Darn impact wrenches

[David Anderson]

I bought new tires for the front of the coach, drove 1500 miles to Colorado and back and noticed this when I got home.  Why do the tire shops have to tighten so tight?

I'm going to back them all out and torque them myself.

[zimtok]

If a shop did this then they need to replace the studs and nuts.
If you did this, well, live and learn.

You may want to remove all the nuts and inspect the other studs before you re-torque them.





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[luvrbus]

David, I would check the wheel close you can not breaks those on a aluminum wheel most of the time without the nut going through the wheel or being crossed threaded so buy yourself a wheel depth gauge and check it     
  Good luck

[NJT 5573]

Don't blame the wrench!

$20 says its a left front and left hand threads. It took the tire man 2 lugs to figure out he was going the wrong way. Problem is they may have been stretched in the past and just now gave up. If you were there and the tire man did not hammer the wrong direction on that wheel to get it off, then I think you are both the victim of old damage.

Not hard to repair, getting the new studs is the hard part.

2 broken studs side by side is "out of service", so it needs immediate attention. You don't want a fluke ticket or something to turn into a forced repair roadside.

If you really believe it was the gun then the other 8 will show signs of being stretched. Look for small stress cracks at the threads, about where the others are broken. If you see any sign of stretching then change them all out.

[bevans6]

I was going to say check for stretching too.  I usually try to run a fresh nut down by hand, it will bind if the stud is stretched.  I don't personally use air impact wrenches  much, but I have heard that they develop a lot more torque in reverse than they do in forward, to break loose stubborn nuts.  if that's a reverse thread, maybe something like that happened.

Brian

[JohnEd]

My two cents are:  You need to verify that the rim isn't damaged cause that is a high dollar item and the shop will need to satisfy itself that "they did it".  I think you defense is that "you people let me drive a 40,000 lb vehicle back out on the road in a unsafe condition".  They might tell you to stuff it but they won't tell that to an attorney.  Trick is to get them to treat you like you had an attorney without your having to involver one of the blood suckers.  Second:  Every stud these guys touched is now suspect.  Brian defined a procedure to verify stretched studs but I think the only way to "really do it", from the standpoint I have, is that the studs need to be measured.

You should not spare any expense or cut any corners when someone else is paying for their screwup.  Take care of your families safety FIRST.

If you put this off you will get no relief due to your responsibility to take "timely action".

Not trying to run your life here.  read everything I say with the prefix: "If it were me".

Good luck,

John

[Airbag]

If something like that happened in my shop I would be installing all new studs and dye penatrant checking the wheel for cracks at minimum. My luck though, I would be buying a new wheel.

You need to stand your ground with them and make them make it right.

[kyle4501]

That's awful & a real bummer to boot!

My take:
Talk to the shop first with a calm tone ( make no accusations until they force the discussion to take that direction, then make accusations carefully ).
You may have to do some discrete documentation of shop practices before you can gain traction with a complaint.

See if you can  take the hub to them to replace all 10 studs & you take care of R & R the hub. I wouldn't knowingly drive it in the current condition, the potential for more studs to pop is too high for me to bet otherwise.

Another thought, the tire shop may be as big a victim to past abuse of the wheel studs as you are. They may have been damaged the last time the tire was put on . . . .


The response from the tire shop will determine your future dealings with them.
A good shop will make it right. Airbag runs a good shop!


Good Luck & I'm glad it wasn't worse!

[JohnEd]

What Rick said!!!!!

John

[Len Silva]

Do you mean that you are now 1500 miles from the tire shop? Bummer!

[bevans6]

Do you have a way to measure the break-loose torque required to undo the remaining nuts?

[Jerry32]

The trouble is they don't touque them , they just slam em on with the inpact wrench. I have tried cheater  pipes 16 feet long and jumed up and down on them with my 190 lbs and still wouldn't budge. Jerry

[JohnEd]

And still, I haven't been in a tire shop in years that didn't whip out a torque wrench to finish tightening my lug nuts.  Infernal blood suck'en lawyers changed everything with a few million dollar settlements awarded by 12 people as smart as you and me.  Darn system!

Why haven't the truck tire shops followed suit?  (No pun intended)

John

[David Anderson]

I don't want to mislead anyone, but I bought these new tires July 2008 and have about 5000 miles with no problem.  It was the last trip to Colorado and back that this happened.  Fortunately I am home and the bus is parked.   It has been too long to make demands from the tire shop.  Besides we are friends and it's not worth the argument to me for 2 $11 studs. 

I removed the wheel, hub, and bolts.  I cannot see any conspicious damage.  All the other nuts could be removed by hand after breaking loose.  I'll pick up some new studs tomorrow.

David

[kyle4501]

David, looking at the broken end of the stud, was it one solid color? Or were there lines like tree rings.

Solid color is a single overload failure.
Lines means it was a fatigue failure. (Damage was done a long time ago & the action of normal use finished it off.)



There is a formula that approximates bolt tension, but there are loads of variables. Empirical testing proved the following simple equation to be as accurate as the long version that accounted for thread details.

T = KDW/12

Where:
T = Torque (ft lb)
K = Torque coefficient (similar to but different from coefficient of friction)
D = Nominal bolt diameter (inch)
W = Bolt tension (lb)

- K Values

- 0.35  Dirty or rusty threads
- 0.30  Heavy galvanized coatings
- 0.25  Dry plated fasteners
- 0.20  Normal as "received" fasteners
- 0.15  Plated lubricated fasteners
- 0.12  High lubricity using grease, oil, or wax


So, for a 3/4" stud torqued to 450 ft-lbs, as received condition
450 = .20 x 3/4 x W / 12

. . . . . W = 36,000 lbs

For anti-seize (K=.12); W = 60,000 lbs

For overtorque to 750 ft-lbs & as received condition,
. . . . . W = 60,000 lbs

Torque to 1000 ft-lbs & W = 80,000 lbs

T=1000 , K=.12 - - - W = 133,333 lbs


Easy to see how easy it is to pop studs if lubricated &/ or over torqued.



Around here, it is rare that torque wrenches are used.
Most shops use the torque sticks, but of all that I've talked to, none knew that the impact gun needed to be 'calibrated', much less how to do such a calibration.