Corksport Lightweight Lug Nut Failure

[Gringo East]

This past weekend CCSCC held a two day autocross event on Sunday and Monday. This is what happened on my fourth run on Sunday.

Lug Failure - YouTube

Lug Failure - YouTube

I figured that would be a good introduction to the issue. This post isn't intended to burn CS, but warn anyone with a similar setup. I consider myself very lucky that the car didn't suffer anything more than the apparent damage, and most importantly that no one was hurt.

I like most was stoked when my CS custom UPS box arrived (08/22/13), and even more so when I got the lugs out and into my hands. I think I bragged to everyone I talked to about them, and after reading the directions and some posts. I went right to the local Sears store to pick up a 3/8 ft lb torque wrench(08/23/13). This was a huge leap forward for me. My first set of aftermarket wheels (Konig Illusions 18" x 8") with some really bad ass lugs. I installed my wheels and followed the torquing instructions to the letter (65 ft-lbs and check torquing after 50mi).



I than decided to order a set of JBR 5mm spacers, which arrived the Friday before the event (08/30/13), and I installed them the night before (08/31/13). Now before everyone starts going "why are you running spacers," why not? Is my reply. JBR markets his 5mm spacers just like that other company that shell not be named (SURELY you know who I'm talking about) as not needing extended studs to run them.

Once again I followed CS torquing instructions (65lbs),as well as JBR recommendations for the mileage for re-torquing (i.e. 5,10,15,etc). When I arrived at the event I checked the torquing on the lugs, and then again after my first two runs. It was the forth run that lugs snapped sending my tire flying (again I am very thankful no one was hurt).

So, were does that leave us now...



Well, I'm now going to try and provide you all as much information as I can.

The broken lugs:







The last photo I believe is extremely important. It shows were the weak point is in the two piece lug design. The conical part has a cylindrical shaft of the aluminum with threads in it. This is the piece that snapped from the rest of the lug allowing the wheel to become free.

Now before everyone gets crazy... I did some measurements today through the open end of the lugs with and without spacers using a set of calipers.



From measuring the depth we can then find out how much stud is actually being threaded into the lug. By then using the outside jaws we can get a good visualization of this by deductive reasoning.

Without spacer:



With spacer:



Some other information I can provide (due to Jamie asking if I knew) is the difference in the amount of turns with the lugs. I went a step further, I did it with and without spacers, as well as, the same test on a stock gen pu wheel.

Stock Gen 2 Wheel using Corksport Lightweight Lugs:
Without Spacer: 8 1/2 Turns
With Spacer: 5 1/2 Turns

Konig 18" x 8" Illusion Wheel using Corksport Lightweight Lugs:
Without Spacer: 7 1/2 Turns
With Spacer: 4 1/2 Turns

I believe that information speaks for itself, and I wish I would have noticed how low the turns were with the spacer. I also think it would be unsafe to run these lugs with a stock wheels and spacers. Just my .02. Anyway, the rest of my vehicles suspension is stock and has been so the life of the vehicle (yes I am the first and only owner).

Some other photos I think some would like to see:





Without Spacer:



With Spacer:



In my opinion I believed Corksport should warn its customers of using the lugs with 5mm spacers without using extended studs.

What I've learned:

1. Don't use aluminum lugs.
2. Seriously don't use aluminum lugs.
3. Don't use spacers without extended studs period (my opinion as of now).

Just to give a little after story:

The car was jacked up and we stole a lug from each of the other three wheels. I drove it to the pits, made some adjustments to the damaged wheel well, and drove to a local auto store to get some steel lugs.

When my wife and I got home this is what we did:



And we went back out the next day:



I did remove the rest of the lugs and spacers from the car, and it will stay that way for now.

I hope someone finds this information useful so it doesn't happen to someone else.

[Chimmike]

@Haltech;

[SofaKingAwesome]

Damn, these lugs reduce weight on a whole new level.

Did you sip the potion before you hit the 3 wheel motion?

[Gringo East]

Originally Posted by SofaKingAwesome Damn, these lugs reduce weight on a whole new level. Did you sip the potion before you hit the 3 wheel motion?

Is that why it wouldn't fly... I knew I forgot something.

[Deldran]

I saw all this carnage.

