By Moe
October 22, 2001
This article is intended for private use only. The details enclosed cannot be used for commercial use without the author’s permission.
This article provides some detail to a Discovery rear bumper that I recently designed and made. I made my own rear bumper because currently there are few aftermarket options, they tend to be overpriced and of questionable construction, and I was really interested in relearning how to weld. Before this project, I had had very little experience welding and working with metal and that experience was over a dozen years old. This project is not difficult, requires several afternoons or a solid weekend, and the simple repeating of a number of steps: measure, cut, weld, grind—and grind again!
Tools used:
Material used:
Above is a photo of the finished product. The bumper blade that runs across the rear provides the main skeleton for the bumper. Welded to the end of the blade is quarter panel protection that wraps around and under each panel. Attached to the blade is a fuel tank skid plate. The bumper has four direct attachments to the frame, one indirect attachment to the frame via the skid plate, and two attachments to the body in the wheel well area.
First, I removed the factory bumper, cut off the old tabs that most aftermarket bumpers use as their main attachment point, cut off the tow hitch, and ground down any rough welds around the frame horns. For me, grinding the frame horns was necessary because it gave the finished blade a much tighter fit.
The rear blade is made of 3 pieces of ¼” x 2 x 4 mild steel rectangular tube. The first piece, cut at 31” long, sits horizontally on top of the frame horns. The other two pieces, each cut at 16” long, are welded vertically to the first piece. These 3 pieces of rectangular tube are joined at two points by two pieces of ¼” 2 x 2 mild steel angle. The angle also serves as the first attachment point to the frame.
In this photo you can see the first frame attachment and the Dixon Bate jaw I placed on either side of the frame horns. Later a steel tab will be welded to the bumper on the inner side of the frame horn to make the attachment more secure. Even though the Dixon Bate hides it slightly, the photo above shows how the 2 pieces of rectangular tube are joined together. The first piece of angle iron is stacked in front of the vertical rectangular tube, and the second piece of angle is stacked underneath the rectangular tube and behind the first piece of angle. All seams are welded and then ground clean. The rectangular tube is also butt welded on all seams. If one was concerned that this was not quite strong enough, a small piece of angle could be welded across the entire rear of the blade. The frame horn bolts represents 2 out the 4 direct frame attachments.
The photo above shows the other 2 frame attachments. Once you remove the tow hitch you will find two reinforced bolt holes on the crossbrace that runs between each frame rail. From recollection the holes will take a 14mm bolt. To make use of this attachment, I used a piece of ¼” 2 x 3 angle spaced by a piece of 3/8” flat bar. I tack welded washers and nuts to the top of the cross brace so I can simply insert bolts and tighten. This attachment point is later covered and reinforced when the tow hitch is welded in front of it.
After the blade is made, next comes the quarter panel protection. To do this requires some serious trimming of the quarter panels and rear end. I cut the quarter panels leaving approximately two inches below the black plastic trim. I also needed to cut a small part of the body just below the rear lights to accommodate the bumper as it wrapped around the side. To make the quarter panel protection, I first extended each end of the blade with a ¼” 2 x 4 rectangular tube with ends cut at ~ 45 degrees. The photo above shows how the rectangular tube wraps forward at a 45 degree angle. It is hard to notice that I have already cut the main bumper blade ends at 45 degrees too. Later, I welded plate over the open hole left on each end of the bumper.
The quarter panel protection visible in the photo above consists of a piece of ¼” 2 x3 angle butt-welded to a piece of 3/16” x 3 strap. This provides a total 6” of vertical protection. When I welded the strap to the angle iron, I made sure that it swept inwards and toward the body so that the lower edge of angle iron would protrude the most, as this is the strongest point. The panel protection, not visible, under and behind the rear tires attaches to same ¼” x 2 x 3 angle. Butt welded to this is a length of ¼” x 6 plate that runs all the way back to the rear blade. This is supported by a small piece of angle, providing an 8” ‘slider’ platform protecting the underbody behind the tires.
The photo above also shows the 3/16” x 3 strap that was used to cover a small section below the rear lights. Not having the tools to bend a single piece, this is simply two pieces welded together with one piece that sweeps forward and is shaped to meet the quarter panel protection. This strap sits on a large piece of ¼” x 6 plate that runs from the rear blade to the quarter panel protection. This can be seen in the slide below.
