Shawn D.'s E28 Gauge Panel Bracket Modification, Wiring, and Installation Notes
This page was last updated on 16 Sep 03.

Angle Rings

The angle rings will be firmly sandwiched between the gauge and the panel once the gauge mounting nuts are tightened. They do not need to be attached to the face panel by glue, epoxy, etc. The angled holes in the panel are drilled for leftward-only tilt, relative to the plane of the panel; the gauges will obtain their upward tilt by the position of the gauge panel once it is installed in the console.

Bracket Modification:

The bracket legs need to be cut to allow the bracket to conform to the gauge angle, and the center section must be modified to allow adequate clearance for the wiring terminals.

Cut and trim the bracket legs. Use a hack saw and flat file.

In order for the bracket to clear the electrical connection studs, modify the center section so that there will be at least 1/16” clearance between the power and/or sender terminals and the bracket when finally assembled. Use flat and rat-tail files.


Use brass machine nuts and lockwashers to install the gauges into the panel, and cut the extra stud length flush with the face of the nut (cover the open holes in the gauges with tape). Use a hack saw or a Dremel with cutoff wheel.

Wiring:

The wiring is pretty straightforward, with the only caveats being that the wiring studs and light holders must be modified.

For ease of installation and access, I used a 6-pin Molex connector from Radio Shack between the gauge panel wiring and the wiring that goes to the senders/power/ground/lighting; for setups with full-electric gauges and a switch panel, you will have seven wires, so I’d suggest running the ground wire outside the connector.

The wire terminations for the gauge panel side were all #8 ring terminals for the gauges themselves, with butt connectors to wire the lighting in parallel, and (for switch panels only) flag terminals for the switch. The wire lengths for the gauge panel side of the connector were about two feet.

The chassis side connections and wire lengths varied (as noted below); these lengths might seem excessive, but you’d rather you have to cut some off instead of coming up short, and your wire routing might be slightly different than mine. You could run the chassis-side wires, then terminate both ends in-car, but I think it’s easier to assemble the chassis-side connector out of the car and then feed the wire thorough the firewall.

I used 16-gauge wire for all circuits, but only because most of the wire colors I already had were in that gauge, and the other colors I got for free were in that gauge also. I’d suggest you stick with 16-gauge for the power and ground connections, but 18-gauge will be fine for the lighting and senders.

 ColorFunctionConnectionLengthComment
 Whitelightingbutt or splice2’to grey/red or brown/white wires in center console area1
 Blacklightingbutt or splice2’to grey/red or brown/white wires in center console area1
 Red+12Vblade or bare3’ or 6’to aux fuse box (under hood)2
 Brownground5/16” ring2’look for existing under-dash ground points above the OBC/door chime
 Yellowoil temp#10 ring10’use a shrink-seal terminal for weather resistance
 Light Bluewater temp#10 ring10’use a shrink-seal terminal for weather resistance
 Purpleoil pressure#10 ring10’use a shrink-seal terminal for weather resistance

1Lighting is drawn from the radio, HVAC, or cigarette lighter lighting wires, which are grey/red and brown/white (on my ’86, at least). I had installed an aftermarket radio, so I had my radio lighting wires free and I simply used a butt connector, but you could use a splice connector for wires which are still in use. Polarity doesn’t matter with the lighting connections.
2For power, I am using the auxiliary fuse box under the hood (next to the main fuse box); the green wire is switched power. I suggest wicking some solder into the exposed wire end before tightening the hold-down screw onto the wire.

For the outer two gauges, you will have to shorten the light holders so that only about 1/8” of the rectangular part remains, then bend the exposed connectors inwards (towards the center gauge). I used a Dremel with a #199 bit. Be careful -- this area is delicate! I didn’t insulate mine, but I am using heat-shrink tubing in production.

  

Once the wiring is attached to the gauges, cut the extra stud length off the outer two gauges; I used a Dremel with a cutoff wheel. Do this a bit at a time since the studs can get quite hot, and it’s conceivable that the heat could damage the gauge internally.

I ran the wires to the left of the fan housing, under the fan opening. The wires can “swoop” under easily and not be seen. Then, the connector is positioned in the vicinity of the A/C thermostat. I ran the chassis wire harness over the steering column brace, and through an existing hole/grommet in the dash where there’s a black hose-looking conduit with a red stripe on it. This comes out under the hydraulic pressure distribution block (on M30-engined cars, that is) and it’s hard to see, but there are limited pass-through options in our cars.

Mechanical Pressure/Boost/Vacuum Gauge Line Installation:

For those with a mechanical gauge in the center position, the basic line routing follows the same path as the wiring, with the exception that I installed a bulkhead fitting in the firewall, above and aft of the under-dash terminal block.

  

Installation of The Grille into The Console:

Installation of the assembly follows the reverse of the grille removal procedure, with one exception:  modification of the A/C fan housing.

The big issue in the installation is the possibility of needing to dent the A/C fan housing. Until you test-fit the gauge panel, you won’t know whether you have the required clearance –- all cars are slightly different, and I only had to do this on the driver’s side. Remove the rubber/tar-like insulation and gently heat the plastic with a propane torch, keeping the flame constantly moving while you test the pliability of the plastic. I had to dent mine about ½”, and used the handle end of a ratchet, angled to match the angle of the gauge bracket. This picture was my initial effort of about ¼” depression (with a straight-on push with the handle), but once the dash was back together, I could see I needed more, as the gauges kind of bowed-out a bit.


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