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Discussion Starter · #1 ·
Hey everyone, new here. I’m almost done building a homemade bumper for my GMC Canyon using the $150 eBay bumper kit for XJ’s as a starting point.
I have for you experienced peeps a question about the mounting setup: I cut ~2” off the front of my frame rails to help approach angle because the frame protrudes so low, and have holes thru each frame rail to accept 4 (2 each side) big 5/8” bolts.

How I built the bumper so far, there are 4 (1/4”thick) plates (2 on each side) with matching 5/8” holes that are spaced to perfectly sandwich both frame rails (see pictures); then the torque of each bolt will hold the 1/4” plates to sandwich each frame rail. Is this a bad or overkill idea? Possibly limit how much friction I can actually put onto the frame rails with the bolts torques?

The other option is to cut the 2 inner 1/4” plates completely off and reinforce the outer mounting plates. That way all the torque will be directly applied to the frame, but then I only have the strength of one 1/4” plate on each side. It will have a 12k winch and recovery points on it so it has to be strong. First time making a bumper if you couldn’t tell. The more I think about it, the second method seems more and more logical but I need expert opinions before I start cutting again.

Any thoughts or ideas?

Thanks in advance!
 

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Discussion Starter · #2 ·
This photo didn’t survive uploading for some reason. Might help y’all visualize what’s going on. Thanks again.
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Either way will work. And either way just be sure not to over do the tightening and as going through a box without internal sleeves can collapse or "pinch" the frame rails in.

Don't worry about only one plate, a 1/4 mounting piece on the outside of frame rail is pretty standard practice.

If doable though I like to either add a third hole further back or a mounting bolt or two on the underside of frame also. I've found that using only two bolts on the sides allows the bumper to rotate or pivot slightly up and down. A third hole further back triangulates the mounts and a bottom side bolt inhibits any movement up or down.

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blatant asshole
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Meh. Make sure you put some spacer tubes in the frame or it will just crush the rail and never be tight enough to be solid
 
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Discussion Starter · #6 ·
Yeah doing some sort of sleeve in the frame’s holes crossed my mind briefly. Not sure why I didn’t just do it. Best way to do it would be drilling my frame’s holes out to whatever the OD of the sleeves happens to be, and then welding the faces of the sleeves to the edge of the holes, right? I will try to find some tube stock at Home Depot that is 5/8” ID or slightly bigger and see if it’ll work. Just gotta make sure the holes on the driver side rail are perfectly parallel to the holes on the passenger side before I weld those sleeves in 😅

someone on a different forum I posted this in also recommended that I make a crossmember/brace that directly connects the fronts of the frame rails to each other so they can’t bend left or right when winching at an angle. Good idea or no? And welded in or bolted in?
Thanks again for y’all’s help!!!
 

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blatant asshole
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Its a lot easier than trying to hold the bumper up and finger fuck the sleeve in as to work the bolt through the stack.

Would t be a bad idea to make something to shear the load across the rails. You mounts are lil soft for the loads youll see so a bridge plate between the inners and the bumper would go a long ways.
 
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blatant asshole
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And 1/2" pipe should take a 5/8 bolt.
 
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Discussion Starter · #9 ·
Ok awesome, thanks. I’ll get some 1 1/2” angle iron to make the frame brace. Should I make it two parallel pieces spaced apart a few inches and going straight across from one rail to the other? Make them in an “X” shape? Or just one?
And about the sleeve, can normal black pipe be welded to the hot-rolled 1018 steel of my frame? I feel like I remember hearing that pipe is much higher in carbon content.
 

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blatant asshole
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It will weld just fine. Pipe has wierd properties. It works great in conpression. Not worth much in deflection/cross plain strength.


I would get a piece of 3/16-1/4" plate about 6" wide and weld it to the bumper and your mount tab
 
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Ditto on last comment- make a flat gusset that spans between the bumper and your inner mounting plates. Your bumper is essentially a cross member, so there’s no need for another one next to it. The gussets at the inner braces to the bumper surface will help keep lateral loads from bending your mounting tabs. Sleeves and another pair of bolt points as suggested are also good ideas.
 

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Discussion Starter · #12 ·
Ok awesome, thanks! I’ve got the pipe and plenty of 3/16” scraps. I guess I’ll just keep that angle iron, it may come in handy some day.
Welding in those bolt sleeves is definitely in the plan. However The 3rd mounting bolt in the rail is iffy. There’s not any length of frame rail left to work with. However I hadn’t really mentioned these original bumper side supports that I plan on tying into (picture below). I could even gusset those up on that body mount too. They wouldn’t be directly supporting the winch-plate of the bumper but would give that third mounting point to eliminate that last degree of freedom. Another idea is to weld in that angle iron crossmember between the rails and add brackets on the bumper to bolt into that new crossmember. Just an idea. Thoughts?
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also, I’m really thinking that I should cut off either the inner or outer pair of mounting plates so that I’m not relying on the four 1/4” plates deflecting to clamp onto the frame rails tight and have the friction needed to keep shear stress off the bolts. But I’m undecided if I should keep the inner plates or the outer plates. The outer plates would resist twisting forces better and look cleaner, but the inside plates are much much easier to gusset (see picture) What are y’all’s thoughts?

thanks again I REALLY appreciate this help.
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Willys Fan
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I think you could leave your current tabs on both sides of each rail in place as long as they fit to the rail width reasonably well, and you add the crush sleeves. I’d put the gusset on the inside tabs, as it helps support the center section of the bumper where your winch load is applied. When you add the crush sleeves, chamfer the ends of the sleeves and the edge of the frame holes so you have a “v” at the joint in order to get full weld penetration, then smooth the weld with a grinder to bring it flush with the face of the rail. That will allow a strong joint while maintaining a good fit of your tabs against the rail. You’ll want to make sure the gusseted tabs are a good fit to the rails since they will be pretty rigid once the gusset is added. By leaving no gusset on the outside tabs it will let them flex a little to pull up tight to the sleeved rail. I like your idea of maybe tying in to the side supports or body mount with another bumper bracket- the side support looks kind of wimpy, but would probably be strong enough to keep the bumper from rocking/rotating vertically on the two main mounting bolts.
 
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