One more project in the books...tach mount.
I wanted to add a tach to my Dart. This isn't a race car though so I don't need it to be huge and "in your face". I wanted it to be a little more subtle then ones you see mounted to the steering column or top of dash. I like the look of the factory console tachs but they are really expensive. Since I changed the gauges and radio faceplate to white, the factory black faced tach wouldn't look right anyway. I had an Autometer "in-dash" tach just sitting on the shelf from another project so I thought I might as well use it. So, I set out to make a tach mount that resembles the factory console tachs. I'm lucky to have a father-in-law with a lathe and a mill!
I picked up a 6" long piece of 3-1/2" solid aluminum round stock at the local metal shop. That piece of aluminum cost me $25. After measuring the "in-dash" tach, I made up a cardboard template to see how it would look and to make sure it would fit on the console. This picture shows the raw aluminum round stock, my template, the tach insert and what the factory console tach body looks like.
I determined that I only needed to start with a 5" long piece, so after cutting an inch off I mounted the aluminum in the lathe and started hogging the inside out so the tach insert would fit. I drilled 3" into the center with a 1" drill bit to start with. Then used a few different tools to enlarge the hole little by little until the tach fit inside.
With the tach fitting, the aluminum was turned around and I machined a taper on the back side to give the mount some shape.
Once that was done, the aluminum was mounted in the mill so I could machine a "flat" on one side. That "flat" lets the tach sit at an angle once it's mounted to the console. During each of the machining steps I referenced the template I made to make sure everything was turning out right.
I traced the shape of the "flat" onto some paper and transferred that to a piece of 1/2" aluminum to use as the base. I drilled three holes through the base and counter sunk them for some allen bolts. Then I drilled and tapped three holes in the tach mount so I could attach the base. Here's what the two piece look like together while sitting on a table.
Then it was time to make sure it looked good and fit on the console. I was worried at first about if it would interfere with the aftermarket shifter I'm going to use. It's a very tight fit but both tach and shifter will work.
Now that I knew it was going to fit, I had to make clearance for all the wiring. To locate where I needed to remove more material, I put some Play-doh in the bottom of the hole. Then I inserted the tach. The spade terminals on the back of the tach made impressions in the Play-doh.
Once I had clearance for all the wiring, I drilled and tapped the base for a hollow 3/4" stud. Then all that was left was a lot of sanding and polishing. The finished product looks really good. Due to the size of the tach insert, it doesn't have the exact measurements of the factory tach but it does look very similar to the factory piece...that's what I was going for.
So, this just cost me $25 and a lot of time. Most of my $25 ended up on the shop floor...
