Installing Aftermarket Gauges In Your Classic Car
If you hot rodded your car back in the 70’s, you probably remember how limited your choices were when it came installing gauges. You could get a chrome or a black bezel, but choosing colors was like the first Model T: you could have any color you wanted as long as it was black.
There were no choices to color-match your paint or interior, no special fonts or backgrounds, and the back lighting was limited to a bulb cover that didn’t really give you the color you were hoping to get. So just about everyone had generic looking gauges, and the only thing that stood out was where you mounted them.
If you like the nostalgic look of those old gauges, you can still get that sort of gauge today with either a mechanical or electrical sender. But that’s not where you choices are limited, you have a lot more choices than you can ever imagine.
Most gauges available today have either black, white or silver faces, and your lighting isn’t limited to whatever bulb cover you can get. With the various colors and sizes of automotive LEDs available, you can choose just about any color for the back lighting.
We contacted Dakota Digital to get some insight into the technology behind their new VHX series of gauges. These new kits combine the look of analog gauges while being completely digital in function. We also looked what Auto Meter has for the both enthusiast and motorsports, as well as AEM Electronics and Innovate Motorsports, who offer gauges that handle specific functions to help tune and monitor crucial information.
If you want to customize your gauges, Auto Meter allows you to design your own custom gauges on line in their Custom Shop using hundreds of combinations. Your choices on gauge faces, bezels, lighting, color, style, fonts and pointers are almost endless. You will pay a little more, but if you want to match or contrast your car, you have that option now.
When it comes to gauges, a few searches on the internet can have you completely overwhelmed with choices. Sometimes that makes it very difficult to make a decision on what you want, how you want it to look, or whether you can afford it. The more custom you get, the more it’s going to cost you, so if you have a budget in mind, that’s a good place to start.
Choosing the Right Gauges
Before you decide on which style or brand of gauge to buy, it’s very important to decide which specific gauges you want, and why you want them. You also need to know if you’re going to have room for them in your dash.
Do you want just a basic set with five or six gauges? Or will you be racing your car and you want more advanced gauges so you can monitor specific functions? Sometimes the gauges you want will be more important than whether they all come in a matched set. Many individual gauges that racers install won’t have a matching speedometer or tachometer.
Keep in mind, if you’re going to be racing then some gauges will likely be mounted somewhere in your direct line of sight or where you can easily read them when you’re on the track. You don’t want to have to take your eyes off the track or try to figure out what the reading is because you mounted the gauge too far away. So you must choose a location that is convenient and can be read at a glance.
If you make a list of the gauges you want and decide where you’re going to mount them it helps to plan your installation. If you’re mounting individual gauges into your existing dashboard, be prepared to cut up your dash a little to mount them. You’ll also need to do some planning on how well they’ll fit, because one wrong cut and you could botch the entire installation.
Gauge Sets – Analog and Digital
If you don’t need anything other than the basic five or six gauges, some companies like Auto Meter and Dakota Digital sell complete gauge sets, giving you the basic readings that many people already use with factory gauges. A five gauge kit will have a speedometer, fuel level, water temperature, oil pressure and a volt meter, and the six gauge kit adds a tachometer. For most people, the gauge sets will do the job just fine.
For many of their kits, if you decide later that you want to add another gauge or a clock, they might have one to match your set. If you don’t want to go all out in Auto Meter’s Custom Shop, you still have dozens of different styles to choose from. These choices will keep you busy, so give yourself plenty of time to go over the on-line catalogs and see what each company has to offer.
If you don’t care for bright orange pointers but you like the glow of digital readouts, Dakota Digital has universal instrument panels and vehicle specific gauges for many cars. If you can’t get a complete cluster for your specific vehicle, both Auto Meter and Dakota Digital also offer individual digital gauges as well as a few complete digital gauge sets. Digital gauges are very high tech looking, and can enhance the trick look of your car’s interior.
Speedometer and Tachometer
Speedometers are rather simple, but you do have some choices there, too. There are are two types of input for a speedometer: a cable or an electronic pulse signal that comes from the transmission. Most of the cable-driven speedometers have a standard fitting that accepts a square-end cable used on many cars, and has a 5/8 threaded cable input.
Some speedometers are programmable, meaning you can calibrate them yourself. There are a couple different types of input for these as well, depending on what type of sender is on your transmission. The instructions that come with the speedometer will walk you through the calibration process. You’ll have to have it installed and drive your car, and use a calibration button on the gauge.
Most tachometers today are very simple to install, it’s just a matter of connecting a few wires. There is a lead wire that will connect to either your coil or to the tach output on an aftermarket ignition box, hot and ground wires, and lighting wires. A switch on the tach allows you to select between 4, 6 and 8 cylinder engines.
For racing, many people prefer to have a shift light on their tach. This shift light is set to light up when a specified rpm is reached, indicating to the driver to shift up. This light is great for racing, but not such a good idea on the street as it’s a bright light that can distract you when you’re paying attention to traffic. Setting the rev limit on the tach to a higher point is one way to disable it when you’re driving on the street.
Oil Pressure and Water Temperature
While most people tend to think a sender is a sender, the truth couldn’t be any further away. Most gauges come with their own sender that must be used with that gauge. When you install a water temp gauge you have to also install the sender that comes with it or you won’t get the proper reading. The same holds true for the oil pressure sender, you must install the sender that comes with the gauge. Many factory senders are just an on-off switch to operate a light on the dash, indicating the existence of pressure, but not how much.
