To do a neat job of installing a new radio it is advisable to remove the entire moulded plastic panel of the central console rather than attempt to make the cutout in situ. This will also allow you to make some improvements to the mounting arrangements as suggested here.
Remove the switch array lamp diffuser, which secures the upper part of the panel, and the heater control knobs and their escutcheon, which secures the central part. Remove the ventilator control switch and air conditioner control (if fitted). The lower part of the panel is secured by the cigarette lighter assembly and removing this can be the trickiest part. It is secured by a coil spring which is held in place by two clips which lock into the rear of the holder and these clips have to be disengaged by pushing them towards the front of the holder to allow the spring to be removed. Access may be restricted by a foam pad of heat insulation glued to the top of the cigarette holder itself.
The whole panel can now be eased forward sufficiently to allow all the wires to the rocker switches to be marked and removed from them. (Although there are connectors on most of the wires, the cable routing through the narrow slot between the two horizontal brace struts may preclude extracting them). The panel can now be lifted free from the console and all the switches removed from it. Any defective switches can be dismantled for service.
The standard 182 x 53 mm DIN-ISO 7736 autoradio cutout can now easily be made in the plastic panel, taking care to support it well as the material is delicate. I suggest making the cutout 1-2 mm above the original centreline to ensure that there is sufficient clearance between the bottom of the mounting chassis and the switch array lamp holder but the displacement should be kept as small as possible to minimise the encroachment of the upper part of the cutout in the strengthening bar near the top of the moulding.
Purists will want to replace the components as they were originally. Others may wish to replace the cigarette lighter with the more modern removable-element type which can also be used as a 12v access socket. I am a non-smoker (an anti-smoker, in fact) and preferred to remove the cigarette lighter entirely, to move the ventilator control to the central position and flank it by new accessory toggle switches.
Later production vehicles are equipped with a metal support bracket reinforcing the cigarette lighter mounting which is secured only by rivets on the lower flange. To prevent the bracket leaning forwards and so distorting the plastic facade, I secured it to the heating control bracket with small countersunk-head screws. I then secured an additional small metal panel behind this bracket, drilled with a smaller hole to hold the ventilator switch in its new position.
For aesthetic reasons I mounted the ventilator switch above the original centreline. The original switch knob has a moulded pointer which is far too small to be seen. After filing down the knob, I fitted it (by araldite) with a larger diameter pointer skirt which is readily visible and which covers the larger hole left by the cigarette lighter. Although the switch has 4 positions (Off-1-2-3) it may be noted that the fan has only 2 running speeds - positions 1 and 2 of the switch select the same speed!
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