Rust Repair Plan of Attack!

[ab1752]

Ah ok, ya cut and paste. Looks to me like you have the line about right, I'm guessing you have the restoration design replacement parts? The fun part will be seeing how far rust extends up the rocker. 911s are magicians at hiding rust...

[Shaun @ Tru6]

Originally Posted by Coultl

I wish it was just the door jam. The “kidney” chassis supports are rusted and I can’t get to those without cutting a chunk of the fender out. That should also make the door jam repairs easier at least…

I have done this on an 86. The more you cut away, the more rust you find. You may need a new jack point and rocker sheet metal like I did. The whole area was rusted away when I got in there.


EDIT: You have probably done this but if you haven't, peel up the rubber rocker strip to see what is underneath.

[Coultl]

I have the Restoration Design fenders but they are partial…they only extend about 8” from
the door jam and don’t go to the wheel well. My plan is to reuse the fender piece that I cut off and use the RD pieces to patch anything rotted.

I’m hoping to remove the minimal amount of metal when cutting the fender since I’ll have to butt weld it back together…basically moving the panel up by the amount of metal removed when I did the cut. With a thin cutoff wheel it should only be about 1.5mm.

Yup, I’ve pulled everything off including the side skirt. I can’t find more rot but I’m aware that I
Won’t know until I get in there. The rust on the front end was confined to a small area and most metal was perfect. Gives me hope…

[AlBackus36]

OP, you seem to be handy with the steel if you know what I mean. I think you've got this.

Do I understand correctly that due to your repair panel shape/size, you'll be sectioning your quarter both horizontally and vertically? That is going to be a challenge to get the shape right and not inducing heat weirdness along the way. You may want to bite the bullet and get a panel that includes the full section you're repairing here. I'm not familiar with the repair panels available for this area so I may be out my ass, but that's my advice. Always look for opportunities for less welding if available.

Question about moving the panel - Why does it have to move up the cutting wheel thickness? I was taught to cut through the new piece and the old at the same time while cleco'ed or tacked, then leave the even gap around the new part while tacking it in for keeps.

Whatever you decide, thanks for documenting and sharing it. I'm always pumped to see this one pop up.

[Coultl]

The fenders have little to no rust on them. I’m cutting them off just to get access to the kidneys and rockers. The plan is to weld them back on after the repairs underneath are done. The metal is in good shape and I’d rather keep it. I bought the RD panels bc they are cheap insurance in case I need to replace some parts of the fenders…but hopefully I don’t.

[Coultl]

I’m about 30 min into the job and stuck. Ha. Hoping you all have ideas on this one.

I removed the paint along the door jam seam and I removed the lead on the lower edge. The issue is that I see no welds connecting the fender to the door jam. I thought I’d find spot welds after getting the paint off, but it’s just perfectly smooth. I did find a seam weld and a few spot welds under the leaded area…but nothing along the door jam seam.

How is the fender connected to the door jam / striker panel?

I plan on reusing the fender piece I’m cutting off so I need to remove it without destroying it.

[Shaun @ Tru6]

The rear quarter folds over the door post panel and is spot welded together.

[Coultl]

Okay, that’s what I thought but I can’t find any spot welds. Not sure how to separate the two if I can’t find the welds. I could cut the quarter panel about an inch from the seam. That should give me enough room to planish the weld after putting it back on. Not ideal but that could work.

[Coultl]

I did a little more digging and found the spot welds on the back side in the wheel well. They are very easy to see there after scraping off the underbody coating. It’s really interesting bc they are completely invisible on the outside. I heated and scraped and there’s definitely no lead on there. They must have sanded this edge at the factory to hide the welds.

It would have been nice to separate the parts at this seam but that’s not possible as I can’t drill out (or even access) most of the spot welds from the back side.

The new plan is to cut the fender about an inch away from the seam. That should give me enough room to get a dollie back there to planish the welds after I weld it back on. Not ideal as I’ll have a lot more weld on an exterior surface to deal with.

[Loz]

Originally Posted by Coultl

I did a little more digging and found the spot welds on the back side in the wheel well. They are very easy to see there after scraping off the underbody coating. It’s really interesting bc they are completely invisible on the outside. I heated and scraped and there’s definitely no lead on there. They must have sanded this edge at the factory to hide the welds.

It would have been nice to separate the parts at this seam but that’s not possible as I can’t drill out (or even access) most of the spot welds from the back side.

The new plan is to cut the fender about an inch away from the seam. That should give me enough room to get a dollie back there to planish the welds after I weld it back on. Not ideal as I’ll have a lot more weld on an exterior surface to deal with.

That's a good move to leave the edge on the quarter panel. Scribe some horizontal lines first to serve as relocation marks. It'll help line everything up.

[Coultl]

Well, I’m in it now! I started on the passenger side as it’s much worse than the drivers side. A borescope helped me get a better idea of where the rust was. Inspecting through the holes under the rubber door sill was especially helpful.

I ended up cutting a strip rather than cutting straight back to the wheel opening. I’m still not sure this was the best idea but I did it bc the sheet metal I have will cover the entire area. It gives me the option replacing everything I cut out. I also just cut the rusted door jam section at the same time.

All in all, I’m really lucky that the rust stopped where it did. There are so many layers of metal in that area that it could get messy quickly.

I made the cuts with an air saw as it gave me the smallest kerf and it’s easy to control. Other than that the job took a lot of the spot weld drill, air grinder, and air belt sander. That mini air belt sander tool is awesome.

I’ll post a bunch of pics to help anyone in planning this job.

[Coultl]

More photos

[Shaun @ Tru6]

Great progress! Glad to see your rocker end and jack tube are fine.

[Coultl]

The replacement kidney in place but not welded in

[Coultl]

At this point all rust has been removed and all surfaces have been cleaned up. Next, I’ll tackle the repair one section at time.

[AlBackus36]

Great job man. Looks like a very tidy repair.

[Coultl]

Kidney is welded in. The kidney and chassis were sprayed with weld-through primer and I sprayed some fluid film in the chassis cavities before welding it up for peace of mind.

I also managed to roast some of the interior. Not sure what I was thinking but I didn’t remove the interior panels and the insulation lit up near the seat belt. That was stupid and could have been worse. I caught it right away and no damage was done. The seatbelt got a little scorched so I’ll probably be looking to replace those…

That little incident got me thinking about the fire risk so I checked the car with a thermal camera a couple times to make sure there wasn’t something smoldering out of sight. I’d rather not wake up to find my garage gone.

Next up is repairing the rocker.

[ToySnakePMC]

Impressive work and results here. Your photos will be great help to others, I’m sure. Best of luck to you.

[MBAtarga]

Using your photos - this is a great example to keep to show what a "little" rust showing at the surface can look like underneath:

[Coultl]

Absolutely! I will say that this damage was visible when looking under the car and deep in the wheel well. Also, there are access holes to the rocker under the rubber sill. Using a borescope, this damage was also visible.