VDO Gauge Panel Build - Using factory housing - 86 C20 Suburban

[cal30_sniper]

Hey all,

I recently finished swapping a GM NV4500 transmission into my Suburban, and was left with the dilemma of how to get the speedometer to work with the electric sending unit on my new transmission. Given the fact that I have never been too impressed with the factory gauges (other than the layout), lacked an in-dash tach for my new manual trans, don't like the fact that I only had an 85 mph speedometer, and was never liked the factory lighting, I figured it was time for a complete upgrade.

After a lot of research, I decided to go with a different route than most folks who upgrade to autometer aftermarket gauges bolted to the back of the dash bezel. Instead, I decided to dissect a factory gauge panel, and use VDOs new spin-lock gauges to build an entire panel that would bolt in place of the factory gauges, allowing for easy removal of the dash bezel in the future, and maintaining the ability to remove the instrument panel as a component rather than individually disconnecting and removing the gauges if necessary.

The following is a write-up of how I did it...

First, the part list:
-Guage panel from a 70s squarebody that has a black metal gauge face instead of the plastic put in later gauge panels. Look for one with a mechanical oil pressure gauge, that's where I found one with the metal face.
-VDO Vision Series 2 1/16" Water Temp Gauge, Summit # VDO-3101051
-VDO Vision Series 2 1/16" Oil Pressure Gauge, Summit # VDO-3501041
-VDO Vision Series 2 1/16" Voltmeter, Summit # VDO-332103
-VDO Vision Series 2 1/16" Fuel Gauge, Summit # VDO-301106
-VDO Vision Series 4" 120mph Electric Speedometer, Summit # VDO-437155
-VDO Vision Series 4" 8k rpm Tachometer, Summit # VDO-333160
-Painless Wiring .312" Blue Warning Light, Summit # PRF-80206
-Painless Wiring .312" Red Warning Light, Summit # PRF-80204
-Painless Wiring .5" Green Warning Light, Summit # PRF-80210
-Painless Wiring 15 pin Quick Connect Wiring Kit, Summit # PRF-40012
-Assorted Color Electrical Wiring (I used some old burnt out turn signal switch harnesses, as well as some other assorted stuff I had lying around to keep the colors different)
-Female Electrical Connector Spades (lots)
-Small Zip-ties

Tools Needed:
-Soldering Iron
-Wire Pliers
-Dremel Tool with assorted grinding and cutoff attachments
-Drill w/ 5/16" bit

The Process:

1. The first step was too completely gut the donor instrument panel of all gauges, circuit boards, light sockets, etc. All you will need to keep is the white plastic gauge housing, the black metal housing face, and the clear plastic lens, as well as the screws to put those back together.

2. Once you have it apart, you are ready to start working on the metal housing face. As it sits, the speedometer, tachometer, and both green indicator lights for the turn signals will fit in perfectly. The Speedo and Tach are very, very snug, but they will go in. Here's a picture of the turn signal indicators and tach test fit into the housing with the spin-lock installed, front and rear:




It's not necessary to install anything at this point, you will just have to take them back out to do the dremel work for the smaller gauges. On to that... The smaller gauges (2 1/16" diameter) are slightly oversized for the panel, which has about 1 5/16" holes in it for the four smaller gauge spots. In order to correct this, you are going to need to slowly grind out the holes until the gauges fit snuggly. I accomplished this by placing the gauge on top of the panel, and marking the outline of the base with a sharpie. I then slowly ground out until I had reached the mark, test fitting periodically until it fit right. The picture below shows one installed gauge, a modified hole, and two unmodified holes above:



Once all the gauges are fit and properly aligned, go ahead and clamp them down with the spin locks. You are now ready to move onto the next step, modifying the gauge housing so that the larger than factory gauges will fit in, and allow the wiring to pass cleanly through to the gauge terminals.

3. I used a dremel and cutoff wheel to remove the plastic bosses inside until the gauges finally fit all the way in. I also cut access holes in the back for the wiring to run to the gauges. Once satisfied, I used a grinding wheel on the dremel to smooth everything up and get rid of the melted plastic around the cuts. Please note, I left as much of the plastic inside the housing as I could, so that it would remain as rigid as possible. The following two pictures show the finished housing, front and back:




And the housing with the panel and gauges test fit:


Test fit of bezel over gauge panel:


4. Once satisfied with the housing, you're ready to modify the lens. Given that most of these old lenses are pretty scratched up or discolored, and would greatly take away from those shiny new gauges, I had originally planned to just get rid of it completely. However, I realized that I could retain part of the lens to cleanly mount the Emergency Brake and High-Beam indicator lights where the gear shift indicator used to be. If you're doing this mod to an auto truck, you'll have to figure out a different place to put these. I cut the lens in half, keeping only the part that covers the speedo and tach, leaving it with four bolt attachments. I then cut oversized circles where the speedo and tach were, allowing the lens to stay in place without being visible. I then used a drill to put two 5/16" holes in the shift indicator part of the lens where I wanted the two indicator lights to be. Once satisfied, I painted what was left of the lens flat back, installed the lights, and put the entire gauge housing back together. The photo below shows what it looks like:



5. Now you're ready for the hard part: wiring. Take your time, draw a diagram of what you want running where, and carefully tuck the wires as close as possible to the back of the gauge panel for a clean result. I used different colored wiring whenever possible to keep things from getting too confusing. Here's a photo of the back of the finished housing, with the 15 pin connector soldered on:



You'll also want to cut out the factory wiring connector that used to fit into the back of the old housing, and wire in the other end of the 15 pin connector. Here's where it gets tricky, as you'll have to break out the factory wiring diagram and figure out exactly what goes where. Once you've checked and double checked your diagram for both sides of the 15 pin connector, go ahead and finish soldering in the dash side. Also, it might be a good idea to leave several inches of wire attached to the back of the connector in case you ever want to solder it back in and go back to the factory gauges. Here's what the dash side of my wiring ended up looking like:



6. Its all a matter of putting everything back together, changing out the oil pressure and water temp sending units, running the wires for the speedometer and tach to their senders, and testing it out. The following pictures show different stages of reassembly, as well as the finished product. Once it gets dark out, I'll get a picture of the night lighting. I installed all the gauges with the red covers installed over the bulbs. I also found some red bulbs at Autozone that fit my extra autometer gauges and the the bulb for the heater/AC controls to give completely red night lighting. I took this cue from the instrument panel in my '88 GTA, as it makes it much easier to drive at night. Another huge advantage of the VDO gauges vs Autometer is the gauge lighting. Rather than illuminate the face ala Autometer, VDO actually uses through the face lighting to illuminate only the pointers and numbers of the gauges. It results in a much, much cleaner looking panel at night.

Housing installed in dash:


Test fit of bezel:


Finished Product:


All in all, I'm very satisfied with the result. All of the gauges function flawlessly and appear to be much more accurate than the factory units. Night lighting is unbelievably better. I'm still fine tuning the speedometer (which is very, very easy to calibrate), and I also need to get the cruise working again. I'll be using a DRAC box out of a 90 Suburban, as well as a spare Dakota Digital signal converter box I have laying around to wire up the cruise. I'll try and remember to post a write-up on that as well when I get it properly working...

If I had to do it all over again, I would change only one thing. The High-beam indicator light is too large/bright at night. As is, I will probably just make a plate to cover it up, using some sort of high beam indicator and parking brake shine through I source from the junkyard. I may also simply figure out some way to tint the light so its less bright. That's about my only complaint with the whole setup though.

Plan on a weekend to get it done right. After that you'll be cruising with an even bigger smile on your face than normal.

-cal30sniper