Most of your oil pressure and temperature senders are National Pipe Thread (NPT) fittings that will fit most manifolds, and include adapters for various sizes.
Senders and fittings are often tapered and they will become much tighter as you turn the sender or fitting, so you want to be sure not to over-tighten the senders.
Some gauge manufacturers advise that you do not use Teflon tape or sealant on the threads. Tape or sealant may prevent the sender from grounding properly, giving an improper signal. Always check with the manufacturer when installing electrical senders.
Fuel Gauges – Ohm’s Law
Fuel level gauges are more involved than oil or temperature gauges. Fuel level senders are mounted in the fuel tank, and are specific to each vehicle.
The ohm ratings for senders are specific to the manufacturer and year, so you will need to find out what your fuel level sender is rated at for both empty and full in order to get the proper fuel gauge. For example, some GM vehicles up to 1997 will have a reading of 0 ohms empty and 90 ohms full, while many Ford vehicles up to 1988 will read 73 ohms empty and 10 ohms full.
Chances are that someone has already done the hard work and posted the readings on the internet, so you can check automotive forums specific to your car or manufacturer to get some help. Most gauge manufacturers will provide applications and how many ohms.
Some fuel gauges are programmable or adjustable and the process is pretty simple, but still requires a full and empty tank. There are also universal sending units that you might be able to use with your fuel tank. Installing a universal sender is a bit involved for a beginner, however.
Optional Gauges for Specific Functions
If you find that you want a couple more gauges in your car, but they don’t match the one’s you already chose, that’s a good time to think about mounting them somewhere else, like on a pillar or below the instrument panel where they can be seen. Or you can go all out race driver with Auto Meter’s Multi-Function Dash Logger (MFDL) and monitor everything you need through a single data cable.
Companies like Innovate Motorsports specializes in gauges to monitor things like air/fuel ratio and to acquire data from your engine. They have both sweep and digital gauges, and also an OBD II vehicle interface for using with your iPhone or iPod Touch.
You can turn your phone into a wireless communication device to read your engine information, and to store it for future reference. You can monitor things like RPM, TPS, MAP, IAT and timing advance, to name a few. If you want to scan your car because of a check engine light, the OT-2 device will scan your vehicle for Diagnostic Trouble Codes (DTC), or give you efficiency readings.
AEM Electronics is another company that specializes in specific gauges, such as Wideband AFR and Boost/Vacuum gauges. They also provide plug and play Programmable Engine Management Systems and various sensors. The gauges that they offer are available in analog or digital, and they allow you to track your engine’s stats and performance with data loggers.
Digital Gauges vs Analog
When someone refers to gauges as being “electrical”, that’s not the same as a “digital” gauge. Many analog gauges have electrical input from a sensor, but there isn’t a digital signal that operates the movement of the needle. Digital gauges receive a digital signal and will either display a digital reading or provide that digital signal to an analog output.
Some digital gauges, like the new VHX gauges from Dakota Digital, combine the looks of an analog gauge with the ease of a digital gauge. While the odometer and data are displayed digitally, the analog movement of the speedometer and other gauges is still present.
Dakota Digital has been making digital gauges for 25 years, and they’ve come a long way since their early days of gauge sets with the familiar aqua-blue Vacuum Fluorescent Display (VFD). Dakota Digital introduced their VHX line of analog gauges last year and has really turned it up a notch when it comes to instrumentation.
We currently have 110 vehicle specific VFD applications and 30 applications for our VHX line. We plan to add about 15-20 more in the next year.
“We currently have 110 vehicle specific VFD applications and 30 applications for our VHX line. We plan to add about 15-20 more in the next year”, he told us. Greg says that the decision to add more vehicles is a combination between customer feedback, vehicle popularity and from what they see in car shows.
At SEMA, Greg said he noticed a Chevrolet S10 with an early Ford VHX gauge cluster installed in the dash. So people aren’t just buying the new gauges for their specific vehicle, but sometimes adapting a kit from a classic car into their newer vehicle.
Their new VHX series combines the beauty of analog gauges with two full character message displays. The VHX line works much like the VFD line in that there is a module you can mount anywhere under the dash to run all of your wires to. From the module there is a ribbon or cat 5 cable to deliver the data digitally to the instrument cluster.
If you want to add on to your existing cluster, there are Expansion Modules that you can purchase and plug into your existing set. Like the VFD line, the digital displays on the VHX can be cycled through to get that additional information, including boost pressure, A/FR or even an OBDII interface, to name a few. Greg said you can add up to 16 gauges to the existing panel.
If you’re looking for a clean, custom look to your car, you can spend as much or more to restore your original gauges as you’d spend on a nice set of aftermarket gauges. The advantage of aftermarket gauges is that you can monitor engine functions and diagnostics like never before – a necessity when you drop that modern power plant into your classic car. When you neglect to upgrade your instrumentation, it’s like installing a set of drag radials and never checking the pressure.
We installed a set of VHX gauges on a ’69 Camaro, and a set of VFD gauges our ’71 Nova, Project Swinger. Click the links and check out those stories for more detailed information about the installation process for digital gauges. Installing your own gauges assures two things: pride for a job well done, and a happy car owner.