Rust Prevention Inside Sub Structures

All the ones you mention work well. The 1/2" dia frame rail drillholes (3 per side) work well. Some then cork up their freshly drilled holes and fill their frame rails with drain oil or something similar. Let set for a few hours, then pull the corks and drain. And many of us drill an additional 3/8" dia hole in the extreme base of each leg of the horseshoe shaped stamping that holds the rear a-arms (2 holes per side).
One method that does NOT work is filling the subframes with urethane foam meant for boats. It does not completely bond to the sides & bottom of the steel rails, and post-cure shrinkage adds to the problem. So water wormholes down to the bottom of the rails and does what water does best- it rusts- even worse than normal since evaporation is now impossible. The damage must be cut out and rewelded as in your car.

Rust is a chemical process. Spray the inside of the chassis with an oil based spray. If the air/moisture cannot get to the bare metal, it will not rust. Simple.
Do not use undercoating, IMO.Its useless when it dries out.I saw many cars in the 70's/80's with rotten metal under the dried out tar. Use a proven oil/wax rust proofing spray.It also creeps into seams, unlike undercoating.

I like to use Rust Blast (phosphoric acid) followed by a liberal dose of fish oil based (non drying) rust preventative. Never use any permanent sealer without first treating the rust as eventually the rust will get oxygen and rust under the sealer as previously stated.

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Originally posted by Bosswrench:
All the ones you mention work well. The 1/2" dia frame rail drillholes (3 per side) work well. Some then cork up their freshly drilled holes and fill their frame rails with drain oil or something similar. Let set for a few hours, then pull the corks and drain. And many of us drill an additional 3/8" dia hole in the extreme base of each leg of the horseshoe shaped stamping that holds the rear a-arms (2 holes per side).
One method that does NOT work is filling the subframes with urethane foam meant for boats. It does not completely bond to the sides & bottom of the steel rails, and post-cure shrinkage adds to the problem. So water wormholes down to the bottom of the rails and does what water does best- it rusts- even worse than normal since evaporation is now impossible. The damage must be cut out and rewelded as in your car.

very good advice but I wonder one thing. does anyone have pictures or drawings showing where to drill these holes?

Freddy
7207

Here are a couple of helpful pages ...

Lots of good shots of rust-prone areas and advice on where to drill drain holes on this page ...
http://www.panteraplace.com/page57.htm


On this page, do a search for 'Rust Proofing' and it will take you to additional shots of where folks add or enlarge drain holes ...
http://www.banzairunnerpantera.com/adventures.htm

In an old issue of the POCA Newsletter I showed the preferred areas, but basically, we all pick our spots; there is no perfect location. And no- the front subframes seldom cause the problems found at the rear, so they don't usually need drilling.
The lower subframe rails are about 2 feet long on each side. There are numerous doublers and internal/external reinforcements that are visible from below. Divide up the length from the bellhousing to the rear crossmember into 3 rough areas, pick spots that have convenient drill access and try to avoid the doublers as it only makes drilling harder going thru 2 or 3 layers of steel. And don't forget the bottoms of the rear a-arm supports. When drilled, a cascade of talcum-fine red dust will start coming out: this is finely ground rust, dirt and other things best not thought about too much. Some owners fish around with flexible magnets thru the oval top holes in the frames to pull out magnetic debris. Sometimes its possible to fish out sizeable rocks, too. Then they use an air gun to blow as much of the dust out before applying rust preventative.

If you're up on jackstands already, consider also clearing the rocker panel drains. There are several on each side and nearly always there will be one that's smashed flat. The drains should be elongated ovals about an inch long with a dividing panel lengthwise thru the middle. The rockers are made in 3 pieces: inner, outer and a central stiffener panel that's perforated with giant holes. The central stiffener is visible as the divider thru each drain hole. If the central divider is knocked sideways or plugged with paint/undercoating, it actually isolates an area of the rocker panel assembly from draining. With a small screwdriver, pry/bend/tweek the metal so the oval again open on both sides of it's divider.

JAG13CAT,

Careful when seeking advise from someone in the Western US. It is all desert out there with no humidity in the air -- so they can fill their rockers with salt and there would be no corrosion. Well, that may be an exaggeration, but there is very little humidity in the air out west -- that portion is true.

I live in the upper midwestern US, and humidity in the summer is an issue here. The summer kills untreated metal here because of the constant condensation when the temperature changes. If there is air inside the boxed structure, I guarantee there will be some moisture in that air and when the temperature changes, BAM; you will have water coming out of that air and onto bare metal. Ever see concrete sweating after a temperature change? If you have, the same is true for your cars.

There is a way to deal with this though as 4NHOTROD alludes to. I figure, if it is good enough for Porsche, Volvo, BMW, and Mercedes Benz, then it's good enough for my Pantera. They use rustproofing -- NOT UNDERCOATING TAR. Rustproofing is an oily substance that crawls like crazy and never gets hard once dried out. You shoot it with various length wands out of a schutz gun -- which is just a paint gun looking thing that shoots larger particles through it. I use the stuff from either PPG or Wurth. I don't have the trade names off the top of my head, but a good paint shop will know what you are talking about when you say RUSTPROOFING and waxy, oily substance. I know that Wurth is the OEM supplier to Porsche, BMW, and Mercedes, that's why I said what I said above. The Wurth product is great, but kind of hard to find. I've used PPG as well and it works almost as well -- it's just a little thicker but it covers really well.

This rustproofer makes a heck of a mess, but I guarantee that if you coat every boxed area, you will not have future rust issues. It also works well on the overlapped areas of cars too. This stuff will creep into seams that are overlapped so you won't have that ugly rust colored stuff on your paint at the seam.

As full disclosure, I do not work for either Wurth or PPG; I'm just a car guy who likes to protect his stuff with the best stuff and practices found on earth........

Best of luck!!!

Mark

Hi guys,
Has anyone used this "Eastwood" rust proofing for inside structures?

Eastwood Internal Frame Coating

or this SEM product:

SEM 39574

Just starting to research ideas ......

Thanks

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De Tomaso Internet Community

Here's another thread on the subject, along with what I did. Apparently the pictures I posted are no longer showing up because my POCA photo album has disappeared. Once I get it fixed, the pictures will return to the thread, as well as Jack DeRyke's article that I posted:
http://pantera.infopop.cc/eve/...5562/m/215107066/p/2

As I mentioned in the thread I linked, if I were to do it over again, I would use the Eastwood Internal Frame Coating, as Rob recommended, for a simpler process instead of building my custom sprayer.

Thanks to the responses received. I am in the process of drilling additonal drain holes, especially in the rear support structures. Also, I ran across a product called rust bullet. www.rustbullet.com
Curious if anyone has had any experience with this product?

What I did was POR15 great stuff