My 4x4 labs bumper build - 100 series 2/2020 (1 Viewer)

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So I decided that my first welding project ever would be to build a 4x4 labs bumper. A few of us from the local club bought various kits and were able to save some on shipping by getting it all sent out on one pallet. I have had allot of fun building this so far, but I did find the instructions in another mud thread a bit lacking in some spots (4x4labs rear bumper build - https://forum.ih8mud.com/threads/4x4labs-rear-bumper-build.142286/). A few things seem to be different and the instructions are for an 80. While I am 99% done right now using just those instructions and many others have done it as well, so it isn't impossible. I just thought I would share and document my experience.

1) Open everything up and try to visualize how it all goes together. Admittedly I didn't completely do this, but it helps once you get to a section to see it in place.

2) Remove factory tow hitch, bumper shell, step plate, etc. and spare tire. This took much longer than I was planning for and I have some suggestions here.
  • PB blaster the factory tow hitch bolts ahead of time. I had to PB blast, heat, and use 1/2" breaker plus a cheater to get these loose. My rig is pretty rust free, but dang these were in there good.
  • I would recomend a breaker bar instead of impact gun so you don't break away the tacked in captive nuts (more on this later)
  • During or before this time it is good to check your body behind the OE bumper shell near the rear wheels. Before you even get your stuff it is a good idea to remove the screws by the rear wheels and peak in there. I had a little bit of rust, but nothing that requires body work. Honestly I will probably just give it a quick grind and spray some paint on there before final bumper install.
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3) Remove ground off of rear cross member (if you have one there) and cut cross member out in sections with a sawzall. Have a few metal cutting blades ready or higher quality ones than the HF ones I had.
  • Remove a series of bolts and pieces along the way - resonator hanger, etc. Keep these pieces if you think you might want to put your resonator back on at some point.
  • Remove spare tire hanger deal (Note from friend's experience - you cannot put a spare tire back in here after install, at least not a 33).
  • I cut exhaust at this point to get it out of the way. I cut just rear of the axel.
  • Grind the sides of the frame clean with an angle grinder (flap disc or grinding wheel)
  • Paint over the cleaned metal
  • You are now ready to start fitting pieces
  • Note I did not trim the frame horns back at all. Don't think you need/want to on a 100.
  • Here is what it looks like at this point:
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4) Bolt up side pieces - inner and outer.
  • Note - The inside side captive nuts weren't an issue for me but I had a couple issues with the bottom captive nuts that the tow hitch went into. There are 4 on each side that are tack welded onto plates.
  • The threads on the ones used were mostly fine, but a little tight on the new bolts (vs old ones)
  • The ones closest to the back weren’t used and the threads were super tight and a little rusted. I broke one free trying to drive a bolt in with an impact and WD-40. I wouldn’t recommend this. I ended up buying a tap (M14-1.5 not in most tap kits) and we’ll see how that goes.
  • I also broke another nut free second in. I ended up buying new nut, cleaning some metal and welding these nuts in place – spray some paint in there to protect.
  • Here is first time I tried to tack barely in place, this ended up failing again with an impact (impact = impatient me)
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I ground down to bare metal with a die grinder, welded in replacement nuts with a bolt to hold it in place (and be a ground), then sprayed some paint in there:
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I would try very hard not to break free the two further back nuts. Would need to stick weld them back in place.
  • With the side pieces on you can fit the shell. It really helps to have a second set of hands (and eyes) for this. If doing this solo, check out a hydraulic table. A friend is letting me use their's and it eliminates the need to ask folks for help all the time.
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I had to grind a bit on the circled part to get the bumper to fit. Don't rush this step. Fit. look. use a sharpie to mark where you want to grind, grind, fit, repeat as necessary. It doesn't need to be perfect, but your welding will be easier if you get a better fit.
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Once you have a good fit tack weld and remove.
 
