Lug nuts loosening on older aluminum rims

[mburatyn]

I have a Dodge Dakota quad cab with aluminum rims. All of the 6 lug nuts on the rear drivers side came undone 1800 km (1000 miles) after they had been installed. I read the post about loosening nuts on aluminum rims however the concensus seemed to indicate that this typically accurred with new rims. My rims had approximately 40,000 km (24,000 miles) on them.

Can anyone explain why such a delay would occurr from installation to failure. If the nuts were improperlly torqued I would expect that the problem would have shown up much sooner.

 

[GregLocock]

What had you done to the truck when you had the wheel off?

Sounds very odd, 24000 miles is nothing. Oh are these OEM rims and nuts on an unmodified vehicle?



Cheers

Greg Locock

 

[tireman9]

All 6 would indicate to me that they were not set to proper torque or were tightened when the wheel was very hot.

 

[mburatyn]

The primary reason for the wheel coming off was to remove snow tires. While the wheel was off the rear brakes were cleaned. The truck is totally in its stock form, no modifications.
The wheel was reinstalled with all vehicle elements cold.

I would suspect that the initial rate of the nuts backing off would be related to the magnitude of the random vibrational inputs from the road or a substantial frequency shift that came closer to resonances within the back wheel/stud assembly however my driving routes hadn't changed so I don't beleive these inputs have changed.

I would also think that once the bolt preload was gone that the rate of backing off would have drastically increased. This corresponds to me hearing a new noise for approximately 100 miles prior to the failure. The main question is why did it take say 900 miles for the initial preload to dissipate?

After the failure 2 of the studs were broken off but unfortunately I didn't think to ask the mechanic to give me the studs so I don't know if a fatigue failure was the catalyst.

 

[evelrod]

Sounds like this is a case of 'can't see the forest for the trees' deal. I'll bet when you had the rear brakes apart the drums did not properly seat when you torqued(?) the wheels.
One of the primary reasons for retorquing newly installed custom wheels after a few miles is the 'set' of the aluminum but, not in you case as you describe it.
I can think of no definitive problem with either the Dodge or the wheels that would cause your problem aside improper installation.

Rod

 

[jons999]

I have seen wheels come off after approx. 300 miles of driving caused by the overzealous use of anti-seize compound (light oil is recommended on the studs instead of anti-seize), 1000 miles does seem excessive however. If the drum/wheel was not seated properly it would have come loose much sooner.

From my experiance the failure of the studs probably occured during the final few miles before the wheel came completely loose. The wheel wobbling back and forth as you drove with the loose nuts pounded on the studs causing a fatigue failure.

-Jon

 

[SeaFury]

I have also experienced a similar situation. I had new snow tires installed on older aluminium rims. After 1400 km my front wheel came off. I have covered a lot of ground, trying to prove negligence on the part of the garage. The main reasons for wheels coming off or studs coming loose are under torque followed by over torque and then corrosion on the rim or studs. There has been no studies on the distance required to loose a wheel because there are too many factors that would cause the distance to very. Do not over analyze, the simple answer is the right one in most cases. I have been researching this for a few months and I find that people do not report cases of wheels coming off or coming loose, therefore the data is not there.

 

[evelrod]

"Do not over analyze, the simple answer is the right one in most cases."

I stand by my original post last year. The simple answer to 99% of these problems is--- [highlight] improper installation [/highlight] !
In whatever form the fault lies, improper installation is most probably the underlying cause in almost every instance I have seen in just under 50 years of looking. I lost a wheel---rather---had the lugs come off and rattle around in the hubcap of my 49 Merc in 1958 while on campus. Sure tought me a valuable lesson I have never forgotten.

Every wheel mfgr has torque and installation specs that, if followed, guarantee the wheels will stay on. This includes
torquing the the lug nuts/bolts and not just banging them on with a pneumatic impact wrench!
Most specs reccommend a retorque after a short period---even though this procedure is seldom followed. There is no good reason to loose a wheel if it is properly installed, IMO.

Rod

 

[patprimmer]

Once again. I absolutely agree with Rod, and would add, that not only torquing to spec, but also good practises such as inspecting the threads and mating surfaces to ensure everything will fit nice and snug onto clean uniform surfaces.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
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[Tmoose]

An acquaintance is a registered mechanical engineer and one of the sons of a dad who had a very successful business making alloy wheels for big trucks. And in my opinion he is a thoughtful, practical fellow. While discussing bolts and dowels for joints in a big machine tool he mentioned TRUCKS have to retorque their wheels forever. As a truckless outsider I confidently believe that is "proof" the studs are too short, making the bolted joint susceptible to preload loss. The preload loss comes from the micromotions that passenger cars, and most vehicles with un-glamorous steel wheels with the subtle built in belleville at each lug.

I think if you put wheel back on with decent mating surfaces and the proper torque it will never happen again.

"If the nuts were improperlly torqued I would expect...."

Improperly torqued might be anywhere between 1 lb-ft and 64 lb-ft. If I torqued my left wheels to 5 lb-ft and my right wheel lugs to 45 lb-ft should I expect all the wheels to fall off at the same time?

 

[red300zx99x]

I had a car stolen a few years back and had some 'shoes' on it. Police found the car and it was on cement blocks. Low on cash I headed over to a local junk yard. Searched and searched and searched until we could find a set of wheels that used my bolt pattern. Oddly enough one was found off an old Beemer I drove an Acura Integra. Tightened these babies as much a i could with my trusty well used tbar from the truck and off I went. A few weeks later as I made a slow turn off comes my right front tire............. in front of a moving bus full of school kids, and I off into the ditch I drove while scrapping my rotor againt the road. Long story for the short ending of me learning that when using alloy rims, they must first be tightened with load and another time a few days later. No more 'shoes' for me

 

[evelrod]

red300... You pretty much make my point and I need not add anything further to your post!

Tmoose---"Every wheel mfgr has torque and installation specs that, if followed..." That is what I said, that is what I ment. Properly torqued nuts/bolts,properly torqued to the mfgr specs, properly re-torqued at the mfgr reccommended intervals---the wheels will not just fall off! Of course normal service should include bolt and nut snd wheel inspection for damage, I should not even need to bring that up, but it appears from what I read that we all do not posess what my dad called "horse sense"!

I torque my truck wheels to 350lb/ft(OEM specs) and double check them at every normal service. I have yet to find a loose one in over a million miles. The race car (Mini Cooper) Minilite wheels get 45 ft/lbs and is re-torqued after every session if the wheels are not removed. The Lotus American Libre wheels are torqued to 55 ft/lbs and the same procedure is followed. I have been following this basic procedure since my close call in 1958 and have yet to loose a wheel.

Rod