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bolts meant to shear in the chassis?

Discussion in 'Commercial Snow Removal' started by LINY Rob, Dec 24, 2004.

  1. LINY Rob

    LINY Rob Senior Member
    Messages: 478

    I was speaking to a old timer the other day about my new plow versus my old plow, telling him stories how its going to be so nice to plow in comfort and hopefully not break as many things as I used to, talk got around to how I sheared 2 bolts in the plow chassis where it bolts to the truck last year on my jeep.

    he told me they are meant to do that to limit the damage to your truck and asked if I bought the same replacement bolts, I responded how I went out of my way to find Grade 8 hardware to fix everything and how I went to the trouble of replacing ALL the old bolts with the grade 8 to make sure. He then cautioned me how I have the wrong bolts in the jeep and if I hit something else I will cause alot of damage to my jeep's frame.

    while it makes alot of sense, anyone else hear of this?
    I would think there would be some caution of it in the owners/installaion manuals?

    makes me wonder if something like grade 5 would be better?
  2. Bolts Indus.

    Bolts Indus. PlowSite.com Addict
    Messages: 1,176

    Yes this is true. Mount bolts are meant to shear to protect the vehicle. The mount bolts have to be weaker than the frame or you will damage the frame when you hit something and sooner or later we all hit something. this is not in your manual except under bolt torque and specifications at least Blizzard is.
    Last edited: Dec 24, 2004
  3. justme-

    justme- 2000 Club Member
    Messages: 2,138

    If your breaking those bolts your doing something wrong! 10 years plowing and not a single broken bolt for me. Try not hitting the piles and curbs so hard- I can only imagine what the tranny is like.
  4. Kramer

    Kramer Senior Member
    Messages: 386

    See! I learn something new from you guys all the time!

    Didn't know about the shear bolts either.

    This might be a good thing to bring up to those who might be installing plows themselves. I doubt everyone knows about it--- I've been plowing personal drives for > 20years and never broke a bolt or bent a frame-----but this is great to know.

    Thanks! :waving:
  5. earthwerks

    earthwerks Junior Member
    Messages: 16

    Not only should those bolts break when over-plowing (abusing) but I believe it has been on the law books since 1996 (USDOT regulation) that in the event of a collision--single-car or 2 or more, the "chassis" (which you don't have on a Jeep of that type-- it's a uni-frame or uni-body---all sheet metal parts welded together to form a sort of structure or frame) has to crumple or collapse in a pre-designed way to reduce or mitigate the impact energy. By stiffening it, technically/legally you are violating the intent of the law (discalimer: it has been 6 years since I was in automotive engineering so the laws may have changed) Also, airbag depoyment may be impacted (if so equipped) by simply adding a plow or other accessory to the vehicle.
    Those same DOT regs. I speak about, for example, apply to wider than stock tires, frame lifts, bumpers, not wide enough fenders to cover tires, running lights, etc. That is also why since 1996 you don't see the typical pre-1996 snow plow mounts that stayed on the trucks all year round, because of collision concerns.
  6. LINY Rob

    LINY Rob Senior Member
    Messages: 478

    just4me- I hit a submerged bolt that was in place for a new sign going up next door to the place I was plowing, they had removed the fence to put up a new fence as well, I plowed nice and gently like I had for the 7 years prior to that night, and rammed a piece of threaded rod that was concreted in place for a new sign going up, a piece of threaded rod covered by 8" of snow mind you.

    How was I possibly to know it was there?
    Sometimes accidents happen, I have been plowing long enough without breaking anything, I think I know what im doing.
    As far as the tranny- I only wish the tranny on my new truck will last as long as the one in my jeep has- it never missed a beat. Thanks for your concern though :gunsfiring:

    and earthworks- my jeep is in fact a full boxed frame, it puts the frame of many newer trucks to shame.

    all this lecturing and only one person actually answered the question- thanks BOLTS!
    Last edited: Dec 29, 2004
  7. SkykingHD

    SkykingHD Senior Member
    Messages: 368


    I have jeep with box frame. The meyers fastners on my rig are all grade 8 and the special "j" bolts are hardened. You should look at your frame for cracks and damage. This frame is just sheet metal bent to be strong and how meyers mounts the black iron to it can cause problems if you abuse the rig. You have to remove the black iron to see the damage. I dont like how the "j" bolts attach to the frame as it only grips a very small area.

    I have had to repair the frame on my jeep. Cost of doing business.

  8. LINY Rob

    LINY Rob Senior Member
    Messages: 478

    the bolt I broke that time sheared right off, frame was perfect, not a mark or crack in it.

    I heated it and removed the remaining threads and used the same hole over again. Truck is semi retired now being used as a back up truck and to clear a repair shop that my friend owns.