Voids inside and behind front wheel arch

oldcoupe

oldcoupe

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Getting ready to install these protective plates at the back of the front wheelarch -

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I took a closer look - what to do about the void with the large opening behind the strut?

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I'm thinking about spraying aerosol grease to coat and protect the interior, then fill it with closed-cell spray foam.

Similarly, the gap inside the outer skin is just waiting for water and mud, so again I thought grease and closed cell foam.
(the small piece of galvanised plate held with the hex head screw is a) to temporarily close the fixing hole for the protective plate, and b) check out the screw fixing before I install the protective plate)

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If the car was kept in an area with surfaced roads I wouldn't worry so much, but we have three miles of dirt roads before tarmac.

Any helpful comments welcome.

Thanks
 
Make sure you use the gasket that is suppose to go with the protective plate. I used a profile bought from Steele products as I think it may be NLA.
Others will chime in about the Lokari set up which is the ultimate in protection. You can search for it here, many posts.
 
Please no closed cell spray foam!

Most of those are polyurethanes and start to crumble in ~5 years if exposed to water. These foams indeed start as closed cells, but in 3 years time, most of the cells have become open cells if exposed to water. And then it just get worse fast.

I'd blow out the triangle opening with compressed air to get the debris out.
Then inject your favorite wax.
Then Lokari's (google them) are the best option. Leaving pandora's box open is asking for rust; it's the most expensive corner to rust, as it starts deep down inside the construction.

It ain't easier, but trying to sell a car with spray foam is even worse.
If you're really in a pinch, then I'd seal the triangle hole with a plastic sheet and stick it there with caulck. Better watertightness, and easily reversible.

The gasket to the inside of the fender is great advice from @bavbob ; it'll will prevent most debris and some of the water, but not all.
 
I have the OEM gaskets for your metal plates. If interested, I can send you pics and the part #'s. My car had some undercoating sprayed all around the area ,so I used SEM caulk to completely seal the entire plate. Here are pics of my front wells. The holes in the plates match up with the threaded holes in the wells. A machine screw secures them. I had to bend the pointed bottom of each plate to get a tight fit.
 

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I coated mine with cavity wax years ago, then bi-annual cleanings with compressed air to remove the debris (also along the fender seams). I prefer air to be circulating back there and not condensing. I also leave off the 2 small top seals (in the engine compartment under the forward heaterbox/ hood seal) to allow air in from there, I install the seals if I'm going on a road trip where I might encounter rain, but otherwise I keep the air moving.
 
I have fitted Lokari liners but have put open cell foam to ensure that any moisure drains. This isn't spray on as that takes an age to remove, but large sections of solid foam which I can remove as needed. Closed cell with block the cavity but any moisture in there, from say condensation, will not be able to drain. Am I making a mistake?
 
When i restored mine I opted to weld them shut, perhaps an option would be to use butyl cord around the aperture and install a moisture barrier similar to inside the doors?
 
Drew Gregg said:
I have the OEM gaskets for your metal plates. If interested, I can send you pics and the part #'s. My car had some undercoating sprayed all around the area ,so I used SEM caulk to completely seal the entire plate. Here are pics of my front wells. The holes in the plates match up with the threaded holes in the wells. A machine screw secures them. I had to bend the pointed bottom of each plate to get a tight fit.
Click to expand...
Hi Drew - PM'd you - I'd be very grateful for pictures and part nos for the gaskets.
Oldcoupe
 
nosmonkey said:
When i restored mine I opted to weld them shut, perhaps an option would be to use butyl cord around the aperture and install a moisture barrier similar to inside the doors?
Click to expand...
Thank you - I've been thinking about caulking the gaps between the fender and 'chassis', with something removable, after using rust preventative as much as possible on the enclosed area.

When I first owned the coupe over twenty years ago, and our DD was wrecked by my son - am I the only parent that's happened to - fortunately only a learning experience, I used the coupe as the family transport for a few years, and didn't know enough about the rust vulnerabilities so didn't worry. Now I want to protect it.

My thanks to the responders to my post.
 
Stevehose said:
I coated mine with cavity wax years ago, then bi-annual cleanings with compressed air to remove the debris (also along the fender seams). I prefer air to be circulating back there and not condensing. I also leave off the 2 small top seals (in the engine compartment under the forward heaterbox/ hood seal) to allow air in from there, I install the seals if I'm going on a road trip where I might encounter rain, but otherwise I keep the air moving.
Click to expand...
This is an important observation. All air contains moisture. If you seal up any space with any reasonable volume of air inside, then as the temperature falls, the moisture in the air will condense on the cool inside surfaces. The only way to assure that this doesn't happen (or happens as little as possible) is either to keep the car at a temperature above the dew point, or to provide sufficient ventilation to help dry the air space, which means do not seal up the space.

I suppose you could weld up the cavities in a dry environment and hope they never leak, but that's pretty challenging. You have probably noticed that even in an unheated garage, you don't generally find moisture condensing on your car. Move it outside and the temperature swing and added humidity will cause condensation inside the car cabin (and any other enclosed space). My parents had a sail boat for many years. They always berthed it with a small light on inside. The light added just enough additional heat to keep the temperature of the inside air above the dew point.

Using a cavity wax protects the surface against any moisture that appears, but you need to assure that there is no gap between the wax and the metal, or you are then back to an enclosed cavity that will condense over temperature swings. Paint would also work as long as it was applied everywhere.
 
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I agree with Scott the best thing to do is accept that there will be some moisture and debris that will get in there so prepare the area for everything to get out or easy to clean and is well sealed so nothing reaches the metal. I personally, would not put any foam in those areas, no matter what kind, moisture will gather and stay there All that I know is that after enough years of doing this, I do it the same way each time and after lots of years, everything is still ok . This works for me so this what I do Everyone can always try something else

Thanks, Rick
 
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