Building a Steel Front Bumper

Discussion in 'Fabrication' started by blue_kjR417, Sep 26, 2011.

  1. blue_kjR417

    blue_kjR417 Platinum Renegade

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    Hey fella's I've been looking into building me a steel front bumper for my KJ. I was just curious what thickness of steel I should use for it? Any suggestions?
     
  2. cplchris

    cplchris Full Access Member

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    i would say 3/16 would be a good starting point...not sure what the weight would be but if you have access to autodesk inventor you can design it in that and select a material ad it will also give you a total weight, you can apply load forces and it will show points of stress concentration...if you dont have access to inventor go on to autodesk.com, in the student community section you can sign up and get access to any version of inventor for free up to 18 months, then you just upgrade ...so long story short: 3/16...4140 is good for welding as well
     
  3. Xodius

    Xodius Full Access Member

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    My rear bumper ranges from 11 to 14 gauge. I am not sure how much it weighs other than a lot. Lol. If you have a chance too check out a arb so you can get some ideas for support and trusses for extra strength.


    Sent from my iPhone using Tapatalk
     
  4. tjkj2002

    tjkj2002 Full Access Member

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    If you gauge off a ARB you will end up building a weak bumper as yes they make them thinner but use HSS which costs alot more but is much stronger then regular sheet steel at twice the thickness.
     
  5. cplchris

    cplchris Full Access Member

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    for a reference; 11 gauge is about 1/8th inch thick, like tjkj2002 said the arb might appear to be very thin, it is also a higher quality steel making it stronger, explaining the higher price than a do it yourself bumper, my sugestion would be to make a frame/skeleton from 4140 square or round tube and then you will be able to make the skin a little thinner wthout compromising the structural strength/integrity of the bumper, reason i say 4140 is for weldability and the fact that is not heat treated, welding anything that has been heat treated will ruin properties obtained from the heat treating not to mention if it was quenched when it cools off slowly after welding rust forms much easier
     
  6. KJbandit

    KJbandit New Member

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    Wrangler TJ bumpers work good for a front and rear bumper for the kj, that's what I've planned to put on mine
     
  7. Red_KJ_666

    Red_KJ_666 Full Access Member

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    My SFA build is about to get Bumper builds with a front internal winch mount added keep your eyes open for some decent ideas.
     
  8. ajohns1288

    ajohns1288 New Member

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    I'm looking into making a steel bumper plate like the backbone with a aluminum fascia to save on weight on my KK. That way I can have a winch and better front clearance without a lot of added weight.
     
  9. tommudd

    tommudd Moderator Staff Member Moderator

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    and then when you hit something :shrug:
     
  10. Ry' N Jen

    Ry' N Jen Banned

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    Couldn't be worse than a stock Liberty with a plastic bumper skin!
     
  11. theroofable

    theroofable Full Access Member

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    Someone backed into me at a stop, I had a tiny crack where I cut out for tow hooks anyway.
     
  12. tommudd

    tommudd Moderator Staff Member Moderator

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    Thats true but why even try to upgrade then?
    Most everything I do is to make it stronger
    I'm not afraid of the Toyota Camry slamming on his brakes in front of me with the ARB :shrug:
     
  13. Ry' N Jen

    Ry' N Jen Banned

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    Until you get T-Boned by one...
     
  14. ck2012

    ck2012 Full Access Member

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    What year tj bumpers does everyone use on their kj and was there a lot of custom work that has to be done to make them fit?
     
  15. blue_kjR417

    blue_kjR417 Platinum Renegade

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    Any "TJ" factory bumper will work, which is like 97-06 wranglers.

    Here are some pics showing what it looks like and sort of how to do it. These are of a members here screen named "dalton" he no longer has this kj though.

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    This is a diagram of how to mount the TJ bumper using receiver hitches.

    After removing the front bumper cover you will see the bulging black sub-frame rail covers on the front cross member. dalton removed the covers and trimmed the openings to fit a 2" receiver. Then bolted the receivers into the frame rails through the front crossmember. Then he cut two openings into the TJ bumper to fit the ends of the receivers through. He also made some U shaped brackets to go between the TJ bumper and the front cross member as you can see in the drawing.

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    The only thing I didn't like about using the TJ bumper was that you had to trim your stock bumper to be able to still use your factory signal lights and if you didn't trim it then you left the space between your flares and the top of the bumper open which is kinda crappy looking in my opinon.
     
    Last edited: Jan 10, 2012
  16. first&lastKJ

    first&lastKJ Full Access Member

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    I like it, looks good to me. Looks more like a Jeep.
     
  17. blue_kjR417

    blue_kjR417 Platinum Renegade

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    I agree! I like the idea alot but would want to highly mod the TJ bunmper to fit within a couple of inches of the fender flares and build in signals.
     
  18. BjBnet

    BjBnet Full Access Member

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    Looks good but I think I would weld on a piece at each end at a 45degree angle or whatever it takes and have it partially cover the wheels...instead of just a straight bumper. Make sense?
     
  19. SabaII

    SabaII Full Access Member

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    So I have been looking in to this as well. I am looking at getting a welder and running flux core through it. The only thing I have read is that I need to clean the welds very well before I put any paint or anything over it. Also from what I read it is just as strong if not stronger then regular mig with gas. Is that correct? Thanks for the input guys!

    -Mark
     
  20. de63

    de63 New Member

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    You'll get a binary response concerning flux-core welds and their strength vs. gas. Some hate FC, others love it. Not too often you get the middle ground.
    Myself, I wish I could afford gas right now, but the FC has to make do. And make do it does. I'm in the process of building some steel-based tech furniture for the recording studio, and all my FC welds are strong and dependable.
    Yes, you do need to clean the area around the weld very well... this can be with a grinder and a finer wheel (200 grit or so), or it can be as simple as a can of M.E.K. (Methyl ethyl ketone), a sturdy rag, and sturdier gloves (rubber recommended). Make sure your work is well-lit so you can see exactly where you're going, and move steadily. This might even mean, no coffee before welding. :D
    My welder died a few months ago, and in order to finish the job I had to go to Harbor Fright and pick up a 90 amp MIG unit (fortunately it was on sale). As uneasy as Harbor Fright's stuff makes me, I have to say this particular welder is kicking ass. One thing I think is extremely helpful is, pick up a jar of the flux goo/nozzle dip... that stuff reduces spattering very well and helps with the overall flow of the work. Clean your tip often.

    Be mindful that steel likes to warp during welding, so tacking your joints - a spot here, then a spot on the opposite side, then back, etc. - really goes a long way towards keeping your work straight and square.
    Remember, too, this guide: A little welding, a lotta cooling.