[Track/S]

Originally Posted by E90convert

Maynard these are really good points. Ironic you dampen our materials engineering debate and bring in fastener engineering 101! I 100% agree with the points you made. I suspect the hub is hardened steel given that the thread engagement looks to be about 1.0x the thread diameter. Moving to a stiffer 12.9 might make stud fatigue more problematic based on bolted joint stiffness diagrams. However a 10.9 tightened to factory spec with racing slicks end up slipping the joint and causing loosening. I’ve not heard of that happening so I suspect the clamp is adequate.

The collared fasteners were factory on my Cayman. I thought the design was unique, and in the manual you had to grease the threads and flange to collar face with a very specific grease type. I suspected this was to give a consistent friction coefficient for more consistent clamp.

Question: do you think the stud and nut eliminates a failure mode of the bolt fracturing at the ball to shank transition? Or would the transition be smooth enough that the notch factor is basically doesn’t matter.

Anyone know the tightening torque of a CS-R wheel nut?

I suppose that all the points have been copied from google.

1. The oem bolts have a minimum hardness of 10.9 and are tightened to 140nm, if we use 12.9 bolts the tightening will be the same 140nm...

2: Before breaking the hub thread you would break the bolt.


The e9x platform is the one that has suffered the most breaks, and I am convinced that all the studs that broke were hardness 10.9 maximum. the csr studs are M12 and we haven't seen any broken.

In 4-5 days we will know for sure.

[F87source]

Originally Posted by Track/S

I suppose that all the points have been copied from google.

1. The oem bolts have a minimum hardness of 10.5 and are tightened to 140nm, if we use 12.9 bolts the tightening will be the same 140nm...

2: Before breaking the hub thread you would break the bolt.


The e9x platform is the one that has suffered the most breaks, and I am convinced that all the studs that broke were hardness 10.9 maximum. the csr studs are M12 and we haven't seen any broken.

In 4-5 days we will know for sure.

- I'm pretty sure it's grade 10.9 not 10.5.

- If the hub material is softer and weaker than the bolt material, then you will strip out the threads long before you break the bolt. So it depends on the bolt material.

- We may not have seen any CSR stud breaks because the number of studs out there used by non race teams is extremely low (and of these people that have CSR studs, the number of them on the forum is likely to be extremely low), and the number of breaks that are reported are even lower (not everyone who experiences issues post online). Last but not least, the CSR studs were meant for racing, and like most race parts they are replaced very frequently, so the chance that they break during use would be very low.

[Track/S]

Originally Posted by F87source

- I'm pretty sure it's grade 10.9 not 10.5.

- If the hub material is softer and weaker than the bolt material, then you will strip out the threads long before you break the bolt. So it depends on the bolt material.

- We may not have seen any CSR stud breaks because the number of studs out there used by non race teams is extremely low (and of these people that have CSR studs, the number of them on the forum is likely to be extremely low), and the number of breaks that are reported are even lower (not everyone who experiences issues post online). Last but not least, the CSR studs were meant for racing, and like most race parts they are replaced very frequently, so the chance that they break during use would be very low.

It is as if you say that if the hub is made of plastic it would break, these are just talking for the sake of talking.

10.9 wanted to say.

M4 GT4 has been on the track for longer, and nothing has been seen yet, gt4 and csr are exclusively for track and go with slicks, no user of this forum will know more than Bmw Motorsport.

in section f82 someone said that after intensive use there have been some cases with broken hubs on M4 GT4, and never studs... bmw motorsport has quickly replaced the rear hubs with new version.

[F87source]

Originally Posted by Track/S

It is as if you say that if the hub is made of plastic it would break, these are just talking for the sake of talking.

10.9 wanted to say.

M4 GT4 has been on the track for longer, and nothing has been seen yet, gt4 and csr are exclusively for track and go with slicks, no user of this forum will know more than Bmw Motorsport.

in section f82 someone said that after intensive use there have been some cases with broken hubs on M4 GT4, and never studs... bmw motorsport has quickly replaced the rear hubs with new version.

