fabrication suggestions

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Just got some plates for the frame horns back from the cutter. My initial plan was to cutout blue area (to make room for body mounts on the outer plate) and bolt on the plates in the rear (red holes). and either bolt in front of the body mounts---or weld. (?)

the plates are 3/16" and i plan to run one lower 2"dom (.120 wall)crossmember in between the frame as well as one main wraparound tube.

i plan to box the underneath so the stock bolt holes can be used---- and cap the ends.

My question is --which is stronger-bolt on or weld on???? obviously welding is easier----but i thought bolt on would be nice and some people may like a few of these produced.
 
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The frame is fairly thin guage. And (forgot where) i read that heat from welding on the frame directly will weaken already thin material. Toyota apparently uses a tempering process to insure the thin guage material isnt structurally fatigued from welding.

Toyota tends to disperse things like connection points to the frame over a larger area in stress points and they also double up on the wall thickness in higher stress spots as well as honeycomb like with tubes from side wall to side wall in heaviest stress spots.

The plates would simply be mounting points for the tubing and help disperse the energy over a wider area of the frame.
 
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Is the blue cut out going to be that large? does it have to be square? any radius you can add to the two lower corners will help, as drawn it pretty much make the rest of the plate useless.

bolt vs weld depends, you would almost need an engineer to answer that with any certainty
 
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actually ive been fumbling for ideas on that blue area. Thats where the stock 80 body mounts are and im contemplating cutting into the lower 1/3 of the mount to decrease that blue area......and then regusseting that lower 3rd of the body mounts onto the plate.

the other idea i had was simply to split the outer plate into two--and fully box the front inner and outer together and just bolt the rear outer plate to the inner. The idea on the outer plate was simply to have a welding point for the outer wraparound supports without tieing directly to the thin wall frame.
 
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No need to overkill---You think i could get away with two side bolts and the two stock underframe bolts (the ones used by the aftermarket hitches)???????
 
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I'd weld them up. Triangulation is going to do a lot more for strength once you cut off the stock stuff than full frame reinforcement, but that's a bumper design issue. Welding theory I think is about half welded, half not, so you don't essentially weld a cutout of the frame and rip the entire thing off.

So the real question is...what does the bumper look like when it's done? Post up pics, looks like a good design start that will definitely give you a wide range of mounting options for the tube. :cheers:
 
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The frame is fairly thin guage. And (forgot where) i read that heat from welding on the frame directly will weaken already thin material. Toyota apparently uses a tempering process to insure the thin guage material isnt structurally fatigued from welding.
.

perhaps true but out at the end of the truck there isn't anything to support anyway. weld that up and skip the plates
 
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i was planning on throwing a 2"receiver as well as doing a swingout carrier( 7500lb HD 4x4Labs spindle to possibly do a swingout-high clearance cargo tray). The plates are still a good chunk less weight than the rear member thats cut out---so any reinforcement they add are simply to keep everything in line with original support. That rear crossmember-although thin walled- is channelled fairly broadly as well as triangulated near the frame.

The plates i thought solved a few issues like having it bolt on (so i can send it out for a powdercoating)-welding on frame-and helping box the rear to somewhat replace the strength of that crossmember thats getting chopped out of the equation.
 
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Where you mocked up that lower tube section, put in an "upside down" drawtight hitch instead, you'd be amazed how it goes in there to keep the hitch between the frame rails with the frame mounts resting on top of the rails (this is a weld solution). That will be all the strength you'll ever need as well as reinforcing the frame and providing a true rear crossmember that should be a lot stronger than the stock junk.

From there, you can mount the upper tube to wrap around the sides and tie back into the frame.

The problem with a tube bumper where you just try to tie in a hitch is you end up pulling off the tube, and that is a dubious solution, which is why I ended up not doing it. It was only was I picked up a drawtight for those rare times I tow that I realized how it would fit when flipped to form the core of a new bumper if desired.

This is an idea that I think would work well with the plates you just designed and would be extremely strong with good clearance as you can recess the hitch a bit. I decided to forgo the receiver entirely with this solution (Nissan tow hook inside the frame, which I have now bolted as well as welded).
Tow Hook Bumper View.jpg
 
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I actually contemplated using my hitch flipped- but then once i thought about the plates.....i thought placing the inner crossmember Dom directly behind the reciever would essentially be the same and forego the hefty drawtite.
View attachment 221957
 
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I actually contemplated using my hitch flipped- but then once i thought about the plates.....i thought placing the inner crossmember Dom directly behind the reciever would essentially be the same and forego the hefty drawtite.

