I just had an accident! At the first glance, can you believe NO major damage!! (have not looked real good yet)
My tire came off the car while driving down the road!!!! It appears that the Lug Nuts backed out?!?!
Found two in the road in the area.

So now I need to get another set of 5 OR the correct ones OR longer studs or learn that torque means nuts also.


On with the show!

Here is what we are dealing with (came with car)
Accorn Lugs






The "one of a kind wheels" (make note no spacers are used, was informed B.C. made these for this car)


You can see the depth, the stud goes just about halfway in the hole (stock studs)


The "Key" for them is a star type head


So I need to know some real infomation about this.
Does it look like the correct lug nut for the size tire(255/50) and rim(16x9.5)
What is the torque # for the studs?
What is the size stud I need to get?( one sheared off) or length if I need a longer size?
PUBLIC SERVICE ANNOUNCEMENT Don't forget to check and torque your nuts!! ( or this will happen)

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Don't be a dumb bunny!






I will tear into it today. Pics request?

Other than the B.C. label and design, my 16x7 AR86's are identical mounting...

I have the same style of "Tuner" Acorn lug nuts. They came with the wheels. I torque them to the same specs as aluminum wheels (since they are), 100 ft-lbs. I am also using the same studs as the factory with my Wilwood brakes and AR86 wheels. I have not had any issues for 10+ years now.

You should be fine with the right torque on the nuts.

-Dave

Normal Fiero lugnuts and studs are 12mm x 1.5 in (thread) - the same as most GM cars. My old S10 and my Trailblazer have the same thread.

I wouldn't think that you need longer studs for those wheels if there are no spacers. The lug that you pictured looks like a normal conical (tapered) seat lug - although a very narrow one, which is required to fit the holes in the wheels.
(You can probably get away with replacing your lug nuts with the splined/tuner type that are sold at the parts stores.)

Wheel nut torque, from my 88 owners manual, is 100 ft.lbs. I have heard the same figure quoted for aftermarket aluminum wheels.

Edit - Dave beat me to it.

[This message has been edited by Raydar (edited 08-19-2012).]

Lug threads = 12mm x 1.5 pitch
Torque = ~100 ft/lb on Al wheel and Install Dry.
Any lube, including anti seize, can cause lug problem by over torquing.

Aftermarket lug nut maybe low quality.
See if McGard makes them to fit your wheel.

You may need to replace the lugs too.

I carry a cheap beam type 1/2 drive torque wrench to install wheels. Stop allot of guessing....

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

The only thing I can add is that you should make sure that your nuts are engaging the stud to at least the same depth as the stud is wide. In other words, the studs are 12mm diameter, so make sure that at least 12 mm in length of the stud are threaded into the nut when tight. If you can't achieve that, then you need longer studs.

Also, aluminum wheels need special attention... after tightening the nuts to the proper torque (100 lbft) you are supposed to recheck the torque after 60 miles (100 kms) of travel. In Canada, almost every shop you go to now, the paperwork specifies that you must return to have the torque rechecked on aluminum wheels within the first 100 kms (although next to no one ever does) in order to absolve them from liability for the type of thing that just happened to you.

Along with the proper torque, are these hubcentric wheels? If not, you may have one hell of a lot of stress on the lugnuts rather than the hub itself. If they are not hubcentric, make sure to get some aluminum hub rings.

quote Originally posted by IMSA GT: Along with the proper torque, are these hubcentric wheels? If not, you may have one hell of a lot of stress on the lugnuts rather than the hub itself. If they are not hubcentric, make sure to get some aluminum hub rings.

I don't know what hub centric means. Is it the size of the Fiero's hub in realition to how it fits inside the hub of the wheel? Then yes they do fit in that area.

I have had the tires on and off several times lately for one thing or another (plus more room to work.) I always tighten with the impact gun then when I set it on the ground another turn with the 4-way not torque wrench

VERY GLAD to hear a few new studs and a new set (s) of lugs are the answers. I guess the best thing to do will be replace all studs in the 25 yld old car.at least in th eback for the most part.
cool. I am about to go jack it up now. I 'll let ya know what the under side looks like.