That's not even remotely close to what I am saying. You said "Before breaking the hub thread you would break the bolt." But how do you know this will always be the case? That is a blanket statement that will not always hold true. There is a high likelihood the hubs aren't made of steel as strong as grade 12.9, so if you used grade 12.9 studs, the hubs will strip out long before the bolt snaps making your statement inaccurate. So you cannot make that blanket statement.

Your second point is also unrelated to what I had to say. I'm saying these studs are made for motorsports use - where parts are replaced extremely frequently so they never get a chance to fail. Combined that with the fact that these parts are used in such low numbers, and that there is not likely to be many users present online to report these issues means an inaccurate representation of true failure rates when a normal owner uses these studs and doesn't replace them at the rate a pro race team would.....

[Track/S]

How I know? Well, very easy, by experience not by assumptions.

You have to use a bit of logic, if there are cases of broken hubs after intensive use and we see that BMW has redesigned the hub and not the studs, it means that the studs don't have any breakage problem, don't you think?

[F87source]

Originally Posted by Track/S

How I know? Well, very easy, by experience not by assumptions.

You have to use a bit of logic, if there are cases of broken hubs after intensive use and we see that BMW has redesigned the hub and not the studs, it means that the studs don't have any breakage problem, don't you think?

Your experience tends to be shoddy at best so I don't trust it, for example being unable to identify that carbon build up was due to oil carbonizing on the hot valves and blaming it on exhaust gas and thinking your "experience" was more accurate than the research done by multiple billion dollar companies including toyota...


Also lets not forget replacing the stiffening plate that is used for structural rigidity of the front subframe for a thin piece of carbon mounted ONLY by the outer trim panel screws that go into a thin metal clip on the car's underfloor. So you pretty much just lost a crap ton of structural rigidity (and risked frame damage due to bending) and called it an upgrade. Nice....
Here's that thread: https://f87.bimmerpost.com/forums/sh....php?t=1938793

Not even sure why you did that in an attempt to copy the GTS's underbody cover, because the M4 GTS only has that panel for aero reasons (lower drag and potentially create some downforce) and the GTS retains the factory aluminum skid plate.

https://autocouturemotoring.com/prod...nt-plate-cover

Overall is the cover nice? Yes, was it made well? Also yes.Was it used correctly - absolutely not. Should you sell it? Yes - given it is used as a cover and not a replacement for the stiffening plate.


So when you say "experience", I highly question that.






First off what does the hub breaking have to do with the CSR studs being ok? They are 2 different parts that are largely unrelated, it could just mean the hub is weak or failing in other areas.


Now lets say they are related, i.e. the stud mounting holes kept failing meaning the stud is so strong it breaks the hub - still doesn't mean the stud can't fail but lets say for some reason that means the stud is unbreakable even though that makes no sense. That's still not enough evidence to draw a conclusion like that because studs are easily replaceable and hubs aren't, studs are also cheaper. Studs are also recommended to be replaced for tracked cars, so it is common to replace them before failures hence why we don't see enough failures to warrant a redesign. It may also be that BMW accepts that studs are consumable parts so failure due to over use is normal, and this is ok because again it is a racing part.


BTW your hypothesis on the hub failures meaning the studs don't have a problem is refuted by bimmer world:

https://www.bimmerworld.com/Drivelin...008328143.html

Originally Posted by Bimmerworld

The lightweight factory hub may develop cracks on the outer wheel hubcentric surface over multiple long, endurance-type events and use. We have not seen any failures on street-driven or lightly-tracked vehicles. The updated Motorsport part has a full hubcentric mounting surface for less stress*.

So it's not the stud holes, it is the hub centric wheel mounting surface that failed......

