This job was inspired by SteveT, who added an oil pressure gauge to his first GDI and did all the legwork in establishing what parts were needed. Steve relocated his clock and added the oil pressure gauge in the centre of the dash. This has been on my list for a long time. I wanted to add an oil pressure gauge and also a voltmeter, because I like the four-gauge set up on my Roadster.

Ordering the parts from Holden Classic was simple enough, thanks to the parts list supplied by Steve.

I decided to go for a twin binnacle but locating this was a bit of a challenge. I decided that it had to be under the dashboard, and close to the centre line of the dashboard. However, certain things come into play. Visibility is one. A test fit showed that centre mounting concealed the offside instrument behind the steering wheel. Not only that, but the gauges had to be located far enough back under the dashboard to allow 1st, 3rd and 5th gears to be selected. The 12v socket was in the way and so needed relocating. Thankfully the diagnostic port was far enough back not to be a problem. The last consideration was sufficient clearance for the handbrake. These three factors meant that only one position works.

Next, I considered the electrics. To have the panel lights on with the ignition simplified matters. I needed a 12v ignition switched supply to both panel lights, and both gauges. Distribution blocks are available, which are simply 4 male spades joined together on a plastic base. I obtained one with a 4/4 split, so eight terminals, which allowed an easy distribution of 12v supply and earth.
Under the dashboard are a number of spare spade connectors, and I located a switched live (white/green tracer) in the offside corner. I ran a feed wire from this connector to the centre of the dashboard, having added a heat shrink cover and threaded it through all the cable ties so that it looks original.

Each panel light needs an earth as does the voltmeter. The oil pressure gauge earths through the sender, and so this needs a feed from the gauge down to the oil filter housing. The 12v socket under the dashboard has two spare spade connectors off the loom. One is permanent live, the second one is earth, and so that was my earth return.

My first job was to remove the oil pressure light sender from the filter housing and replace this with the T piece. I added a smear of thread lock. Access is quite fiddly, and it has a fine thread, so care is needed. The side hole which takes the new pressure gauge sender must be at a certain angle to fit, again with a fine thread. The original light sender locates in the end. I decided to run the first length of wire from the sender to a waterproof connector at the top offside bulkhead corner. This is where the electrics pass through the bulkhead. I wrapped the cable in heat shrink tube and threaded it along the existing cable run, through the cable ties. All connections were soldered. Where a male and female spade were used, I added a wrap of plastic tape. Red for live, black for earth.

I dropped the aluminium panel from under the dashboard. It is held in place with around 8 small crosshead screws. Before sliding this out, with the steering column fully depressed, I removed the diagnostic port (two plastic clips), disconnected the 12v socket (T shaped spade block), and removed the dimmer switch (grub screw in the knob, standard switch nut and star washer fixing it to the under-dashboard panel). Once on the bench, I drilled four holes in the marked locations to attach the instrument binnacle and cut a new hole for the 12v socket just over to the nearside of the original position. The wires are plenty long enough to do this. The instrument binnacle is a standard black finish metal pressing, but I decided to give it a casing. I didn't have the right thickness of aluminium on hand, so used a piece of stainless steel. Cut to size, leather trimmed, and held in place with two pop rivets into the front metal pressing.

Next, I extended the oil pressure sender feed by adding a cable from the waterproof terminal at the bulkhead corner. I threaded this through the existing large grommet by first inserting a small-bore nylon tube, passing the feed wire through this, then removing the tube. A splash of Captain Tolley's was added just in case! This cable, covered in heat shrink tubing was threaded through the cable ties under the dashboard. While all this was in play, I dropped the dashboard and checked for any signs of leaks. It was totally dry. I lubricated the heater mechanism while access was easy.

With the binnacle fixed in place on the under-dashboard panel, the cables passing through the old 12v socket hole (now grommeted), all the was left to do was offer the panel up, refit the dimmer switch and diagnostic port. Refit the 12v socket into the new location and connect the live feed and earth to the spade connections noted above. The one thing I had missed was that the sender cable would have to be passed down through the grommet into the binnacle and connected up. That was tricky in the confined space.

On starting up, all was well, although the initial pressure reading was very high. After a full warm up cycle, tick-over is around 30psi (2 bar), revving around 80psi (5.5 bar). I'll become more familiar with what to expect with some road mileage added.

So here are the images: Oil filter housing with the light sender unit disconnected.



T Piece and feed cable added.



Location of the waterproof connector.



Reference of the underbonnet panel.



Binnacle and 12v socket'



How it looks.




The voltmeter steamed up immediately on starting!

Top job!

Great work as always Dave. I know it is sad but I miss the oil pressure & volt meter on Belle. I guess because sports cars in the 60s had them.

I decided to put a voltmeter on my Roadster ( series 3 ) and opted for the spot normally occupied by the clock which was a simple solution. On the Plus 4 I moved the clock to a small black box in the glove compartment.

Good work Dave

If the instrument misting remains you might try LED illumination allowing a choice of colours.

Nice work as always Dave!

Nicely integrated Dave

Thanks 👍👍👍

Stefan

Here's the parts list from Holden:

070.152 Rim Full Vee for 52mm Gauges - Chrome (replacement outer rims)
070.006 Smiths Classic Oil Pressure - Electrical
070.026 "T" Piece adaptor1/4 in NPTF
070.185 Oil Pressure Sender 1/8 in NPTF
070.009 Smiths Classic Voltmeter
070.158 Bracket for two 52mm gauges.

Hell Dave, you are a glutten for punishment but, as usual, a totally professional job. Well done, now of course you will probably sell the car and by something else to play with.!!!