Interesting. I would make sure you triangulate forward from that rear tube back to the frame. You have no shear strength off the DOM, just the strength of those two tubes not bending or small weld contact not failing.

Now, I had a 2" receiver in the stock "bumper" (Slee) and did all kinds of heavy work, and only the triangulation is back to the frame from the receiver, but the stock piece has a lot more material and mounting than two sections of 2" DOM. You are in there with tube and welding anyway, so triangulate from where receiver meets rear DOM forward to the frame and that would be a pretty strong setup.

I was going to do about the same thing with my Slee receiver and new tube bumper...Jim at SROR wasn't comfortable with the reliability of that design as an FYI. I am as "low weight" as you'll get without chopping the top, but between the two, I'd flip the drawtight. It's probably a 10 lb difference or so by the time you are done, and then you don't need that rear bar that is somewhat subject to impact and bending.
 
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The rear dom tube will also be connected to the wraparound dom tube like in pic--- so shear forces on the rear tube will be doubled as they will be directly opposed to the front tube and have to sheer those welds as well.

Also - the plates that the DOM is welded to should offer much thicker welds than onto the frame- with .120wall dom to 3/16"plate. Should be about twice as thick of a weld if fully penetrated to the plate than to the frame.

Still im really not planning on towing much with this- just some oddball utility trailer or the oddball fj55 carcass.
View attachment 222034
 
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The rear dom tube will also be connected to the wraparound dom tube like in pic--- so shear forces on the rear tube will be doubled as they will be directly opposed to the front tube and have to sheer those welds as well.

Also - the plates that the DOM is welded to should offer much thicker welds than onto the frame- with .120wall dom to 3/16"plate. Should be about twice as thick of a weld if fully penetrated to the plate than to the frame.

Still im really not planning on towing much with this- just some oddball utility trailer or the oddball fj55 carcass.

I like the design the in that pic. It should look sweet and be extremely strong. Thats enough to get me to want to add that lower bar. You might consider triangle gussets from frame horns/brackets to upper tube like the pic below. I really like the idea to add strength to a center rear impact point (such as backing hard into a tree, or a road accident that hits on an angle.

Keep going - the bracket reinforcement with bumper design is looking slick, and I always give a vote to weight and clearance saving tube designs. I think you have the bases covered here, looking forward to seeing the final output :cheers:

You going tube up front as well? Trimming the lower quarters? (you'll need to with the height of the upper tube based on where you notched those brackets or you won't be able to run the side brace back to the frame).
Rear Bumper Inner Gusset.jpg
 
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yeap- im gonna sell the SLEE Shortbus and fab up an all tube high clearance one as well. I really like the SLEE but would rather have something to match the rear and shave 50lbs.

Im still getting 14mpg around town even with the metaltech sliders-shortbus bumper/winch- triple batteries and 255/85MT's. The rig is liking the diet.

The corners are going to get trimmed up for sure- not sure how far yet. Im thinking there will be a slight angle up from the rear wheelwell to keep with the slight upward rake that the lower stock look has(rather than chop along the true horizontal). Ideally im going to try to snug in the corners.
 
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yeap- im gonna sell the SLEE Shortbus and fab up an all tube high clearance one as well. I really like the SLEE but would rather have something to match the rear and shave 50lbs.

Im still getting 14mpg around town even with the metaltech sliders-shortbus bumper/winch- triple batteries and 255/85MT's. The rig is liking the diet.

The diet is a beautiful thing, matched only by the clearance and strength to weight ratio - will be interested to see your take on the front. My first design had a lower and upper bar with struts between the two (looked kind of like this :D), and if you are going to avoid the stinger look I think this could be done in a way that creates a great look, low weight, and excellent protection for a winch consistent with your approach angle.

I'd post a pic of my "Sharpie" design, but I deleted them after my final build.

I'm just :clap::clap::clap: to see anybody on this board actually post that they are selling a Slee Shortbus of all bumpers to save 50 lbs. Never thought I'd see the day. Build it for a Warn 9.0Rc and you'll have gained a winch but not a pound, and the 9.0Rc should be extremely strong for a dieted 80 (understanding the degree of oxymoron here) pulling off the drum with only 50 ft. of wind (carry extension(s) ).
 
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