?
I’m concerned that I may have screwed up my brand new ride’s rotors and lugs.
Please let me know what I should do?
By the way, I returned that POS torque wrench that failed me after only using it once.
I don’t understand:
I loosened the lug bolts, and re-tightened them again to the proper amount of torque. I checked one of them, and it was at about 150lbs, instead of the 88lbs it was supposed to be at.
If you tightened them to the proper torque, (88#) then how did they get to 150#?
Signs of damage from overtorqueing lug nuts include studs that have been slightly stretched at the base threads, deforming them just enough to cause the lug nuts to tighten before providing sufficient pressure to the wheel to properly hold it on the hub. Studs can be checked for thread damage with go-nogo thread gages.
Warpage is also possible. Warpage shows up as pulsating braking.
I doubt if you overtorqued them. “Breakaway” torque, the amount it takes to free the nut, will always be much higher than application torque. 50% higher would not be cause for concern. And 100lb/ft is common spec on many stock applications. 150lb/ft of breakaway torque could easily mean you had in the neighbor hood of 100lb/ft of applied torque. Not a problem.
How much did you spend for the torque wrench?
Tester
I would not be overly concerned about the rotors; I would be concerned about the threads on the wheel studs being pulled and weakened.
For sure, OK. The studs and nuts need replacing ASAP.
Over torqued and unevenly torqued lug nuts can certainly cause rotor problems. Some cars and trucks are more succeptable than others. I think you do not need to worry, but need to learn what is the proper torque. A good torque wrench is a wonderful teacher. Unfortunately you did not have one. If you are feeling no pulsing in the pedal, the rotors are fine, I have been through various experiences too long to go into but would not think anything needs replacing at this time. So where do we go from here, first you must realize to properly torque the wheels is to follow the tourque pattern, basically tightening bolts in a criss cross type pattern, then torque (tighten) to specs. It is properly done in my book in stages with a min of 2 or 3 repetitions of the torque pattern leading up to the final bolt foot pound torque. Try a new wrench, even a loaner and see if you can come to terms with what I have said.
Others have speculated; I will too.
Can you imagine the nightmares that mechanical engineers can have, knowing that in one instance, a 90 lb small person will replace a flat tire with a spare and in the next instance, a 300 lb giant will do the same thing? In addition, people of more ordinary weights will have widely different thoughts on what is tight enough.
Lug nuts, and I have no data on this, must withstand a wide variety of torques due to varying concepts of what is tight.
Know too, that a stressed lug bolt will initially become stronger due to work hardening before it finally gets weaker. My guess is that your lug bolts are OK. Watch for a while, however, for missing lug nuts. One gone is not a need for panic. There must be a lot of cars running around loose with one missing lug nut with a section of lug bolt according to my frequent noon hour walks in an urban area. I have seen many of these on street corners in the gutter where they seem to finally fall off.
it is possible that you are not tightening them in the correct sequence, or incrementally in two or three stages.
if you tighten one nut to specs, then proceed to tighten them all one by one, then you indeed could have one finally way over tightened.
this happens when you tighten one to spec, and the rim actually ‘pulls down’ on that stud. but then tightening the rest you multiply the force on the initial stud. the potential force applied by improperly torquing is like using a lever to greatly increase the leverage which will cause stud stretching and breaking.
you must tighten them hand tight, all the way around, then tighten about half way all the way around, then tighten them fully the third time. the pattern is to cris-cross, or follow the pattern of one nut, then skip to the third, then to the fifth, then to the second, then to the fourth. then repeat at the final torque.
One excellent mechanic i know has the philosophy that if he ‘hears’ one of the nuts squeek during torquing, he loosens them all and starts again.
personal observation is that if the nuts dont go on freely by hand until snug they ARE deformed, and need replacing. that is why you NEVER use a air wrench to apply lug nuts. removal by air wrench is OK, but never installation. I get a kick out of seeing the guys at tire shops using air wrenches, then getting out a torque wrench to final torque them. have you ever looked at them and seen how most all the time they NEVER have to torque anymore after the air wrench?
Ok, I’ll respond the best I can.
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The torque wrench was about $30, from AutoZone
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I tightened all wheels in criss-cross pattern as advised, and finger tightened before taking out the torque wrench.
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To find out they were at 150lbs, I set it around that mark and immediately heard the clicking of the wrench, telling me that it was at least that amount. I read that you’re never supposed to loosen anything with a torque wrench, only tighten.
Ok, so here are my questions.
**** So should I take all 20 lug bolts out and inspect them for signs of stretching? I don’t have one of those expensive thread gauge tools though. Will the naked eye be good enough?