The slide above provides a top view of the bumper. Ideally if one could have a local metal shop brake and cut the quarter panel protection, a lot of weight (and time) could be saved as you could potentially go with a lighter gauge metal. Also in the slide above, you will notice that a small piece of angle is welded to the leading edge of the underside of the quarter panel protection. I drilled three holes in the front lip of the angle, took the existing metal mud guard/flap that comes stock and then cut and bolted to fit—this simply requires removing several inches and bending the edge to the correct angle. This provides the body attachment point for the bumper. Given that bumper did show slight (and expected) movement at the leading edge of the quarter panel, the body attachment appears to work well as the body does shift too. For those concerned that the quarter panel protection could give way, you could easily fabricate a brace extending across from the frame.
The slide above details the rear view of the bumper. An expanded view is given to show how the rectangular tube (the main blade) is joined together by two pieces of ¼” x 2 x2 angle. Note that the Dixon Bate attaches to both the angle and rectangular tube, requiring different length bolts. If I did not have the Dixon Bates on hand, I would have gone with a standard hoist ring from Actek that can be found for around the same price (http://www.gromax-usa.com/supplies/ring/hoistring.htm). Even though my Disco is not called on to tow trailers, I kept the tow hitch for a central recovery point. The tow hitch is obviously cut from the original stock hitch. I cut the hitch so there is about 1-3/4” of tongue left behind the center of the pin. The slide above also shows the ¼” x 1-1/2 strap that works as the attachment point for the skid plate. I used six bolts to attach the skid plate to the rear bumper.
;
The skid plate is also attached to a brace that bolts to the frame of the vehicle at four points. The photo above shows one side of the skid plate brace. It makes use of the existing bolt hole in the frame that is used to attach the tie down point. I also drilled an additional hole in the side of the brace that secures the sway bar to the frame. The skid plate brace is a combination of angle and strap welded together—the important piece being the strap that runs under the fuel tank. I welded washers and nuts to the top side of that cross brace to accommodate the skid plate bolts. Note that I drilled the holes for the bolts too close to the edge on that section.
The photo above provides a side view of the skid plate and skid plate brace. You can see that the brace only covers the lower part of the skid plate and does not extend all the way to the bumper. If you were concerned about the strength of the plate, you could run the brace all the way to the bumper. The skid plate is held on to the brace by 8 convex headed bolts (for countersinking in the aluminum plate), and it is attached to the bumper by 6 of the same bolts. The photo above was taken at a local shop that removed the resonator and bent a piece of tail pipe so that it now tucks up high and is protected by the bumper.
The slide above provides the dimensions and angles of the rear skid plate. It is made of ¼” aluminum plate that was cut and broken at a local sheet metal shop. I designed two bends in the plate. Bend 1 is supported by the brace, while bend 2 has no direct support. Not shown are a number of notches and small bends, made to rear edge, that are needed to accommodate the tow hitch and the bumper itself. These can be seen in the photo below.
The photo above shows the attachment point for the skid plate. You can also clearly see the rectangular tube just below the light. This area is potentially the weakest area on the bumper as it is the furthest point from any frame or body attachment. At this weakest point there is a total of 1” of steel. I ended up filling the area behind the bumper with a small length of split metal, but if one was concerned with strength then you could use plate instead—at the expensive of more weight.
For now I am happy with the bumper, but I mentioned above there could be a few potential problems or redesigns to consider. The end product seems solid. A real advantage is that it has multiple jacking points that are very secure, meaning that the tongue of the jack will not easily slip out. Another advantage is that the bumper is securely attached to the frame. The bumper has shaved several degrees from the departure angle, even more so directly behind the wheels. The skid plate really completes the bumper. Recently a Safari Guard equipped Disco and my rig dropped into a mud hole. My skid plate received a scratch. The SG plate gouged the aluminum and bent the brace, requiring major repair.
This bumper was designed and manufactured on my back porch—I do not have a workshop. Besides the welder, no special tools or knowledge are required. This is a very simple and straight forward project with the biggest cost being time. Hopefully this article helps shave a few work hours for those wanting to do something similar.
Total Cost in material ~ $300