[E90convert]

In every bolted joint design, analysis, and testing I’ve ever done, the fastener is to be the failure point, not the female threads. Going from an 10.9 to 12.9 may change the failure mode to the female threads whether you tighten it more or not simply because it is a stronger material. This does not address the stiffness change of the fastener and subsequent increased alternating fatigue amplitudes the 12.9 fastener will see. BMW may still have switched to a 12.9, but they have done the calculations, analysis, and testing to prove it. The stud material, manufacturing process, and coatings all play into the testing. And likely would be using a modified 12.9 spec to avoid HE risk. So if they are 12.9, those are the only 12.9s I would use. Track/S Unless that bolt gets sectioned, ground, and checked around the core, the data isn’t really useful. Surface measurements on a fastener don’t tell you the full story (hence why that first fastener was out of spec)

Also a stronger hub does not automatically imply that thread stripping is a problem. It could more than likely be a fatigue problem. All the wheel loads go through the hub and then the bearing so there is quite a bit of alternative bending fatigue on that part. Force amplitudes are magnified with racing slicks. Supporting what F87 uncovered.

[Track/S]

Originally Posted by F87source

Your experience tends to be shoddy at best so I don't trust it, for example being unable to identify that carbon build up was due to oil carbonizing on the hot valves and blaming it on exhaust gas and thinking your "experience" was more accurate than the research done by multiple billion dollar companies including toyota...

I do not need your opinion on the parts that I have mounted on my car, this is the first, and the second after so many years that you are investigating the forums, you could never learn why carbon accumulates in the valves of gasoline engines, you just know that a youtube engineer uses colored bottles to accumulate oil... I understand that it bothers you that someone knows more than you but that's life.

I'm still waiting for you to answer me because a diesel without egr does not accumulate carbon .

If you want to answer, send me a PM, don't dirty the thread with your battles anymore.

Originally Posted by E90convert

In every bolted joint design, analysis, and testing I’ve ever done, the fastener is to be the failure point, not the female threads. Going from an 10.9 to 12.9 may change the failure mode to the female threads whether you tighten it more or not simply because it is a stronger material. This does not address the stiffness change of the fastener and subsequent increased alternating fatigue amplitudes the 12.9 fastener will see. BMW may still have switched to a 12.9, but they have done the calculations, analysis, and testing to prove it. The stud material, manufacturing process, and coatings all play into the testing. And likely would be using a modified 12.9 spec to avoid HE risk. So if they are 12.9, those are the only 12.9s I would use. Track/S Unless that bolt gets sectioned, ground, and checked around the core, the data isn’t really useful. Surface measurements on a fastener don’t tell you the full story (hence why that first fastener was out of spec)

Also a stronger hub does not automatically imply that thread stripping is a problem. It could more than likely be a fatigue problem. All the wheel loads go through the hub and then the bearing so there is quite a bit of alternative bending fatigue on that part. Force amplitudes are magnified with racing slicks. Supporting what F87 uncovered.

I will do the test in 2 different points of the stud.

[F87source]

Originally Posted by E90convert

In every bolted joint design, analysis, and testing I’ve ever done, the fastener is to be the failure point, not the female threads. Going from an 10.9 to 12.9 may change the failure mode to the female threads whether you tighten it more or not simply because it is a stronger material. This does not address the stiffness change of the fastener and subsequent increased alternating fatigue amplitudes the 12.9 fastener will see. BMW may still have switched to a 12.9, but they have done the calculations, analysis, and testing to prove it. The stud material, manufacturing process, and coatings all play into the testing. And likely would be using a modified 12.9 spec to avoid HE risk. So if they are 12.9, those are the only 12.9s I would use. Track/S Unless that bolt gets sectioned, ground, and checked around the core, the data isn’t really useful. Surface measurements on a fastener don’t tell you the full story (hence why that first fastener was out of spec)

Also a stronger hub does not automatically imply that thread stripping is a problem. It could more than likely be a fatigue problem. All the wheel loads go through the hub and then the bearing so there is quite a bit of alternative bending fatigue on that part. Force amplitudes are magnified with racing slicks. Supporting what F87 uncovered.

