How to Bob a Bed

How to Bob a Bed

This write-up is provided solely for reference purposes. Any modification or maintenance that you do to your vehicle is not the responsibility of All-Terrain Armor. Work that you do to your vehicle is done AT YOUR OWN RISK!

When venturing onto serious off road trails, every degree of approach and departure angle helps. The bed of my Tacoma had a lot of overhang from the factory which I often caught on large rocks and ledges when wheeling, so I decided to “bob” it, or take a section out of the middle and weld the two halves back together to make a shorter bed. On a Tacoma with a 6 foot bed like mine, 13 inches is a common length to shorten the bed by because it makes the bed the same length as that found on a double cab Tacoma. This means that if I wanted, I could install a double cab bed cover or bed cap.

I found this modification to be much more simple than I expected, but I will say that it does take some skill and patience. You must be confident in your ability to measure and mark correctly, cut straight lines, weld sheet metal, and perform body work. With that being said, if you have the skills and tools necessary, this can be completed from start to finish in a weekend for little more than the cost of a cutoff disc, a can of bondo, a can of spray paint, and your time.

1. Begin by removing your taillights, bed liner (if you have one), tailgate, rear bumper, and anything else that will get in the way. Once you remove your rear lights, gather up the wiring harness and move it forward of where your foremost cut will be made. You don’t want to accidentally cut through your wires while cutting the bed.

2. Now its time to start marking your first cut. I began by making a mark with soapstone on the bedside that was approx. 5 inches forward of the lower side taillight screw hole. I used this reference just so I could make sure both sides were relatively even. When cutting, it isn’t as important that the cut is perfectly 90 degrees to the front of the truck, but moreso that there is exactly the same amount of length being removed between each point of the two sides being mated back together. I put the tape for the second cut, before I made my first cut, but only for reference.

3. After marking the inside of the bed and making sure that the entire cut will be as close to a straight line as possible, go ahead and make your first cut to remove the tailgate section of your bed. I used a cutoff wheel on a 4.5” angle grinder. It allows me to make a very straight cut and follow my tape lines almost perfectly. I have heard of people using a sawzall and having to spend hours afterwards trying to get both sides to fit together.

4. Now you need to mark your second cut. To do this I measured exactly 13 inches ahead of the first cut (you can use whatever length you plan on bobbing) and made a mark with soapstone. I did this every couple inches along the cut to give me a good idea where to cut. I taped the next cut with the edge of the tape directly against each mark I made. This ensures that even if I didn’t make my first cut perfectly straight, the two sides should mate together perfectly.

Once you are sure that you are removing the same amount of material along your first cut, double check your measurements. Remember, measure twice and cut once. If all is well, go ahead and make the second cut

5. Before I could hold both ends of the bed together, I had to make some modifications to the tailgate section. First, I had to make some notches in the lip underneath the tailgate to clear the frame rails. I also had to trim the rearmost bed mount because for the length that I bobbed, the rearmost bed mount on the tailgate section sat atop a crossmember bolt on the frame, making it not able to sit flat on the frame. For different bob lengths, you may run into different clearance issues or none at all.

With those things done, you can hold the tailgate section up against the second cut and if needed, you can grind down any high spots that create a gap between the seam. With the cutoff wheel, my cuts came out very straight and needed VERY LITTLE grinding to sit flush with each other. One tool that is very handy to help you line up both body panels is a large magnet to hold 2 pieces in a straight line as seen in picture below right

6. Once you have both cuts fitting together (I would recommend that you grind down any high spots until you have no gaps in the seam larger than 1/8”), make sure that the tailgate section will be straight with the rest of the bed once it is welded on. Now grind the paint from the edges of the cuts, put your mig welder on a setting suitable for sheet metal and make a tack weld every inch or 2. When welding sheet metal, tack a section where both pieces are perfectly straight, and try to hold/force them straight as you work your way down the seam. The sections with body lines may not line up perfectly so I skipped over those when tacking, and used a hammer to try to line them up once the rest of the seam was tacked.

7. With the entire seam tacked together, go ahead and weld up the whole seam by either placing your welder on a very low setting or by making lots and lots of little tack welds. This is the part of the process that takes the most patience just because it takes so long. With the seam completely welded, take out your grinder and grind the welds down flat. If the panels didn’t line up perfectly and one side is higher than the other side, then stop grinding once your weld is flush with the higher side. You can always fill in the lower side of the seam with bondo.

8. Now its time for the bondo. Bondo is not very difficult to work with, but it may take a little bit of practice to get good at. Start by mixing the fiberglass filler with the red hardening cream until it is all one color (should turn pink). Then use a scraper to apply a smooth coat over the area to be filled. All that really matters is that there is enough bondo to fill what you want to fill, but it will make it a lot easier when sanding if you apply it smoothly and don’t build up more than you need to. I will be leaving the seam on the inside of the bed un-grinded/bondo’d because I will be putting a bed liner back on top of it so this will save me some work time.

9. Starting with a rough grit sand paper, sand the bondo down until its almost in the shape that you want it to fill in the body. Then use increasing finer grits until it blends smoothly with the metal and follows the body lines to your liking. When finished, the bondo should look like part of the body and be completely seamless. You can now apply paint over the bondo. Since my truck was painted with spray paint, I was able to easily touch it up with a new can. Some people with factory painted trucks try to find color matched paint to blend onto their body panels.

10. Now you will have to rework your rear bumper. Depending on what kind of bumper you have, you might be able to find a way to modify the mounting brackets. I decided to cut my frame rails and build a new bumper off of those. This writeup is more about bobbing your bed than modifying a bumper so I will leave this part up to you.

After completing this project, your bed should hopefully look like it was never cut at all. As I said before, the project was much easier to complete than I expected, but the process will take some patience and skill. I still need to make a set of custom mud flaps for legal reasons, and depending on your local laws, you might need to as well. If you decide to tackle this project on your own rig, just remember to measure twice and cut once. Its much easier to spend an extra couple minutes measuring than spending an extra 2 hours trying to get both pieces of your bed to line up.

Enjoy!

See you on the trails