A hub centric wheel is a wheel that fits perfectly over the center wheel hub on the brake rotor. This take ALL of the stress off of the lugnuts during driving. Most wheel manufacturers make a huge hub size to fit any car rather than a specific fit. When the hub bore of the wheel is too large, the hub on the brake rotor is no longer supporting all of the weight of the car....the lugnuts do the work and this could cause failure, ovaling of the wheels lugnut holes, and even loose lugnuts like you experienced. Here is a picture of a factory rotor with an adapter ring installed to fit aftermarket wheels:


Here is the general idea of how the rings work. The factory wheel fits perfectly around the hub so no adapters are necessary. This photo shows an oversized wheel bore with the adapter ring to make it fit perfectly over the hub on the rotor:


If you need adapter rings, you need to know what the Boyd wheels use for a hub bore size.
http://www.1010tires.com/hubrings.asp

[This message has been edited by IMSA GT (edited 08-19-2012).]

Dude, you just hellaflushed a fiero.

I'd get the rings if needed, but if those wheels where made for that car, you should NOT need them..
if you need the rings you know the p/o was blowing smoke up your arse about the wheels..
if needing the rings, and none used.. REPLACE THE STUDS!!!!!!!!!!!!!!!!!. you stretched them.. as you drove and is WHY they came loose..

asuming they where correctly torqued. in the first place..
100ft lb in a star pattern, and retorqued after a 10-20 mile drive.. then at every oil change..

I have a yellow paint marker(like the ones the junkyards use to mark parts) with valvestem at 6 oclock.. I mark all retorqued lugs, at 12 o clock..
this lets me "see" if they are moving at all.. between oil change miles ..

In the pic IMSA posted, that is refering to the wheel, but wouldn't the rotor's be the first defence in the Fiero? Like on the other car I got centric rings for the 12" rotors.
So there should be NO to little slop inside the hole around the studs?

How can I do a proper check? It is obvious isn't it?


It is amazing! I have little to little damage! a very small bit of the fender cracked pretty good, all the torque rods and bottom of the spindal are fine! small scratches but that's it! I can see in the rim where the rotor rolled off the tire, still I think the rim is saved. I will get it balanced .
Pics later, but nothing really, a broken stud and lots of grinning

quote Originally posted by revin:

I think people up in the Bay Area pay to have this style on their car. I believe it's called "hellaflush" - looks like you saved a whole bunch of money with your method.

quote Originally posted by theogre: Lug threads = 12mm x 1.5 pitch Torque = ~100 ft/lb on Al wheel and Install Dry. Any lube, including anti seize, can cause lug problem by over torquing.

Agreed. I have used anti-seize on my wheel studs since the late 1960s, and using data from the manufacturer I reduce torque on the Fiero from 100 ft-lb to ~80 ft-lb. YMMV.

I can't emphasize enough: Always use a torque wrench when tightening wheel lugs! Your safety depends on it, and a "good enough" torque wrench from Harbor Freight will cost less than $20.

quote Originally posted by Bloozberry: The only thing I can add is that you should make sure that your nuts are engaging the stud to at least the same depth as the stud is wide. In other words, the studs are 12mm diameter, so make sure that at least 12 mm in length of the stud are threaded into the nut when tight. If you can't achieve that, then you need longer studs.

Put another way, assuming a stock 12 x 1.5 mm stud, the nuts should be at least 8 full turns from start of engagement to fully tightened.

Finally, when using a closed-end lug nut you should always verify that there's enough clearance that the wheel will be fully tightened before the stud bottoms out in the nut.

[This message has been edited by Marvin McInnis (edited 08-19-2012).]

"Lug threads = 12mm x 1.5 pitch
Torque = ~100 ft/lb on Al wheel and Install Dry.
Any lube, including anti seize, can cause lug problem by over torquing"


Clean, dry threads on both lug and nut. If they are not clean and dry, you'll get just as false a reading as any other way. I've never seen a head bolt spec that wasn't lubed threads. I always lube, and use 75-80 lbs on my lug nuts, except for my larger truck stuff, where I go higher.

quote Originally posted by IMSA GT: Along with the proper torque, are these hubcentric wheels? If not, you may have one hell of a lot of stress on the lugnuts rather than the hub itself. If they are not hubcentric, make sure to get some aluminum hub rings.

Maybe...
Help tho... And racing can use extra support.

Wheel type above is fine w/ Lug centric because the cone lug will center well IF NO loading on the wheel when tighten!
See my cave, tires in suspension section.

quote Originally posted by Marvin McInnis: I can't emphasize enough: Always use a torque wrench when tightening wheel lugs! Your safety depends on it, and a "good enough" torque wrench from Harbor Freight will cost less than $20.

Flea market often sell for less... Craftsman etc even.