Nice write up gringo. I was glad to see you out the next day.

Did you get into MSM hopefully the fender isn't to much from them to get replaced

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[England15j]

3 of mine failed the exact same way but I was Installing my wheels.

[Code Monkey]

Wow, that sucks balls.

I thought it was common knowledge though to run extended studs with spacers.

[bhamitgeek]

@nindoja Did yours break going down the road or were you taking off the wheels?

[pzr2874]

Only over 5mm I thought

[usgiorgi]

Holy shit this is scary.... I wonder how much of it had to do with faulty design and how much of it is not having extended studs..

[Code Monkey]

Originally Posted by pzr2874 Only over 5mm I thought

I heard anything over 3mm.

[Gringo East]

Originally Posted by Deldran I saw all this carnage. Nice write up gringo. I was glad to see you out the next day. Did you get into MSM hopefully the fender isn't to much from them to get replaced Sent from my XT1080 using Tapatalk 4

Its on my list of things to do. From what I'm seeing online the fenders are at most a couple hundred. The real expense will be the paint.

[breakfstincluded]

christ I'm glad you came out fine,

I'm sure CS will do something about this.

I wanted to rock some nice black nuts like the CS ones but went with Mcgard's because from amazon they fit my budget better.

Is the conical part a rotating washer like mcgard's thats meant to prevent scratches?

[usgiorgi]

Originally Posted by Code Monkey I heard anything over 3mm.

That's what I've also heard also 7+ turns for the nuts/bolts.

[Deldran]

Originally Posted by usgiorgi Holy shit this is scary.... I wonder how much of it had to do with faulty design and how much of it is not having extended studs..

Hard to tell a mix of both I would think. Also that turn where the wheel came of was one of the fastest in the course. It was was on a bit of a down slope. And you end up doing a bit a breaking through that corner, at least I did. Which put a lot of weight and force on the outside front tire.

Its hard to tell on the pics but the threads pretty much got ripped out of the lugs.

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[naoandlater]

Holy shit. @nindoja; your lucky this didnt happen to you at gingerman.

Sent from my DROID RAZR

[Deldran]

Originally Posted by breakfstincluded christ I'm glad you came out fine, I'm sure CS will do something about this. I wanted to rock some nice black nuts like the CS ones but went with Mcgard's because from amazon they fit my budget better.

If you plan on doing any autocross or tracking please don't. Edge sells some nice looking steel lugs go with those. Aluminum is just to soft for me to trust holding all of that force.

Also if you have a shop do any wheel and tire work for you I would bet they will over torque them which will also cause a lot of problems

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[maisonvi]

Hell of a write up man. Good luck getting it sorted out.

[phate]

I'm interested to hear what @CorkSport; had to say about this. Their site doesn't mention anything about spacers or thread engagement length. Since it's not a steel lug, I'm not sure the old 1.5x stud diameter applies.

[Kyle Undefined]

@nindoja;

[kritz]

Contacted @CorkSport;

[breakfstincluded]

Originally Posted by Deldran If you plan on doing any autocross or tracking please don't. Edge sells some nice looking steel lugs go with those. Aluminum is just to soft for me to trust holding all of that force. Also if you have a shop do any wheel and tire work for you I would bet they will over torque them which will also cause a lot of problems Sent from my XT1080 using Tapatalk 4

I haven't had the opportunity yet but, would you trust the stock lug nuts for tracking?

I would have either used stock lug nuts if I had a set of track shoes or like you said looked around at edge, so that's good to know.

And don't worry, I'm from MSF so I use a torque wrench, and I don't let shops touch my car (:

[Lex]

How much total thread in terms of length was inside the lugs? How much of that were you threading into/was engaged with the spacers?

There are cars that run OEM aluminum lugs such as my 944T but they are a single piece.

Glad no one was hurt.

[[R]usty]

Sorry this happened to you. Glad I didn't go aluminum.

[pwdunmore]

I think this has more to do with the lugnut design and materials then spacers, but lets not rule that out of the question.

The size and spacing of aftermarket lug nuts plus the threading type + type of material have a lot to do with the outcome.

I have a feeling the light weight aluminum expanded while on the track due to excessive heat and the fact that there was less thread for it to hang onto with the spacer on helped the lug nut dislodge itself.

