Page 1 of 2 12 LastLast
Results 1 to 25 of 31

Thread: studs vs bolts , blah blah

  1. #1
    Join Date
    Mar 2003
    Location
    somers,ny
    Posts
    3,321

    studs vs bolts , blah blah

    so all us track guys know using studs is widely accepted, but they are a wear item!, and stories exist where there were catastrophic fails,..right?...and many believe bolts are waaaay safer.

    so yesterday at Lime Rock an instructor goes off..........ALL 5 BOLTS sheared......

    turns out he runs wheel spacers and had instlld longer bolts, but he didnt recall where he sourced them from.

    Another instrctr( also a mech eng) looked at sheared bolts sticking out of hub and it was clear to him they appeared below grade. I didnt ask what he noticed. Car had body damage, susp damage brake damage.$$$$$$$

    soooo........pls use only good hi grade stuff........it can get scary out there.

    MZ3 coupe.....nice car.
    Attached Images Attached Images
    Last edited by jrkoupe; 04-15-2018 at 02:03 PM.

  2. #2
    Join Date
    Apr 2006
    Location
    Australia
    Posts
    108
    My Cars
    mini cooper S racecar
    Even if you use good quality parts, change them out every year as routine maintenence. Probably one of the cheapest components on the car, but as you point out if they fail ......

  3. #3
    Join Date
    Oct 2004
    Location
    Northeast PA
    Posts
    1,132
    My Cars
    3 - E30 M3s, '04 Ford F350, '06 Audi A3
    Quote Originally Posted by robbo mcs View Post
    Even if you use good quality parts, change them out every year as routine maintenence. Probably one of the cheapest components on the car, but as you point out if they fail ......
    I dunno if I can be 100% onboard with this rec.
    Yeah better safe than sorry is a good mantra,,, but I change studs "preventively" when I change wheel bearings preventively which is about every 5-6 seasons and I know I am throwing away perfectly good studs (and wheel bearings for that matter).
    I can only say from my experience I have never broken a stud or had one fail since I installed my first set in 1998.

    Now newer bigger, heavier, more powerful cars may change the game, I race a 2200 lb E30M3 but I am on slicks and its not driven timidly.
    I think every year is excessive unless there is data out there to back that up of failures occurring after one year of use.
    jimmy p.


    88 E30 M3 Zinnoberot - street
    88 E30 M3 Lachsilber - SCCA SPU
    87 E30 M3 Prodrive British Touring Car 2.0 Litre
    04 Ford F350 - V10
    06 Audi A3 Brilliant Red / 2.0 / DSG

  4. #4
    Join Date
    Jan 2007
    Location
    A house
    Posts
    2,029
    My Cars
    '87 325e, '05 4Runner V8
    That's why I'll only ever buy studs from GLS (I'd buy from ARP too if they made something for us). They're the only ones who will tell me where they're made and how/from what. There are a pile of "motorsport" things out there who make claims about their products but when you ask them for proof of certification and the manufacturing facility, you get crickets or that it's secret bro.

  5. #5
    Join Date
    Mar 2003
    Location
    somers,ny
    Posts
    3,321
    GLS?........never heard

  6. #6
    Join Date
    Jan 2007
    Location
    A house
    Posts
    2,029
    My Cars
    '87 325e, '05 4Runner V8
    Quote Originally Posted by jrkoupe View Post
    GLS?........never heard
    http://glstopstud.com/

    Their web store:
    http://www.trackstuds.com/

  7. #7
    Join Date
    Mar 2003
    Location
    somers,ny
    Posts
    3,321
    very awesome....

  8. #8
    Join Date
    Aug 2012
    Location
    Central, MD
    Posts
    1,151
    My Cars
    1995 M3
    I just broke ONE. Cause, I set my torque wrench in the dark. On inspection found 2 others that were ever so slightly bent. They were 3 years old. So, replaced them all with BW race bullet nose;
    http://www.bimmerworld.com/Wheels-Ti...Stud-82MM.html

    They sure do look extremely similar to the GLS studs.

  9. #9
    Join Date
    Nov 2005
    Location
    Wakefield, MA
    Posts
    2,616
    My Cars
    '97 M3, '17 GSW 4Motion
    After four years, i just swapped in a set of the standard Bimmerworld studs. Race were kinda pricey.
    COMSCC T70 E36 M3

  10. #10
    Join Date
    Aug 2012
    Location
    Central, MD
    Posts
    1,151
    My Cars
    1995 M3
    Yea, they're probably overkill. But I liked the sizes they came in. I also mixed and matched and put longer ones in front.

    Thinking about it, there's the engineering/metalurgy question that asks if higher tensile strength is actually better in this application?