I guess some areas of the country, no anti seaze is ok.. here.. not a chance.. back of wheel also..

when i purchased my car almost 3 yrs ago. the alum. rims where almost frozen on the rotor because of no use of anti-seize. i always use my torch wrench. i do own inch and ft pound wrenches. my rims are made by cz and have been on the car i think since 1989. it's a 87 gt.

quote Originally posted by IMSA GT: If they are not hubcentric, make sure to get some aluminum hub rings.

Why aluminum as opposed to polycarbonate? I'd like to hear some feedback on this from anyone who's got an opinion.

I just bought some CSA alloy rims for the Fiero and I'm now needing to get some 57.1mm-73.0mm hubcentric rings.

quote Originally posted by Patrick: Why aluminum as opposed to polycarbonate? I'd like to hear some feedback on this from anyone who's got an opinion. I just bought some CSA alloy rims for the Fiero and I'm now needing to get some 57.1mm-73.0mm hubcentric rings.

Honestly I just posted that at random. They say you get the same results with the plastic ones or the aluminum. However, I have seen some manufacturers where you don't have a choice. They only make one or the other. The only reason that I would say go with aluminum if you can is that the brake rotors get pretty hot and I would think that over time, it would make the plastic rings brittle.

quote Originally posted by IMSA GT: The only reason that I would say go with aluminum if you can is that the brake rotors get pretty hot and I would think that over time, it would make the plastic rings brittle.

Hmmm... possible I suppose.

I've read to avoid the aluminum rings because of corrosion issues.

Apart from centering the wheel on the spindle, I can't see how the hub centric rings support the weight of the car or take any loads off the studs as many people claim. The wheel is held against the rotor flange by the friction between the two pieces caused by the tension on the nuts/studs. The studs aren't in shear unless they aren't torqued enough and are loose. Even under cornering loads the studs only see more or less tension depending on where they are in relation to the ground as the wheel turns. A ring that protrudes at the most 1/4" into the wheel provides nothing except to center the wheel.

quote Originally posted by IFLYR22: Other than the B.C. label and design, my 16x7 AR86's are identical mounting... -Dave

Dave,
Got a pic?

quote Originally posted by Bloozberry: The wheel is held against the rotor flange by the friction between the two pieces caused by the tension on the nuts/studs. The studs aren't in shear unless they aren't torqued enough and are loose.

Of course you are correct, but most people ... even most gearheads ... don't understand how bolted joints work. Yes, neither the studs nor the hub/wheel center are loaded in shear once the lugs are tightened to spec. All the in-plane loads (i.e. forces perpendicular to the wheel/hub axis) are carried by the friction between the wheel face and the mating hub face.

[This message has been edited by Marvin McInnis (edited 08-20-2012).]

quote Originally posted by revin: Dave, Got a pic?

My wheels. They are about 10+ years old now. AR does not make them anymore.
I do have hub-centering rings installed, but they were designed as lug-centric.




My car... Built it up and put it on the road back in 2001/2002...



-Dave

[This message has been edited by IFLYR22 (edited 08-20-2012).]

quote Originally posted by Marvin McInnis: Of course you are correct, but most people ... even most gearheads ... don't understand how bolted joints work. Yes, neither the studs nor the hub/wheel center are loaded in shear once the lugs are tightened to spec. All the in-plane loads (i.e. forces perpendicular to the wheel/hub axis) are carried by the friction between the wheel face and the mating hub face.

not totally true.. side loading of the car in a corner, will stretch the bolts ever so slightly, over time this makes them loosen up..
the rings are to center the wheel.. on the hub.. they also take some of the load off the studs.. not that the cars corner weight really stesses the studs much.. but pot holes, etc does.. , the friction of them being bolted and torqued is only PART OF the whole equation.. these studs and lug nuts are torqued then go through heat cycles, and you have axle flange, rotor,then wheel.. trusting the friction of two small surface areas to hold the complete load.. is not a good idea.. if that worked, cars would not shear off all 5 studs as the studs whould never see any loading,, if the friction was all you needed..

quote Originally posted by E.Furgal: not totally true.. side loading of the car in a corner, will stretch the bolts ever so slightly, over time this makes them loosen up.. the rings are to center the wheel.. on the hub.. they also take some of the load off the studs.. not that the cars corner weight really stesses the studs much.. but pot holes, etc does.. , the friction of them being bolted and torqued is only PART OF the whole equation.. these studs and lug nuts are torqued then go through heat cycles, and you have axle flange, rotor,then wheel.. trusting the friction of two small surface areas to hold the complete load.. is not a good idea.. if that worked, cars would not shear off all 5 studs as the studs whould never see any loading,, if the friction was all you needed..