The thermal expansion in the light weight aluminum plus the reduced threading probably had something to do with it. All of that would hinder the frictional force holding the lug nut to the wheel stud. Then one hard corner with the weight over that wheel and pop!

[Deldran]

Originally Posted by breakfstincluded I haven't had the opportunity yet but, would you trust the stock lug nuts for tracking? I would have either used stock lug nuts if I had a set of track shoes or like you said looked around at edge, so that's good to know. And don't worry, I'm from MSF so I use a torque wrench, and I don't let shops touch my car (:

Oh I do to but I can't mount my own tires. And the shop in town I work with always over tighten shit drives me nuts. I have used stock logs nuts for a year auto crossing now. No issues

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[Dash08]

It really sucks you're having problems with your nuts.

No man likes to hear that.

[Gringo East]

Originally Posted by phate I'm interested to hear what @CorkSport; had to say about this. Their site doesn't mention anything about spacers or thread engagement length. Since it's not a steel lug, I'm not sure the old 1.5x stud diameter applies.

Just got off the phone with Joel. He told me about how 3mm spacers on stock studs were the max, about how there is away to measure the width to get how much of the stud needs to enter the lug so it won't break, as well that 5mm spacers + stock studs with steel lugs would have failed as well, also that they have sold hundreds of sets with zero problems, and that if I would like to get another set when they come back in stock that I could get a deal on them.

Hey, I'm done it is what it is.

[breakfstincluded]

Originally Posted by Dash08 It really sucks you're having problems with your nuts. No man likes to hear that.

Even black nuts got problems

[usgiorgi]

Originally Posted by Gringo East Just got off the phone with Joel. He told me about how 3mm spacers on stock studs were the max, about how there is away to measure the width to get how much of the stud needs to enter the lug so it won't break, as well that 5mm spacers + stock studs with steel lugs would have failed as well, also that they have sold hundreds of sets with zero problems, and that if I would like to get another set when they come back in stock that I could get a deal on them. Hey, I'm done it is what it is.

I'm not sure if this was on the site before this thread, but this is what it states now.

WARNING: DO NOT USE WHEEL SPACERS OR ANY WHEEL THAT ALLOWS FOR LESS THAN 11mm OF THREAD ENGAGEMENT, DOING SO WILL VOID YOUR WARRANTY AND COULD CAUSE FAILURE.

I'd like to add that if this wasn't on the website when you got these, they are liable. If you followed their instructions to the fullest, it is not your fault. I know the air tools part was on there because I was looking into these a few weeks ago, but I'm not sure about the spacers/minimum thread depth.

[daafisch]

Originally Posted by Gringo East Just got off the phone with Joel. He told me about how 3mm spacers on stock studs were the max, about how there is away to measure the width to get how much of the stud needs to enter the lug so it won't break, as well that 5mm spacers + stock studs with steel lugs would have failed as well, also that they have sold hundreds of sets with zero problems, and that if I would like to get another set when they come back in stock that I could get a deal on them. Hey, I'm done it is what it is.

I've been running 5mm spacers with stock studs and gorilla lugs for over a year and half. Over that time I've done 4 track events and probably 20 autocross events. Not a single issue.

[Gringo East]

Originally Posted by Lex How much total thread in terms of length was inside the lugs? How much of that were you threading into/was engaged with the spacers? There are cars that run OEM aluminum lugs such as my 944T but they are a single piece. Glad no one was hurt.

I believe I lost about three threads with the 5mm spacers + 1mm for the non-stock wheel. Like I said it had 4 1/2 full turns with spacer. I'm not sure if I answered your question or not Lex sorry...

[[R]usty]

I just noticed these lugs sell for $100 . Got my gorilla's for $25, they look just as good and are probably a lot stronger.

[pwdunmore]

Originally Posted by Gringo East Just got off the phone with Joel. He told me about how 3mm spacers on stock studs were the max, about how there is away to measure the width to get how much of the stud needs to enter the lug so it won't break, as well that 5mm spacers + stock studs with steel lugs would have failed as well, also that they have sold hundreds of sets with zero problems, and that if I would like to get another set when they come back in stock that I could get a deal on them. Hey, I'm done it is what it is.

