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wierdscience
09-20-2016, 02:01 PM
Had a good one today,lady came in to the shop last week with a front wheel drive hub and bearing assembly a new bearing and four new wheel studs wanting the bearing and studs changed.No problem,routine job,pressed it apart,pressed the old studs out,new ones back in and pushed the whole assembly back together.I noticed that all four studs were broken off,but that's not too unusual given how tight some tire shops gun the lugs down now.

Monday she calls up,tells me the four new studs broke off,the wheel came off and put her car in the ditch.She had to have it towed and she said we owe her for the tow and the repairs because her mechanic told her the studs weren't pulled tight with the spindle flange(no way in hell).So we sent one of our guys over to the car,he pulled the assembly off the car and brought it and the tire and rim back to the shop.

This a 20xx Honda Civic,but the rim says FORD in the center cap.Turns out she had warped a rim a month back and her "mechanic" got one from a salvage yard and put it on the car.Then a week later the first set of wheel studs broke,then all the fun started.

So a quick check confirmed the Honda has a larger center pilot than the Ford Escort the rim came off by a good 2mm and her "mechanic" just ran the lugs up anyway because according to him "the pilot doesn't do anything anyway"-and what a jacka!! he is too.

So I gave her a stack of hi-res photos of the studs,the documentation regarding the pilot diameters and a written report from a mechanical engineer including his PE stamp.Told here here-go sue the stupid b@!@#~! before he kills somebody.

Arcane
09-20-2016, 02:36 PM
While it might seem like the cause of failure was the non piloted wheel, it might not be. I say this because of a couple of things, one being my experience as owner/driver and later as crew member on a Street Stock class oval track race car where we used non piloted rims with stock wheel studs and 1" wheel nuts and we never had a single problem nor did I see anyone else have a single problem. Nothing side loads a wheel like oval track racing does! (We won 8 championships in a row with the car I crewed on too btw.) Another thing is I've also ran non piloted rims on a 1980 Chevy 4x4 3/4 ton truck for years without any issues ever albeit rarely hauling much weight. (No cracks about my girlfriends either, eh! :D)

I think it's highly likely you nailed the cause of the failure when you said "I noticed that all four studs were broken off,but that's not too unusual given how tight some tire shops gun the lugs down now." I'd bet my own money that the wheel nuts were severely overtightened and just a bit more load on them from normal driving put them into failure mode.

Either way, it was her mechanic's fault!

dave_r
09-20-2016, 02:46 PM
It may also depend on the lug nuts themselves, as if the wheel is hub-centered, then the lug nuts are generally flat, vs when it is lug-centered, and the lug nuts are tapered to position the wheel correctly.

Odd are, the stock car would be using tapered lug nuts to go with the lug-centered wheels. :p

strokersix
09-20-2016, 03:41 PM
The pilot was BIGGER than the hole in the rim. this prevented the wheel from contacting the hub and leaving a gap between wheel and hub. Result is all cyclical loads, cornering and simply rolling vehicle weight will be seen by the studs and cause fatigue failure. TWICE.

Read up on bolted joint diagrams to understand:

http://www.boltscience.com/pages/basics1.htm

If the pilot was smaller than the hole in the rim it probably would have been fine.

JRouche
09-20-2016, 03:49 PM
So a quick check confirmed the Honda has a larger center pilot than the Ford Escort the rim came off by a good 2mm and her "mechanic" just ran the lugs up anyway

Thats just crazy!! And some mechs wonder why there is a bad rap in the mech business. JR

A.K. Boomer
09-20-2016, 04:00 PM
Some peoples kids lol serious business... you gave her everything needed to hang his ass with - perhaps he will think twice when trying to pass the blame onto someone way more intelligent than he is... what a world...

she was actually going to go easy on you with her demands - with him after being caught in a lie - probably not - so be it...

Yondering
09-20-2016, 04:44 PM
The pilot was BIGGER than the hole in the rim. this prevented the wheel from contacting the hub and leaving a gap between wheel and hub. Result is all cyclical loads, cornering and simply rolling vehicle weight will be seen by the studs and cause fatigue failure. TWICE.

Read up on bolted joint diagrams to understand:

http://www.boltscience.com/pages/basics1.htm

If the pilot was smaller than the hole in the rim it probably would have been fine.

Absolutely right.

Lug centered is fine. A gap between wheel and hub - not so much.

Willy
09-20-2016, 05:20 PM
Another reason I do all of my own automotive work, I've seen worse examples of "mechanics" at dealerships that charge $120/hr.
Not to besmirch all auto mechanics, there still some very good ones around. If you find one treat him well.

Unfortunately there is still a very large segment of "professionals" around who still have not grasped the concepts and differences between hub piloted wheels and stud piloted wheels. The design and function of their respective wheel mounting hardware is also totally different in design and execution.
But yeah bolting a hub piloted wheel onto a hub that has a pilot 2mm bigger than the one that the wheel has just screams stupidity.

