Porsche Enthusiasts Club Forum

My 944 has a couple of small rust patches around the rear quarter just in front of the rear wheels and another patch behind the drivers side rear wheel. To fix it I had to remove the side skirts, rear diffuser and do a little welding. Thankfully the rust was not too bad, and the sills were in good condition. The biggest issue was the number of seized nuts and bolts. The captive screws and plastic nuts that hold the side skirts on were all seized up, and now matter how careful I was (soaking in wd40 overnight, undoing them a tiny little bit at a time, back-turning etc.), I still managed to snap two of the captive screws. The captive bolts on the diffuser were also siezed up, causing the bolt to turn inside the diffuser. I did manage to cut the nut off from the inside, but I think the diffuser may be not be repairable. The allen screws that hold the diffuser to the plate under the exhaust pipe were also seized, and when I tried to undo the them, the captive nut turned. Old cars have different characters. Some are quite happy for someone to work on them, some aren't. This car is fighting me every step of the way. So what is going on? What does Porsche find so hard about creating a reliable captive screw/nut that does not seize up? I have worked on many old cars, some cheap, some expensive, but I expected better build quality than this. I understand that the 944 was assembled in Neckarsulm at the Audi factory - does this explain why the screws for the sideskirts are such junk? Does anyone know how to fix them when they snap off?

Same problems here ....

The skirts - well, let's just say that mine haven't been re-fitted yet, mostly as a result of some of the problems you describe. All of my threaded spikes are still there but without much thread at all, maybe not enough to grab the plastic nuts. I've considered grinding them down and using a self drilling self tapping bolt similar to those that hold the wings on and just smothering them with seam sealer. The biggest problem I had with the skirts was that the steel brackets riveted to the skirts had rusted away so I've re-made some others to suit,m but just not got round to jiggling with them.

The captive nuts on the diffuser - these are set in rectangular clips (a little like 'U' bolts) but are a sliding fit to accommodate any tolerance needed when fitting. Mine were so rusted I just gave up on them and used a drill to fukkemoff then banged what was left out of their setting holes in the body. ... However that gave me the problem of having the setting holes in the body (about 10-12mm square IIRC) which were clearly too big to be able to use a nut on, and it was too far away from the edge of the panel to be able to locate a washer AND a nut all while holdijg the diffuser and trying to get a bolt through ... I solved that particular issue by using a length of 2x20mm mild steel strip and drilling it to correspond to the holes on the diffuser/chassis. I welded a couple of 6mm nuts over the holes and was able to slide the strip into place from underneath then screw the bolt through into the diffuser.. Because the setting holes were quite bit it gave a reasonable amount of 'jiggle' to get everything in place before tightening,

HTH

Greg

Welcome to 944 ownership! On certain fixings Porsche didn't do much more than just use standard bits (along with many other manufacturers), and over the years they all rust...this is to be expected. However, in general I think Porsche did do a good job as many 944s are still around and on-the-road, when so many cars from the same period of time have simply rotted away and left for the big parking lot in the sky.

The captive nuts on the diffuser are actually very easy to obtain as they are basically the same fitting used in equipment racks and the like, so readily available from a number of suppliers.

I have successfully repaired a diffuser which had broken and rusty studs, I pulled them out, replaced them with stainless steel ones and epoxied them back in. Pretty strong and no more rust.

Also, using stainless steel self-tappers when refitting the side skirts should help too.

Really ? 25 years on and some fixing are rusty. You had the welder out OP, tack some new fixings onto the sills.

Have you looked at using Rivnuts to replace your broken fixings which are basically a rivet with a thread down the middle that you press into a blind hole. You do need a special tool to put them in but once you have bought it its worth its weight in gold the amount of times its got me out of the mire.

HTH

I think the OP's problem will be the same as mine in that the punching for the captive nut in that panel is square and the captive nut is mounted on a clip that fits in the punching, but that also allows it to be moved a few mm each way to allow for fitting tolerance. The punched holes are reasonably large, so not suitable for a rivnut. There's also the problem of access as there's very little wriggle room between the panel and what I think (from memory) is the bottom of the spare wheel well.

I think the problem is that I am quite spoilt by my Soarer - it is 21 years old and has no rust at all anywhere (and it is not pampered in the garage either!). Lexus build quality is something that nobody else was anywhere near in the early nineties. It is still a tank around corners (hence buying the 944), but on build quality it is much better than the Porsche.

Exactly - it is the clip that rusts and collapses. If I could weld a captive nut on, that would be fine, but there just isn't room. Are the clips available?

Great tip - cheers Greg.

Type 'rack captive nut' into the search on eBay...

Couldn't resist an opportunity to google something ...

I'll take your word that they are the same as the OE fittings, there was nothing left of mine when I'd finished... Can you push them into place from underneath then??

G

If you buy the right ones (thread wise), then yes they are basically the same as the OE ones. I used them to fit a diffuser on my first 944S and they worked fine. They easily fit from either side of the hole using a small screwdriver to compress the clip. I recognised what was needed as I have spent many hours racking up electronic equipment and that is what is used - grabbed a few and the job was done. Real cheap too..