  11. #11
    Join Date
    Jan 2007
    Location
    A house
    Posts
    2,029
    My Cars
    '87 325e, '05 4Runner V8
    Quote Originally Posted by aeronaut View Post
    Yea, they're probably overkill. But I liked the sizes they came in. I also mixed and matched and put longer ones in front.

    Thinking about it, there's the engineering/metalurgy question that asks if higher tensile strength is actually better in this application?
    In the absence of a real engineer, in my opinion, yes. Yield strength specifically. The wheel fastener's primary role is to clamp the wheel to the hub, they should not be shear load bearing structures (granted, shear strength will go up with tensile too). Which is why GLS makes theirs out of 4340, chromoly that gun barrels are made out of. It doesn't mean you need to make use of the added clamping force capacity but it will just have an easier time with the application being so far below the limits.

  12. #12
    Join Date
    Nov 2009
    Location
    Realville
    Posts
    1,161
    My Cars
    93 525iT,91 318i
    I agree with the tensile strength being important for cornering, but wouldn't the shear strength be important for braking/accelerating?

  13. #13
    Join Date
    Jan 2007
    Location
    A house
    Posts
    2,029
    My Cars
    '87 325e, '05 4Runner V8
    Quote Originally Posted by locknload View Post
    I agree with the tensile strength being important for cornering, but wouldn't the shear strength be important for braking/accelerating?
    As I understand it, with the hub/wheel joint under proper tension, the fasteners should not be under shear load. But again, shear strength goes up with tensile so if for some reason your wheel is loose and moves, the higher tensile strength fastener will add a measure of safety there too.

  14. #14
    Join Date
    Aug 2012
    Location
    Central, MD
    Posts
    1,151
    My Cars
    1995 M3
    I was just thinking that a higher tensil metal ?may? be less flexible, or less resistant to heat cycles? Don't know, just spitballing. Anyway, I bought the fancier ones mostly because I could get the exact lengths I wanted.

  15. #15
    Join Date
    Jan 2007
    Location
    A house
    Posts
    2,029
    My Cars
    '87 325e, '05 4Runner V8
    Quote Originally Posted by aeronaut View Post
    I was just thinking that a higher tensil metal ?may? be less flexible, or less resistant to heat cycles? Don't know, just spitballing. Anyway, I bought the fancier ones mostly because I could get the exact lengths I wanted.
    I can't think of a downside personally (other than cost). They will certainly be less flexible which is also a good thing, as they will be less likely to fatigue out. And chromoly is sensitive to heat but not at this level (you'd have to heat them up to the transitional temp). GLS also rolls their threads instead of cutting so they are much stronger.

  16. #16
    Join Date
    Feb 2007
    Location
    Springfield, IL
    Posts
    1,591
    My Cars
    '95m3(Avus)/996tt/4.8is
    Could easily be mis-handling of re-torquing procedures on hot studs or lack of re-torque after initial heat cycling. Seems like this is just as important as the blingy-ness of your wheel studs/bolts.

  17. #17
    Join Date
    Jul 2012
    Location
    Orlando, FL, USA
    Posts
    188
    My Cars
    1993 BMW 325i
    Very happy with my GLS studs, ~3 years thus far, r-compounds only

  18. #18
    Join Date
    Apr 2008
    Location
    Alpharetta, GA
    Posts
    335
    My Cars
    06 330i, 88 M3
    While the tensile strength is important, the most important point is using the proper torque spec. The idea of torquing the fasteners is to be in the elastic range of the fastener. This will slightly stretch the stud, but in the elastic range it will always return to its original dimension and properties.

    When you torque the bolt past the elastic range and reach plastic deformation, the bolt will neck, usually at its thinnest point (point of highest specific stress) also lengthening the bolt. This will result in strain hardening of the bolt in the regions of plastic deformation. The bolt may be harder in this region, but its ductility is also reduced. Future applications of load will now also experience higher specific stresses in the necked area.

    I have heard nonsense arguments that the brakes can heat the fasteners enough to soften them, but this is not the case. The eutectoid temperature is 727C (transformation) for carbon steels, so your studs on a Z3M are not going through recrystallization.

    Make sure that you find & abide by the torque spec for your studs. I use the Italian ones from BW, and on contacting them they have told me to use 75ft-lbs. I have the same studs for over 10 years and too many events & wheel changes to count. When torquing, stop application of force once the ratchet clicks. I see a lot of people misuse torque wrenches by clicking & then giving an extra oomph. If you want to check, release the wrench & only reapply enough force to click.

    Finally, wheel studs are not the only fasteners to torque properly. BMW has assigned specs to most fasteners, and following these is important to the longevity of the parts & fasteners and overall reliability of the vehicle. It really takes very little extra effort to properly torque fasteners.

