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Steve Wright's Serious Moddin' - Cabriolet rear plastic window demister.

Alex

Nordschleife
Joined
6 Mar 2014
Messages
23,113
It's Friday, it's Sunny, Steve Wright's Serious Jockin' is on the Radio. There's only one thing for it - Serious Moddin'!

Yeah, yeah, I know......it's Friday morning, Steve isn't on the radio, but as a tribute to the legend that is DJ Silly Boy, I thought I'd do a serious moddin' thread in respect of such an asset to the air waves.

The 'heated rear window' mod for cabriolets with plastic rear windows.

One thing that's always bugged me with cabs are condensed rear windows (unless it's a glass screen with the usual heater matrix). I used to have a 306 cab and that had an electric fan in the rear parcel shelf that blew warm air on the screen when activated, so I thought I'd replicate something similar on the 996.

As you are aware there's a heated rear window switch on the dash that operates the hardtop heated rear window and the door mirrors. The twelve volt supply to the hardtop is through the passenger side rear location pin/socket for the hard top. Once removing the rear parcel shelf (4 plastic rivets along the top edge of the shelf), if you look at the socket where the hard top pin locks in, you can track the wires back to a plug and socket located next to the cabriolet ECU.

Rear shelf removed and heated rear window power supply identified:

4 plastic rivets holding the shelf in place.

1708680325262.png


Not the best photo, but the wire and socket can been seen here - red arrow and circle:

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When the heated rear window switch is pressed, this switches a 12V supply to the socket for a time period of approx. 10 - 15 minutes. I sourced a dual socket cigarette lighter extension lead from Halfords for a tenner that I could remove the cigarette lighter end and fit a pair of sheathed sockets that would connect to the power supply pins, ensuring I wired it up the correct way round - pos to pos, neg to neg.I now had a switchable pair of 12V cigarette lighter sockets in the rear.

Halfords extension lead:


1708681636076.png



As well as purchasing the above, I also purchased a couple of 12v fan heaters from eBay for £6 each:


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The stands slide off the fans but there's a raised up track on the underside for the stand to slide in, so I just hacksawed that off to make the underside flush so I could get better surface contact when I stick it to the shelf. Fan must be stuck to the shelf with the vent side on the outer side to be able to draw air in to avoid burning the fan out and allowing it to operate correctly (like the air intake on the rear of a hair-dryer).

Once plugging both fans in the extension socket and testing with the switch on the dash that they both operated correctly, I moved on to modifying the shelf to accommodate the fans. I did want to mount them on the outside of the shelf to prevent cutting holes in the shelf, but when the roof's down, there is no spare space there.
I marked out on the inside of the shelf where I wanted the fans locating, then with a Stanley knife, cut along the shelf horizontally, then a vertical cut at either end to produce a flap, rather than a letter box, so that if I remove the fans at a later date, I can fold the flap back and seal it up back to normal.

Parcel shelf with the flaps cut in and fans installed in position to check aesthetics:


1708683026167.png

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I wasn't to fussed about it being a super tidy job as the rear parcel shelf of the 996 cab is quite hidden, so not visible in the car or with the roof down and can only be seen through the rear window with the roof up. Once happy with the fans positions, I fixed them in position covering the full underside of each fan with double sided tape ( the slightly thicker stuff) and stuck them on the inside of the parcel shelf. Once placing the parcel shelf back in the car, I checked there was enough ventilation space around the inlet to the fans. Passenger side was fine, but driver's side fan was up against one of the relay/control unit boxes. I made some 1/4" thick aluminium blocks around an inch long and glued them to the outer face of the fan at either side of the inlet, thus holding the fan away from the electrical box to ensure adequate airflow in to it.

Did a final check with the fans plugged in before then securing the cigarette socket to the strengthened roll bar hidden behind the shelf.

Socket connected up and in location before securing:

1708683723443.png



Final dress rehearsal before putting the shelf rivets back in:

1708684065977.png

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All cables located correctly under the shelf as to not snag on anything then shelf repositioned in it's exact location and rivets refit:

1708684200579.png


Roof taken out of service position and locked back down with the anchor cables, then put in it's closed position to check out the view looking in from the outside:

1708684317724.png



Job Done!!

So I now have a rear window demister that operates from the dash switch :cool:

Had to nip out to Tesco last night for some supplies and an ogle at the chick at the filling station and due to the rain and cold, had quite a rear steamy window. Switch activated for a test run and bingo, within minutes a clear rear window!!!!! Started off looking like an old war movie when the geezers looking through his binoculars and the screen shows point of view, but doesn't take long to fully clear it. 🤩🤩🤩

1708686260305.png

Another successful mod I should've done years ago.

& one final comment:


RIP Steve Wright MBE 26 August 1954 – 12 February 2024
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Last edited:
nicely done Alex
 
Looks like it came that way - nice job. (y)
 
Tempted to see if I can rig something similar in the Boxster. but could be a challenge with the rear storage box and a large engine cover in the space. 🤔
 

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