I don't disagree that the studs are likely fail before the female threads, but I disagree the blanket statement saying it's an absolute guarantee. Because there's always a chance you strip a thread vianover torquing it, that's a female thread failure before the stud snaps. Or there could be a freak accident where the hub does fail first.

Originally Posted by Track/S

I do not need your opinion on the parts that I have mounted on my car, this is the first, and the second after so many years that you are investigating the forums, you could never learn why carbon accumulates in the valves of gasoline engines, you just know that a youtube engineer uses colored bottles to accumulate oil... I understand that it bothers you that someone knows more than you but that's life.

I'm still waiting for you to answer me because a diesel without egr does not accumulate carbon .

If you want to answer, send me a PM, don't dirty the thread with your battles anymore.




I will do the test in 2 different points of the stud.

And yet my opinion still stands, even in ISTA it states not to drive the car without the stiffening plate - whether that be due to the possibility of chassis flex damaging the front subframe or debris damaging the exposed sump. I'm leaning towards chassis flex/loss of rigidity because even the GTS retains the stiffening plate instead of deleting it for weight savings since it now has a cover to protect the sump from debris. But I guess you know more than BMW.




Not sure what YouTuber you're referring to - but if you're talking about octurbojoe and his oil catch can setup that was an example of how complex the ocv setup is and how to prevent carbon build up, and despite you discrediting him, he is an air craft mechanic and does absolutely excellent work as seen by his craftsmanship and I'm certain he would give you and your shop a run for your money when it comes to quality of work. But I'm talking about the peer reviewed research done by 2 billion dollar companies, one being Toyota and the other being lubrizol (iircl, as mentioned by edycol) both saying carbon build up was due to oil carbonizing on the hot valves. The fact that you refute this peer reviewed in favor of your hypothesis which is pseudo science at best, and based purely on observations that clearly have no controls or constants or statistical tests and is susceptible to confirmational bias is borderline narcissistic.


Lol you think I'm bothered by people knowing more than me? That sounds like projection at its finest, you can't ever accept when you're wrong even when confronted by peer reviewed research.

I'm a scientist, every single day my work involves peer reviewed research where I try to prove myself and my hypothesis wrong - that's how real theories are created trying to be proved wrong until it's evidently (with the limits of today's technology and knowledge) impossible to do so. I read hundreds of articles from people way smarter than me, you think that bothers me? No, I enjoy learning more and being proven wrong because that lets me learn and better myself. Even on the forum and in the car world I know I'm not the smartest, I know that I have a wide bredth of knowledge but I'm not the most knowledgeable - I'm a jack of all trades and I'm always willing to accept when I'm wrong and learn more. For example enabled has corrected me numerous times on the tools that can be used for bmw diagnostics, and I know for a fact he's likely one of the smartest people on here when it comes to understand the bmw ECU architecture and his knowledge obliterates anything I know. I know edycol is an expert at oil and again trumps my knowledge of oil hundreds of fold, and so on so forth. The fact I'm able to acknowledge this and accept my errors, admit them means I'm able to learn and actually be factually correct and knowledgeable. On the other hand you refute actual peer reviewed science and basic engineering analytical techniques in favor for your skewed and biased "experiences" thinking you're the smartest guy in the room, and you tell me I'm bothered people know more than me? Right...

[Track/S]

Of course, with enabled you don't argue because you have no idea about diagnosis, with edycol same thing

[F87source]

Originally Posted by Track/S

Of course, with enabled you don't argue because you have no idea about diagnosis, with edycol same thing

I never said I don't question or debate edy or enabled, I have in the past argued that stock diff oil is better to use than aftermarket oil because of how sensitive these diffs are to the FM levels as seen in the past. With enabled I discussed diagnostics systems such as ISTA and tool32.