Guys like this "mechanic" kill people by inflicting the effects of their ignorance onto the the unsuspecting.

MikeWI
09-20-2016, 07:23 PM
her mechanic told her the studs weren't pulled tight with the spindle flange(no way in hell).

I hate that phrase "my mechanic told me". If the person has a regular mechanic, then why did she come to you? Always means trouble.

kendall
09-20-2016, 07:29 PM
While it might seem like the cause of failure was the non piloted wheel, it might not be. I say this because of a couple of things, one being my experience as owner/driver and later as crew member on a Street Stock class oval track race car where we used non piloted rims with stock wheel studs and 1" wheel nuts and we never had a single problem nor did I see anyone else have a single problem. Nothing side loads a wheel like oval track racing does! (We won 8 championships in a row with the car I crewed on too btw.) Another thing is I've also ran non piloted rims on a 1980 Chevy 4x4 3/4 ton truck for years without any issues ever albeit rarely hauling much weight. (No cracks about my girlfriends either, eh! :D)

I think it's highly likely you nailed the cause of the failure when you said "I noticed that all four studs were broken off,but that's not too unusual given how tight some tire shops gun the lugs down now." I'd bet my own money that the wheel nuts were severely overtightened and just a bit more load on them from normal driving put them into failure mode.

Either way, it was her mechanic's fault!

Think you missed the 'Larger pilot on the Civic then there was on the Ford rim' part. That means he either stretched the studs or bent the rim to make it fit. I've used rims with bigger pilots than the axle on my trucks with no trouble ever, but if I ran into a rim with a smaller pilot, I'd go looking for another, or grab 3/8" spacers I have in the shed would never just crank them down.

kendall
09-20-2016, 07:31 PM
Think you missed the 'Larger pilot on the Civic then there was on the Ford rim' part. That means he either stretched the studs or bent the rim to make it fit. I've used rims with bigger pilots than the axle on my trucks with no trouble ever, but if I ran into a rim with a smaller pilot, I'd go looking for another, or grab 3/8" spacers I have in the shed would never just crank them down.

Darn, beat by everyone!

wierdscience
09-20-2016, 07:59 PM
Thats just crazy!! And some mechs wonder why there is a bad rap in the mech business. JR

Yup,just a few bad apples,worst is he robbed her first time around IMO.If I heard her right he charged her $350 to pull the assembly and re-install it.On a Civic that's about an hour each way IIRC.

wierdscience
09-20-2016, 08:10 PM
I hate that phrase "my mechanic told me". If the person has a regular mechanic, then why did she come to you? Always means trouble.

We do general machine work and fabrication and one of the services we offer is press work removing bearings,straightening things etc.Several shops around town send their wheel spindle work over either because they don't have a press or the puller set to remove them,plus we get a slew of DIYers.
It's a money maker for us and 99% of the time everybody is happy and all is well,of course there is always the 1%er's that make life interesting.

wierdscience
09-20-2016, 08:17 PM
Yes and this one had a burr of Aluminum 3/4 the way around the rim bore and about 1/8" deep where the rim tried to stretch over the pilot.So I figure 1/8" off kilter at the pilot,that must have translated to 3/4"-1" run out at the tread.

If he had just put the car in neutral and rolled the wheel around a couple times he would have seen it.

garyhlucas
09-20-2016, 08:20 PM
I had a customer get bearings replaced on a tire tread grinding machine. The machine shop took the shaft back to their shop and used a 100 ton press to get the pulley off, then pressed it back on the same way. The machine still sounded bad with new bearings because the pulley wasn't in the right place. I showed the customer and told him I'd have it fixed in a few minutes. That was when he told me about the press. He about fell down when I loosened the three bolts on the TAPERLOCK bushing and moved the pulley over by hand! Remember half the class is always below average.

Arcane
09-20-2016, 08:42 PM
Think you missed the 'Larger pilot on the Civic then there was on the Ford rim' part. That means he either stretched the studs or bent the rim to make it fit. I've used rims with bigger pilots than the axle on my trucks with no trouble ever, but if I ran into a rim with a smaller pilot, I'd go looking for another, or grab 3/8" spacers I have in the shed would never just crank them down.

