Rust proofing rear wheel wells, I have questions Options

[john77]

While I have the arches cut for the flares I figured it was a good time to strip the wheel wells to bare metal, fix anything I find, and reseal them. I’ve completed the fronts, but just started stripping the rears yesterday and have some questions.

What’s the best way to reseal/rustproof the section above the rear light housing?

I’ve stripped a lot of 1970’s German rubberized seam sealer in my time but was surprises to find that section was filled with what looks like some kind of expanding foam. The area is obviously a crud catcher, so I’m wondering the best way to seal it back up? Seam sealer? Or is there some other product I should fill the void where the foam was first?

https://photos.app.goo.gl/2RYXDYXEVmRorirE9

The other section I’m wondering about is in the front of the well where the sail panel meets the quarter panel (the L shaped section coming down into the wheel well).

It seems odd that this was so open - is it supposed to be covered in seam sealer?

I’ve scraped some debris out of it, but would love some advice on what to do with it when I paint/reseal everything.

https://photos.app.goo.gl/K2gqHAMPtzvMgiMB7

[Cairo94507]

I would clean out all of that foam filler junk and clean all of the metal very clean and then treat it with a rust converter, epoxy prime, seam seal, prime and paint.

Porsche had good intentions with that dense foam junk but it acted like a sponge and collected/held moisture and other junk which led to major rust. It is also applied to the areas of the sail panel near the door handle.

[john77]

I would clean out all of that foam filler junk and clean all of the metal very clean and then treat it with a rust converter, epoxy prime, seam seal, prime and paint.

Porsche had good intentions with that dense foam junk but it acted like a sponge and collected/held moisture and other junk which led to major rust. It is also applied to the areas of the sail panel near the door handle.

Thanks man. This has to be my least favorite job in the world, but I keep having to remind myself there won’t be a better time to do it than now.

I realized the “debris” I scraped from inside the L shaped section is actually the foam (or whatever it is) they put inside the sail panel. Should I seam sealer that gap up, or is it supposed to be open?

[Cairo94507]

Can you post a picture the area you are referencing?

[bbrock]

I've been mulling what to do with that area for over a year now as I get my car closer to going back on the road. Here is the problem I have with how people decide if things the factory did was good or bad. We clean off a bunch of undercoating and find rust underneath and condemn the undercoating as a moisture trap that promotes rust rather than prevents it. Same goes for the body foam shot into the tail light section and sail panels. We pull nearly 50 year old foam out and find rust and immediately blame the foam. What we rarely consider, and almost never have data to evaluate, is how quickly those areas would have rusted WITHOUT those products being applied. These products have a service life and it is not surprising that they become ineffective or even counter productive when they begin to fail. Since we can't answer that question, we can only guess about the right choice.

Here are a couple things to consider though. My car had the same rusted out sail panels that we see on so many others. The rust was in the exact same places. When I removed them, there was zero evidence they had been replaced before. Perfect factory spot welds were intact and absolutely no hint these were not original. Yet, when I removed them, there was NO foam inside. I don't know why, but there wasn't. Yet, they had rusted the same as so many others. It's only one sample, but worth thinking about. Also, AFAIK, all modern car manufacturers still apply body foam and undercoatings at extra expense. Why? Modern materials may be better than the old stuff, but again, worth thinking about.

For my own car, I'm strongly leaning toward replacing the foam and seam sealer in the tail light section. The reason is that every trip in my car will include 6 miles of gravel road. Even at low speed, dust is likely to settle and accumulate in that little hollow. I doubt wheel well liners would seal well enough to prevent dust buildup but foam and seam sealer will. I'll treat it as a maintenance area and inspect every year to make sure the sealer remains intact to seal the cavity. In addition, the entire car has 3 coats of epoxy primer and I will likely spray the cavity with cavity wax before applying foam. I have no idea whether it is the right or wrong decision, but I haven't found suitable information to confidently know what the right decision would be. Simply condemning the foam because it is found in rusted areas is not good enough for me. The factory applied foam to areas the already knew would be rust trouble spots. That's why it was put there to begin with.

[john77]

I have nothing against what the factory did, it seems to have worked very well on my car because all I’m finding is clean metal underneath it. I’m just wondering the best way to replace it now I’ve removed it.

I've been mulling what to do with that area for over a year now as I get my car closer to going back on the road. Here is the problem I have with how people decide if things the factory did was good or bad. We clean off a bunch of undercoating and find rust underneath and condemn the undercoating as a moisture trap that promotes rust rather than prevents it. Same goes for the body foam shot into the tail light section and sail panels. We pull nearly 50 year old foam out and find rust and immediately blame the foam. What we rarely consider, and almost never have data to evaluate, is how quickly those areas would have rusted WITHOUT those products being applied. These products have a service life and it is not surprising that they become ineffective or even counter productive when they begin to fail. Since we can't answer that question, we can only guess about the right choice.

