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Thread: Lug bolt question

  1. #1
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    Lug bolt question

    My 80 E21 is wearing its original steel wheels and I also have a nice set of 13" 320is sport wheels (FPS) that I'd like to mount. (keeping the steelies for posterity and if I want to get all fuzzy with originality again)

    According to Real OEM and Maximillian the lug bolts I have (black, M12X1,5) are the same for the alloy wheels but I'm not convinced. They sit in too deeply and only if I carefully use a thin 17mm socket will I not scrape up the landing around the bolt hole. I wouldn't even think of letting a tire shop mount them with these bolts.

    Is there a bolt with a bigger cone that should be used with the alloys? Can anyone recommend a source? Better yet do any of you have a set to sell me?

  2. #2
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    There are two sizes of lug bolts I know of stock and really long. The really long ones are to be used with 10 to 12mm spacers.

    I have used the stock bolts with BBS sport wheels and steels with no issues.

    After a short time I went to studs with nuts when running spacers - just easier.
    Last edited by OLD MAN; 01-13-2018 at 04:36 PM.

    Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link

  3. #3
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    e21 Lug Bolts.JPG

    It looks like they are different. The one with the alloy IS wheels has overall length of 51.5mm and cone max diameter of 23.25mm.

    One for steel wheels, 46.75mm and 21.25mm.

    This is side by side comparison of 1983 IS lug bolt with 1982 lug bolt from e21 with steel wheels.

  4. #4
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    ^ That's easily within the normal variation between bolt manufacturers. It won't help with scraping the wheel anyway, the 17mm socket is the same size.

    Aftermarket BBS RA wheels use long bolts, and the heads sit flush on the outside. I suspect BMW made BBS bore the deep holes in the S package wheels to avoid the danger of using the regular bolts when long ones are required. So scraping the sides of the hole is just a side effect of that. Just get a thinner socket or buy "tuner" lug bolts.

  5. #5
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    Actually The S package wheels I've seen are either made by Lemmers or FPS,
    That 2mm could actually be enough to "fill" the top of the opening allowing the socket or lug wrench to land on the top of the cone.

    No doubt the bolts I have can be used but the wheels are refinished and I'm trying to avoid messing them up.

  6. #6
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    Quote Originally Posted by okieflats View Post
    I do not understand. Don't see what the "socket" problem is.
    Because the socket or lug wrench should press against the landing on the top of the bolt's cone. The smaller (steel wheel) bolts sit below the face of the bolt hole in the wheel. Less contact area on the bevelled part of the hole too. There is a flat area around that on the wheel (painted) that the lug wrench will ride against instead and scrape the paint as a result.

    Found these that look like they'll work. Chrome or black finish. Sent email to confirm the width of the cone but the cone looks long enough to do the trick.

    http://www.ezaccessory.com/Black_Lug...nk_p/954bk.htm

  7. #7
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    My car is an original iS and I just have these bolts - so did not know about the difference. Sorry for the bad info Neu Alt.

    I have just put steels on it that were on my 81 runabout.

    Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link

  8. #8
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    Not bad info at all. I wouldn't be surprised if the factory shipped cars with alloy wheels running the bolts designed for steelies.
    A lot of us haven't ever seen the steel wheels. As with ALL steel wheels the surface area where the bolt makes contact is raised and shaped to create strength. The contact area is less and the conical area of the bolt doesn't have to be as deep.

    I'm no engineer, (well maybe in my mind) but not using a bolt that can utilize the contact area of the full bevel on an alloy wheel will add stress to that area. My concern with damaging the painted surface is secondary but important to me.

    The funny thing is I bought this car because it had the original steel wheels and the original owner never thought to run anything else. To me that spelled originality. They won't be sold.

  9. #9
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    The smaller (steel wheel) bolts sit below the face of the bolt hole in the wheel.
    OK, I understand now.

  10. #10
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    Quote Originally Posted by okieflats View Post
    e21 Lug Bolts.JPG

    It looks like they are different. The one with the alloy IS wheels has overall length of 51.5mm and cone max diameter of 23.25mm.

    One for steel wheels, 46.75mm and 21.25mm.

    This is side by side comparison of 1983 IS lug bolt with 1982 lug bolt from e21 with steel wheels.
    okieflats, can you confirm that the shaft length is the same and the extra length is in the cone and bolt head?

