5 Minute Fix For Broken Lug Nut on Stud Conversion

[203E90]

I planned on doing a video for this to help some people out but it ended getting fixed so quick that I didn't have time to do it. I apologize if this info is already out there but I couldn't find it for weeks. If you don't want to read my whole life story below, the fix is to use a bolt extractor set to remove the stud instead of trying to remove the broken lug nut if you have a stud conversion. It worked flawlessly, repeatedly, for me in this situation. Lesson learned, I will be the only one to take off and put on my wheels. I'll just bring the wheels to a tire shop in the back of my Chevy from now on or get a mobile tire mounting service to come out. More details below.

Broken lug nuts are nothing new. About a year ago I bought a stud conversion kit from Turner and threw it on no problem. Used Permatex Blue threadlocker and torqued to spec. A few months later I damaged a tire and had to get it changed at a shop near my house. Great reviews and a lot of high end cars go there so I felt safe taking it to them. I noticed they put the wheel back on with the air gun and I asked them to loosen it back up and put it back on with hand tools. I carry a lug nut socket and torque wrench in my trunk plus various other tools. They backed it off and said they would turn the gun down. Showed me that the bolts came off easy with no damage. Ok fine. I'm just trying to get out of there and get on the road for a vacation.

Fast forward to about 6 months later. Time for maintenance and another set of studs and nuts from Motorsport Hardware. I try to replace mine every year max. I start to loosen the roughly 10 month old nuts and I noticed that two I thought I loosened didn't break free. They broke off. The head still in the wheel and the rest of the nut free spinning on the stud. I'm pissed at this point. Now I have to drill out a stud. I've done it on other cars but really wasn't looking forward to it. Before I went to that step, I asked my guys at my usual BMW performance shop. They all pretty much agreed that I'd probably have to drill it out until the owner said "here try these" and hands me a set of bolt extractors. I said nah won't work. There's not enough of the head of the nut left to catch. He said not for the nut, you have studs. As long as you didn't just jam the studs into the hub, you got a chance of getting the entire stud to back out.

Well I'll be damned. Found the extractor that fit the stud perfectly, tapped it on lightly with a mallet, and started to reverse it on. It caught instantly and started to dig in until the tip of the studs was fully seated and with about the same amount of effort it normally takes to take a lug nut off, the stud started backing out with the broken lug nut. No drilling, no double nut trick, or torches. No damage to the hub or wheel

Once I got those 2 studs out and replaced, I took my car back to the shop that put them on so tight and let them do the rest so they could see what I was talking about and take ownership of this mess. They tried to take the others off and snapped all of them as well. I figured that would happen so I bought the extractor with me because they were clueless on what to do next. 10 minutes later I had the other 3 studs off and was prepping the new studs to go in. Maybe this is common sense and I missed it but I was pretty excited that this worked and hopefully anyone else in the same situation finds this before they find YouTube videos of dudes welding nuts on studs to back them out or drilling out studs. Just make sure you use a medium threadlock on the studs when you put them on, mine called for 25 lb ft on the studs and 105 for the nut.

Happy wrenching.

[louielouie]

Granted this is before I had a stud conversion, but I also had issues with a, "performance shop" taking an air gun to the OEM wheel lock and completely stripping it. Getting it off was a whole ordeal.

I felt the same as you - lesson learned about being careful where I take my car

[Signature Wheel BMW]

Here's the set I personally run, BW Premium Wheel Stud. It's built by MSI, very easy to remove and they're indestructible for track or street. MSI makes the best studs money could buy, built for NASCAR, IMSA, NASA racing.

Stud side comes with dry thread lock, no need to apply red stuff which is impossible to remove without a torch. Also, on the nut side I usually apply copper antiseize and reduce the torque required by 20% (lubricated torque). MSI studs require lower torque to install and lower torque on the nut. Cheers.

I track my cars with MSI, never had to replace them each year. Maybe every 3-4yrs as a precaution. Expensive, but there's a reason for it. My personal recommendation, not Signature's, we don't sell or have any affiliation with MSI studs. =)

https://www.bimmerworld.com/Wheels-T...d-Package.html

Here's one of my wheel customers using MSI studs. Haven't broke, few years already.