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5) With the bumper tacked and off the vehicle I fit the cross member into the obvious square holes of the side piece. Mine was flush, but you may need to trim a little off ends or grind a bit later.
  • Put receiver in and place flush against cross member. Also nearly flush at top
  • The face of receiver was just beyond the shell
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  • Tack xmember and receiver into place – note don’t tack the cross member on the side were the recovery points will sit flush (I messed this up and had to annoyingly trim these welds back).
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  • Slide recovery points in to flush with xmember and tack
  • Tack tow gussets into place
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6) Put back on vehicle. Some of my pictures above were taken later, but at this point I had tacked and somewhat welded side pieces, bumper shell, cross member, tow reciever, recovery points. When fitting back onto truck I had to grind the tacks on the cross member/shell point where it sits against the frame. You probably want this to be a tight fit.
  • At this point I took the bumper back off and finish welded everything to this point. This takes awhile and again this is my first welding project ever, so I tried to make welds look good, but more importantly i tried to get good strong welds. I was using a 240 V Miller 211. Others have done this with 120V machines. I think it is probably easier with a 240 but I am a total welding newb.
  • Now I think the instructions actually say to do as much welding on the vehicle as possible at this point to avoid flexing etc of plates. I didn't do this because a) I have a bad back and welding on my back was gonna suck and b) I think I was able to weld much better at a bench.
  • With that said I did have a little bit different fit after finish welding. My external side pieces had pulled up a little. Wasn't to big of a deal. I didn't have the hydraulic table at this point, but if I had I would have put it on and off more frequently.
  • The inner side pieces had also pulled in a little. I just used a wrench with a cheater bar to pull them back a little. Easy fix.
  • Don't rip my welds too much:
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7) Little side wing pieces. Here is an example where I only understood how these fit together once I had the bumper more built. There are two little sheets. Once has an angle bent in it and one has a round piece and two notches. The notches go in the notch spots, the rounded part will terminate the tube, and the bent piece spans the side wing to the other little side wing piece.
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See the bent piece behind the spindle here:
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I welded these off the vehicle. In retrospect I would have fitted and tacked them while on the vehicle, but it didn't hurt me. If doing it on the vehicle you could tack them and then fit the side tubes and tack those at the same time. Again I didn't, but next time I build a 4x4 labs bumper... ha don't ask me to do that.
 
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8) Fit top tubes. Here is where you fix and alignment issues and this is really genius by 4x4 labs because you have some fudge factor here if the bumper doesn't follow body lines. Just put the tubes how you like them parallel to your body lines and then tack.
  • Well it should be that easy, but you are gonna have to cut these tubes.
  • I cut the back side to length first. Fit, estimate, mark with a sharpy and cut. I used a sawzall, but a chop saw would have been better.
  • Once I was happy on the back side I marked the forward side with a sharpy to follow the line of the wheel well and cut just back as you have an oval shaped end cap piece which will take up a little space.
  • Getting these lined up actually took much more time than I though it would. I was trying to get it perfect, but I think this is one of those things that I will notice if its off, but no one will ever see when its driving.
  • I will add another picture once I get it on the vehicle again.
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At this point I took the bumper off and finish welded everything I had on so far.
 