  11. #11
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    E21 Lug Bolts2.JPG

    yes the threads are the same length, and the cone is taller. Here's the measurements:

    End of bolt to where cone begins (ie thread length) is 26mm for both.

    Cone height is 10mm (IS) and about 8.75mm (steel) - harder to measure, not too accurate.

    17mm head is about 10.5mm tall in both cases.

    BUT for the IS bolt there is also a pronounce "hump" on the top side of the cone, which also takes up some extra length.

  12. #12
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    Thanks. That confirms the difference in the cone area.
    The "iS" bolt is similar to the one that I have linked above.

  13. #13
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    Yeah, at least buy one and check it to see if it's good for your use, if you're not comfortable buying a full set. The picture makes it look like the "IS" bolt but maybe not exactly the same. Hard to tell just from the pic.



    Cone looks pretty big though, so it should work.
    Last edited by okieflats; 01-14-2018 at 03:14 PM.

  14. #14
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    I have these wheel bolts on my E21, they take a 12mm Hex bit.
    Stock style wheel bolts that take a 17mm, do not fit in the wheel bolt holes at all. (Aftermarket wheels)


  15. #15
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    Quote Originally Posted by okieflats View Post
    e21 Lug Bolts.JPG

    It looks like they are different. The one with the alloy IS wheels has overall length of 51.5mm and cone max diameter of 23.25mm.

    One for steel wheels, 46.75mm and 21.25mm.

    This is side by side comparison of 1983 IS lug bolt with 1982 lug bolt from e21 with steel wheels.
    I assume the bolt on the left is for steelies and the bolt on the right is for aluminum wheels? The bolt on the right looks like the later e30 style bolt (for aluminum bottlecaps or BBS e30 wheels) and not the e21 wheel bolt. E21 bolts that came with aluminum wheels are the same length as the e30 bolts (photo on the the right) but have longer heads which makes it easier to reach using the factory wrench. I think that what you need to find to use with FPS mesh wheels. My e21 that originally came with turbine wheels has these bolts with longer 17mm heads.

    Wheel bolts you buy from BMW today are similar to the lug bolt on the right (longer bolt but shorter head) and are black.

    I'd say keep the bolts you have with steelies and order a set of new bolts from BMW that will have thicker seat for aluminum wheels. I would avoid aftermarket bolts unless they are german made BBS or H&R bolts, but these are usually for spacers and longer.



    Max
    Last edited by mxl556; 01-15-2018 at 12:33 PM.

  16. #16
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    The bolt on the right looks like the later e30 style bolt (for aluminum bottlecaps or BBS e30 wheels) and not the e21 wheel bolt.
    The bolt on the right is from a 1983 e21 320IS and I have every reason to believe that set of bolts is original to the '83 e21 with it's original white mesh wheels. That car was abandoned at an auto repair shop with about 135k miles and just sat there for 15-plus years. There is no reason to think anyone swapped wheel bolts on it.


    For all I know the bolts used on '81 and '82 IS models could have been different.


    The bolt on the left is also original to the car it was taken from, a 1982 320i with steel wheels, not an IS model.

  17. #17
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    Interesting... I wonder if the cars with turbine wheels had bolts with longer 17mm heads for easier reach or something...Or it just looks that way on the photos my car that likely came with turbines originally has the same bolts as your iS. Can you measure the length of the head of the bolt on the right,starting from the widest part of the cone? I am seeing 16mm but the head looks longer than the one on the photo above with the overall length being approx. 51.5mm.

    Thanks,
    Max
    Last edited by mxl556; 01-16-2018 at 08:16 AM.

  18. #18
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    I've got full sets of both. They're yours for $10 plus shipping if you're interested. Or I've got some 57mm studs with conical lug nuts from Ireland engineering if you ever plan on running spacers.

  19. #19
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    Thanks. I wish I had known. I ordered a set and will have them on Friday.

  20. #20
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    Allen has lots of parts. If anyone is looking for something it's best to PM him or else he doesn't know what people are looking for.

  21. #21
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    Quote Originally Posted by okieflats View Post
    Allen has lots of parts. If anyone is looking for something it's best to PM him or else he doesn't know what people are looking for.
    ↑↑What he said↑↑ (and nearly always willing to part with them at whatever they cost me plus shipping---please excuse the bad pun)

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