MB dealer nuts and bolts - whats the difference

Discussion in 'General Discussion' started by SilverSaloon, Mar 27, 2014.

  1. SilverSaloon

    SilverSaloon MB Club Veteran

    Messages:
    7,759
    Joined:
    Mar 16, 2004
    Car:
    1994 W124 E300D Estate, 1985 R107 280SL
    hi

    I had to cut off a suspension arm nut to remove it on my W124.

    So, I have two options:

    (1) go to dealer and spend £9.00 on a new nut & bolt as per correct part numbers

    or

    (2) go to local hardware shop, get same length, thickness of bolt for less than £1.00

    I've actually gone to the dealer and spent £9 this time, but what differs the dealer bolt from the hardware shop's bolt? Dealer bolt is heavier and is grey matt in colour. Hardware shop bolt is shiney metal

    I assume the dealer bolt is high strength for suspension? whats the code/type/name of the type of bolt so i can seek elsewhere for cheaper?

    cheers!

    derek
     
  2. Druk

    Druk Administrator Staff Member

    Messages:
    5,309
    Joined:
    May 28, 2004
    Location:
    Not far from Edinburgh.
    Car:
    2011 S212 E350CDi. 1981 R107 300TurboDiesel.
    Tensile strength of bolt might be cast on head. 8.8 or 10.9 are high tensile and 12.9 being the top grade.

    Grey appearance is zinc plating. Dealer bolt might have threadlok already on but big deal on that. Bottle of Loctite and it's sorted.
     
    Last edited: Mar 27, 2014
  3. R2D2

    R2D2 MB Club Veteran

    Messages:
    6,935
    Joined:
    Mar 23, 2004
    Car:
    C350
    Why would you take a chance on a bolt that holds your suspension together. £9 is a small price for the peace of mind surely!
     
    6 people like this.
  4. BTB 500

    BTB 500 MB Club Veteran

    Messages:
    17,501
    Joined:
    Aug 7, 2005
    Location:
    Berkshire
    Car:
    R129 SL500, W639 Vito 120, S203 C230
    £8, if the non-M-B one costs £1 anyway :)
     
  5. Stratman

    Stratman Hardcore MB Enthusiast

    Messages:
    4,096
    Joined:
    Jun 15, 2003
    Location:
    Sunbury
    Car:
    W203 C200 CDI '04Estate
  6. OP
    OP
    SilverSaloon

    SilverSaloon MB Club Veteran

    Messages:
    7,759
    Joined:
    Mar 16, 2004
    Car:
    1994 W124 E300D Estate, 1985 R107 280SL
    Don't dispute that but £8 is a lot for a bolt if the same type of bolt can be purchased elsewhere - it would become very expensive if u needed to renew a few of them
     
  7. DSM10000

    DSM10000 Hardcore MB Enthusiast

    Messages:
    3,994
    Joined:
    Jul 12, 2011
    Location:
    Near Salisbury
    Car:
    E32O CDi Sport, C320 saloon MX5 1.8 Sport, RR 4.2 SC
    I would look at it this way Derek:

    The MB supplied bolt will have been designed, manufactured and tested to meet the loads and stresses that the suspension undergoes, unless you can find these design specifications and then satisfy yourself that another manufacturer and supplier meets all of the required standards would you really want to risk it?

    Just because a part appears to be simple in design and without obvious fancy features does not mean that it has none.

    Compared to the cost of other suspension components is £9 not rather good value?

    The fact that the two bolts you compared, whilst seeming to be the same in size had differing mass shows that the materials are clearly very different.:thumb:
     
    Last edited: Mar 27, 2014
  8. OP
    OP
    SilverSaloon

    SilverSaloon MB Club Veteran

    Messages:
    7,759
    Joined:
    Mar 16, 2004
    Car:
    1994 W124 E300D Estate, 1985 R107 280SL
    indeed but i suspect a site such as:

    Hexagon Bolts

    may be worth looking at. You can get >10 bolts for the price of 1 MB bolt, of the same strength spec.
     
