Home-made Instrument Cluster

One way to spice up the appearance of your ride and give it just that much more functionality is to create a custom instrument panel. For most models of vehicle there are several options out there for after market instrument panels. But where’s the fun in that when you can build your own!

In this case I had to build my own from scratch considering I require gauges that will work with a Chevy LT-1 and the vehicle is a 1990 RX7 that originally came from the factory with a 13B rotary engine. Of course a rotary does not have pistons so things like tachometers do not behave the same. There is not a crank position sensor to signal tach pulses, because there is no crankshaft in a rotary.

Originally when the Small Block was put in to the RX7 I modified the resistance values of the factory tach to work very close to correct over most of the range, but as of late it has begun to act up and I’ve decided to switch over to all Autometer Phantom gauges.

Using parts of the original instrument panel and guage pod can be very helpful. I wanted to leave a relatively stock look on the vehicle when you’re looking in from the outside casually so I’m not doing something crazy like building a custom dash out of fiber glass (this is Ubermodder kids, not Unique Whips) but just modifying what Mazda gave me. I started by removing the stock gauge pod from the vehicle, and removing the gauges from the pod.

Hollowed out gauge pod

Next I cut the original gauge bezel out.  When I cut the factory bezel out I left some of it intact as tabs so i can affix my new bezel to it with rivets.

So I have a chopped up gauge pod.  I need to start a new one.  I used a piece of 18 gauge sheet metal for this.  I also looked at other options.  I’ve seen other people use carbon fiber board.  Also a piece of anodized plate aluminum would work fairly well too.  However I settled on steel because its cheap and looks great with paint on it.

I used a set of tin snips to rough the piece in and then used a hand file to hone in the dimensions. I wouldn’t suggest using a hack saw due to the tendency of the metal to warp. This is probably the step where the most time is spent. Getting the fit as tight as possible is very important for the cosmetic appearence. For the layout that I used there is not enough room to put a trim piece in to cover up sloppy fit.

Roughed in steel bezel

Next I found gauge cluster layout that would fit with the space i was given to work with and stenciled it on to the metal with a marker. One thing to keep in mind is that the edges of the gauges are not normally flat and therefore if you stencil the face too closely the gauges will rub against each other when they’re installed. I found that a 1/4″ or so of clearance was enough for a tight yet not too tight fit.

With that piece of sheet metal fitting in snugly, it was time to chop out the holes. Had I been able to get my hands on the properly sized bi-metal hole saws and a good drill press i would have gone that route to cut the holes out. Unfortunently the standard sizes of hole saws don’t match that of my gauge proportions. Thus I again got the dye grinder out and choped X-shaped slices in the gauge holes to rough the shape in, then finished it off with a rotary grinding bit. These holes don’t have to be perfect, yet they need to have a tight fit on the gauges. At this point I also drilled holes out for the pop rivits I will use to affix the bezel and holes for turn signals and high beam lights.

Bezel with holes drilled

Once all the gauges fit properly and I had knocked the rough edges off the piece, I sent it off to the paint shop to get a coat of paint that matched the car’s body color on it. Now there are a lot of other options you could do at this point as well. Powder coating, or anodizing (if you’re using aluminum) would work well too. I would try to stay away from using spray paint due to it’s tendency to scratch easily.

Once It came back from the paint shop I threw in all the parts and it looked like this:

All painted up and guages in

At this point I did a lot of test fitting and measuring to make sure one last time that every thing would fit, especially that there was clearance behind the gauges for everything to be bolted in on the original mounts. Once I confirmed everything fit well, I wired it all up. To do the wiring you’ll need a wiring diagram for you particular year and model. Keep in mind that gauges like Oil pressure sensors will need new sending units put in to the engine block. Also depending on how the Vehicle speed sensor is run out of the car, new wire may need to be ran to the transmission. All of this should be covered in the gauge’s instructions. I used a wire that was 20 gauge stranded, it was probably a little bit overkill but that’s what I had on hand. I soldered all the joints and sealed them with shrink tubing. Using crimp connectors can cause a lot of problems down the road since they tend to loosen up from thermal expansion and contraction (also you’d have an enormous ball of plastic connectors). To connect the pod to the car, I used high quality bullet connectors for the master wire connections. You could solder these joints if you wanted, but if you ever need to get behind the gauges, you’ll have to cut the wire and re-solder.

So all that was left after that was to put it in to the car  and wire up the connectors.  Voala its done!

View from outside the car

Home-made Instrument Cluster installed