Hatch sill rust... What are people doing about this?
 

My recently acquired GSL-SE is going well. Overall the rust isn't too bad. BUT living in the Pacific NW eventually takes its toll.

I happened to pull off the hatch seal the other day to see if there was an obvious reason so much water was leaking into the trunk. Sure enough, there are big chunks of the hatch sill missing due to rust. When I say hatch sill I mean the part that the seal slides on to.

Check it out:

Attachment 670210

Different spot:

Attachment 670211

Anyway... My theory is that over this car's 29 year life span that hatch has been slammed shut about 8,257 times. Paint probably chipped and boom, theres your rust.

I'm not as concerned about how this happened as I am about how to go about fixing it. At the moment I would guess that I'd want to cut the whole piece out and fab up a new one to weld in. Then coat the F out of it with some sort of industrial paint.

Is there a better way? Do body shops do this sort of work? Any locals around here (Portland) that would like to give it a crack? I've never welded anything in my whole life so I'm hesitant to jump into this one too quickly.

:scratch:

I would either weld in patch panels or use several layers of fiberglass mesh/resin. Either way get ALL the rust out first!

If you don't have experience with welding and you want to fix this yourself I wouldn't want to learn on a project like this. I have done some hobby mig welding for 16 years (little at a time) and the thought of working with this paper thin sheet metal makes me cringe.

On a side note, I only wash my '85 2-3 times per summer, but everytime I do I take the bottom half of that weatherstripping off, wipe dry with a cloth, and let the weatherstrip air dry before replacing. It seems like the water gets sucked up into/under the weatherstrip in the hatch channel. I wipe dry the sunroof channel too.....

You might not have to go as extreme as I did (see pics below) but the correct way to do it is cut out the bad areas and weld in a patch from a parts car, or fabricate your own piece out of some 20 or 22 gauge sheet steel...

In my experience (over 10 years of restoring cars as a hobby - most of it dealing with rust and bodywork) when rust has gone that deep into the metal, sanding/grinding it off and then using something like por15 to seal it up will be a temporary fix at best. Plus you are still left with a gaping hole in the metal to fill. Fiberglassing/bondo'ing that hole closed will again only be a temporary fix. It all depends on how long you plan on keeping the car.

Here is what I did on mine... On top of the hatch channel rot it had a dealer sticker above the driver tail light that had been removed at some point in the cars life which took all the paint off with it (previous owner didn't think to touch it up??) and it was rusted badly as well...

https://www.rx7club.com/attachments/...e-100_0247-jpg
https://www.rx7club.com/attachments/...e-100_0249-jpg
https://www.rx7club.com/attachments/...e-100_0252-jpg

Oh and jeremyferguson4444 has a good suggestion to dry that area as best you can after washing the car etc. Hard to do if you car sits out in the rain etc (like mine) but good advice either way.

The work above was done in 2006 with a flux cored mid welder so don't be afraid to tackle a job like this without the "right" tools.... :)

Jeremy, good info! Unfortunately, in my area most cars have to live outside. Theres very little garage space to go around here in the P (for whatever reason...). If I could, I would definitely wipe all that down every day but it POORS here 8-9 months out of the year.

Luckily at this point this car is nothing special. It has more chassis miles then I care to think about, and was suffering a mold epidemic until I got a hold of it.

82transam, haha you make this project look/sound easy. I do like what you did there. Never thought of cutting that much out but it almost seems like it would make things a lot easier to line up and all.

One issue on mine that I didn't touch in this thread is that there is some fairly deep rust on that same panel you cut out that sort of goes through to the right side that center framework that holds everything up. I'm not too worried about it but your process above would solve that problem as well.

Well the wheels are now turning in my head. I think I'll try and hunt down a rust free one that I can cut that piece out of and go from there.

I'm open to more ideas as well! I'm sure lots of people have had to deal with this.

What kills the hatch seal area is plugged drains, keep those corner drain tubes clean and clear!

Isaac

^So true. Mine clog like crazy this time of year from all the pollen and tree seeds etc falling on it. What a pain.

Yeah it was not an easy project at all, but then again none of the rust repair projects I've tackled have been lol, what a pain...

I removed as much as I did for a few reasons. One obviously was the amount of rust I was dealing with, but the other reason was keeping the welded seams as invisible as possible. The tail light trim piece hides that one whole seam, leaving just the two, relatively short, vertical seams to have to fill and smooth... Now the car has an IMSA spoiler on that that nearly the whole thing anyway lol.

Yeah, I can already tell the drains need help haha.

Well it looks like good work and is a good idea. I've also been thinking of an IMSA spoiler for mine. Love that look. This is reminding me why I didn't go Japanese initially for my first car project. There is something to be said for the quality coating the germans put on their quality steel. Oh well, rotary engines make up for all of it :)

lmao! the reason the 70's BMW coupes are so rare is that they built the bodies in one factory, and then trucked them in the rain to the other factory and then painted them, so they were rusting before they even got painted. the survivors probably got trucked on the day it didn't rain.

Mercedes did this too, the 70's SEL's have unfixable structural rust problems, for the same reason, they left em in the rain before it was painted....

^That's insane!

any dangerous/hokey or just plain stupid thing you can do with a car, the germans have done in mass production.

Haha!! I knew I would get crap for that one! But yeah you are totally right. Most of the porsches came out in good standing. The 914 seems to be an overwhelming exception :(. I guess I'll re state that as "quality coating on quality Porsche steel".

I'm not going to let rust stop me, though. I'm kind of having fun with all this. In the process of un-denting/bending a front fender as we speak. :lol:

Hey Sean, can I fly you down here to do my metalwork? You can live in the shop. Full room and Board lol.

the 356's rust pretty badly, so they were ahead of the rust game, as the 911 isn't that bad, and then got better in the mid 70's with the galvanizing.

at least the rear lip on the Rx7 is a single wall, all you really need to do is match the bends, it could be worse

hey autobahm don , I would use self etching primer, paint it , and tape the holes with metalized tape. If the drain rails have holes like that, recessed areas (thise that you cannot see) below it is probably 50% gone due to rust.

82transam shows master's level fitting and welding there. If I didn't see it, I wouldn't believe two pieces of thin steel could be filet welded like that without all kinds of heat warp age .

and my 914's floor boards just loved to rust.

Ooooo man thats another good idea!! I think the drains are ok, I'll check them more thoroughly but at the moment all my rust appears to be in places where paint has chipped from hard hits and vibration.

Yes, the more I think about it, the more I admire 82transam's work. Might have to fly him out here haha :lol: at any rate, I doubt I would have success the first time around with a project as such.

If it wasn't for my climate, I would most certainly own a 914 by now. I decided I would save the heart ache and wait till I live somewhere with a massive garage/dry weather.

i remember my friend looked for a 914 like 15 years ago, and they either had badly repaired accident damage, or a rusty battery box, or both... tough car to find a good example of