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9) Spindles. With the bumper on the vehicle follow Luke's instructions from the other thread on attaching the spindles regarding hight etc. I wish I had another set of hands to help hold things steady while I was doing this part, but I think I got it fine. I think the key is just to make sure the spindles are square relative to the shell. Note there was a little bend on my shell where they press the spindle hole out, so obviously don't use this for square.
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10) Swing arms. I used some crushed cans as my 1" spacers and measured multiple times... My mistake was not realizing the square tube swing arms have rounded edges. You really want to have a full 1" from the bottom of the arm to the shell for the stops. I really don't think it would be an issue if you were at 1 and 1/8 or 1.25", but 7/8" caused me to have to trim the stops.
  • So I assembled the bearings, races, and shell with a little red and tacky grease to help get everything in place.
  • As per the instructions I put the notch centered and facing forward.
  • Get those arms AT LEAST 1" above the shell and tack in place. I also often covered the bearings with some masking tape/paper to protect from contamination. I welded the arm fully to the shell at this point.
    • What I should have done is assemble the stops with the arms just tacked in place, then I could have cut the arms off and fixed my 7/8" mistake. At this point I was just hoping that it wouldn't mess up the gas strut clearance...
  • As per the instructions I clamped a straight piece of metal to both arms, fit and tacked the center stops in place.
    • I had to trim one edge of my stops a bit to clear the bumper. Again >1" not an issue, to too close is.
  • I also welded the swing arm caps on at this point.
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  • I then put the open stops in. I didn't measure the angle. I know what 90 degrees is and I just went a little beyond that. Put the tab down and tacked.
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  • There were also these two unexplainable pieces with a radius cut out of them that fits the swing arm shell. I think these are antenna mounts...? I might put one on the PS spindle shell since my CB antenna is already on that side. What do you think like this:
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11) Swing arm latch. It is a little odd to me that this kit comes with a latch and the instructions are to cut that s*** up, but its what I did. Note the latch retainer on the opposite arm is a little different than the style in the other thread. Hopefully I put this on correct. Regardless it is a beefy latch and I hear great things about it. Also the other instructions say red handle and mine is blue. I am thinking about quitting this project and demanding a refund due to this. I need to take a better picture of the latch assembly (and stops)
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12) gas struts and swing arm sleeves. At this point I pulled the swing arms off (set the top bearing aside someplace safe). I don't remember the order I did these but it shouldn't matter.
  • I hammered the sleeves in and welded around as per the instructions. I was getting a ton of spatter all of the sudden and couldn't figure out why. It ended up being the tension of the wire feed, but some of these welds were extra ugly.
  • But it didn't matter too much since you are really just welding to hold these sleeves in place. I ground those crappy welds down.
PICTURE
  • I drilled out the appropriate sized holes in the bumper and swing arms for a 5/16 -18 tap. Other thread says somewhere that this threading has changed. Well if you have a tap set you should be able to confirm the threading before you start tapping. I just have a HF one and it is one of the most useful things I have bought for replacing and fixing things on a 20YO vehicle.
  • ball studs go in great, but s*** these gas struts are strong. I had to use the swing arm to compress them with the help of another person to help align and tighten down the bearing on the spindle as we went. Have heard of other folks using bailing wire and ratchet straps to compress, which would probably also work.
  • So the moment of truth arrive does my 7/8" vs 1" mistake screw me over here or is there enough room for the gas strut... THEY CLEAR!!!
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13) Tire carrier attachment. This one was pretty easy (compared to the gas/water carrier).
  • I tacked the attachment bracket to the double angle cut square tube. Got it centered, tacked. Should have though ahead to where gussets were going for where I put my tacks.
  • The gussets that came with this piece were the same length and size and the tow gussets. They didn't fit for me on the mounting bracket and the pictures in the other thread showed a smaller gusset like what came with my can carrier attachment. So I trimmed these down. Hopefully my tire doesn't fall off...
  • Tack those up as per the instructions "crossing the plane of the upright". I just studied the pictures in Luke's thread to get this right. Then i welded them.
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  • The top piece was a little confusing and I should go take some better PICTURES of it, but I figured it out based on the descriptions.
  • I put the long cap piece on the tubing thinking why is this so long? Do I need to cut it? But it turns out to be the width of the side pieces. Ah ha. I fit all the pieces together with a spacer like Luke suggests, placed it on top of the tube and threw a few tacks in place.
  • I then tacked the 5 point star on the angled cut tube as shown below. Here you must make a big decision. star point up or star point down... I went star point up. I figure that is easier to align lifting a heavy ass tire to chest hight.
  • I pulled one stud in, but will do the rest later, but before powder. These are M14 1.5 studs I would get a bigger washer than what you have for bolting to frame since the stud teeth went into mine a bit. But that is the bolt size you need. Also this is not the same size as the your wheel lug nuts, which kinda sucks. Would be a good place to store spare lugs.
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What you don't see above is the little space that I used to provide room once powder coated. I just used some random scrap piece. What you do see is my sons badass buzz lightyear sweatshirt. It randomly snowed a foot in Denver last night and he was out of school today.
 