Ahh! Right you are! I don't know why I got it reversed but I did. My ONLY excuse is I can't believe anyone would ever even try mounting a rim on a hub where the hole in the rim was smaller than the pilot on the hub. Ignore all I said!! lol

achtanelion
09-20-2016, 09:05 PM
Well, I sure feel a lot better. I was fixing the parking brake backing plates on my jeep (held in with aluminum pop rivets. I wonder what could have happened to make the rivets fail chrysler?) when I read the wrong row of the table and overtorqued (read twisted off) one of the studs. Which were only for 2 model years of the liberty. Which are 10 days away in a warehouse in Michigan. Which chrysler refuses to expedite, no matter what. On the day before the rifle season opener. Dammit.

mattthemuppet
09-21-2016, 12:02 AM
that's alright, I discovered that the left rear wheel spindles on Ford Meteors are LH threaded. 2ft breaker bar with 4ft iron pipe slipped over it got it off nicely :)

although this case sounds like an idiot of a mechanic, sometimes they screw up just because they don't know the specific ins and outs of that model. General techniques that work 95% of the time, totally screw stuff up the rest. On my old Focus I needed to replace the rear springs (bad ride and excessive tire wear), but knew from reading online that the control arm to knuckle bushing seizes and trying to unscrew that bolt will trash the bushing. I tried getting one off with a spring compressor and spent about 4h to do one. Took it to a mechanics, got it quoted at $70 and then had to stop the guy from undoing the control arm to knuckle bolt. He ended up undoing the other end and spent nearly a couple of hours wrestling with it. Paid him $70 and got him a 6 pack as compensation. Eventually replaced all the bushings - that plus the new shocks and springs cured 95% of the tire wear problem.

wierdscience
09-21-2016, 01:02 AM
I had a guy come in from off the side of the interstate one day-

"Oh man,I hope you can help me.I'm broke down on the side of the interstate with a flat on my travel trailer.I had to bring the hub in because the lug bolts were on so tight I had to use a cheater pipe and all five....... of them........... twisted right ...................off"

He said as I was spinning the lef thand thread remnants out with my fingernails,I felt bad for the guy and didn't charge him anything :D

becksmachine
09-21-2016, 01:23 AM
I had a customer get bearings replaced on a tire tread grinding machine. The machine shop took the shaft back to their shop and used a 100 ton press to get the pulley off, then pressed it back on the same way. The machine still sounded bad with new bearings because the pulley wasn't in the right place. I showed the customer and told him I'd have it fixed in a few minutes. That was when he told me about the press. He about fell down when I loosened the three bolts on the TAPERLOCK bushing and moved the pulley over by hand! Remember half the class is always below average.

:rolleyes:

LMAO, that is a classic!!

Dave

PStechPaul
09-21-2016, 01:38 AM
I think the studs and lug nuts on my 1989 Toyota P/U and my 1999 Saturn are all RH, as were those on most of my other cars, AFAIK. I really wonder how important it is (was) to have them tighten in the same direction as the normal rotation of the wheel.

I also ran into LH threads on the right-angle drill attachment I took apart. The input shaft housing has something like 24mm x 1mm RH threads, which makes sense, since that would be the rotation of the power drill. But the output shaft has 24mm x 1.5mm LH threads, which is the direction for tightening the retainer into the gear housing. But it seems unnecessary because the shafts are supported on ball and roller bearings, so there's very little torque. Besides, the threads were sealed with some sort of Lok-Tite, and I had to pretty much destroy the parts to get the thing apart:

http://enginuitysystems.com/pix/tools/Drill_Angle_Attachment_3043.jpg

darryl
09-21-2016, 02:18 AM
I'm reminded of the fact that when you tighten a fastener, the more you tighten the less strength is available to handle the load. Tighten to the breaking point and there is no strength left. Not only is there no point in over-tightening a fastener, it is wrong- and dangerous- to do so.

strokersix
09-21-2016, 07:36 AM
I'm reminded of the fact that when you tighten a fastener, the more you tighten the less strength is available to handle the load. Tighten to the breaking point and there is no strength left. Not only is there no point in over-tightening a fastener, it is wrong- and dangerous- to do so.

This is incorrect. Fasteners too loose are likely to cause joint and/or fastener failure particularly in cyclical loading situations. Please read up on joint diagrams in the link I posted previously to the boltscience website.

Willy
09-21-2016, 09:24 AM
I'm reminded of the fact that when you tighten a fastener, the more you tighten the less strength is available to handle the load. Tighten to the breaking point and there is no strength left. Not only is there no point in over-tightening a fastener, it is wrong- and dangerous- to do so.


This is incorrect. Fasteners too loose are likely to cause joint and/or fastener failure particularly in cyclical loading situations. Please read up on joint diagrams in the link I posted previously to the boltscience website.

I can certainly appreciate where both of you are coming from.
Clamp load is imperative to a properly fastened bolted assembly. The fastener acts like an elastic member in that the fastener's elasticity is what keeps the proper clamping force on the assembly to a pre-determined and engineered tensile load.

Exceeding the yield point of a fastener in effect reduces the clamp load and the fastener is now mostly ineffective.
I believe this what Darryl is saying.

