Ever since I have owned my 89S4 auto the radio has been quite bad, it forgets the radio stations and the speakers flap about which sounds like a lot of the presenters are passing wind. I thought it was about time to update it and do it on a budget. I expect I could have spent much more on it and included amplifiers and replace all of the speakers with components sets. I decided to replace 4 speakers, the 2 10cm speakers in the front doors and the 17cm speakers in the rear behind the seats, remove the old amp if installed and power the speakers from the head unit. The Apline speakers came to £75, the Kenwood radio was also around £75 and then I spent about £20 at Maplins.

I needed;

  • Phillips screwdriver
  • Small flat blade screwdriver
  • 10mm socket and extension bar
  • Wire cutters and strippers
  • Crimping tool
  • Speaker wire, red and blue spade ends, bullet connectors or terminal block, project box (to hide the connections from old to new speaker wires) and some heat shrink insulation.

Disconnect the battery

I had to remove the old radio but didn’t have the keys so I took the dash centre console apart and removed the carpeted panels from the sides so that I could use a screwdriver to release the radio from the cage. I found a small box with a modern din connector at one side that connected into the din of the radio and at the other end was the original connector that goes under the carpet to the amp by the passenger seat. There are guides about how to take the console apart so I won’t go into that now, I will cover the door and rear speaker install.

Each door has a couple of Phillips head screws and 10mm bolt head screws and the driver has the mirror and seat memory controls, there are also guides for this, but I will just go over it quickly. The old speaker grills can be removed carefully with a flat blade, protect the vinyl or leather as you do, then you can unscrew the old speaker and save it for later. At this point I tested the new speakers for fit and found that the holes lined up and the depth was ok. If you wanted to use the old crossovers and amp you could just connect and screw in the new speaker without removing the door panel, but I want to bypass it all.

Remove the door handle screw and the plastic bit comes out with a bit or wiggling, then unpop the trim panel at the top edge and it then lifts out, proceed to undo the screws as shown;

Porsche 928 radio upgrade - trim panel screw locations

All Pics: Mike P

When the door handle section is loose it lifts up slightly and then comes away at which point you can reach behind and pop the modules out for the mirror etc and disconnect the plugs, be careful as the plastic clips holding them gets brittle.

Porsche 928 radio upgrade - trim panel disconnects

Around the edge of the door and in the centre there are trim clips, these pop out with careful persuasion, the panel then lifts up and towards the front of the car as there is a small metal hook that goes under the small panel left by the door pin.

Disconnect the wires from the crossover as these will be used for the new speaker.


Porsche 928 radio upgrade - speaker locations

Ignore the black clips around the speaker, I was on a learning curve and didn’t use them in the end.

The old speaker needs to be cannibalised so that the original grills can be used again, basically cut the cone to leave a plastic ring. I used a rotary tool and a miniature circular saw. The ring then fits over the new speaker and the screw go through both and fix to the original clips, connect the old crossover wires to the new speaker.


Porsche 928 radio upgradcannibalising old speakers

The wiring convention seems to be brown for negative and a colour for positive, so you can make a note of this as you go, but if the original amp is still be the seat there is a sticker on the top which describes the connections and therefore colours or wires to the various speakers in the car.

Fit the door panel back on and move to the passenger one. This is the same except for the mirror and seat memory control.

The rear speaker grills will also come off with a flat blade, and then four screws. There are a couple of 4 way molex connectors one coming from the amp and the other going to the smaller rear speakers. The 4 wires coming in are the pairs from the amp, so we can cut two back, cut the molex off and fit a blue spade on the coloured wire and red on the brown. Make a note of the wires as these will correspond with the old amp.

I used the old speakers and cut the cone again so that the new speaker fits behind it and then I drilled 4 new holes, used the metal clips and just held them in place and screwed the new speaker to the plastic ring. I found I had to mount the speakers upside down so that the speaker wire connections didn’t foul the bodywork; I used heat shrink insulation and stuck some plastic to the metal where they might meet the speaker connections.

Porsche 928 radio upgrade - rear speaker locations

I removed the old amp and cut the plugs off the wires I am to use to connect the old speaker wires to new from my notes. I left two alone as I won’t be usingthem. You cold use bullet connectors here, but I used a terminal block, stripping and tinning the wire ends before screwing in place. I ran 4 lengths of speaker wires in place of the old radio to amp lead, by cutting the end off and taping the new wires on and tried to pull it through, but I found I had to take up the floor mats and carpet and remove the plastic cover in front of the seat. The wire is held in by some clips so these need to be opened up and the wires threaded through.

Again I tinned and connected them to the terminal block and encased it all in the project box. At the other end by the radio I cut the connector off the old converter box and wired that to the new speaker wires in the same way using terminal block, checking the continuity so that I got the correct front left and so on in the right place. The connector is modern coloured wiring compliant so it was easy to get the wires in the right order. The benefit of this is if in the future I decide to replace the head unit, it will just be a straight plug in job. The only other bits to think about are the permanent and switched live the aerial amp and earth from the original connector (not the new radio from PO). This had already been changed and bullet connectors used so was a simple matter of plugging in the right one, referring to the head unit manual (yellow and red). I used the switched live already present and as I mentioned before the old radio forgot its settings and although there was a permanent live wired in there wasn’t any voltage. I guess it could just be a fuse, but as there was permanent live at the amp position I just ran another wire from there. I used the blue ‘remote’ lead to connect the aerial amp and the earth was already provided.

I tested the setup before putting the radio in place (and this was how I found there wasn’t a permanent live) and I had the rear left and right round the wrong way, but was a simple matter to fix at the terminal block.

I also replaced the old broken LCD clock with an analogue one while I was there, the connections are different, spades on old and plug on new, so I had to cut the spade connectors so that they fitted over the pins, and thanks to the list I learned the pins, from top to bottom, earth, blue black (lighting) and red (live).

It looks far better as I hope you will agree;

Porsche 928 radio upgrade - finished and working


The sound quality is much clearer, but because the speakers are fitted to trim rather than bodywork, the bass is not very strong so I will probably add a speaker level input self contained bass unit in the future. It should be very simple to connect it at the old amp position as there is a switched and permanent live along with the speaker wire junction box.

Mike Parris ’89 S4 auto – Forest Green Metallic.


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