Wheel stud kit on order ... now worried about them breaking on the track?

[S14]

since last june, i've gone to the track 16 times and i run apex wheels/studs and had zero issues. i'm probably going to change over to the FCP set and do a full swap annually with their warranty. in 2021, i'll finally be joining in NASA time trials.

That's an impressive amount of track time for any season, let alone a COVID one!

I've run a bunch of different studs of the years and right now my car has Motorsport Hardware ones from FCP euro because I plan to warranty them every other season.

[George Hill]

Core4 is the first to offer press-in for BMW right? At least they're the only ones I've heard of. The science and engineering behind it seems sound, but I'm also not an engineer and it's technical info posted by Core4 themselves. Need a larger sample size and more time before one can say.

I'm not sure if they are the first, but I'd definitely say they are the most out spoken about their product and known.

Absolutely need a larger sample size to know for sure, but it's crazy to me to think that we have all just decided this component that literally keeps the wheel attached is such an unknown and everyone is "relatively" ok with that idea.

[bigjae46]

What is just as if not more critical than torquing the lug nuts properly is making sure the hub surface and back of the wheel is clean. Especially the hub lip where corrosion always builds up.

BMW does not recommend it but I put anti seize on the lip.

If you don’t, dirt and corrosion will prevent getting a proper mating between the back of the wheel and hub. I would suspect THAT is what causes many wheel stud failures outside of the Apex wheel studs.

Although warned many times, my buddy used the same studs for about 8 years and probably 100 track days. Don’t ask.


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[r4dr]

I'm not sure if they are the first, but I'd definitely say they are the most out spoken about their product and known.

Absolutely need a larger sample size to know for sure, but it's crazy to me to think that we have all just decided this component that literally keeps the wheel attached is such an unknown and everyone is "relatively" ok with that idea.

Agreed. For anyone who hasn't read their technical material (though keep in mind they're also selling the tech): https://www.core4motorsports.com/tech

To me, a big entry for the "pros" column is that all OEM wheel studs, to my knowledge and in my experience, are press-in. These thread-in studs are only aftermarket conversion options as far as I can tell.

Does tire compound affect the studs' integrity as well? I feel like it wouldn't, since the entire hub/bearing assembly is what absorbs the massive increase in lateral forces from running R-comps or slicks, and the wheel itself is statically mounted on the hub face.

[mrgizmo04]

BMW does not recommend it but I put anti seize on the lip.

If you don’t, dirt and corrosion will prevent getting a proper mating between the back of the wheel and hub. I would suspect THAT is what causes many wheel stud failures outside of the Apex wheel studs.


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The slight issue with anti seize is that it creates a wet environment for dirt and brake dust to stick to, so you have to clean those surfaces and reapply every time you take the wheels off.

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[Obioban]

I'm not taking a stand on the reliability of track studs or wheel bolts.

However.

I think a lot of people hugely over torque their wheels at track events by checking their wheel torques when they come in and everything is still hot. Hotter bolts/studs are longer, so the torque is lower. Once they cool, you're over torqued. Rinse, cycle, repeat every session, and you have hugely over torqued wheels by the end of an event.

[Tbonem3]

In regards to the wheel hub/lip surfaces-

I clean them with wd-40 and red scotch pad. I wipe it all away with a rag that's already somewhat saturated with wd-40, so I believe it leaves behind a thin film. This seems to keep water away, but not enough to attract dirt/sand/pebbles. FYI.

[eacmen]

I'm not taking a stand on the reliability of track studs or wheel bolts.

However.

I think a lot of people hugely over torque their wheels at track events by checking their wheel torques when they come in and everything is still hot. Hotter bolts/studs are longer, so the torque is lower. Once they cool, you're over torqued. Rinse, cycle, repeat every session, and you have hugely over torqued wheels by the end of an event.

This! Always check BEFORE a session. IMO if you're finding lugs are loose after the second session of the day and the wheels have stayed on the car there is something fishy going on.

The first session often will loosen things up a bit with high forces on track. But snugging them up before the second session is generally the last time I have ever had to tighten them. I always check them but they have always been to spec after the second session.