In a somewhat very similar vein I used to haul a lot of heavy equipment on lowbed and highboy trailers. One thing that I learned very early, and a point that is still highly stressed, is that although load securement equipment should be properly tightened, it should not be over-tightened.
Much like a bolt, a chain that is tightened close to it's yield point will have no reserve left during transport, when due to vehicle dynamics the movement on the deck of the load will exceed the yield point of the chain rendering it useless. Hitting a dip in the road effectively eats your safety margin.
All of the strength of the fastening device has been used in preload, almost as bad as no preload. Probably worse because now you are lulled into believing all is well because it's tight.

strokersix
09-21-2016, 10:01 AM
Yup. It is all about the stiffness ratio of the fastener compared to the joint. The trucking chain binder example would be considered a "soft" joint where the fastener (chain) will see tension fluctuations in service.

Joint diagrams!!!

J Tiers
09-21-2016, 10:08 AM
I'm reminded of the fact that when you tighten a fastener, the more you tighten the less strength is available to handle the load. Tighten to the breaking point and there is no strength left. Not only is there no point in over-tightening a fastener, it is wrong- and dangerous- to do so.




Not quite right.

If you bolt a beam to a block, tightening the bolt to an initial tension, the block and beam are pressed together by a clamping force which is the initial tension. If you then apply an external slowly increasing force that tries to move them apart, the bolt does NOT see the sum of the initial tension plus the load.....

IF the bolt "saw" an added load, it would stretch more, and a gap would appear between the block and beam with ANY added force. This does not happen.

What actually happens (in the ideal case) is that the increasing force against the beam gradually transfers the clamping force from pressing against the block to being sustained by the external increasing force. Only when that external increasing force reaches the initial tension, the clamping force, does the bold "see" any increase in tension.

Essentially, you cannot apply more force to the bolt without moving the beam relative to the block. But since those two are pressed together, you must first overcome that force that presses them together before you can move the beam and stretch the bolt more than it was to begin with.

Reality is not quite like the ideal case, but is similar to it.

kendall
09-21-2016, 11:33 AM
that's alright, I discovered that the left rear wheel spindles on Ford Meteors are LH threaded. 2ft breaker bar with 4ft iron pipe slipped over it got it off nicely :)

Was heading home after work one Friday night, pulled in for gas and there's an older Charger with the left rear tire off sitting in the corner of the lot next door. After I got gas and coffee, I walked over to see if they were having problems, and that's what they did, broke off 4 studs before they figured out what was wrong. Then he mentioned that the station attendant had told them that they just shut down the garage and couldn't fix it till Monday morning, with Illinois plates on the car I figured it was pretty bad to make them sit for that long. So I grabbed my jack and a hammer, then knocked a stud out of each of the other three wheels, and put them in place of the broken ones.

As I was letting the car down and giving him directions to an open garage and telling him to drive carefully, the attendant came out saying he was calling the cops for stealing his customers and that I was performing 'illegal repairs'.

mattthemuppet
09-21-2016, 12:14 PM
interesting, never heard of wheel studs being LH threaded - in my case it was the spindle nut that held the drum on the wheel spindle. You must have had a big deposit in your karma account after that. What an ahole attendant though..

H380
09-21-2016, 01:09 PM
She had to have it towed and she said we owe her for the tow and the repairs because her mechanic told her the studs weren't pulled tight with the spindle flange(no way in hell).

AND if she died in the crash or hit a schoolbus full of children. The attorneys would have been like flies on S**t around you and the mechanic. This is why a lot of machine shops and even welders will not take work for parts on vehicles or trailers. Even if the mechanic is 100% at fault. You will STILL need an attorney to prove that in court. All about liability.

wierdscience
09-21-2016, 01:35 PM
AND if she died in the crash or hit a schoolbus full of children. The attorneys would have been like flies on S**t around you and the mechanic. This is why a lot of machine shops and even welders will not take work for parts on vehicles or trailers. Even if the mechanic is 100% at fault. You will STILL need an attorney to prove that in court. All about liability.

Yup,we are very careful about what we do,no suspension or steering components period and no trailer hitches.We also will not do repairs to components,it's either new replacements or go someplace else.After that it's insurance and the grace of god.

It's a shame we live in a country where the legal system has been perverted by quick settlement con artists and an out of control Tort system.

dave_r
09-21-2016, 01:43 PM
interesting, never heard of wheel studs being LH threaded - in my case it was the spindle nut that held the drum on the wheel spindle. You must have had a big deposit in your karma account after that. What an ahole attendant though..

Depends on the vehicle. Chrysler was using them for quite some time on the drivers side wheels up to the mid-70's and GM used them on some vehicles before '65.

kendall
09-21-2016, 04:47 PM
Depends on the vehicle. Chrysler was using them for quite some time on the drivers side wheels up to the mid-70's and GM used them on some vehicles before '65.

I've always thought it was a holdover from when knock-offs were the norm, because it was pretty common on a lot of the older cars.