If they are stretched, I could probably get new lug bolts (exactly the same ones) that fit my wheels straight from TireRack.com (where I bought the wheels). Then replace them all with the new ones.
- For the record, I’m not a handy person by any means, but did everything correctly up until the crappy torque wrench broke (without my knowledge), forcing me to keep tightening my bolts as I waited for the clicking sound.
Make sure you get the right type, metric, or inch based.
You don’t have ot remove them. The best way to check them is with a thread gage such as in the link below. You should ba able to buy these at any tool shop. They normall come in a “go/no-go” set, where one is used to check minimum thread conditions per the Machinist Handbook and the other for maximum conditions. Threads are complicated, and involve pitch diameters, root diameters, peak diameters, and the phase of the moon in July (little joke there). The “go/nogo” gages provide the best test without an optical comparator, and that would definitely be overkill.
All you really need is the “go” gage. If it successfully spins all the way to the base of the stud, the stud is not stretched.
Since you were unusually consistant in your application protocol, I think checking 2 or 3 studs per wheel will be sufficient to tell if you have a problem.
Yes, if need be you can get new lugs anywhere, including the local parts store. However, while I know that many people pound them in with a 3-pound sledge, I’d recommend an arbor press. They tend to go in straighter that way.
Or you could have a shop put them in.
Thanks for all the advice and info guys. I emailed TireRack and wrote them of the situation. Within 5 minutes they called my house (good customer service). They recommended getting new lug bolts. So at $2 a bolt, 20 bolts plus shipping costs $50. They said I could have weakened them and sometimes that isn’t noticeable to the naked eye. Sure, the less costly way would be to examine each one with a gauge and only buy as many bolts as I need. But, I just went ahead and bought all 20 bolts. It’s a brand new car and I own it, so I feel it is worth it to be on the safe side. I’m going to take it to a buddy of mine who is a mechanic who’ll put it on a lift and put the new lug bolts on when they arrive. The torque wrench they have doesn’t break after one use.
Ok, so who knows the name of a good torque wrench that lasts longer than one day?
Much depends on how much you want to spend. I’ve got several Craftsman torque wrenches that are pretty decent.
I’ve also got a 1/4" drive German made (can’t pronounce the name) inch-pounds wrench and a Snap-On 1/2" drive that are about 30 years old and have never had a problem out of either one.
A Snap-On stamp equates to big bucks and while they’re generally not as pricy, a Mac, Matco, or Cornwell tool is also very good.
There’s been a proliferation of Chinese made tools over the last few years and while a few are at least decent, many are downright junk from the get-go.
On a whim now and then I’ve purchased some inexpensive tools and my rough guess is that about 75% of them are either junk from the start or shortly after the first use.
To be honest, when it comes to many tools even brand names such as Craftsman, Black and Decker, etc. are becoming equally worthless. Imported from China, throw their tag on it, and foist it off on the general public.
Within a 2 year span I purchased 3 Craftsman brand floor jacks from Sears and every one of them was carp (sic) within 6 months.
Don’t even get me started about the king of junk; B and D.
GREAT NECK. AutoZone. $25 three years ago. Change out my stock wheels May 1 to Summer HPs and back to stock on Nov 1. Done this for three years so that’s 6 changes just for the wheel’s switch. Also, have done four break jobs on two cars in the same time and 1 set of rotors changes (that’s 4 rotors) in the same time on one car. Same $25 torque wrench, which actually cost me only $5 + tax (on the $5) because of a $20 bonus card I had from AutoZone. AutoZone usually guarantees their stuff for life so you should bring it back.
Personally I much prefer beam-type torque wrenches. They have a pointer indicator at the handle end and a bending “beam” for a shaft. They’re forever and virtually unbreakable.
That is the exact brand I bought (“Great Neck”, at AutoZone), which broke after one use. Either you got lucky and got a good one, or I was unlucky and got a poorly made one.
Couple of points;
On clicker torque wrenches, you want to always return the dial to 0 (zero) after each use for storage. This relaxes the spring and helps keep it in spec.
You can’t re-check torque settings. The breakaway force required to overcome the friction will give you a false reading. You have to loosen and then re-tighten to check torque. I noticed you tried the former initally and then did the correct procedure later.
All my torque wrenches are Craftsman and I check them every year or so against a standard at work. Never had any issues with them since bought and a couple must be 20 years or older.
The only issue with beam style wrenches is you must be able to see the dial. Often, when working in confined spaces, that’s tough to do.