Rust prevention on interior panels

[alsoHarrison]

I've begun to strip the interior of my 73' 240z and there is surface rust and luckily not much welding required! I've had to strip off all the old paint, primer and I'd guess old bedliner to get it back to bare metal. I was curious as to what people can recommend to reseal the exposed metals backup with before adding the interior back in?

I've been told bedliner/stone guard is a great way of doing it but I've also been told, that stuff is great for cheap cars but for a classic I should ask for an alternative, someone told me they think there's an aerosol wax based product?

Before I commit I thought it best to ask the community as I'm sure there's many of you here that are more knowledgeable then myself on what is best to use!

 

[jonbills]

I think most people treat the rust and then paint it with the same paint as the rest of the body, and then add Dynomat etc for sound / heat insulation etc. I'd think reserve the wax treatment for the cavities.

 

[richiep]

If you are talking about the metal surfaces inside the car, from the factory they had a bitumen-based sound deadener on areas such as the floors, trans tunnel, rear deck around the spare wheel wheel, etc. That might be what you mean by "old bedliner". This was all then overpainted in the body colour. Part of the surface and worse rusting problem occurs because the original sound deadening was applied direct to bare metal and then overpainted. Meaning no surface protection when it starts to crack and dry with age. The restorer's approach would be to treat the rust (convert, mechanically clean, blast, etc) epoxy prime first, then install factory-style sound deadener, prime and overpaint on top. That's what I've done with my project (see the relevant posts in the Project Dixie thread in the resto section of the forum).

That's me being anal about the materials used and the look of the sound deadening to achieve a factory look though. What people generally do is prime, paint, use something like dynamat sound deadening over the top.

As the for the rust prevention and cavity protection part of your query - you need to start learning about cavity waxes. There are various key manufacturers; Waxoyl is the most well-known in the UK, but is TBH old hat now and poor compared to the alternatives. Dinitrol or the Bilt-Hamber products are much better. Dinitrol 3125 and ML are cavity waxes that can be used inside sills, rear quarters, inside doors etc. to provide a water-proof layer that prevents or inactivates any rust. Generally, one of the last stages of a good resto, or even just general rust prevention would be to treat all the inner structures of the car (cavities, chassis rails, etc.).

You do not want to be spraying that stuff on floors or rear deck though. It is not meant for that and will make a sticky mess under carpets, etc.

 

[alsoHarrison]

If you are talking about the metal surfaces inside the car, from the factory they had a bitumen-based sound deadener on areas such as the floors, trans tunnel, rear deck around the spare wheel wheel, etc. That might be what you mean by "old bedliner". This was all then overpainted in the body colour. Part of the surface and worse rusting problem occurs because the original sound deadening was applied direct to bare metal and then overpainted. Meaning no surface protection when it starts to crack and dry with age. The restorer's approach would be to treat the rust (convert, mechanically clean, blast, etc) epoxy prime first, then install factory-style sound deadener, prime and overpaint on top. That's what I've done with my project (see the relevant posts in the Project Dixie thread in the resto section of the forum).

That's me being anal about the materials used and the look of the sound deadening to achieve a factory look though. What people generally do is prime, paint, use something like dynamat sound deadening over the top.

As the for the rust prevention and cavity protection part of your query - you need to start learning about cavity waxes. There are various key manufacturers; Waxoyl is the most well-known in the UK, but is TBH old hat now and poor compared to the alternatives. Dinitrol or the Bilt-Hamber products are much better. Dinitrol 3125 and ML are cavity waxes that can be used inside sills, rear quarters, inside doors etc. to provide a water-proof layer that prevents or inactivates any rust. Generally, one of the last stages of a good resto, or even just general rust prevention would be to treat all the inner structures of the car (cavities, chassis rails, etc.).

You do not want to be spraying that stuff on floors or rear deck though. It is not meant for that and will make a sticky mess under carpets, etc.

Ah yes I have also removed the old sound deadener too and then there was a thick black coat of bed liner underneath on the floor pans as is would seem these are aftermarket and have been replaced. The rest of the car has no deadening and just the paint to match the exterior which is whats set me on this path now.

The car was far too noisy in terms of rattles and road noise so I've bought new sound deadening to cover the inside but whilst I had the interior out I figured I may as well check for rust and amend any parts that need it. At this current stage I dont have the budget to get the car sprayed, even just the inside so I was hoping for a at home solution that will prevent rust for a few years until I can afford to get the car painted. I thought bedliner would be fine but just wanted to check to make sure!

I'm not too concerned about keep the car stock at this time, just keeping it solid and safe.

 

[richiep]

You could potentially look into something like POR-15 as a rust proof paint for under sound dealing etc. Expensive for a paint, but is super tough and works if the prep is done right. You could do the floor pans, deck, etc. with it in gloss or satin black. It’s self-levelling so brushes nicely.

For getting down into seams, check out Dinitrol ML (now called Penetrant LT apparently) in aerosol form. It sprays nicely compared to crap like waxoyl and you can use a spray wand to get inside box sections etc.
3125 is less runny, more waxy, and also aerosol sprays nicely. Better for vertical surfaces.

Dinitrol cavity wax rust proofing | Rust prevention

Dinitrol cavity wax is capable of good penetration into joints for sound rust proofing by forming a waxy water repellent protective film.

rejel.com

 

[alsoHarrison]

You could potentially look into something like POR-15 as a rust proof paint for under sound dealing etc. Expensive for a paint, but is super tough and works if the prep is done right. You could do the floor pans, deck, etc. with it in gloss or satin black. It’s self-levelling so brushes nicely.

For getting down into seams, check out Dinitrol ML (now called Penetrant LT apparently) in aerosol form. It sprays nicely compared to crap like waxoyl and you can use a spray wand to get inside box sections etc.
3125 is less runny, more waxy, and also aerosol sprays nicely. Better for vertical surfaces.

Dinitrol cavity wax rust proofing | Rust prevention

Dinitrol cavity wax is capable of good penetration into joints for sound rust proofing by forming a waxy water repellent protective film.

rejel.com

Many thanks, this definitely sounds like the products I'm looking for right now!

 

[Faster Behr]

I did an Alpina with Waxoyl years ago. I used a big can in a hot bucket of water to help mobilise it then squirted it around with a stonechip gun with a flexible hose added to get inside the cavities.

I agree that Waxoyl is old hat given the amount of more scientifically enriched coatings that are around these days

More recently I researched and used the Bilt Hamber Dynax for my BMW 2002. The Dynax range come in aerosols with long lances on them. They made it super easy to do inside cavities etc. iirc Dynax have got lots of examples and case studies on their website. For reference - the S stays quite fluid and is self-repairing. Ideal for cavities, inside doors. For anywhere that is exposed the UC (clear) or UB (black) is used. I used the latter on all my floor pans. Beware though that even that stays very slightly sticky to the touch. Opie Oils were a good supplier to use for this back then.

The areas inside the cabin were all repainted body colour and had sound deadening material on top.

 

[Kieronpollock]

I’ve used Lanoguard for a few years now on a number of cars, good for cavities and chassis; can also be used on rubber, hoses etc. it’s a natural product, easily applied, not very messy - just reapply every 6 months or so dependent on usage.

 

[Mr Tenno]

Have you been able to get underneath the car and give things like the chassis rails a poke with a screwdriver yet? Not worth spending time on the interior if you've got rust or a patchwork of old plates down there!