  9. GordonTarling

    GordonTarling Hardcore MB Enthusiast

    Messages:
    1,596
    Joined:
    Jun 29, 2004
    Location:
    Grantham
    Car:
    2007 E63 AMG V8 Estate
    Would you really want a front suspension bolt shearing off at an inconvenient moment? Forget the inconvenient moment, I wouldn't want one shearing at all! Just bite the bullet and fit the correct bolts.
     
  10. OP
    OP
    SilverSaloon

    SilverSaloon MB Club Veteran

    Messages:
    7,759
    Joined:
    Mar 16, 2004
    Car:
    1994 W124 E300D Estate, 1985 R107 280SL
    as i stated in my 1st post, i have fitted the correct bolts, from the $tealer this time.

    All i wanted to know is what type of bolt they are, so in future i can look at alternative sources, which are of the same style/strength/type of bolt.

    why pay more than you have to for the same thing?
     
  11. IanMSpencer

    IanMSpencer Active Member

    Messages:
    95
    Joined:
    Mar 26, 2014
    Car:
    C220Cdi Estate
    The chances are that the MB bolt is sourced from any old quality bolt manufacturer so in principle you can buy generic bolts rather than branded bolts however to do this you need to understand the specification of the bolt. You also need to know not just the length and width, but the thread pitch - not all metric bolts use the same pitch.

    There are different grades of steel and treatments which have different properties, and it may be that one bolt has to be good at twisting forces, another might get occasional shocks. The designer will have considered this.

    Also, materials are important, differences in material can cause electrolytic reactions, steel bolts into aluminium for example.

    If you are an experience engineer, you'd be able to assess the task of the bolt and either identify an exact generic equivalent or have a reasonable idea of a sound alternative.

    Consider it £8 for expert advice from a Merc engineer.
     
  12. V12

    V12 MB Club Veteran

    Messages:
    5,610
    Joined:
    Jun 17, 2002
    Location:
    Southampton
    Car:
    S320CDI LWB
    As you have cut the old bolt off you'll know how hard they are compared to the majority of the hardware shop lurpak bolts.

    Lots of sound advice above!
     
  13. NOMONEYBUTAMERC

    NOMONEYBUTAMERC Hardcore MB Enthusiast

    Messages:
    930
    Joined:
    Aug 27, 2010
    Location:
    Weston super Mare
    Car:
    1973 450 sl. w202 C240 . W168 A160
    As Druk says , the tensile strength is marked on the head of quality bolts. I always look to save money in every area that I can , except Safety. The saving of £8 on a bolt is not the last thing you want going through your mind just as a detached wheel starts working its way up your ars*e!
     
  14. WDB124066

    WDB124066 MB Club Veteran

    Messages:
    5,222
    Joined:
    Apr 17, 2009
    Car:
    1996 E320 Sportline Cabriolet x 2
    The MB bolts generally have their threads rolled [i.e. forged] as opposed to a straight out machine cut, their shape and design minimises stress raisers, they are a nice piece of engineering all on their own. Washers should be the through hardened type, not the soft ones you'll pick up cheaper, as they do not transmit torque as evenly or hold the bolt tension as well as the through hardened types.
    The things that can go wrong with bolt manufacture would surprise you, especially when you are heat treating them. Accountants just love to try and cut corners on starting material and heat treatment processes.

    How would the Insurance Co's deal with a car that has non-genuine bolts installed in critical locations - are they concerned about this at all...??
     
    Last edited: Mar 27, 2014
  15. gazz

    gazz Hardcore MB Enthusiast

    Messages:
    435
    Joined:
    Mar 9, 2006
    There is also the issue of counterfeit bolts. There are some dodgy things floating about that come in on the same flights as rubber dog poo and fake vomit. They are often stamped on their heads with the same 8.8 or 10.9, but yield strength way lower. Why take the chance with your life and, potentially, the lives of others?
     
  16. Dieselman

    Dieselman Banned

    Messages:
    34,206
    Joined:
    Jul 13, 2003
    Car:
    Peugeot 403 Convertible
    I thought he was talking about bolts, not firing a bullet into his head?


