The battery box (tray) on our truck project is, in comparison with cars, a fairly complex assembly, in that its rather beefy vertical supports bolt directly to the frame. Its condition was well beyond a "clean-and-repaint level," so we decided to create a new one using the vertical supports from the original.
This is where we started...a little rough.
The first thing we did was sandblast the old assembly. After doing so we were sure of the condition of the various pieces, the only one of which needing replacement being the tray portion itself. Next, we measured its thickness with a caliper and determined that we would need 18-Gage (.040 in) metal to replace it.
Eighteen-gage metal is pretty thick, but we had some in the form of pre-bent box material. We did the cutting with our trusty sawzall because our air nibbler couldn't handle such thick steel. Bending the metal proved to be beyond our strength so we used our 20-ton shop press to turn the metal into a usable shape.
Our Sawzall cuts through the steel in short order, although using it is not unlike using a jackhammer...don't use it if you have loose fillings in your teeth.
The original battery tray had four raised 90-degree sides. We made the proper measurements on our new piece, including drawing lines where we would bend the sides. Fortunately, our new piece already had one 90-degree bend so we used it as a reference. Cuts were made to facilitate bending the corners of the remaining three sides and we found the best way to create the bends was to use the vise. We clamped the sheet tightly into the vise jaws and then pulled it down (it took two people) until its bend approximated 90-degrees. It took further "persuasion" by a sledge hammer to pound the bend into acceptable shape.
We convinced our steel that a 90 degree angle was best.
Actually, we only had to bend two sides because our new sheet was slightly smaller than the original tray. Since we had a leftover piece of the box steel material with its 90-degree bend, we cut off a portion and butt-welded it to the newly-bent three-sided tray.
We welded an existing piece onto the tray that already had a 90 degree bend.
Once that was welded in place we made the necessary cuts to the ends and bent the corners, using a hammer. Now we had to remove the pieces off the old assembly and transfer them to our new tray...
The old tray had a riveted-on bolt on one side and a spot-welded, bent sleeve on the other, both of which formed the hold-down hardware for the battery. Both pieces were in good condition so we ground off the rivets on the bolt to remove it. The sleeve was removed using a cold chisel.
We measured the locations of the bolt and sleeve on the original tray and transferred those measurements to the new one. We decided to weld both pieces to the new tray for strength, not to mention convenience over riveting (note to purists: If this truck were for show, we'd take the extra time and effort to rivet the piece, and to make it look like the original. But this is a parts-hauler for our next restoration projects, and it doesn't need to be exact.)
Now we turned our attention to the vertical supports. These were removed from the old tray using the cold chisel. Since the old tray was largely rusted-out, it took relatively little effort to remove them. We took off one at a time so that we could keep accurate measurements of their locations, not to mention their correct orientation.
We placed the vertical supports, one by one, on the bottom of the new tray and measured several times before welding them in place. We were glad to have done so, since we hadn't noticed that one of the supports was actually 1/2 inch closer to the engine side of the tray than the other on the original assembly. If we had placed both supports in line we would have discovered later that they wouldn't match up correctly to the fender. It never costs anything to double-check.
Removing the old tray from its supports with a cold chisel.
Welding the tray onto the vertical support. Note that the bolt and sleeve for the battery hold-down are already welded on.
Once the new assembly was welded and cooled we temporarily bolted it in place to check for alignment. Everything fit, so we removed it to finish up the little details, such as grinding the four sides smooth and get it ready for finishing.
A little cleaning up with a grinder before getting ready for paint.
Our battery box assembly took 3 hours to build, start to finish. It looks very much like the original. Once we've sanded, primed and painted it, the assembly will look so close to original that only an expert will be able to tell. Even better, it cost us virtually nothing other than the amount of welding wire and gas we used.
The finished battery tray positioned on frame.