Here are a couple things to consider though. My car had the same rusted out sail panels that we see on so many others. The rust was in the exact same places. When I removed them, there was zero evidence they had been replaced before. Perfect factory spot welds were intact and absolutely no hint these were not original. Yet, when I removed them, there was NO foam inside. I don't know why, but there wasn't. Yet, they had rusted the same as so many others. It's only one sample, but worth thinking about. Also, AFAIK, all modern car manufacturers still apply body foam and undercoatings at extra expense. Why? Modern materials may be better than the old stuff, but again, worth thinking about.

For my own car, I'm strongly leaning toward replacing the foam and seam sealer in the tail light section. The reason is that every trip in my car will include 6 miles of gravel road. Even at low speed, dust is likely to settle and accumulate in that little hollow. I doubt wheel well liners would seal well enough to prevent dust buildup but foam and seam sealer will. I'll treat it as a maintenance area and inspect every year to make sure the sealer remains intact to seal the cavity. In addition, the entire car has 3 coats of epoxy primer and I will likely spray the cavity with cavity wax before applying foam. I have no idea whether it is the right or wrong decision, but I haven't found suitable information to confidently know what the right decision would be. Simply condemning the foam because it is found in rusted areas is not good enough for me. The factory applied foam to areas the already knew would be rust trouble spots. That's why it was put there to begin with.

[mlindner]

On mine John, lots of cleaning, some painting and undercoating I made fender liners front and rear to fit the flared fenders. I don't want all that shit up in there again. Best, Mark

[burton73]

What do you think of fender liners?

My 86 928 has fender liners. This should help a lot. Brent and some other members drive on non-finished roads. Liners may help

Bob B


http://www.914world.com/bbs2/index.php?showtopic=320615


https://914rubber.com/fender-liner-set-of-4-1

[bbrock]

I have nothing against what the factory did, it seems to have worked very well on my car because all I’m finding is clean metal underneath it. I’m just wondering the best way to replace it now I’ve removed it.

Oh I hear you. I was just reacting to the many frustrating hours I've spent trying to figure this out myself. In fact, there is a thread on here somewhere that I started asking this very question.

As for fender liners - I think they are great and am considering installing them. The concern I have in my situation is that the fine dust kicked up even driving slowly out to pavement might drift past those liners and still accumulate in that cavity. The down side is that the liners would require removal to inspect that area. With or without liners, my leaning is toward filling that cavity and sealing it so dust can't get in there. That may be the bottom line on what is "best." It might depend on the kind of conditions we drive our cars in. If I planned on only driving my car on good roads in fair weather, I wouldn't be nearly as concerned about leaving that cavity open.

[bkrantz]

I dug out all the original foam on both sides from around the tail lights and sail panels, and then used local seam sealing after treatment and paint. I also plan to use liners (from 914 Rubber). I hope to keep most water and crud from reaching those areas, and if they are open they should dry out quickly.

[Jamie]

I have nothing against what the factory did, it seems to have worked very well on my car because all I’m finding is clean metal underneath it. I’m just wondering the best way to replace it now I’ve removed it.

Oh I hear you. I was just reacting to the many frustrating hours I've spent trying to figure this out myself. In fact, there is a thread on here somewhere that I started asking this very question.

As for fender liners - I think they are great and am considering installing them. The concern I have in my situation is that the fine dust kicked up even driving slowly out to pavement might drift past those liners and still accumulate in that cavity. The down side is that the liners would require removal to inspect that area. With or without liners, my leaning is toward filling that cavity and sealing it so dust can't get in there. That may be the bottom line on what is "best." It might depend on the kind of conditions we drive our cars in. If I planned on only driving my car on good roads in fair weather, I wouldn't be nearly as concerned about leaving that cavity open.

If you do decide to replace the foam, what type of foam would you use? (IMG:style_emoticons/default/confused24.gif)

[bbrock]

I have nothing against what the factory did, it seems to have worked very well on my car because all I’m finding is clean metal underneath it. I’m just wondering the best way to replace it now I’ve removed it.

Oh I hear you. I was just reacting to the many frustrating hours I've spent trying to figure this out myself. In fact, there is a thread on here somewhere that I started asking this very question.