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[S14]

I'm not taking a stand on the reliability of track studs or wheel bolts.

However.

I think a lot of people hugely over torque their wheels at track events by checking their wheel torques when they come in and everything is still hot. Hotter bolts/studs are longer, so the torque is lower. Once they cool, you're over torqued. Rinse, cycle, repeat every session, and you have hugely over torqued wheels by the end of an event.

AMEN!

[George Hill]

I'm not taking a stand on the reliability of track studs or wheel bolts.

However.

I think a lot of people hugely over torque their wheels at track events by checking their wheel torques when they come in and everything is still hot. Hotter bolts/studs are longer, so the torque is lower. Once they cool, you're over torqued. Rinse, cycle, repeat every session, and you have hugely over torqued wheels by the end of an event.

I'm not going to disagree with you, there are so many variables and everyone treats them differently, but I have never heard of a factory wheel bolt failing

This! Always check BEFORE a session. IMO if you're finding lugs are loose after the second session of the day and the wheels have stayed on the car there is something fishy going on.

The first session often will loosen things up a bit with high forces on track. But snugging them up before the second session is generally the last time I have ever had to tighten them. I always check them but they have always been to spec after the second session.


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This is certainly good practice but that's not always reality. Also, I run bolts on my cars, mainly because I don't like the look of studs, lol. But I have never had a wheel bolt take any additional torque after a session when properly torqued before. My experience is not enough of a data poll to make a over reaching conclusion, but just sharing my experience.

[BBRTuning]

Does removing nuts with an impact gun affect the life of the stud?

I would think removing is ok, but tightening is where you run into trouble.

I use a 20v impact on high torque to remove nuts, but switch it to low impact to put them on - then follow up with torque wrench. I have never reached target torque with the impact gun on low torque.


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I can't say for sure, but I can tell you doing it by hand will certainly be easier on the stud, and I'm not taking any unnecessary risks based on how many broken studs I've been seeing online 😅

Breakaway torque will almost always be much higher than installation torque, and with an impact gun literally shocking the nut loose from the stud, if a stud was ever going to break (other than on-track), I'd imagine it breaking during removal. It does add an extra minute or two to the whole process, so obviously it's probably not an option during endurance racing for instance. In that case, though, where you're gunning super hot wheels on/off quickly, I'd do the Core4 setup without question.

[bigjae46]

The slight issue with anti seize is that it creates a wet environment for dirt and brake dust to stick to, so you have to clean those surfaces and reapply every time you take the wheels off.

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That’s fine. Don’t really need to use a lot.


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[SQ13]

Ordered a kit from Motorsport Hardware. Thanks to those who posted about their sale. They’ll be replacing nearly four year old Apex studs. Haven’t had an issue, but I’d been putting off replacement and finally decided to do it. I usually torque to 80 lb-ft. For DEs, I torque once a day, before the first session.

[r4dr]

Core4 says this about hot torquing:

We recommend checking torque during pit stops, or at least every few hours. Yes, we want you to check torque when “hot” during pit stops, contrary to what dogma has led many to believe. Over the course of a race/endurance race, many factors can contribute to self-loosening of lug nuts. The implications of losing clamping force are far greater than torquing when “hot.” Lower torque 10% if you feel there’s lots of heat input at the stud-hub interface and check.

I'm not for or against this, but I thought this was interesting because my intuition and what I've been told are both not to torque them when they're hot. Once in the morning then done.

[bigjae46]

Core4 says this about hot torquing:



I'm not for or against this, but I thought this was interesting because my intuition and what I've been told are both not to torque them when they're hot. Once in the morning then done.

The elasticity of steel increases as it gets hotter. You will stretch the fastener more. So when it cools the torque will increase A LOT.

I doubt that anyone has ever tested a commonly available stud or has data. Hell...you don’t even get an MTR for a critical fastener like this.

I’d expect that I would get an MTR or some test results with the more expensive studs to verify that the torque spec when the bolt is hot is the same when cold.


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