    Lynne Faulds-Wood alert.

    A Potential Death trap...
     
  17. gazz

    gazz Hardcore MB Enthusiast

    Messages:
    435
    Joined:
    Mar 9, 2006
    Do you have an opinion, or prefer to belittle that of others?
     
  18. hotrodder

    hotrodder Hardcore MB Enthusiast

    Messages:
    845
    Joined:
    Sep 28, 2008
    Location:
    south east
    Car:
    '93 320te
    For the typical sizes found on cars and the like virtually all commercially made bolts have rolled threads. Once you get into really large diameters and/or oddball sizes threads may be cut but pretty much everything else has rolled threads because it's cheaper (faster than cutting threads and chipless so no waste) as well as better. About the only time i come across cut threads on commercially made fasteners (and the difference is typically obvious to the naked eye) is with studs and even then you have a choice unless you want grade 8.8 or higher in which case it's typically rolled threads only

    For the vast majority of things i fabricate i use flutess thread rolling taps over conventional straight or helical flute cutting taps. Half the time the extra strength of the rolled thread is immaterial, i use 'em for speed and lack of chips/swarf in any compatible material for sizes under M10

    MB don't make bolts and in most cases probably won't design anything either, why bother when you can select a spec that'll do the job and is available off the shelf
    Sometimes the fasteners that OEMs use are harder to find elsewhere but often the difference is something that only mattered when the car was made, things like this
    [​IMG]
    long thread lead-in which is about making the fastener almost impossible to cross thread for example
    Occasionally you come across a weird grip length i.e. the bolt has an odd length shank in relation to it's total length. That can make a difference on suspension bits as the nearest 'off the shelf' thing that'll physically work results in a portion of the threaded section being subjected to bending loads when the fastener is used in double shear instead of tension. Last saw that one on an old aircooled VW, a grade 12.9 cap screw that does double duty functioning as a pinch bolt and a cotter pin on a ball joint. With generic 12.9 cap screws the grip length is wrong and some of the threaded portion ends up being used as the cotter pin :eek:

    If the grade, overall and grip length can be matched then pretty much the only risk of buying a generic bolt is counterfeit cheapnese tat (as already said) and if buying from somewhere reputable i'd say the risks of that are probably no higher than going to MB and paying several times the going rate
    The electrolytic corrosion thing is rarely an issue as most manufactures use plain ol' BZP, yellow passivated or black oxide fasteners which are a lot easier to find than uncoated. Not relevant to a suspension bolt but as magnesium castings become more popular for weight saving reasons the corrosion thing does come into play with not only aluminium bolts being used but weird flavours too instead of the more common 7075-T6... http://www.kamax.com/fileadmin/user_upload/dokumente/veroeffentlichungen/alu_fast_for_magn_comp.pdf
     
    4 people like this.
  19. WDB124066

    WDB124066 MB Club Veteran

    Messages:
    5,222
    Joined:
    Apr 17, 2009
    Car:
    1996 E320 Sportline Cabriolet x 2
    Agree with most of this but MB do make bolts AFAIK, as soon as they put their logo on it regardless of who actually physically made it. In other words legally AFAIIA MB are deemed to be the manufacturer once their logo is on it. Rest assured there will be MB specs for bolts that the makers will need to comply with before the logo may be applied.
    When people start buying their own hardware for critical applications they need to know what they are buying, cut threads are a bit of a no no, as are the qualities listed above. Stick with the Genuine part - you know you are getting it right first time, most of the time.
     
    1 person likes this.
  20. markjay

    markjay MB Club Veteran

    Messages:
    16,958
    Joined:
    Jun 24, 2008
    Location:
    London
    Car:
    W204 C180 Executive SE 2013 Automatic / COMAND NTG4.7 and Morel speakers fitted by www.comand.co.uk
    Unapproved bolts is a serious issue for airlines - several aircarfts have crashed in the past due to industrial bolts being passed off as approved aviation parts to unsuspecting (and potentially incompetent) airline buyers.
     
    1 person likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.