Mitsubishi Projects: Beefier Rear Bumper
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Author/Photographer:Don Huysmans | Editor: Phil Hansford
December 22, 2001

A SERIOUS upgrade for a worn out rear bumper

06-series.jpg
This series shows the transition from the old OE bumper, to the new, low-porfile rock sliding bumper.

Editor's Note: Don's bumper was made for the Montero/Raider with 4 cylinder engine. To fit the six cylinder SWB or LWB, modifications would need to be made to the mounting brackets.

Materials:

After driving the Rubicon it became very apparent that stock bumpers are simply too bulky and "delicate" for serious off road use. So here's my solution:
After removing the existing bumper and attached bits, it became obvious that there was a whole lot of space behind the rear wheels. Apparently the 2 door and 4 door rear ends are different, though they share the same bumper. With no body to protect, the end caps on the rear bumpers of the 2-door are protecting empty space, and basically getting in the way. I wanted to keep this "empty space" for better off-road clearance, so I modified my original plan, and lifted the sides.



tn_05-truck-end.jpg
08-new-old.jpg
In the upper picture, the red lines indicate the bumper mounts, and the blue line shows the position of the channel. The lower picture compares the OEM to the beefier bumper

Remove the stock bumper. Wow, look at all that rust! Time for the wire brush and rust paint, and maybe new bolts... There are 4 bumper mounts (indicated by the red lines), the 2 outer mounts are thicker steel, and a continuation of the frame. The inner mounts are probably not as important, they're thinner steel, but I used them as well. Notice the body mounts beside the outer bumper mounts. These stick out further than any other part, and I wanted to protect them with the new bumper. The 4" channel just fits over them, and still lines up beautifully with the bottom of the inner bumper mounts (the lower blue line). The blue line shows the position of the 4" channel, and also shows that if extended it protects empty space (dashed blue line). When fitting the channel iron, you'll need to grind a small notch into the base of the inner mounts to allow the iron to get in a little closer. Then the outer mounts need to be modified (yellow line), the lower edge needs to be cut off, or partly cut then bent

02-rearbump-plan.jpg
This diagram gives all pertinent measurements

Mark and cut the metal as shown on the diagram. Heat and bend, check for fit, then groove and weld if OK. I removed the weld bead on the outside welds for a smoother finish. The groove in the cut gives the weld something to hold if you're going to grind it flush. I used an arc welder with E7024 1/8 rods @ 110 amps. Called "jet-rod" (you can move fast), it's limited to non-vertical surfaces, and required a lot of material re-positioning to make all the welds. E7018 1/8 rod would have been more convenient as it can be used in vertical welds, but it's harder to strike. I stayed with the easier rod.


01a-patterns.jpg 01-materials.jpg 03-mounts.jpg
The patterns, in wood The raw materials The newly fabbed mounts

The corner parts are optionally complex. They can be a single 90 degree bend. During construction, my Wise Intellegent Female Expert (W.I.F.E), requested a rounded corner rather than a square one. The round corner isn't that difficult, but the actual gap must be exact. I practised on strips of cardboard first... Several of the trucks frame mounts were slightly twisted. To get an exact fit, I made some 90 degree angles from peices of 2x4, and 1/4" plywood. The bumper was held in place with my knees, and then the mount plates were clamped to 1/4" plywood, pushed up against the truck's frame mounts, and then the 2x4 was clamped in place in the channel iron. You'll figure it out...

04-ends.jpg 07-ready.jpg tank_bumper.jpg
Don elected to make low profile endcaps, but the dividend is very good clearance at the corners The new bumper is ready to be fitted, after a lot of grinding, polishing and painting Along with his tank armour, Don's worries about dragging his truck on the trails are over!

The 2" HSST is wider than the 4"channel's top edge, and welded together flush on the outer edge. Cut the 1" slope on the 2" HSST only AFTER you get the corner done, and welded to the channel. This way you can adjust to fit.

Polished with a wire wheel, and then primed and painted with rust paint, and installed!


Definitely looks better!


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