    Sent from my SM-T713 using Tapatalk

  19. #19
    Join Date
    Aug 2012
    Location
    Central, MD
    Posts
    1,151
    My Cars
    1995 M3
    ^ Great post. Usable info!!
    I've been torquing to 100Nm (=74ft-lb), so this makes me feel good.:

  20. #20
    Join Date
    Apr 2008
    Location
    Alpharetta, GA
    Posts
    335
    My Cars
    06 330i, 88 M3
    Quote Originally Posted by locknload View Post
    I agree with the tensile strength being important for cornering, but wouldn't the shear strength be important for braking/accelerating?
    There should be no shear load on the fasteners on a properly installed wheel. The studs will be under a tensile load. There is a fictional interface at the hubs which translates the forces from the wheel into the suspension.

    This is why you should make sure that the wheels are tightened to the hub before lowering the car onto the wheels.

    Sent from my SAMSUNG-SM-G900A using Tapatalk

  21. #21
    Join Date
    Mar 2003
    Location
    somers,ny
    Posts
    3,321
    This is why you should make sure that the wheels are tightened to the hub before lowering the car onto the wheels.




    bingo

  22. #22
    Join Date
    Jan 2006
    Location
    Gateway To The West
    Posts
    682
    My Cars
    2001 BMW M3
    Noticed the lug nuts were getting a little shoddy when swapping tires at NCM last weekend along with some more advanced front rotor cracks. Opted to order the Bimmerworld Premium Race (12.9 grade steel) stud & lug nut kit and new front rotors.

    http://www.bimmerworld.com/BimmerWor...d-Package.html

    Had the street version (10.9 quality steel) on the M3. I'm not sure how old they were so it seemed like prudent preventive maintenance.

    Feff

  23. #23
    Join Date
    Apr 2008
    Location
    Alpharetta, GA
    Posts
    335
    My Cars
    06 330i, 88 M3
    Keep in mind that harder is not always better. A harder bolt will necessarily have a higher torque spec to get into the elastic range, and this may be more than the bolt threads or mating surfaces can handle.

    A 12.9 has an ultimate tensile strength about 20% higher than a 10.9, so I'd guess that you won't deform or gutter out good aluminum wheels, but I would check.

    Also note that 12.9 might be a more exotic alloy than the carbon steel 10.9s, so make sure that the alloys are designed for the application to prevent corrosion-induced failure.

    BW is a good company, so just reach out to them to verify proper installation.

    Sent from my SAMSUNG-SM-G900A using Tapatalk

  24. #24
    Join Date
    Jan 2007
    Location
    A house
    Posts
    2,029
    My Cars
    '87 325e, '05 4Runner V8
    Why do you need to torque it to yield just because it has higher yield strength? Keep the same clamping force, just have more overhead if things don't go right (such as a bad torque wrench or a gun-happy tire installer)

  25. #25
    Join Date
    Apr 2008
    Location
    Alpharetta, GA
    Posts
    335
    My Cars
    06 330i, 88 M3
    Sorry I wasn't clear, and I hijacked a little to cover all fasteners.

    You don't want to yield the bolt, but you do want strain (deform) in the elastic region. The reason for the higher torque spec on harder fasteners of a given dimension (M12 10.9 or 12.9, for instance) is due to the stretch that you want in the bolt. Clamping force between the parts is one aspect, but the orthogonal force between the threads, which is what keeps the bolt from backing out, is equally important.

    Again, I'm not saying that it won't work. I just wanted to point out that:
    1 Higher strength is not always better for a given application
    2 Contact the seller and make sure that you understand if there are changes into the torque spec.

    Sent from my SM-T713 using Tapatalk

Page 1 of 2 12 LastLast

Similar Threads

  1. Crankshaft Main Studs Vs Main Bolts
    By TheM3nsah in forum Track, Auto-X & Drag Racing sponsored by Bimmerparts.com
    Replies: 1
    Last Post: 02-14-2011, 09:22 PM
  2. ARP head studs vs bolts!
    By ramzisleiman in forum Forced Induction
    Replies: 4
    Last Post: 09-18-2008, 09:44 PM
  3. war war war .. blah blah blah
    By Dj Waffelz in forum Off-Topic
    Replies: 17
    Last Post: 02-13-2003, 03:15 AM
  4. Some newer items on my car, some blah blah
    By Khoalty in forum BMW Rides & Events
    Replies: 41
    Last Post: 01-19-2003, 06:30 PM
  5. Canada, Tires: duty, brokerage, taxes, blah, blah, etc.
    By MZNorth in forum Tire & Wheel Forum sponsored by The Tire Rack
    Replies: 2
    Last Post: 05-04-2002, 08:38 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •