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Rust hole wisdom

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<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I have a crazy idea: use some Touch 'n Foam expanding foam to fill the hole. After it's dried, sand/shape the outside surface to match, then use some metal meshing to cover, and then filler/Bondo over that.[/QUOTE]

DON'T!!! DPO!!! Plus, it'll cause more rust because it'll hold moisture.

Now, for the body panels you'll need; in addition to the dogleg:

#10 - rocker
#11 - inner membrane


MGB-061.gif
 
tony barnhill said:
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I have a crazy idea: use some Touch 'n Foam expanding foam to fill the hole. After it's dried, sand/shape the outside surface to match, then use some metal meshing to cover, and then filler/Bondo over that.
Click to expand...

DON'T!!! DPO!!! Plus, it'll cause more rust because it'll hold moisture.

Now, for the body panels you'll need; in addition to the dogleg:

#10 - rocker
#11 - inner membrane
[/QUOTE]

I don't understand why such a small hole needs such major treatment, since it's not structural. Why?

The hole is about 9" across, and maybe 5" tall. It's in the outer two metal sheets which are not load bearing, and really just form the shape of the body. The sill itself, which is load bearing and is the strength of the car, is in good condition.

If I understand the body panel diagram, the rocker and inner membrane are very large pieces, which to fit will require removing a vast area of good metal from Harold. Not only that but they will need welding ... and I'm not a welder! Or do I cut the rocker and inner membranes to fit, somehow?

The Touch 'n Foam is water resistant - it's polyurethane - why would it hold moisture? It expands to an essentially impervious "blob", so any water would just run off it. Since the inside of the cavity is now POR-15'ed, then it's protected against rust anyway ... indeed, isn't using new sheet metal panels just providing more area for rust?

Maybe I'm being too theoretical and analytical about this, and I should just accept that others have been there and done that, and not go this route.

But then I have a serious problem: I cannot repair Harold myself, and I'm not sure I can justify hiring a restoration shop to do the work for me - to me that's like "giving up". My goal is to do a good, lasting repair, that looks bespoke (as Doc would say) and satisfies me ... I don't really care what any future owner might think about it, or whether he/she would have done the repair differently. That maybe sounds callous, but Harold is my car, and I'm not restoring it for anyone else's benefit, just my own :smile:

Wow, I seem to have prattled on a bit!
 
gcan said:
so in the picture is that the inner membrane you see or the inside of the inner seal
Click to expand...

It must be the inner membrane. But I'm not sure!

Here's a couple more photos ... one taken looking towards the front of the car:

358975634_f22f151ad8.jpg


and another head-on after I'd angle ground around the hole to make sure I had good metal:

358975525_88e6f8d466.jpg
 
Julian - just as you I'm reading and learning and agree with your comments/questions - why cut out 5' of good metal to replace the inner membrane and inner seal when you only need a small section of the outer seal which is the least structual of the lot.

All I can say is when I cut into mine if it looks like that I would patch the outer seal and glue on a dogleg repair patch and then go for a ride. Just my thoughts but hey I'm a new so I must be missing something
 
Yep - your inner membrane is good - all you need is the rocker & dogleg..man are you lucky!!!

&, a good body man could probably do a patch job on the rocker to keep you from having to remove the entire thing (I sometimes do that - cut an end off a rocker & weld it in place whewre the rocker is rusted).
 
Wish you were in Northern Cal. I have the equipment and knowledge to do this and would love to help you out. Sometimes I hate the distance in CA from one end to the other.

Bruce /bcforum/images/%%GRAEMLIN_URL%%/mad.gif
 
jjbunn said:
I don't understand why such a small hole needs such major treatment, since it's not structural. Why?
Click to expand...

Julian - trust me, that's not major treatment. And forget the foam/chickenwire/bondo idea - it WILL retain/trap moisture despite the claim. You really REALLY don't want to do this. It will fall out in 6 months.

jjbunn said:
The hole is about 9" across, and maybe 5" tall. It's in the outer two metal sheets which are not load bearing, and really just form the shape of the body. The sill itself, which is load bearing and is the strength of the car, is in good condition.
Click to expand...

Well lets get some terminology straight. The "sill itself" is comprised of 4 separate pieces that sandwich together to make a rectangular box: a thick L shaped inner, a thinner flat membrane, a corrugated bottom "runner", and the curved outer sill. There are a couple of other filler bits/braces but thats the gist of it.

