When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Swing Out Modular Rear Cargo Bumper for 1st gen 4Runner
I designed a bumper that uses a modular system on the typical swing arm bumper set up.
Ignore the scale, it is going to be a trim to fit type deal that will be hashed out as the build progresses. Ignore things like holes and passages that may not appear correct.
Rough parts list:
Main tube size 4"x3"x 3/16"
Swing arm: 2"x3"x 3/16"
Forward armor tubes: 2"x3"x 3/16"
End cap plates will be 1/8"
Hinge is the comp4x4.com heavy-duty dual-shear type
Brackets are frankensteined from the old Smittybilt tubular (1/4" plate)
Cargo rack: 1-1/2" x 1-1/2" x 1/8" angle iron with expanded metal
Shackle mounts from comp4x4.com
The "receivers" on the swing arm will not be bonafide hitch receivers. I'm planning on using 2-1/2"x2-1/2"x 3/16" square tube.
The hitch-bars on the cargo rack will be 2"x2"x1/8" (I might downsize this whole deal a half inch, ie: 2"x2"x1/8" receivers with 1-1/2"x1-1/2"x1/8" hitch bars)
Am I way overboard on tube thickness? Or way under? More gusseting needed anywhere? Better latch ideas?
I'm open to critiques and criticisms. I'm in a welding class at the community college (SMAW. And I've already completed flat, horizontal, vertical up, and overhead with 7018). Not saying I'm a hardcore welder, but I'm not some yahoo who just bought one at Lowe's last week either.
I am re using the 1/4" plate brackets from my old Smittybilt tubular bumper. I will likely gusset the plates with angle iron to the main tube of the bumper. Those small triangles under the forward armor are just to clean up the shape a little. They will just be 1/8" plate welded into the corner.
Scale is not accurate. Plan is to cut the tubular part of the Smittybilt off then weld the main bumper tube to the plates (while attached to truck), then trim to fit and stay centered.
Latch detail, not sold on this idea yet.
The cargo rack. The square tube will fit inside receiver tube.
This is a separate model showing how the receiver tube would go through the swing-arm tube. The cargo rack would slip in then be held with hitch pins.
I designed a bumper that uses a modular system on the typical swing arm bumper set up... I'm open to critiques and criticisms...
Latch detail, not sold on this idea yet....
I like the clean lines and low-profile. Minimalist! (The more you know, the less you need.) and like your drawing, too.
Make sure it would allow access to hoist mechanism for spare tire, IF spare tire is kept in stock location. Maybe run the jack handle extension rod through the hitch receiver to reach the hoist drive mechanism?
Consider putting the hinge on the left side?
It would allow you to stand on the right side of the tailgate (away from traffic) when you're working with cargo on the side of the road, not always exactly behind the tailgate, in case someone loses brakes or loses control of his vehicle on icy mountain road.
would also allow easier movement of cargo from rear deck to curb, without having to go around the swing-arm.
(I'm an engineer, sailor and climber, always thinking about efficiency and safety, have seen lots of bloody training visual aids in the military and have Final Destination scenes running through my mind when I review safety of things - LOL!)
I believe 3/16" is a good thickness.
In fact, IF I were to design a bumper from scratch I would choose a thickness such that:
1) It would be stronger and more rigid than most other vehicles stock bumpers - enough to protect the body,
2) BUT Has some give to absorb most of the impact so frame does not get bent.
In case someone rear-ends you, Body is protected, frame is not bent. Better to sacrifice a bumper than to have a bent frame. Let other party's insurance pay to replace your bumper (keep receipts and document man-hours you put in the project).
I think a Pin-type latch would be more reliable and simpler to set-up.
Make sure it would allow access to hoist mechanism for spare tire,
Had not even thought of that, good point. The spare will continue to live under the truck for now.
Originally Posted by RAD4Runner
Consider putting the hinge on the left side?
Man, you are absolutely right. I thought about it and the only reason I put in on the driver side was to make it a shorter distance from the driver seat. But your point about the curb side unloading is a winner. I'm going to put the hinge on the driver side, latch on the passenger now.
Originally Posted by RAD4Runner
I believe 3/16" is a good thickness.
I was leaving towards 3.16 too; save cost and weight. My welding instructor said go with 1/4" wall though, so I guess that's what I'll do. Peace of mind is a valuable thing. Main tube and swing arm tube will be 1/4" wall. The front armor tubes will be 3/16" still.
Originally Posted by RAD4Runner
I think a Pin-type latch would be more reliable and simpler to set-up.
There are just so many ways to set up the latch. You're right, pin would be easy, and a lot cheaper than the $50-$70 latches I've been looking at. I really don't want the thing to rattle though. It will drive me crazy and could cause fatigue. I'll probably just do something temporary with a pin and see if it works OK. Most things can be changed later.
The other unanswered question is how to do the swing arm receivers. I'm hoping I can just buy 2.5" x 2.5" x 0.25" receiver (ie, seamless) tube. I don't want to spend the money on prefab hitch receivers, they're like $20 each and I don't need them to be rated for towing or anything like that. Otherwise I will get 2.5" x 2.5" x 0.25" regular square tube then use 1-7/8" x 1-7/8" x 1/4" square... I don't even know if that works. I just want to limit the amount of slop. But maybe it won't matter since I'll have two mounting points? Maybe some slop will be good for trying to keep those bars aligned...
Any suggestions on coating after it's completed? Rhino or Raptor line? Epoxy paint or some kind of corrosion resistant primer/base coat? What about inside the tubing, should I use FrameSaver or something like that?
Hey, I know its an ambitious project for beginner but I think it's do-able. I need to knock it out before the end of April when class is over. I've got 27 hours of shop time left. I think having the instructor around will be a big help. Plus we've got a whole shop of equipment that I won't own myself for many years. If I don't get you some build pics before May you'll know I bagged it.
I'm picking up the steel later today. Got the bumper off and cut the old brackets off. Also cut off the tabs that the plastic quarter panel fascia mounted to.
As it sits right now. Next step is to cut the bottom hole for the spindle and get the spindle welded. I tried using a hole saw on a drill press to cut the hole but the bit gave out really quickly. It ended up scoring a nice line to trace though so I went ahead and cut the hole with an O-A torch. Getting around to the bottom while keeping everything square is going to be tricky. My plan is run a piece of masking tape around the tube. I'll line up the tape to the edge of the hole then run it as square as I can around the bottom. If it come back up the other side and lines up with the start of the tape I should be good.
Functionally it's complete. Just a few aesthetic things and handle on the swing arm. I wasn't sure if a bike would work on it since that wasn't the original plan. But it fits! It could easily fit 3 or maybe 4 bikes. The basket dimensions are 56 in x 24 in.
03-24-2015, 02:24 PM
