Damaged lug bolts

Topic: Damaged lug bolts (Read 1467 times) previous topic - next topic

Damaged lug bolts

February 22, 2019, 10:58:19 am

We're at MOT getting service on our brakes. When the guys went to put the wheels back on the front, they found three bolts that could not be torqued to the 400-foot-pounds they use here. The bolts had to be replaced at considerable effort and cost.
When looking at the bolts with the lug nuts on one can see in the attached photo that two are out further... stripped. As Keith Risch (MOT master tech) explained, the problem occurs when someone puts excessive torque on the nuts. Like with an air driver set too high. Since the bolt is smaller in diameter on the inside where the inner nut holds it in place, this is where the damage occurs. Best to used the air driver to put on the nuts with moderate tightness, then torque them as shown in the pic. So who did this? The front tires were replaced by Herman Power last year about this time.

I will have more to say about service at MOT and Keith in particular. Excellent! That has not been the case with other services we have had here in Nac.

Re: Damaged lug bolts

Reply #1 – February 22, 2019, 11:13:47 am

When Herman Power replaced the tires on a rig we had a number of years ago they used only an impact wrench. I asked the tech what he was torquing the bolts and he replied that he just turned up the gun as high as it would go. I didn't know any better at the time. Disappointing that they are still not torqueing properly.
jor

Re: Damaged lug bolts

Reply #2 – February 22, 2019, 11:16:32 am

400# lubed may be too high . Look up the nominal spec for the retainer nut size. My bet is 300# max.
Always better to hand tighten for final torque of course.

Re: Damaged lug bolts

Reply #3 – February 22, 2019, 11:23:26 am

Something else other than lug nut torquing going on there. The threads that would have been up against the inside of the hub are still good. That stud is pulled into the hub and the serrations lock it if the smaller nut on the inside is tight. Looks like the someone stripped the threads trying to put the stud in.

Re: Damaged lug bolts

Reply #4 – February 22, 2019, 11:29:36 am

Right . Almost looks like it was never fully seated.

Re: Damaged lug bolts

Reply #5 – February 22, 2019, 12:17:12 pm

Thanks for the input. There were six bolts that had to be replaced on the front wheels. So it likely happened as I described... over tightening the lug bolts. I took the bolts to Herman Power and talked to Craig Power. Without hesitation, he said to bring him the bill and they would cover the cost. He also said they try to closely monitor the torque of their impact tools, but sometimes problems occur.

I asked one of the MOT crew about the 400 ft pounds torque that they use and they confirmed that is what should be used.

Re: Damaged lug bolts

Reply #6 – February 22, 2019, 12:22:33 pm

Be sure to differentiate between 400 lb-ft DRY vs LUBED. Big difference!

And, with Aluminum wheels, they need to be retorqued after a few hundred miles.

Re: Damaged lug bolts

Reply #7 – February 22, 2019, 12:31:40 pm

They are dry, not lubed.

George

Re: Damaged lug bolts

Reply #8 – February 22, 2019, 12:41:28 pm

Correct.

But, have seen "Bubbas" slap grease on them then use an impact.

I know, you have met Bubba!

Re: Damaged lug bolts

Reply #9 – February 22, 2019, 12:42:31 pm

And to this topic, I have never had a shop use a torque wrench. I doubt many of them even own one that is properly calibrated. So what must one do.

Re: Damaged lug bolts

Reply #10 – February 22, 2019, 12:44:04 pm

Quote from: wolfe10 – February 22, 2019, 12:41:28 pm

Correct.

But, have seen "Bubbas" slap grease on them then use an impact.

I know, you have met Bubba!

What I get is we "set" our impact wrenches. Hummm.

Re: Damaged lug bolts

Reply #11 – February 22, 2019, 12:51:21 pm

When you over torque a stud or bolt it will stretch. This is called necking as the stretched part is narrower and the thread pitch changes. Running the nut onto the stud will show if this is the case as it will jam. Often it's running the nut on a stretched bolt that causes it to strip. It's OK to use an impact for running the nut up or off. It's not OK for final tightening. When I had my front tires replaced they used a torque wrench both on installation and when rechecking the torque 100 miles later.

In my past life with large fleets we always used a torque wrench on critical items like wheels. The wrenches were regularly checked against a reference unit.

Here is Alcoa's wheel service manual with everything you need to know.

https://www.arconic.com/alcoawheels/catalog/pdf/servicemanual-english.pdf

Keith

Re: Damaged lug bolts

Reply #12 – February 22, 2019, 12:52:27 pm

Socket, 3/4" breaker bar, regular 1/2" torque wrench and 5' thick wall iron pipe with 1/2" socket welded into one end: Torque Wrench extensions

You will need some kind of stand and extension to get in far enough to reach the nuts on the rear wheels.

With this, even a 100 pound weakling can properly torque the lug nuts. No expensive tools needed.

Used this for the last two decades with a "custom upgrade"/elegant one made by a fellow Foretravel owner that even has a set screw for holding the handle of the breaker bar in the pipe.

On mine, 400 lb-ft requires a torque wrench setting of 94 lb-ft-- this is dependent of the length of the pipe with longer pipe requiring less input torque.

Re: Damaged lug bolts

Reply #13 – February 22, 2019, 12:58:11 pm

Lubed is much better and fights corrosion .