I agree. Anti sieze is fine around the center hub. I NEVER put ANYTHING on studs or lug nuts. You need the friction to secure the nut, you dont want it slick so it wants to loosen.

quote Originally posted by E.Furgal: not totally true.. side loading of the car in a corner, will stretch the bolts ever so slightly, over time this makes them loosen up.

You should re-read what Marvin said. He was not referring to a situation where the bolts are loose.

quote Originally posted by E.Furgal: ...the rings are to center the wheel.. on the hub.. they also take some of the load off the studs...

If the lugs nuts are torqued to spec, then the centering ring takes no load off the studs... if it were any other way, then they had better start re-writing the physics books.

quote Originally posted by E.Furgal: ... if that worked, cars would not shear off all 5 studs as the studs would never see any loading, if the friction was all you needed..

The only reason all five studs get sheared off is because the lugs nuts weren't tightened to spec. But studs fail for other reasons too, such as in tension when people over-torque their lug nuts. In that case they over-stretch the stud axially into plastic deformation (beyond it's yield point) and significantly reduce the tensile strength of the stud... leading either to failure in shear through loss of torque, or to failure in tension through cornering loads.

really, I know many a car that sheared of all 5 at the tree.. torqued correctly and tripled checked..
fact
torque your studs then run a tight mountain road, and get the brakes nice and hot.. and check your wheels again.. your torque is now different than what it was cold..
fact
the oem's would not have the axle center flange sticking out and the wheel fiting tightly if it was NOT needed.. they'd save the money on the extra steel and tight spec's at that point..
but ofcourse what do the engineers know..

You're confusing several issues here.

quote Originally posted by E.Furgal: really, I know many a car that sheared of all 5 at the tree.. torqued correctly and tripled checked..

The torque specified by a manufacturer is for the safe operation of the vehicle with it's OEM rated engine and tires. Of course if you change the engine torque and put slicks on the car you can overwhelm the friction holding the wheel and hub assembly together and cause relative movement between the two to shear the studs. But that can be cured by larger diameter studs (or more studs) rated to the tensile requirement to keep the two parts from moving relative to each other.

quote Originally posted by E.Furgal: fact: torque your studs then run a tight mountain road, and get the brakes nice and hot.. and check your wheels again.. your torque is now different than what it was cold..

Correct, however this does not help your argument since the hot pieces expand and increase the tension on the studs making them tighter. The cold torque value of the nuts is selected so that under typical tensile and compressive cycles, the tension on the studs is such thatthe boltt remains in the elastic range. That way once the components cool off, the studs contract elastically back to the original tension (or torque value if you wish).

quote Originally posted by E.Furgal: fact: the oem's would not have the axle center flange sticking out and the wheel fiting tightly if it was NOT needed.. they'd save the money on the extra steel and tight spec's at that point.. ..

The axle center flange is there as discussed before to center the wheel, that's why they machine it onto the axle. The manufacturing tolerances on wheel mounting holes and axle flange holes aren't close enough to ensure a perfectly centered wheel. If it were not for the flange, then the wheel would end up being centered about the first and second nut that were tightened to spec. The remaining lug nuts would simply deform their respective seats as they each tugged the wheel in their own direction.

quote Originally posted by E.Furgal: but of course what do the engineers know

In case you hadn't checked our profiles, both Marvin and I are engineers.

it does help my "agruement" I'd call peacefull bench racing, but whatever,..

as the parts explaned they stretch the studs.. and when cooled. are now longer than pre mountain run.. unlike engine head bolts.. the wheel spinning, wants to turn the nuts when accellerating and braking..
at martansville lug nuts can be turned with two fingers after a red flag that where nice and tight prerace

[This message has been edited by E.Furgal (edited 08-20-2012).]

I used the word argument in the context of debate, not conflict.

