# thunk in trunk lead to broken lug bolts?



## BlueBomber (Feb 11, 2005)

ok i've done some searching and i think i may have a new problem that i need suggestions for. ok it started about a two weeks ago, i was pulling into a drive thru and notice a thunk that sounded like it was coming from the rear of the car. the thunk seemed to happen if i rolled 5-10 feet with the car in first. i drove home and the thunk happened more often which made since to me since i was goin faster. i continued to try and troubleshoot the problem when i got home. i discovered that the thunk occurred only when rolling forward with the transmission in gear (the sound did not occur when i rolled backwards in or out of gear or when i rolled forward out of gear). at this point i couldnt tell where exactly the sound was comming from so i waited until the next day and i had a buddy of mine check it out with me (it was kinda difficult to tell where the sound was coming from so i hoped he could tell me standing outside of the car. the thunk went away though, so i continued to drive it around town for the next couple of weeks. 

yesterday i took my car out on the interstate for the first time since i had noticed the initial thunking. well i noticed that i had a decent vibration when i got up to highway speed. i pulled over at the next exit and inspected tires. they were all properly inflated so i thought maybe i had lost one of those stick-on wheel weights that the tire stores balance the tires with. i continued on my way, the vibration continued as well as the "thunk in the trunk" seemed to start happening when driving around town (occured mainly when starting out). so i took care of my things that i had to do and on my way home the vibration gradually seemed to get worse. then all of the sudden the vibration got significantly worse (it sounded and felt like i had blown a rear tire). i got out looked at all the tires and all were still properly inflated. so i called a tow truck. when he got my car loaded i happened to look at my front driverside tire and noticed that two of the lugnuts looked loose or like the little plastic caps where coming off. so i reached down to push them back on and the lugnut including a broken portion of the lug bolt came out. i have two broken lug bolts and one of the lug nuts was finger tight loose. 

needless to say i said a little prayer that it was just a wrecker that came to pick us up and not an ambulance. my car is sitting at the dealership right now. we dropped it off and i get to go talk to the service department tommorrow because they were closed when we got there. i'm curious to any opinions you guys have. or any tips you guys have when i go to talk to them tommorrow.


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## pickinfights (Oct 3, 2006)

So it was broken lug nuts that caused the thunk sound? Or is this a result from whatever was causing the thunk. Either way, glad yer ok.


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## BlueBomber (Feb 11, 2005)

that is the question at hand. i'm glad i'm ok too thanx.:cheers


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## nagoat (Oct 21, 2006)

wow..also glad your o.k. have you had anything done recently..tires,wheels etc.?


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## nagoat (Oct 21, 2006)

maybe it just sounded like it was coming from trunk. i had some stuff rolling around in my glovebox and i swore the sound was coming from the trunk.


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## cammed06 (Dec 12, 2006)

Responding to your inconsistent rolling clunking, when your car is fixed, check again. Mine too made the clunking in gear, clutch depressed only rolling forward. I took it in for the incompetent aussie strut problem and mentioned the clunking. It was in the synchros. From the factory a bushing got placed in wrong, eventially wearing to the point of doing that. It was causing all kinds of problems. Fixed for now.


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## nac4life (Nov 7, 2006)

i had an IROC that did the same thing. was on my way to the beach on the interstate and it was clunking like that. needless to say we came back home and the clunking only got worse with slowing down, sure enough all of a sudden the tire shot off across route 30 and my car ate the pavement. was the lugs. after i got out and got myself some new lugs and slapped the tire back on i always checked the lugs for the rest of the time that i had that car. you were lucky though.


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## BlueBomber (Feb 11, 2005)

yea i had rotated the tires on my own recently. i'm kinda wondering if i overtorqued the lug nuts. i used my 18 volt dewalt impact wrench to remove and install the lug nuts. if this is what lead to me breaking these lugs i'm nervous cuz i tightened all of the lugs pretty much the same.:willy:


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## nagoat (Oct 21, 2006)

BlueBomber said:


> yea i had rotated the tires on my own recently. i'm kinda wondering if i overtorqued the lug nuts. i used my 18 volt dewalt impact wrench to remove and install the lug nuts. if this is what lead to me breaking these lugs i'm nervous cuz i tightened all of the lugs pretty much the same.:willy:


i'd have them all inspected. used to be you could just crank down on lugs, but now everything is torque speced.


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## nagoat (Oct 21, 2006)

there's also the possibility of tightening the wheels on not perfectly straight.


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## oldsow (Aug 6, 2006)

lug nuts must all be checked for centering when puting wheel back on and they must be torqued with a torwue wrench to FTLBS in the specs. The are aluminum wheels, has to be done or bad results can occur.


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## GTO JUDGE (May 14, 2005)

BlueBomber said:


> yea i had rotated the tires on my own recently. i'm kinda wondering if i overtorqued the lug nuts. i used my 18 volt dewalt impact wrench to remove and install the lug nuts. if this is what lead to me breaking these lugs i'm nervous cuz i tightened all of the lugs pretty much the same.:willy:


*
Your 18 volt Dewalt must have some kind of torque. I can see breaking off screw heads with an 18V. but a lug stud?

Best thing to do is snug em up with an air gun, or battery gun in a star pattern then torque em with a torque wrench in a star pattern (with wheel not being able to move). A clicker torque wrench is the best kind to have. 

So many mechanics use just an air gun to tighten up lugs, and then when there is a flat there is no way in hell to break the lug nut loose because of the amount of torque that was applied. How many guys have experienced this in their life?

The method I described is a fail safe method. No way should lug nuts just be torqued with an air gun, no matter how good the guy doing it says how great the gun or he is. 

My recommendation also is to have a 4 way lug nut wrench. The single one with a pry bar end will not allow you leverage on a stubborn lug nut unless of course you have a pipe to put on the end. With a 4 way you can use adequate leverage. Of course if there is 500 ft lbs of torque on the lug, your in deep chit out on the open road and can't budge it.*


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## BlueBomber (Feb 11, 2005)

yea i had no idea that my impact wrench could possibly that strong. i do use the criss cross method to put the lug nuts on that is a common practice for bolting anything back together.


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## 05GTO (Oct 6, 2004)

oldsow said:


> lug nuts must all be checked for centering when puting wheel back on and they must be torqued with a torwue wrench to FTLBS in the specs. The are aluminum wheels, has to be done or bad results can occur.


I agree, I suggest buying 20 new bolts and 20 new lug nuts, there is no way an 18 volt cordless drill overtightened the grade 8 lug nuts to the point of breaking. Probably the opposite occured, the cordless drill did not get the nuts as tight as needed causing play and then snapping the bolts. Buy yourself a good torque wrench and a 4 way lug wrench or let a tire shop rotate your tires.


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