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What Grade Bolts for Plow Mounts on Frame?

Discussion in 'Meyer / Diamond Products Discussion' started by wsmm, Apr 24, 2010.

  1. wsmm

    wsmm Member
    Messages: 80

    Taking the Meyers plow mount off of my Dodge Ramcharger (1979). Having to cut off most of the bolts due to years of rust. My question when I replace them do I need to use grade 2, 5, 0r 8. Does anyone know what grade Meyers supplies with the plow?

  2. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    Most are grade 5 bolts.
  3. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    Grade 5 is fine.
  4. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    Be sure to use the applicable washers and nylock nuts.

    Remember when it comes to hardware tighter is not better. You can actually weaken bolts with too much torque. Remember while most modern 1/2 impact guns are capable of 600 plus ft lbs of torque most of the hardware you are dealing with requires less than 100 ft lbs. Overtighting can internally fracture the bolt severely weakening it.

    Some different torque tables



    page 4
  5. got-h2o

    got-h2o 2000 Club Member
    Messages: 2,440

    8's, always 8's. I do many o' installs and always use gr8 hardware. It's what's supposed to be used for one, and it's only a few bucks more for peace of mind. Do it right the first time IMHO.
  6. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    Not so. The manufacturers use a mix of grade 5 and grade 8 hardware, the Grade 8 bolts are too hard for some applications.

    Here are the instructions for your mount.

  7. got-h2o

    got-h2o 2000 Club Member
    Messages: 2,440

    Lol, I was waiting to be corrected on that, knowing Meyers does supply some 5's with their mounts. BUT I don't deal in Meyer and when I do its typically on a truck that doesn't matter anyhow.

    It is funny that you say that 8's are too hard for some apps. Do they plan on stuff breaking that you would want weaker bolts???
  8. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,415

    Every Western or Fisher mount I've ever installed came with grade 5.
  9. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    The slightly softer Grade 5 bolts will often bend rather than break.
  10. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    Take a moment and learn how bolts do their job and the psychical properties they operate under. It is obvious you don't understand the psychics involved or you would make such an uniformed statement.

    Bolted joints are usually designed so that the frictional forces between the items is greater than the shear force present at the joint. To achieve this the screw is torqued to value to tension the bolt and compress the items; in essence creating a spring-like assembly. This applied tension is called a preload.

    Why the proper torque is required; you need to achieve the desired pre-load. This along with the proper fastener will give you a safety valve for your truck's frame by allowing the bolt to stretch under overload before breaking. This protection allows the bolt to stay intact rather then totally failing and helps prevent the cracking or bending of frame components. This is why checking the torque on your plow mount hardware should be a part of your pre-season maintenance schedule. Loose bolts should not be just tightened they should be removed and replaced by new hardware of the proper type.

    Why every manufacturer uses a combination of hardware. Grade 8 bolts are too brittle as compared to too strong for some applications. A grade 8 bolt will shear when a grade 5 would be soft enough to take the impact.

    Here is the instruction sheet for the western mount install for the trucks you own. Note Western provides nothing but Grade 5 hardware with these mounts. The metric hardware they include is 10.9 metric slightly harder then grade 5 but not grade 8 by any means.