As for fender liners - I think they are great and am considering installing them. The concern I have in my situation is that the fine dust kicked up even driving slowly out to pavement might drift past those liners and still accumulate in that cavity. The down side is that the liners would require removal to inspect that area. With or without liners, my leaning is toward filling that cavity and sealing it so dust can't get in there. That may be the bottom line on what is "best." It might depend on the kind of conditions we drive our cars in. If I planned on only driving my car on good roads in fair weather, I wouldn't be nearly as concerned about leaving that cavity open.

If you do decide to replace the foam, what type of foam would you use? (IMG:style_emoticons/default/confused24.gif)

I've been looking at this 3M Flexible Foam Not cheap, but looks like it might be right for the application.

There is also Evercoat Sealant Foam that is a little less expensive but not by much.

But to be honest, I haven't settled on anything yet.

[raynekat]

On my restoration/build, we dug all that foam out of the rear corners.
The entire underside of my car is coated in body color Raptor bed liner....including the fender wells and where that foam was sitting.
This Raptor is like granite, so should really hold up to debris and moisture.

On top of that, I just finished installing fender liners that are easily removable....couple minutes for each.

http://www.914world.com/bbs2/index.php?sho...amp;hl=raynekat

I used hex headed screws instead of the supplied rivets for easy removal.
When you need to inspect, it's a snap.

[bbrock]

On my restoration/build, we dug all that foam out of the rear corners.
The entire underside of my car is coated in body color Raptor bed liner....including the fender wells and where that foam was sitting.
This Raptor is like granite, so should really hold up to debris and moisture.

I did the same. Forgot to mention that but I made sure I shot a good build up into that area. I do think the metal is pretty well protected between the epoxy and Raptor but still don't want it to fill with crap that can trap water.

[john77]

@Cairo94507 This is the other area I was wondering about, where the sail panel meets the inner quarter panel. Is it supposed to be open? It seems odd that moisture can easily get up their onto the foam inside the sail panel.

(IMG:http://www.914world.com/bbs2/uploads_offsite/live.staticflickr.com-17027-1613290847.1.jpg)

Can you post a picture the area you are referencing?

[john77]

It just dawned on me that maybe I could use cavity foam, and then I came back on here and saw you mentioned it.

I guess another option to make sure it's fully coated could be to use something like Eastwood's internal frame coating and just stick the nozzle up into the space above the turn signal.

https://www.eastwood.com/internal-frame-coa...tBoCa5oQAvD_BwE

I have nothing against what the factory did, it seems to have worked very well on my car because all I’m finding is clean metal underneath it. I’m just wondering the best way to replace it now I’ve removed it.

Oh I hear you. I was just reacting to the many frustrating hours I've spent trying to figure this out myself. In fact, there is a thread on here somewhere that I started asking this very question.

As for fender liners - I think they are great and am considering installing them. The concern I have in my situation is that the fine dust kicked up even driving slowly out to pavement might drift past those liners and still accumulate in that cavity. The down side is that the liners would require removal to inspect that area. With or without liners, my leaning is toward filling that cavity and sealing it so dust can't get in there. That may be the bottom line on what is "best." It might depend on the kind of conditions we drive our cars in. If I planned on only driving my car on good roads in fair weather, I wouldn't be nearly as concerned about leaving that cavity open.

If you do decide to replace the foam, what type of foam would you use? (IMG:style_emoticons/default/confused24.gif)

I've been looking at this 3M Flexible Foam Not cheap, but looks like it might be right for the application.

There is also Evercoat Sealant Foam that is a little less expensive but not by much.

But to be honest, I haven't settled on anything yet.

[john77]

@mlindner those look great. What did you make them from? It's really not that rainy in LA, and we never have salt on the roads, so that might be a really good option as nothing too harmful is going to get in behind them.

On mine John, lots of cleaning, some painting and undercoating I made fender liners front and rear to fit the flared fenders. I don't want all that shit up in there again. Best, Mark

[Cairo94507]

@john77 - I would seal that up the best way you can. I will look at my build photos and see if I have a photo from that perspective to see what we did. But I am sure it is not open like that. Kent, after the sealer, sprayed the semi-flexible rock protector on the entire underside of my car (body shutz) before color, so it is all sealed and painted.

[mate914]

I removed all seam sealer and foam. Then coal blast (yes the evil stuff people charge cars on) whole car. Then use POR15 with metal etch + spray on POR15. Then use eastwoods frame sealer for all cracks. Then UPOL, Then color of choice.

Matt

[Geezer914]

I second the use of bed liner. I undercoated the inner fenders and the bottom of the floor pan using bed liner with a brush and roller.