Re: Damaged lug bolts

Reply #14 – February 22, 2019, 01:01:40 pm

Quote from: Protech Racing – February 22, 2019, 12:58:11 pm

Lubed is much better and fights corrosion .

But, one would have to KNOW how much to lower torque specs when going from factory recommended "dry" to "lubed".

Said another way, lubing and using dry torque specs will over-stretch the bolt!

Re: Damaged lug bolts

Reply #15 – February 22, 2019, 01:06:09 pm

Quote from: wolfe10 – February 22, 2019, 12:52:27 pm

Used this for the last two decades with a "custom upgrade"/elegant one made by a fellow Foretravel owner that even has a set screw for holding the handle of the breaker bar in the pipe. On mine, 400 lb-ft requires a torque wrench setting of 94 lb-ft-- this is dependent of the length of the pipe with longer pipe requiring less input torque.

If you ever want to get rid of it, I know a coach that would love to have it back!

Re: Damaged lug bolts

Reply #16 – February 22, 2019, 02:45:04 pm

Hummm..... I was at Hermann power tire yesterday dealing with a defective tire. My next stop was at the mothership to get a replacement lug bolt that was found damaged when I replaced the defective tire last week. Herman power put the tires on 1.5 years ago.... does anyone see a trend here...

Re: Damaged lug bolts

Reply #17 – February 22, 2019, 03:40:47 pm

Alcoa gives lubed value. About 100# less . or 300+-25.

Re: Damaged lug bolts

Reply #18 – February 22, 2019, 03:54:16 pm

My files show that 12 of them were replaced the last time fresh Michelins were done in 2014.

Re: Damaged lug bolts

Reply #19 – February 22, 2019, 04:26:11 pm

That's why I never let a tire shop air gun our wheels. If you use a little Anti-Sieze Amazon.com: never sieze on the threads, you can torque to 20 percent less and sure the nuts will come off easily.

Our forum is full of shop mistake posts. A big reason to do as much as you can yourself.

Pierce

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Re: Damaged lug bolts

Reply #20 – February 22, 2019, 04:44:57 pm

We believe in torque but have never seen a truck tire shop with a working 400-600 torque wrench. Over tightening can 'yield' the lug nut, stretching it longer and no longer able to keep nut to the tightness setting.

After having two lug nuts overtightened by a truck tire shop. causing them to later break the next time the nut was removed, we started to lubricate stud threads. First, we used gray anti-seize, wiping almost off with a rag after applying. Later we moved to CorrosionX. No more broken studs, at the cost of not being able to correctly torque, as torque specs are for dry threads.

And then there are techs who run the gun pressure to max to remove nuts, but don't realize the 'L' stud is reverse-threaded and they end up damaging stud. Truck tire places are always a risk, as they often put several guys on the job working as fast as they can.

Re: Damaged lug bolts

Reply #21 – February 22, 2019, 05:21:43 pm

Quote from: Barry & Cindy – February 22, 2019, 04:44:57 pm

After having two lug nuts overtightened by a truck tire shop. causing them to later break the next time the nut was removed, we started to lubricate stud threads. First, we used gray anti's, wiping almost off with a rag after applying. Later we moved to Corrosion. No more broken studs, at the cost of not being able to correctly torque, as torque specs are for dry threads.

Over torquing has a cumulative effect on the stud. The more times it's done, the longer the stud becomes plus it loses strength. With MBZ cylinder head bolts, we tightened X foot lbs and then tightened a prescribed number of degrees. But before any of this, we had to measure the total length of the bolt as after being overtightened so many times, it would bottom out in the block before pulling the head down correctly. Long bolts were thrown out.

Using Alcoa's recommended torque with n-seize or just taking 20 percent off, is what is needed to keep the nuts on securely without damaging the stud.

Pierce

Re: Damaged lug bolts

Reply #22 – February 22, 2019, 06:39:25 pm

As I recall from way back when, It was not good to lube a lug nut as that would set you up for the nut to loosen and come off. I suppose that a small amount of non hardening anti-seize or graphite would probably be OK, but for me (old technology) I'll stick to dry (but clean) threads. Also, as I recall, the metal used in the nuts and studs are such that they were designed to be compatible on a dry basis. Have a great day ---- Fritz

Re: Damaged lug bolts

Reply #23 – February 22, 2019, 09:33:23 pm

So should I remove my tires and wheels and deliver them to the tire shop? I can roll them into the back of my truck.

I have one stemco oil bath cover seeping and an inner seal seeping also. Might as well do both.

I only have a 1/2 torque wrench so I would have build an extension to get proper torque.

How hard is it to source studs and ballpark cost, replace them all while hubs are off or just inspect? Same for lug nuts. If the tire shop strips or damages studs do they really screw yah $$$? Best guess as I am a newbie to big stuff dance. Go ahead and buy a hydraulic press cause I am going to need it?
Asking for sage advice from experienced owners of big stuff as I hope to be doing this for 10-15 years. Probably with the same coach.

Re: Damaged lug bolts

Reply #24 – February 22, 2019, 09:50:45 pm

Any "A line" tech guy will lube the studs, as that is the correct way. A little grease, gear lube or anti sieze will do.

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