But again, if the bolts when cooled were longer than the pre-race length, that means that they stretched into plastic deformation (which means they exceeded their yield strength). Once you exceed the yield strength of the bolt, it remains permanently stretched and as you said the nuts would lose their torque. But if that happens, that just means the wrong studs were chosen for the application.

quote Originally posted by E.Furgal: really, I know many a car that sheared of all 5 at the tree.. torqued correctly and tripled checked.. fact torque your studs then run a tight mountain road, and get the brakes nice and hot.. and check your wheels again.. your torque is now different than what it was cold.. fact

Without knowing any of the details I'm not going to dispute what you observed. I do disagree with your conclusions, though. Bloozberry responded very completely and thoughtfully; I doubt that I could have said it better myself. If you are shearing "all 5" wheel studs on "many a car" or the wheels are loosening after a hard run, then something is wrong; either the wheel lugs weren't torqued correctly or the installation is not properly engineered for your service conditions. Too much torque on the studs can be just as bad as not enough. Strengthening one component of an assembly will often lead to accelerated failure in another component and actually weaken the assembly overall.^* Aluminum alloys are softer than steel, they soften even more rapidly at elevated temperatures, and their coefficient of thermal expansion is higher. It is possible that plastic deformation of the alloy wheels, rather than plastic deformation of the studs, was the dominant factor in the failures you describe. In contrast to your experience, over the past 48+ years I've never had a wheel stud shear ... either on the street or on an SCCA track. I have had two lug nuts loosen in street use on my old Porsche 911S due to the alloy wheels not being properly torqued by a shop that should have known better.

You will notice that in my previous post I stated that the lug nuts be properly torqued, and it was implicit in my post that I was talking about a stock car in normal street use. If you have significantly modified anything on a car (bigger or stickier tires, etc.) and are regularly running it hard or racing it, then the whole suspension and wheel attachment loads need to be re-evaluated.

FWIW, here is a link to a document from Sandia National Laboratories and NASA that is a good introduction to Bolted Joint Design and Analysis. There's lots of good information in there. I also recommend Carrol Smith's Nuts, Bolts, Fasteners, and Plumbing Handbook, which is more gearhead oriented. Happy reading!


^*Here's an interesting lab experiment that can be repeated in a well-equipped shop. Build a test specimen out of two pieces of heavy steel joined end-to-end by two identical SAE Grade 5 (120,000 psi) bolts (or equivalent AN/MS series aircraft bolts) in tension. Put the specimen in a tensile rig (you can use a modied a hydraulic press) and try to pull it apart. If you've built it correctly, both bolts will fail in tension at about the same point, which makes intuitive sense. Now take the same specimen, but this time substitute a "stronger" Grade 8 (150,000 psi) bolt for one of the Grade 5 bolts. What happens this time when you try to pull it apart in the test rig? Answer: The "stronger" Grade 8 bolt will fail first. Can you explain why?

[This message has been edited by Marvin McInnis (edited 08-22-2012).]

"The "stronger" Grade 8 bolt will fail first. Can you explain why?"

Because it is less elastic?

Yep. Because the Grade 5 bolt has a higher elongation (i.e. it stretches more before it fails), almost all of the load gets transferred to the Grade 8 bolt and it fails first. The Grade 8 bolt is also more brittle.

[This message has been edited by Marvin McInnis (edited 08-26-2012).]

I would also check to see where your lug nuts are made. Needed some lug nuts for mag wheels & couldn't find any that fit. we started checking the sizes & the lug bolts with the SAME PART # in the SAME BOX (made by Dorman in china) had sleeves that were 17.34 MM, 17.24 MM, & 17.18 MM! I'm sure the THREAD SPECS are just as bad in chinese made lug nuts & bolts.
~ Paul
aka "Tha Driver"

Custom Fiberglass Parts

"The torque specified by a manufacturer is for the safe operation of the vehicle with it's OEM rated engine and tires."

This must be the crux of it, as I imagine the manufacturers left a lot of room for error. I'm 63, and have never had a lug nut failure even tho I always use lube. I've also never had an honest 500 HP.

I looked, they are Dorman Lug Nuts. Not sure about where.

I thought Dorman's was a good reman. I "hope" it is good cause that is who made the 5 new studs!

[This message has been edited by revin (edited 08-22-2012).]

quote Originally posted by revin: I looked, they are Dorman Lug Nuts. Not sure about where. I thought Dorman's was a good reman. I "hoope" it is good cause that is who made the 5 new studs!

I would look to see where they're made. If in china I wouldn't use them. You can probably get replacements at the dealer.
~ Paul
aka "Tha Driver"

Custom Fiberglass Parts

Just an update.
I got the correct new studs (just replaced the rears) used a" freeze the bolt method" seemed to go in very well.
I even got a new Torque wrench 150lbs. (on sale @ Sears $69 WOW every lug on the car was a turn or so from 100 ft lbs!

I just took it for a small "check it out" drive.....AMAZING!!!!! What a differance! Even fixed another issue I was having!
Thanks for all the suport!

Guys, will these work for my Formula? I hate the black caps ;-(

http://www.amazon.com/dp/B0...is-20#productDetails