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14) Jerry can carrier attachment. While the tire carrier probably took me 30-45 minutes, this one took 90-120 min. Much more welding and pieces. I mostly just followed the instructions for this but I have a couple tips that helped me.
  • Starts about the same. attach up piece to mounting bracket. Attach gussets in same way. Potentially consider that you will have another gusset piece on each side to support the carrier, but I didn't have any foresight and I was fine (or lucky).
  • I then tacked the U shaped piece to the angle support.
  • Tacked the flat sheet to bottom hoop as well.
  • I was able to balance a couple of the tube spreaders in place and put the top tube on well enough to throw some tacks in. Fortunately I got it well fitted on the 1st try.
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  • I then welded all these pieces of the basket together. This was actually a challenge for me because again I am a total newb to welding and this was by far the thinnest stuff I had welded to this point. Most likely if you have any experience welding you have more than me and you will do better. I definitely blew some holes threw a couple times, but now a have good practice filling gaps, so I got that going for me.... which is nice.
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  • When it came time to attach the bracket to the mounting tube I was a little perplexed doing this by myself, but I came up with a pretty good strategy (I think). I put the mounting bracket on the floor and then balanced the basket on top, supporting the other side with a floor jack. This actually worked pretty well. I used a digital angle finder to get it pretty close to level and tacked in place.
  • Next I put the long cross supports in place. The thin sheet metal on the bottom of the basket had flexed a little so I used a clamp to pull these together. Tacked that all up and then welded once I was happy.
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At this point I am very close to done so I had to get it all assembled last night to bask in the glory. This was allot of work. I am probably 40 hours in at this point, but I have learned allot and I like building stuff.
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Whats left?
  • Decide if I want to put what I think is an antenna bracket on one spindle shell
  • Finish pulling studs into tire carrier.
  • How to attach high lift bracket? I stole some photos from another's post which I think I will kinda copy:
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So I think I need to attach the bracket like below, but I want to get the bumper back on the vehicle, put a tire on, and fit with a high lift in place:
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Oh yeah and grind a bunch of welds, then take to powder. Will update this thread shortly as I finish these steps.
 
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Nice work dude!

I'm glad you had success welding the bumper together off the truck, I did the same and it warped like a sumbitch haha. My build was thinner steel though so that didn't help. These welding projects are addicting though, learning more and more with every one. I know I drove my neighbors insane grinding the welds smooth.

I love how the face plate on the 4x4 labs bumper angles back, looks good and seems to protect the under side really well.
 

Tanner H

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I just did this build yesterday. I have a friend that is an excellent welder, but has never done a bumper before. So it was basically me doing the fitting/cutting while I told him when and where to weld. Everything went great, my only mistake was that I tacked the top hoops onto the top of the side plates while we tacked the shell into place. It fit PERFECT when we tacked them on, but once we pulled the bumper and then finish welded everything...when we put it back on, the driver side sat higher and at a different angle. Bummer. I'm going to loosen the bolts and try to pull it down to a better angle. Worst-case scenario I'll just cut the welds off and re-adjust that tube.

Other than my user-error....everything went smooth. just a ton of welding haha.



One last thing...I did not cut my rear resonator off. Currently working on just fabbing up a quick post onto the bumper crossbar and mount the hanger at the very end of the muffler.

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. It fit PERFECT when we tacked them on, but once we pulled the bumper and then finish welded everything...when we put it back on, the driver side sat higher and at a different angle. Bummer. I'm going to loosen the bolts and try to pull it down to a better angle. Worst-case scenario I'll just cut the welds off and re-adjust that tube.

Other than my user-error....everything went smooth. just a ton of welding haha.


View attachment 2600525

Yeah mine fits perfect on the driver side, and the passenger side wing sticks out about 1/4" because of warping....drives me nuts
 
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So I finished the last couple of things and dropped it off for powder today.

However, when I went to do final fitment I realized I messed somthing up. Let my mistake help you. I put the stop on the bumper in the wrong way.

Incorrect:
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This is the too tall direction and possibly too far onto the bumper. The way I realized this was during final fitment the tailgate wouldn't go all the way down :( . So I cut it off rotated it and rewelded. Of course then I had to cut off and reweld the stops on the swing arms. This was frustrating but necessary. All good now.

@AlpineAccess Is in the middle of his build right now and will hopefully post some pictures of his much prettier welds and some details we thought would be useful.
 

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