924Board.org

xmcginness · Joined: 01 May 2004 Posts: 94 Location: Denver, CO

Hey so I have a '80 931 that's new (to me). I'm also new to Denver, Colorado where it has been snowing frequently lately. My 931 doesn't have a rear wiper. There's a silver plug in the glass where the arm would extend from.

a) has anyone ever had one installed?
b) did you have to take out a second mortgage?
c) where did you find it?
d) did you have it installed or install yourself?

Paul · Posted: Sat May 01, 2004 12:37 pm Post subject:

Welcome to the board!

The rear wiper is pretty easy to install mechanically. Watch Ebay or post in the classified section of this board.

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

The silver plug was originally black.

That being said, the rear wiper system is fairly easily installed. Porsche even had a kit at one time for what they called "inservice installation". Porsche included some admittedly poor instructions in the 931 Factory Workshop Manual. The kit is NLA (no longer available) but sets of parts that have been removed from salvage cars, and some car owners who remove them to try to save a little weight often sell them on eBay, or at auto parts swapmeets.

Expect to pay somewhere between $50 and $100 for most of the parts, and maybe another $30-35 for a new wiring harness (if it is still available from Porsche) if you don't get it with the parts kit you buy.

I wrote an article that was published in PCA Panorama about 10 years ago that explained exactly what you needed, listed the part numbers, and gave detailed installation and troubleshooting instructions.

You will have to drill one hole (for the wires to emerge from the left side rear interior quarter where they fit into the tube attached to the left side hatch frame.

The rest of the installation is a simple plug in, and bolt-on (even the wiring going to the main harness under the left side of the dashboard).

D Hook · Joined: 02 Nov 2002 Posts: 3158 Location: Omaha, NE

Gohim: any chance of getting you to post the article you wrote? I'm looking at installing a new harness because the new hatch I got came with the wiper but no harness or switch/relay. My '80 NA didn't have it orginally.

924guy · Posted: Mon May 03, 2004 12:31 am Post subject:

ive done this as well.. after sourcing the motor, i was able to scrounge up a complete harness , if i remember right it was in two sections. the 924 turbo factory manual has a step by step on this in the last few pages as a dealer add on.. i still had to improvise a bit as it wasnt detailed enough on the wiring connections under the dash. i added a relay and a momentary switch in the console to control it., though at some point ill add a capaciter so i get two or three cycles of the wiper with one press of the switch. i didnt want an on off, as its not really necessary... the hardest part was threading the wire through the tube that runs up the hatch side....
Also be aware that there are several different versons of the wiper motor. the only real difference (that i can find anyhow) is in the size of the mounting pins on the bottom. i have an early motor and a late hatch (from a 924S) and those pins are slightly short, i had to improvise here as well, and it does break free on occasion (ill have to extend those pins permanently some how eventually, or trade motors with someone who has a 944 unit.) so to save you some headaches, try and source the correct motor and mounting box for your year hatch...
_________________
Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

Sorry, I am not willing to post my article on installing the rear wiper on this message board. Some people on this message board have a different idea of what copyright laws mean, and I intend to keep control of my intellectual property.

In the past I mailed reprints of some of my magazine articles to a limited number of people who asked me to with the inderstanding that I will retain all the copyright protections, and that the articles would not be distributed to any other parties without my written permission in advance.

Someone, or some people did not follow my instructions, and posted some of the articles (I wrote an article on how to install the four wheel disc brake conversion as well) without my knowledge or permission on a/some websites (I believe that those sites are all closed down now.). Some people who are members of this message board were sent copies of the disc brake conversion article as well.

If you need a list of the parts with the part numbers, I can furnish that for you. If you need some help with some instruction on how to install or troubleshoot, I can help you. Or perhaps you can find a copy of the magazine with the article in it.

The wiring harness comes from Porsche in a single piece from wiper motor to the fuse panel and the switch. I have seen some used wiper harnesses for sale that are in two pieces because the Seller cut it (usually at the end of the tube on the hatch frame away from the wiper motor to remove the harness from the car). The correct way to remove the harness is to cut the connectors on the wiring harness at the wiper motor. When you install the wiring harness, there are NO CONNECTORS on the wiper motor end to allow you to run the bare ends through the tube on the hatch frame. After the harness and motor are installed, you are supposed to attach the spade type connectors to the three wires.

The motor has an internal diode and can be permanently damaged if you connect the three wires wrong. It is very important that you get the wiring connected right the first time. There is no second try with the same motor, if you connect it wrong the first time.

There are two different diameters for the motor shaft, and two ways to attach the motor assembly to the glass. The earlier design uses two holes in the hatch frame for two pins attached to the motor plate to slide into. The threaded collar around the motor shaft holds this design secure to the glass. Unfortunately, in some cases corrosion weakens the pins, and they bend, allowing the motor to shift around. The later design uses the smaller design motor shaft. This design uses two studs that are attached to the hatch frame to secure the wiper motor to the hatch with two metal loops that are part of the modified/upgraded motor plate. This is a more secure design, but requires the hatch frame with the metal studs, and a motor plate with the loops. These hatches can be installed as an assembly onto earlier cars, (and used with the same wiring harness), but the earlier cars cannot use only parts of the modified design.

The motor plates are available separately from Porsche should the motor plate get damaged (as in the case of corrosion of the attachment pins).

924guy · Posted: Mon May 03, 2004 6:49 am Post subject:

as i said above, ive got a 79 rear wiper assembly in an 87 hatch, it works fine 99% of the time.. once in a blue moon the pins will slip a little bit as their just slight too short.. i stick the wedge back in and im good to go ... mixing "part" years may not be optimal, but they will work if necessary...
_________________
Eric
78 924
82 931 SE "smokey"
99' VehiCross
Y2K Honda Insight
http://www.cardomain.com/id/924Guy
Performance by Pasha

xmcginness · Joined: 01 May 2004 Posts: 94 Location: Denver, CO

Thanks for the welcome Paul. Thanks very much Gohim and 924Guy for the information and taking the time. Been watching Ebay for parts. Keep you all posted.

xmcginness · Joined: 01 May 2004 Posts: 94 Location: Denver, CO

Okay, so last few months poured about 4k into this machine and register's still ringing on it -- just had the interior redone, seats, header, door panels after replacing tons of stuff generally located in the engine compartment hehe -- decided to chill on the wiper for now.

Wish me luck, still having troubles - see my recent post:

http://www.924board.org/viewtopic.php?t=11706