Rusty rear arch thread

I thought Id start this thread to see what peoples experience with rusty rear arches was. I have some on mine that I plan on getting dealt with in the new year and having looked around it seems more prevalent than I thought. I even bought a 911mag this weekend and lo and behold the editors 996 C2 was in for rear arch rust repairs. So just wondering what issue people have had and the extent of the repair? Not wanting to put anyone off the cars but it would be good to help others to look in certain areas to mitigate or prevent this from occurring. From the info Ive found the rear wing and inner arch have a double skin join at the outer lips and this is where the rust is occurring. It would appear that once its started bubbling on the outside then its most likely a cut out and replace job for theses sections. I bought mine with some bubbling which hasn't got any worse but I just wanted to check some surface corrosion on the very inner edge in the areas where it was bubbling. I wired wheeled in the arch and it was solid enough however where the bubbling was on the outside the metal arch was weak and I managed to crumble in my hands. See pics below. You can see there is very little bubbling on outer paint. My car was a daily car for about 7 years and so has been used in the winter. I will get this fixed but I just wanted to know or use this thread for others to get some tips to prevent this from happening and what to look for so please share your experiences.

No worse than any other car of this age TBH, double skin rear arch repair is bread and butter for body shops. They will of course add P-tax. Depends how perfectionist you are but I would buzz that off, POR15 cavity wax / waxoil and run it daily. I would return to it in a few years (if the 996 booms in value) and have new metal welded in. You are in for some chopping and welding and a rear 1/4 repaint to do it properly so may as well let it get a bit worse! If you do the above it should put if off for a good few years, but I know many couldn't sleep at night knowing it was there.

Ive pretty much done that already in the mean time so I can still use the car if I want to. Other than those bits its solid. Justy wondering if others have had this and to what extent they have gone to repair.

I've had a fair amount of metal cut out of both rear arches and the sill and new metal welded in recently.... anyone looking at a "blister" on their arch and just thinking it is candidate for "minor paint correction" is pretty much deluding themselves i.e. nothing lasts for ever, but if its worth keeping you remove the rot and put new metal to effectively ensure that it does (the 996 has done pretty damned well on the whole considering its origin story, age and amount of use!) Not cheap, but not horribly expensive, particularly if you plan the work logically so that you're repainting a good sized portion of the car each time, but not going back over the same area in the near future Cheap repairs dont last. Nether do good ones, ultimately, but they last a hell of a lot longer. Obviously take advantage of every modern environmental protection you can now apply. Annoyingly Porsche dont offer factory repair sections for the 996 equivalent to older cars - all you can basically get are some short multi-layer sill sections.... or the entire side of a car! FYI - remove the rear inner wheel well splash/mud gaurds before you make a full assessment - in my case, mud had been flung up and over the offside rear one, blocked the drain hole at the rear of the sill and then allowed moisture to sit against the metal....... that side was BAD! :sad:

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Ive had both arch liners out a few times to clean out and everything else is fine. Speaking to a guy I know on a local forum about doing the bodywork and they have some new stuff that I might get them to spray in rear arch and under the body. I am needing door shut + sills repainted as well so it will be rear 3/4's at a minimum and probably both doors to blend in. Front bumper also need done so looking at most of the car. As said its maybe best to get it all done at once hence why Im looking into new bumpers and the skirts. Have you guys used anything in particular to protect yours since being repaired?

I removed all underbody plastics and wheel arch liners this summer and gave it a thorough clean and inspection. Thank fully the summer was so warm and dry, I was able to take my time. There was some very isolated bits of rust which I cleaned up, treated, and then smothered the whole area in Dynax. As mine is a 2002, and not as old as yours and was a Summer/weekend car since about 2012, it hasn't deteriorated anywhere near to the point where it needs metal cut out. Hopefully the liberal amounts of Dynax I applied will keep it that way for the foreseeable future.

Are rear 1/4's and tubs not available new? Tubs shouldn't be too hard to fabricate but I'd like a 1/4 panel to be right. 1 of my arches has a bubble but I've not had a chance to investigate. I'm guessing as I have skirts the sills will be a little worse for wear as well. I'll just be tidying up and going for a full paint job in 2/3 years at a guess. I'd like a new panel as it's obviously a better bet for the future. 1/4 panels should be easy enough to get from breakers and the likes. This is of course, I don't sell it but it's always been the dream to get a 911 so it'll not go anywhere anytime soon.

Mine had a little surface rust on the arch lips but I was able to prepare it and seal it again. Behind my N/S plastic splash shield actually needed some welding, afterwards I filled every grommet I could remove with Waxoyl.

I'm surprised at this and I'm used to welding 70's Alfa's back together! I suppose even galvanised metal doesn't last as long as you'd hope. A lesson to all, get all the wheel arch liners and under trays off, pop all the rubber grommets and get protecting. I've used lots of stuff over the years but prefer Dynax S-50.

Mine is a 99 so an earlyish car. Also probably used in a reasonable amount of winters. I think it will become more apparent as the cars get older, I asked about this on a FB forum and there were quite a few that also had the same.

somebody else said it on another thread - are not all these 996 cars a rolling restoration piece ? I can see my car needs a few bitsof attention and these will be addressed in due course - - - ahh the joy of it all

I'd agree if its an early car, with a mileage reflecting use in all weathers. Theres always something needs attention! My heatsheilds are rattling... 20 years is good innings for holding back rust on salted roads.

...as car is cosy in the garage whilst wheels are being refurbished and I was fitting a Top Gear mild exhaust (thanks Craig)thought I would remove the ***** shields and inspect...given that I have previously restored both a mini and an early Mazda MX5 I know about sill and wheel arch rust... ...so fortunately nothing to report rear arches are as new ...paint shiny with no damage at all and bungs removed revealed as new innards with absolutely nothing to report...same up front so cleaned up, replaced the various trim clips for new ones and reassembled... Didn't take pictures because nothing to see...so I moved on

Decent coverage of this issue in the 911 & Porsche World magazine ....editors car so no holds barred and probably a good advert for the guy who repairs it ...!

Did anyone ever find out if a repair arch can be got? I remember someone saying years ago about using the arch out of a front wing to make the rear. That was a Different car btw

Seeing some of the amazing skills out there, I would have thought that a good body shop would be able to make up replacement sections as necessary. It is amazing how our expectations have shifted re rust. My first Mk 1 Golf was rusting along the leading edge of the bonnet after just two years. Now, a 20 + year old Porsche is just showing a bit of wear and tear.

Just reviving this thread as i'm preparing the car for Winter driving - I'm starting to get a few rust bubbles appear on the inside of the rear wheel arches - so have started to clear out all the silt, sand and crap in the wheel arches. Can anyone recommend a bodywork specialist that could preventatively treat the arches to stop them from getting any worse - ideally in North London/ Herts area. Or do I just douse the whole area in ACF50 and carry on driving?