However, I never really argue with them because they're absolute experts in their fields - far more knowledgeable than you would ever be, and therefore their information is generally consistent and correct so there no need to debate.

For example can you and your shop unlock 2022 ecu's? I bet the answer is no. Can you tune cars? I bet you don't know the first thing about ECU tables and how to modify them. Can you develop coding solutions that have never been developed before, such as turning the gear recommendation indicator into a gear indicator? I bet the answer is also no. Well guess what, enabled can do all of those things, and he's pioneer a whole bunch of new things for these cars.


It's also funny how you entirely dismiss the experience of BITOG thinking you know more, when every single one of their members enjoy testing oil and reading up on oil specs and are largely are part of the oil formulating industry. How many oil analysis have you done, and how long have you been formulating oil specifications for you to think you're vastly superior and the knowledge BITOG contains is inferior to what you know?


If this isn't showing you can't accept being wrong I don't know what does.





The fact that you seem to always argue with everyone - including with peer reviewed research and can never accept that you're wrong, and think you know everything. Really this just shows you are narcissistic at the very least and unable to use the scienctific method or think critically, and this means that you're an unreliable source for information because it always skews to you being right no matter what, even if what you say is blatantly wrong - the prime example is carbon build up.

It's also funny how you believe experience is more important than knowing theory, and yet theory is built up by experience - the only difference is theory is built by trying to prove it wrong. Where's with your experiences are built up by trying to prove yourself right and discarding anything that might violate your idea - i.e. confirmational bias and thus pseudo science.

Btw theory is extremely important, everything you see around you was built using theories. How do you think engineering and stress testing tools are made? That's right the equations are programmed using theories not pseudo science experiments.

[to_riffic]

Well, for what it's worth, I've tracked plenty of times on my Ti studs and must say the Raceseng studs are so much better than MRG Ti studs. The MRG ones I'd end up galling a stud every so often from all the wheel swaps I'd do, but the Raceseng ones have been solid and haven't had any issues at all with them.

[Track/S]

Originally Posted by to_riffic

Well, for what it's worth, I've tracked plenty of times on my Ti studs and must say the Raceseng studs are so much better than MRG Ti studs. The MRG ones I'd end up galling a stud every so often from all the wheel swaps I'd do, but the Raceseng ones have been solid and haven't had any issues at all with them.

Thanks for sharing!

[medphysdave]

What are the longest quality wheel bolts that you can use? If stock is ~27mm and you use a 30mm spacer is there a 60mm wheel bolt?

[GasBurnlife(landapanda)]

I use the Bimmerworld M14 studs - with slicks and 200 TW tires replacing them every 3 years or roughly 50-60 days and haven’t broken any yet. I had a few back out when I was rotating wheels between sessions at MoSport - all on the right side due to the loads in turns 2 amd 3. I cleaned the studs, reapplied red thredlocker and they have stayed in place since then.

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

[Track/S]

E90convert
Confirmed, Bmw Motorsport uses grade 12.9.

[E90convert]

I appreciate you going to the effort to do this. Do you think you could just take it a little bit further? Measuring the outer carbon layer doesn’t really confirm it. See my previous posts about where to take the measurements after sectioning it to determine the fastener hardness.

You mentioned the previous bolt was 12.9 yet it was measuring a 10.9 on the surface. Sectioning is required to measure the core hardness accurately.

[Track/S]

The diamond tip pierces any coating/carbon layer:




I think that more hardness is not necessary, the gt4/csr studs are m12, in m14 they would be even stronger.

[E90convert]

Oh, come on man you’ve taken it this far, you went and bought one! Just section it and do it right! I’ve had some very recent experience with HE problems in 12.9 fasteners. Surface hardness isn’t even considered when determining fastener grade. It’s all about core hardness. Section with lubrication to avoid any accidental heat treatment, grind, measure.

https://wilsongarner.com/core-hardne...-in-fasteners/