In your case, the rear outer portion of the outer sill panel is bad and needs to be replaced. The lower dogleg portion of the rear fender also needs to be replaced. You need to use steel, not foam, not bondo.

jjbunn said:
The Touch 'n Foam is water resistant - it's polyurethane - why would it hold moisture? It expands to an essentially impervious "blob", so any water would just run off it. Since the inside of the cavity is now POR-15'ed, then it's protected against rust anyway ... indeed, isn't using new sheet metal panels just providing more area for rust?
Click to expand...

The "water resistant" blob acts like a giant sponge and holds moisture where you *least* want it. Much better to have nothing there but air. Dont do it. Seriously.

jjbunn said:
But then I have a serious problem: I cannot repair Harold myself
Click to expand...

Nonsense. I've seen a bunch of repairs you have done and this is well within your grasp. I've replaced all 5 pieces of both sills and the floorpans on my current MGB. It just takes time, practice and patience. Plus some determination and motivation (and good beer). Most good rental places have MIG welders, they're easy to use.

All you really need is to replace the rear 16" of the outer sill (not the whole thing) and the dogleg. With the right tools, this is a long weekend project per side, seriously.

Don't despair, this could be much, MUCH worst.
 
You will cause yourself problems if you keep the car and decide work in that area in the future, by all accounts expanding foam is a bugger to clean/remove! A dogleg repair using adhesive would be the most cost effective repair if you have no access to a welder.
 
Your inner membrane is fine. Cut off the dogleg, patch the outer sill, and replace the dogleg. That's all that is needed here.

And please don't put foam in there - it draws and holds moisture and will cause far worse rust.
 
Jack_Long said:
Your inner membrane is fine. Cut off the dogleg, patch the outer sill, and replace the dogleg. That's all that is needed here.

And please don't put foam in there - it draws and holds moisture and will cause far worse rust.
Click to expand...

Hi Jack. I decided to do an experiment: I squirted out a big ball of the foam filler, and let it set in the open air overnight. Then I weighed it. Now I have submerged it in a bucket of water, and will leave it submerged for a few days, to see how much water it absorbs. The starting weight of the foam ball is 25 grams.

Of course, the only really convincing result of this experiment is if the ball weighs 25 grams at the end ... !

The other question is: which is worse, a little water sloshing around against the interior of the panels, or a little water absorbed by the foam? Once there is water in that dogleg area, it must slowly evaporate into the air and find its way out. Perhaps it evaporates more readily if its sloshing around in a foam-less cavity: I can believe that.

Why isn't there a drain hole in that area? Would it do any good to put in a drain hole?

I realise I have many more questions than answers about this topic!
 
jjbunn said:
Why isn't there a drain hole in that area? Would it do any good to put in a drain hole?

I realise I have many more questions than answers about this topic!
Click to expand...

Julian - there is a drain hole, several of them. They are pressed into the outer sill every couple of inches (a small bump). Same thing with the castle/sill bottom (except drilled holes).

Don't mess with the foam. :smile:
 
Julian.................................................
 
It'll be interesting to see the results, but if you just <u>have</u> to spray something in that cavity, I would recommend either Waxoyl or Penetrol. Penetrol is cheaper and can be found at most home improvement or paint stores. Its also easier to spray, as Waxoyl needs to be very hot to flow out well. When I repaired my doglegs and outer sills, I sprayed Eastwood rust preventing paint inside as far as I could reach and when that dried hard I coated it all with Penetrol. Just make sure you put down lots of newspaper under the sills as the excess will run out the drain holes and make a slippery mess. It takes the Penetrol several days to dry hard.
 
Yes, Home Depot carries Penetrol in the pain section. Just don't ask the people working there if you can use it for rust prevention. They'll look at you as if you are from mars.

If you spray it make sure you use a LOT of newspaper, cardboard to similar as it will stain your driveway. it will also clog your sprayer if you, say, go out for pizza before cleaning the sprayer. Ask me how I know that...<grin>
 
Julian,
even if your lump of foam does not act as a sponge itself, surely water will get in between the foam and the metal by capillary forces...
I can but agree with everyone, keep it oily and airy, not tight and wet.
 
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