As avid automotive gearheads, many of us often add gauges, controls, and other devices to our vehicle interiors beyond what came from the factory. That could mean adding auxiliary monitoring gauges, switches for accessories and lighting, or GPS and radio gear. Many times these can be added into the factory dash and console panels, but at some point one may decide to build a dash or dash panel from scratch.
Many times when owners do an engine swap in their rig they may replace all the factory gauges with aftermarket ones that provide more vital information, and relocate them based on visual priority. When laying out new gauge locations, always ensure that the most vital gauges can be easily seen through the steering wheel or in your most direct line of vision.
Make sure you can reach all the needed switches and controls when you're fully secured in seatbelts or harnesses. We've seen cases where a driver couldn't lean forward enough when strapped in tightly to extend a hand to a control. Also, when laying out gauges close to one another, check the mounting bracketry to ensure how tightly they can be placed to one another without interference. Some drivers choose to "clock" or rotate gauges to align a normal needle reading to some notable position.
We find it best to lay out everything on full-scale paper and sit in the vehicle to try out the locations of everything to be placed. Once you have a good idea where pieces should be mounted, a final and very accurate layout sheet can be drawn to use as a marking and drilling template for the sheetmetal. If you don't use up all the space you have, lay out the controls and items to suit your needs best, but consider what might be added in the future as well.
We've seen some pretty extensive and custom dashes built from scratch. To fit everything in and have it all accessible takes good forethought and planning.
Drawing everything out on paper lets you visualize the layout and change it easily without committing to cutting materials. In this case, actual-size images of the gauges to be used were printed and taped in place to check visibility from the driver seat. The same was done with the locations of the controls, checking that they were all within easy reach. Later the same grid layout was used to center-punch drill locations directly on the dash panel.
Circular gauge holes can be carefully cut in thin sheetmetal with good results and without warping the panel. Using a solid piece of 2-inch lumber as a backing can help support cutting with a hole saw in a drill press or hand drill. Drill a proper-sized pilot hole through the sheetmetal and the wood to serve as a steady guide. Use of a metal rod guide in the hole saw in place of a drill bit will hold the saw to center very steady. Cut lightly with the blades and use oil for lubrication.
When cutting holes for switches and other controls, standard tapered-point drill bits can push and warp the sheetmetal. Step drills are better and can make fairly clean holes. The best we've found is to use dedicated sheetmetal cutters such as a Rotabroach. Using the center punch divot for accurate alignment, they cut accurate round holes with little burring and no warping of the sheet.
Switches can be configured and installed individually, or ganged aftermarket switch panels are available if that suits your needs. Use relays as needed to control accessories with heavy electrical current loads. Light to medium electrical loads can be wired directly to switches. Note though that alternating current (AC) ratings on switches are not valid for direct current (DC) applications as in the case of 12-volt accessories. Use correctly rated DC switches, or check for a stated DC current rating (usually lower) on more common AC switches.
When limited in aftermarket gauges due to space or cost, here's a trick to occasionally monitor automatic transmission fluid temperature. Use a second gauge compatible temp sensor in the cooler output line of the transmission or other appropriate location. Wire this sensor and the water temp sensor through a double-throw switch, allowing you to use a single gauge to monitor either fluid temp at the flip of the switch.