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Old 07-27-2005, 12:04 PM   #1
austinpike
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Default STi OEM vs NISMO hub bolts

well after finding the lugnuts on one wheel really loose one day I got paranoid and decided to replace the bolts. I ordered the 50mm Nismo ones (vs the 60mm ones since I don't really want to use open lugs)

anyway, comparing the two, it looks like the OEM ones are made of a hardened steel, while the Nismo ones, well, aren't. So now I'm wondering if I might not be better off with new OEMs. (ie does harder steel trump longer threads? Or will the stretching force be effectively spread out over those extra threads?) The point is for either to withstand semi-frequent wheel changes for autoX.

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Old 07-28-2005, 12:19 AM   #2
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Did you buy the correct Nismo ones? It looks like the knurl is different
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Old 07-28-2005, 09:53 AM   #3
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Uhh.... Well first off common threads (IE the ones on you lugs, not spiralock or whatever) only distribute the tensile force onto two to three threads anyway. Second you would never use high hardness steel in a lug cause the risk of SCC. The tension in a lug is a direct reslut of torque and friction. Do you retighten your lugs after 50mi? How clean are the threads on your lugs that loosened? Did you torque properly to begin with? Most of the damage to fasteners occurs to the nut not the stud. Adding a bit of anti-sieze can almost completely eliminate damage to fasteners from assembly/disassembly cycles. The torque to tension relationship can be altered up to 40% by metallic anti-sieze compounds.
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Old 07-28-2005, 10:14 AM   #4
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Anti-sieze on a lug stud is a very bad idea !!!

Here's why: Bolts or studs provide clamping force by being purposely stretched. Most torque specs bring a bolt well
within its elastic limit. Then when loosened they will return to their original length and can be safely reused (Some
bolts, including many head bolts, are purposely stretched past their elastic limit, and can not be reused). The torque
wrench is the most convenient-but not the most accurate-method of properly stretching automotive bolts. Engineers
spend hours correlating the proper bolt stretch to the required turning effort.

About 90% of a torque specification is used to overcome friction; only 10% of the specified twisting effort provides
clamping force. It is no surprise then that most lubricant tables recommend a 40-45% reduction of applied torque when
using anti-sieze on a bolt. So, a lugbolt coated with anti-sieze should be tightened to a maximum of 49 ft-lbs.
Tightening this lugnut to 85 ft-lbs. means it is now over-torqued by 73%! Considering that most torque specs stretch a
bolt to within 70% of its elastic limit, over-torquing by 73% will easily send the bolt or stud well beyond its
elastic limit-and could be dangerously close to its failure point.

For this reason I would suggest to all forum members to never use anti-seize on your lug hardware.
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Old 07-28-2005, 03:34 PM   #5
LyveWRX
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Ahhh.. Luke did you catch the article in American Fastener Journal? (Vol.22/#3 May June 2005) titled "Wheel Bolts, Studs, and Nuts" by Guy Avellon. Really great discussion about lugs...

One reccomendation is: "Nuts are cheap. If you forgot how many times they have been reused, replace them. Generally, dont go beyound three reuses."
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Old 07-28-2005, 06:06 PM   #6
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Are the Nismo ones the same thread pitch and diameter as the WRX ones, but longer?
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Old 07-28-2005, 06:15 PM   #7
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Intersting..I have cleaned my lug nuts and studs w/ WD40 to get all the dirt out of em..then wiped them off..I'm sure ther ewas some WD40 left on the threads..should I have not tq'ed them down to the tq specs?
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Old 07-28-2005, 11:57 PM   #8
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Quote:
Originally Posted by pio!pio!
Did you buy the correct Nismo ones? It looks like the knurl is different
yep, they are the right ones. There are only 4 options, 50 or 60mm length with 13 or 14.3 mm diameter for the knurled area. Obviously the 13mm wouldn't work at all. I don't think the number of knurls really matters. The hubs don't actually have a knurl cast into them to receive the bolt, it looks like the bolt sort of makes its own grooves as you press it in. So you couldn't really swap out bolts too many times without replacing the hubs since you would chew up all the available mating surface.

Quote:
Originally Posted by LyveWRX
How clean are the threads on your lugs that loosened? Did you torque properly to begin with?
actually they do appear to be somewhat dirty. (greasy?) but no more so than the wheels that were not loose. I will make note of that and keep them cleaner in the future. I am pretty religious about proper torquing and re-torquing; they have never been over-torqued to my knowledge. They had just been tightened on Thursday after a spring install and checked again later that night. I went to check them Saturday (autox prep) and found all of them loose on the one wheel. The other three wheels were not loose at all. As far as using anti-sieze... not somewhere I am prepared to go at this point.

Quote:
Originally Posted by TarmacRally
Are the Nismo ones the same thread pitch and diameter as the WRX ones, but longer?
yep, yep, and yep.

Anyway, after some more searching I found these:



http://www.projectnissan.com/shoppin...&idproduct=352

I talked with a guy at projectnissan who was very helpful; apparently they tracked these down in Japan, where Kyo-ei provides them as OEM to some manufacturers. The description is a little screwy - the 14.2 is the width of the knurled area; not sure about the 56...? The pitch is actually 1.25, same as Nissan and Subaru OEM. They come in 50mm or 60mm lengths. I got these today and feel much better about them than the Nismo parts.
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Old 07-29-2005, 12:37 AM   #9
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I used the 60mm Nismo studs all last year with 245 and 275 Hoosiers with 5-8mm spacers and never had any issues. I also daily drove on them and changed wheels/tires at least 30 times.
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Old 07-29-2005, 09:50 AM   #10
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Quote:
"They had just been tightened on Thursday after a spring install and checked again later that night. I went to check them Saturday (autox prep) and found all of them loose on the one wheel. The other three wheels were not loose at all. As far as using anti-sieze... not somewhere I am prepared to go at this point."
yeah, that started happening to me ~2.5 years ago, my second fall with the car. I just toruqed and re-torqued until they quit loosening (70ft-lbs). After one Lucky Break at a TSD I decided to reduce torque to below factory spec and go with Al-based antisieze.. After one or two wheel swaps they quit loosening.

It all depends on what you want to do. You might have only needed nuts.. here is a quote from that article I noted above:

Quote:
Originally Posted by americanfastener journal
" Nut reuse. Each time a nut is used, its threads bend and collapse slightly as it is tightened. Unlike a bolt's threads that spring back under tension, the nuts threads undergo compression, which is permanent deflection." ..... "When the nut is reused, friction between the threads increases from 40% to 42%, for example. This means that only 8% of the tightening energy is available to attain clamp load instead of 10% when the same torque is used."
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Old 07-29-2005, 10:35 AM   #11
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^^^ good info, thanks.

seeing the thread below a few days before I found my loose lugs was what got me concerned. Hopefully just a fluke occurrence.

http://www.imprezawrxsti.com/forums/...ad.php?t=28875
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Old 07-29-2005, 03:32 PM   #12
LyveWRX
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Oh and just to offer an expert opinion on why his lug failed:

They were loose. The loss of tensile preload in a fastener causes the fastener to be subjected to bending loads. The fracture surfaces shown there are consistant with bending fatigue failure.
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