WOW! It’s been over a year since I last posted on this thread. Truth be told, not a ton as happened since then on the build side of things. I’ve done a lot of trips with the Montero and just been enjoying the rig. That being said, there are some notable additions to the build worth sharing on this thread.
Side note: in this section i will refer to “frame rails” from time to time. The Gen 3 montero is a unibody, and therefore doesn’t actually have a frame (which is actually part of the problem here). However it does have a similar structural component built into the unibody construction that looks like and functions like a frame rail, this is the part that i’ll be referring to throughout this section.
I finally built a rear bumper!! Sort of. The circumstances surrounding the build were sub-ideal. Long story short, I was high centered on some snow, a buddy of mine did a snach recovery trying to pull me backward from my hitch, and ripped 3 of the 5 bolts straight out of my “frame”! This is probably the biggest downfall to the gen 3 platform: it’s a unibody. There isn’t a solid frame rail to build off of and bolt to for structural strength. The twisting motion of pulling on the hitch swiftly overcame the weak mounting points and just like that, my hitch, rear recovery points and mounting points were toast.
BUT every cloud has a silver lining. Armed with a new understanding of how I needed to improve my hitch and rear recovery points, I set out to make a bumper that would better suit my needs.
First thing to tackle was mounting points. Since the factory ones were ripped out I couldn’t reuse those, and frankly, wouldn’t want to seeing how they already failed me once. My options were either weld directly to the unibody, or find other mounting points. While poking around the rear of the truck, I discovered that there are additional holes in the “frame rails” located directly above where the hitch used to mount. In some cases these are used to attach factory recovery points. These holes are perpendicular to the frame rails AND just so happen to be sleeved, meaning that they won't collapse under load. Admittedly, this is the point of explanation where words on a page will fail me. I’m not an engineer who can explain the exact science of shear forces and torque properties.. So what i can say is: There are 4 of these holes, they are extremely strong, and integrated into the body of the car in such a way that makes them nearly indestructible. So I used those as the mounting point for my bumper build. Here’s some pics that will hopefully explain my point better than i can
From there I wanted to make a bumper that accomplished 4 things:
- Higher departure angle
- Strong recovery points
- Fully functional hitch
- As light as possible
To accomplish this, I kept with a pretty simple design: I basically extended the frame rails out past the rear of the car and braced them against any kind of twisting motion. I kept everything in line with the frame rails. This eliminates any twisting or unwanted torque that would be put on the mounting points during a recovery or towing. From there I welded in a bar that would act as a mounting point for my hitch receiver as well as brace the rails from collapsing in on themselves under load. So that made up the base of my bumper. I used 3/16” steel all around, the factory is only ⅛” so that should be penty strong.
A few notable things with this set up. 1) i had to cut a bit of a pinch weld to get these rails to extend past the body. You can see it in the pics. This was a simple job with an angle grinder. 2) The rear climate control system gets in the way of the passenger side rail. I had to do some fancy cutting to get the rail to still fit in that spot. This does mean that the passenger side rail is slightly weaker than the driver’s side, however I don’t think this will actually make a difference for this application.
Now moving onto the recovery points. 2 is better than 1, so for my recovery points i decided to ditch the hitch receiver as my rear recovery point and add 2 that were directly in line with the frame rails. This will allow me to run a bridal strap between the two points and evenly distribute the load and force of a recovery. To make this as strong as possible, i decided to integrate 2 hitch receiver style recovery points into the rails, 1 per side. I used a mill to shave the blocks down to fit into the frame rails, then drilled a hole through the rails and ran a ½” grade 8 bolt through it (basically a hitch pin). I also beefed up the hole by welding some additional ⅛” thick plate to the top and bottom, and filled in the space on either side of the block with some more flat bar steel, welded in place, again, to prevent twisting or moving. All in, i don’t think they are going anywhere!
With all that done i found a 5,000lbs hitch receiver and bolted it on. I also welded a “bumper bar” to the rear so that I actually had some kind of protection against impacts since the other bars sat so close to the body. To get everything to fit up nicely and still look halfway decent, I cut and trimmed the factory rear bumper and step so that it still functioned normally and looked like it belonged there. I also trimmed the plastic (both the rear and the sides) as best I could to accommodate this new set up. I had to just work with what I had on the plastic parts because they got destroyed when my hitch got ripped off.
I will admit, I don’t love how it looks. It’s simple, and somewhat clean, but It just looks like a hack job to me with the plastic parts being torn up. That being said, I didn’t want to add additional metal parts to the bumper to save weight, and i’m still more invested in weight savings than i am in cosmetics.. So for now, it stays the way it is.