I don't think the stock ones would have failed since steel doesn't have the same thermal exapansion coeffecient... you need more information to make that statement that the stock ones would have failed.

Mainly because I run 5mm spacers + RPF1's + stock nuts... taking it out to have some fun, wheels + brakes were hot = no issues at all when going around hard corners.

[Gringo East]

Originally Posted by usgiorgi I'm not sure if this was on the site before this thread, but this is what it states now. WARNING: DO NOT USE WHEEL SPACERS OR ANY WHEEL THAT ALLOWS FOR LESS THAN 11mm OF THREAD ENGAGEMENT, DOING SO WILL VOID YOUR WARRANTY AND COULD CAUSE FAILURE. I'd like to add that if this wasn't on the website when you got these, they are liable. If you followed their instructions to the fullest, it is not your fault. I know the air tools part was on there because I was looking into these a few weeks ago, but I'm not sure about the spacers/minimum thread depth.

That was definitely not there, and he pretty much told me "sorry I can't be more of a help."

Originally Posted by pwdunmore I don't think the stock ones would have failed since steel doesn't have the same thermal exapansion coeffecient... you need more information to make that statement that the stock ones would have failed.

He did not say stock lugs in that comment, he just mentioned any steel lugs.

[phate]

Originally Posted by usgiorgi I'm not sure if this was on the site before this thread, but this is what it states now. WARNING: DO NOT USE WHEEL SPACERS OR ANY WHEEL THAT ALLOWS FOR LESS THAN 11mm OF THREAD ENGAGEMENT, DOING SO WILL VOID YOUR WARRANTY AND COULD CAUSE FAILURE. I'd like to add that if this wasn't on the website when you got these, they are liable. If you followed their instructions to the fullest, it is not your fault. I know the air tools part was on there because I was looking into these a few weeks ago, but I'm not sure about the spacers/minimum thread depth.

It wasn't, I have a screen shot of it. Not impressed.

[usgiorgi]

Originally Posted by Gringo East That was definitely not there, and he pretty much told me "sorry I can't be more of a help."

Well then, they should compensate the damages... They'll fight it, obviously because they sold product which can fail under the instructions they previously provided. If it does not specifically state to not use with aftermarket wheels, then you can use them.

Yes, people will argue common sense, but that's not how our justice system is set up. For better or for worse. And spacers are definitely a foreseeable possibility and their use/lack of use should have been stated in their instructions or warning section.

Especially aftermarket wheels should have been referenced. Since offset is just like using spacers.

[CorkSport]

I have talked to the OP and hopefully sorted things out. I'll do my best to answer most of the questions I've seen in the last few minutes here.

Based on my measurements:

Stock Wheel thickness (at the hub face): 11.4mm
Stock Wheel Stud thickness ( from rotor face) 24.0mm
Stock Wheel Stud Diameter: 11.8mm

Typically, you want a 1 to 1 ratio for the stud diameter to thread engagement. In this case, that would be 11.8mm

Based on the math, that leaves you approx 0.8mm of wiggle room on a stock wheel with stock lugnuts.

The OP had a wheel approx 1.5mm thicker than the OE giving him approx 11.1mm of thread engagement which is below spec but probably plenty safe (as it has been for the literally hundreds of other customers running our lugnuts). When you add in the 5mm wheel spacer you are now left with only 6.1mm of thread engagement for the lugnuts.
The factory wheel studs are a 1.5mm thread pitch so you would then be left with just 4.0666 threads on which to keep your wheels on. With a steel lugnut and a factory wheel, Mazda would not consider that safe and neither would I.

However, I am very interested to hear what anyone else thinks as I want to be as fair as possible and certainly want to treat people the way I would wish to be treated so please, let me know your thoughts.

Cheers,
Joel

[Deldran]

Originally Posted by phate It wasn't, I have a screen shot of it. Not impressed.

That's to bad out of all the vendors on here I at least expected CS to man up and help out in someway. Maybe not anything monitary but at least an investigation and some more testing on there lugs

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[shpeedtree]

Hopefully they won't have to recall all these nuts, and people will realize the risk of using spacers, I have seen posts on stance forums that say you're safe with four turns on the lug nuts.