Tach Dash Installation/Rebuild FAQ

[72BlckButy]

This thread has been created to assist those contemplating the installation of a tach dash in their blazer, suburban or truck. Many of the same processes are used regardless if your truck was initially built with a tach, so if you are refreshing your original tach dash, simply skip a few posts and pick up where needed.

The process described below was used when adding a tach to a truck which did not include one originally.

Items needed:

Paint:
Valspar Flat Clear - Gauge Tins
Valspar Flat White - Gauge Tins
Valspar Semi Gloss Black - Gauge Tins
Valspar Summer Leaf (Satin) - Gauge Tins
Model Master Huggar Orange - Gauge Needles

Parts:
Dash Bezel
Front/Rear Tach Tin
Gauges (Ammeter, Fuel, Oil Pressure, and Speedometer)
Tachometer
Tachometer Circuit Board
Tachometer Lense
Tachometer Wiring Harness

Note: If your dash will include either an air pressure gauge, or a vacuum gauge, account for the additional pieces needed at this time. The only difference will be the added gauge and a different lense.

Tools:
5/16" Line Wrench
1/4" Socket
5/16" Socket
9/16" Socket
Needle Nose Pliers
Phillips Screwdriver
Standard Screwdriver

[72BlckButy]

While building my tach dash, I was fortunate enough to have a spare set of tach tins which allowed to media blast and repaint them to match the original colors. If you do not have a spare set of tins, simply follow the steps listed below, blast the tins, repaint, and begin the assembly.

Here's a few shots of what the tins looked like when I started taking apart the dash, and how they looked following a quick media blast and a quick tape and repaint.







The tins need to be painted as follows:

Front Tin:
Semi Gloss Black - Front
Summer Leaf - Rear

Rear Tin:
Summer Leaf - Front
Clear Flat - Rear

Speedometer Tin:
Summer Leaf - Front
Clear Flat - Rear

Ammeter/Oil Pressure/Temp Tins:
Flat White - Front
Clear Flat - Rear

The benefit of have a spare set of tins is that upon tear down of the original dash, a simple bolt and rebolt process can be done from the old tins to the new ones.

[72BlckButy]

The removal of the original dash will be covered through the next few posts. Follow each step and you will not run into any issues.

First and foremost... begin my disconnecting the battery. If you fail to do this, you will definitely return to your truck with a dead battery, not to mention the opportunity of shorting out the system while working on the dash rebuild.

You first need to remove the light switch from the top left on the dash. In order remove the switch you will need to reach (up) behind the dash and locate a small push switch located on the top of the light switch itself. Before pressing the switch down, pull on the light knob as though you were turning on the headlights, then push down on the trigger behind the dash, and continue pulling the light knob which should remove completely from the dash.





Next move over to the wiper switch. Turn the switch as though you were turning the wipers on high. Once there, peer behind the knob and you will see a small standard screwdriver slot; take a small standard screwdriver, turn to loosen the retaining screw (do not remove), and pull the knob off once it is loose.

[72BlckButy]

Now you need to remove the small bracket holding the rubber seal on the steering column. Use a phillips screwdriver to remove the two (2) screws attaching this bracket to the dash.





Once this bracket it out of the way, you will then take a 1/2" socket and loosen (do NOT remove) the two screws pictured in the second picture below. If you refer the the first picture, you can see an oblong opening in the center of the rectangular bracket; use your 1/2" socket to loosen the two screws holding the steering column in place. You do not want to remove these as you are simply looking for the column to drop enough to allow easy removal/installation of the gauge panel.





While you're under the dash, you will want to go ahead and remove the oil pressure line and the speedometer cable. Using a 5/16" line wrench you will remove the oil line running into the back of the dash, and then reach up behind the speedometer and remove the speedometer cable. You will also need to remove the shift indicator light from the back of the dash. It is located on the driver's side of the rear tin and is the only light which contains a wire lead.

Now that there isn't any additional connections on the dash, you will proceed by removing the six (6) phillips screws holding the gauge panel to the dash. There are two (2) screws above each turn signal openings, one (1) to the left of the ammeter gauge, one (1) to the right of the oil pressure gauge, and two (2) screws at the bottom of the panel below the temp and the 'open' gauge. Now that there isn't anything holding the panel to the truck, begin by removing the panel from the top side first. (Note: If you have a tach dash currently, make sure to pay close attention to the tach/circuit board as they are the items that stick out from the back of the dash the most.)

Once you have this done, you will with up with the following pieces having been removed. (Note: If you notice, you can see the open light socket which contained the shift indicator light described above.)