[RbBugBitMe]

Sadly, I love this boring topic so I'm going to weigh in a little bit as I am currently contemplating exactly what I want to cover with some future blog/vlog content. I also happen to have installed MH studs this weekend against my better judgement and I'm spending this week at my day job with a retired GM global suspension and brakes joint/bolt expert so I've been picking his brain on some personal stuff including these studs.

1. OP you're right to be concerned but if you're that concerned why use them at all? I have to ask you and anyone else reading this that behave the same way, why do you think studs are less reliable than the OEM bolts?
2. Most or all of these stud conversion kits use 12.9 hardware to market to the clueless general public that stronger is better. If stronger is better why are you torqueing to the same 103ft-lb spec as the OEM bolt? Shouldn't you be taking advantage of the higher strength and torqueing higher for higher clamp load you supposedly need and get with "motorsport hardware"?
3. There are a couple issues at play. 12.9 hardware is brittle and subject to hydrogen embrittlement due to the heat treatment that is typically done to achieve the spec material properties.
   1. Brittle hardware fails quickly in bad ways when it fails and torque control needs to be taken seriously. Torque specs are DRY toque specs. If you lubricate the stud/nut without specific guidance from the OEM and without appropriately reducing torque you will be over torqueing and risking failure. If you use an air gun you are risking failure, even if you over torque it once by accident and back it off then use a torque wrench. The damage was done.
   2. Hydrogen embrittlement is real for 12.9 hardware. I'm not aware of any suspension or brake caliper bolt at any OEM in the world that uses 12.9 hardware. GM forbids it from any of their suppliers. Hydrogen embrittlement failures are nearly unavoidable with enough volume and time. MSI can sell 12.9 hardware to NASCAR because they dispose of them after one use. I've walked the pits and talked to the teams, this is what they do with the yellow MSI nuts you see on their website.
4. MH and MSI import some stuff from China, Taiwan, and India. I have no idea what products or raw material exactly but its very easy to find out that they're entire catalog is not 100% made in America. Generally I don't care unless they're falsely advertising it as such and/or their product is junk and they lack quality control. I personally hand threaded my MH nuts onto my MH studs this weekend and ran into spots where the thread was so poor I couldn't freely thread the nut, it was jammed without a wrench. I also think their threads are cut and not rolled, which if true is pathetic, but I need to inspect better before standing behind that claim though the stuck nut supports the cut thread claim. Regardless, this fit and finish is wildly unacceptable to me. MH is a shit product IMO that achieves nothing it sets out to except holding the loose wheel on the hub for convenience.
5. Signature - Regarding MSI spec's lower than OEM torque specs. There is no physical/engineering reason I can think of that justifies this. I'd love to hear more about the reasoning behind it. Joint STIFFNESS determines clamp load required and 8.8, 10.9, 12.9 all have the same STIFFNESS. Material STRENGTH determines how much clamp load you can apply and you're being told to apply less clamp load than OEM which makes no sense. They certainly aren't lowering friction with their coating any appreciable amount to justify reducing torque 25+%. I think you're finding that OEMs are really damn careful about designing safety critical joints like this with lots of margin and you can get away with the lower torque for the loads you're putting into the joint. A proper joint analysis will likely find you're clamp load is too low at the -40C temperature load cases they design to that a California race car never sees.

If I can't find a properly engineered solution I think my dream daily driven stud I may make myself would look like this.
- Class 10.9 stud and nut
- Rolled threads
- Torx/Torx Plus/Torx Paralobe drive feature at the end of the stud if not external hex. Internal hex is stupid and I could feel the tool starting to slip in the MH at 25Nm. Double nutting is unnecessary and annoying (so is 75 ft-lb stud installation for that matter).
- Zinc nickel coated
- Instructions that the warranty is voided if you or a certified mechanic ever uses an impact gun.

Some FEA would have to justify the need to go to a higher clamp load (necessitating 12.9 hardware) BUT CONSIDER THIS... I'm 99.9% sure a C8 Z06 with 200tw tires and a warranty doesn't have 12.9 hardware so what are you doing that you think you need it?