[72BlckButy]

Now that you have the dash removed, it is now time to start changing over the pieces to the freshly painted tach tins. If you do not have a spare set of tins, simply follow the steps below, repaint, and assemble as described below. You will need to find a clean and open space for the tear down as parts will begin to pile up as you start the tear down process. You will also need to document the disassembly as you will reuse many of the parts from the old dash.



I felt it was important to retain the integrity of the original circuit board so I removed that was my first priority.

Follow the next few steps to remove the circuit board:
- Loosen the screw/washer connections (ammeter, fuel, temp) on the circuit board
- Remove the eight (8) light bulb retainers
- Remove the final two (2) screws holding the circuit board to the dash

[72BlckButy]

From this point forward, I did this in four different stages. Since I had my tach tins already painted, I simply removed one tin at a time and swapped the gauges and necessary connections over as needed. I started with the fuel tin, followed by the oil pressure tin, then the ammeter/temp tin, and finally ended with the rear tin itself which houses the speedometer. If you need to paint the tins, document the disassembly and proceed as needed.

We will start with the fuel tin. Remove the three (3) retaining screws and then remove the tin.



Once the tin is removed, grab your freshly painted fuel tin and proceed with swapping over the fuel gauge to the new tin. I wanted to keep everything in order in terms of how the pieces come off the original tin so I layed everything out and made sure it went back together in the same fashion it came apart.

[72BlckButy]

Before I continue covering the tear down of the gauge panel, I want to reference the process of repainting your needles in the event your needles have faded over time.

Start off with a guage, a pair of scissors, and a few sheets of white paper.



Take a sheet of paper and fold it in half, and cut off a triangle section from the center of the paper like picture below.



Proceed to slid the paper under the needle you need to paint as pictured below and then repeat the process described above on a second sheet of paper to completely surround the needle.





Shoot a couple of light coats of paint from the color of your choice. Allow proper dry time as needed. You can also use a brush on style paint, but you will need to ensure you 'load' the brush with enough paint so it won't leave brush strokes on the needle.



Repeat as needed for all needles that need repainting. I would recommend that if you're going to repaint one needle, to repaint them all so they match.

[72BlckButy]

I will now pick back up with the 4-step process of swapping over the gauges to the new tins. I next went to the oil pressure gauge and swapped over the gauges in the same fashion as described above. Remove the one (1) retaining screw for the oil tin.





I then moved onto the ammeter/temp tin and did the same thing. Remove the three (3) retaining screws from the tin.

[72BlckButy]

Now that three out of the four-step tin removal is complete, it is time to move onto the final tin, the rear tin.

Proceed by removing eight (8) screws using the 1/4" socket and the remove the rear tin.









Once removed you can remove the speedometer from the rear tin and we're almost ready to reassemble the cluster. Now that the speedometer is removed, you will need to swap the light tubes, lenses and seals over to the tach rear tin like pictured below. FYI - the lense and tube located behind the speedometer is shorter and contains a red lense for the high beam notifier.

[72BlckButy]

Now that you have swapped over all the gauges to the freshly painted tach tins, you will need to pull out your new/original dash bezel. Once you have torn down the dash you will need to look for the six (6) rubber snubbers that are used to keep the dash from chattering down the highway. They look like the one below and are located in the locations referred to in the second picture.





Next you will take your new/original tach lense and place it in your new/old dash bezel as pictured below. If you are using a repop bezel/lense, I noticed a fairly snug fit which required a slight bit of pressure for the lense to be placed in the correct position like below.



Now you will take your freshly painted front tin and drop it in the new/original dash bezel as pictured below. I noticed the tin fit but seemed to raise up a tad in one area. Once the dash is together the separation will go away.

[72BlckButy]

In order to reassemble the dash, simply follow the steps in reverse order and take your time.

I would recommend replacing the light bulbs so you don't reinstall the dash and have a bulb go bad a week later.

I have included a picture of a partially completed tach dash as there was an issue with the tach at the time it was to be completely assembled.

[72BlckButy]

After finally tracking down the correct mounting location for the tach wire to pass through (thanks VA72C10) on the firewall. According to his build thread (here) [with pics here], the correct location is between the wiring distribution block and e-brake holes.

A quick call to lolife99 and a few weeks later, I was free and he came down with a uni-bit. If you've never used one of these and need to drill a large hole fast, this is the bit for you. It's actually a "step bit" containing several different diameters within the bit, which "step" up while continue drilling. The tach wire needed to be drilled to just at .75" or 3/4" diameter to accomodate for the rubber snubber on the wire. Here's a shot of the uni-bit with an extension and of the gradual drilling process.







The end result will look like this, although it is roughed in at the moment. A little clean up under the hood and we'll be good.

[72BlckButy]

And... who needs a picture of the end result? Why not a video?



Now get out there and in the words of a great board member (see ten)... get-on-it-dog-gone-it!