[heyyouduh]

I was close to getting a stud conversion but after reading numerous stories with stud failures and the frequency in which people are prophylactically replacing them I decided to stay with bolts.

I don't have an engineering background but I'm rather convinced it's due to the thread in stud design. This company designs replacement hubs with press in studs and goes into more detail here: https://www.core4motorsports.com/tech. Again, I don't have enough technical knowledge to support or refute this.

[RbBugBitMe]

Damn great web page. They have some good pictures that are clearly showing embrittlement or fatigue failure. Some simple lab testing would speak volumes. A tensile or shear overload failure will typically have a crack at some angle closer to 45deg from the bolt axis. All of their pics show a crack plane perpendicular to the bolt axis.

Embrittlement failure is purely from the Class 12.9 material selection so many wannabe engineers choose.

Fatigue failure 100% comes down to installation process and maybe coatings/friction effect playing into poor installation process.

[Track/S]

Originally Posted by RbBugBitMe

Damn great web page. They have some good pictures that are clearly showing embrittlement or fatigue failure. Some simple lab testing would speak volumes. A tensile or shear overload failure will typically have a crack at some angle closer to 45deg from the bolt axis. All of their pics show a crack plane perpendicular to the bolt axis.

Embrittlement failure is purely from the Class 12.9 material selection so many wannabe engineers choose.

Fatigue failure 100% comes down to installation process and maybe coatings/friction effect playing into poor installation process.

Lots of theory my friend...
M4 GT4 and M2 CSR use 12.9 studs.

[RbBugBitMe]

Originally Posted by Track/S

Lots of theory my friend...
M4 GT4 and M2 CSR use 12.9 studs.

Race cars, unique stud design unlike what most people buy, and no warranty...
How do you even know they're class 12.9?
Embrittlement issues can be managed with proper engineering, I don't believe all the cheap kits out there are doing what's needed. At the very least they don't market the problem and solution like they know anything about it.

[Track/S]

Originally Posted by RbBugBitMe

Race cars, unique stud design unlike what most people buy, and no warranty...
How do you even know they're class 12.9?
Embrittlement issues can be managed with proper engineering, I don't believe all the cheap kits out there are doing what's needed. At the very least they don't market the problem and solution like they know anything about it.

I dont think Bmw Motorsport will do anything to break 200k $ cars.



I know because I bought a stud to test:

[RbBugBitMe]

I agree. Hence the very different stud design compared to everything in the aftermarket. Why do you think they step down to M12? Since its 12.9, I have no doubt they went through the proper hydrogen bake out heat treatment process. That coating is also clearly different than the typical why-bother-black-oxide coating.

I seriously doubt Chyna studs everyone resells go through this process consistently and its quality checked per batch like an OEM would.

Point still stands though, you'll never see a factory warrantied BMW with Class 12.9 wheel studs.

[Track/S]

Originally Posted by RbBugBitMe

I agree. Hence the very different stud design compared to everything in the aftermarket. Why do you think they step down to M12? Since its 12.9, I have no doubt they went through the proper hydrogen bake out heat treatment process. That coating is also clearly different than the typical why-bother-black-oxide coating.

I seriously doubt Chyna studs everyone resells go through this process consistently and its quality checked per batch like an OEM would.

Point still stands though, you'll never see a factory warrantied BMW with Class 12.9 wheel studs.

I think the reduction to M12 is due to weight reduction, I don't see any other reason.

The coating in pics looked like DLC, but when I held it in my hand it seems black oxide coat.

Probably have some special treatment as they are extremely expensive, but they look excellent quality.

[RbBugBitMe]

I think they used the higher strength and lower stiffness of the M12 to create a better joint. Shifting more of the relative stiffness to the clamped component (the wheel) likely allows for more margin under load before the joint loses clamping force. Less of the applied loads are going through the stud and you reduce cyclic loads on the stud for better life.

[Notyourplug33]

This just happened to me today, shop told me they torqued them down to 100ftlbs but instructions mention 75ftlbs so now I’m here googling and found this.. where did you get that exact extractor?? Harbor fright??