How do I prevent rust inside the frame rails???

[green69rt]

I'm getting ready to install the trunk floor.  To make the welds to the frame rails I need to clean the metal down to bare surface.  So what happens to the metal after I finish, this seems like I have opened up the metal to corrosion inside the frame rails because I can't come back and restore the finish.  What do you folks recommend.  I've heard of Eastwood weld thru primer, or their Cold galvanizing compound ( I don't like the idea of welding a zinc coating.)  Am I worried about nothing??

[FLG]

Id use the weld through primer...ive been told by my cousin to just grab some a can of spray rustoleum or what not, stick it in one of the holes and just kill the inside in paint after is all on of course

[runningman]

I treated the frame rails with Picklex and then when the pans were welded I used Zero-rust with a straw attached and sprayed the crap out of it through the holes in the rails.

[lilwendal]

Whenever I have a floor up for replacement...Media blast all the interior of the frame rail to remove all rust and scale.
Then heres a trick I use.  Once the new floor is drilled up for the spot welds.  On the last fit check. I'll mark the frame rail at each spot weld point.  The I use those small adhesive paper circles...The size of a dime..from any office supply joint. Pull the floor out after final fit.  Put the circles over all the marks for your spots.  Then epoxy prime the sh** out of the inside of the frame rails. Once dry...pull you circles.  Prep solve the adhesive off. 
Now you have a fully sealed frame rail with bare metal weld spots.  Quick blast of weld primer over each bare spot.  Lay in your new floor and weld away.
Promise you will never have rust in that frame rail again.

[runningman]

 

Yep, I use little pieces of tape and do the same thing.  I mark the plug weld holes with a paint marker and apply the tape over the marks and paint everything up..

[69*F5*SE]

I agree with lilwendal and runningman.  I'm at the same point you are with my rear inner frame rails and mapped out a plan alot like lilwendal's description.  It sounds like overkill, and it is.  But, that's what restoration is sometimes.  You won't have any problems worrying about it afterwards. My trunk pan is out and the rails are ready for the attack.  At least till I get to it.   

[runningman]

I believe these cars were dipped in primer so I am sure the rustproofing they got during the immersion has helped keep them relatively rust free on some cars.  I don't think all have been so lucky though.  I figure if you have it torn apart you might as well spend the extra time to do everything possible to at least protect it as well as it came from the factory..

[hemi-hampton]

I was going to post a Pic but on my old computer. I like use eastwoods rust ecapsulator on inside of frame rails & then on edge/lip where welding the plug/spot welds I use weld thru primer. You can weld the hole with this primer there but you'll get alot of splattering so I like to use my little hand held blaster to blast this hole clean. Then welds with no problem. LEON.

[plum500]

I like using FluidFilm inside the frame rails. (and then I read the initial post --- I use fluid film *after* all this...)

[runningman]

Here is a link to the Picklex 20, this is what I use underneath the zero-rust.

http://picklex20.com/

[69*F5*SE]

Picklex 20 and ZeroRust are both excellent products to be used during a restoration where or when needed.   

[bull]

You can try and try but you're never going to get to all the bare metal/rust to treat it. Give it a shot but don't lose any sleep over it.

[BLUE68RT4ME]

The only sure-fire way to seal everything up is to have the car E-coated after you've finished all your welding and metal work.  They will dip they car first and remove all the rust, paint, and primer, and then dip it in the E-coat and seal it tight.  It gets inside the rails and everything.  Just make sure they do a good job of letting the first dip drain.  I've heard of them not draining the rails will and having solution dripping well after it was coated.  I learned this all from a guy in the Chicago area.  He uses a company in Milwaukee to do it.  He swears by them but I'm sure there are many across the country.

[lilwendal]

The only sure-fire way to seal everything up is to have the car E-coated after you've finished all your welding and metal work.  They will dip they car first and remove all the rust, paint, and primer, and then dip it in the E-coat and seal it tight.  It gets inside the rails and everything.  Just make sure they do a good job of letting the first dip drain.  I've heard of them not draining the rails will and having solution dripping well after it was coated.  I learned this all from a guy in the Chicago area.  He uses a company in Milwaukee to do it.  He swears by them but I'm sure there are many across the country.

One thing I've seen is a car that was acid dipped then E coated before any metal work.  Then when you start opening her up..Find the acid and E coating do not get everywhere with noticable areas between seams and welded panels.
Drill the spots to pull off a panel for replacement and find areas of still rusty metal.
One of those issues where if you leave it in the acid tank too long you can do damage.  Not long enough it cannot fully permiate the joints enough to actually be effective.

[BLUE68RT4ME]

Wendal,

I know that can be the case, but much of it has to do with the knowledge of the people doing it and their prep-work too.  The good ones can make the process very effective while others will do a hack job.

[lilwendal]

Wendal,

I know that can be the case, but much of it has to do with the knowledge of the people doing it and their prep-work too.  The good ones can make the process very effective while others will do a hack job.

Very true....Just wanted those who think that nice clean all black E coated shell is "rust free"

[BLUE68RT4ME]

Yeah, sometimes I think I should put a disclaimer in my signature area to say something like "not in all cases" and "depending on experience".  Just because people do a certain thing, it doesn't mean they do it well... or how you need it in particular.   

[lexxman]

Hey,I plan on useing this stuff called por-15. I'm told it can be sprayed with a udercoat gun and if you follow the instruction it will not rust.So I'm told.

[green69rt]

The only sure-fire way to seal everything up is to have the car E-coated after you've finished all your welding and metal work.  They will dip they car first and remove all the rust, paint, and primer, and then dip it in the E-coat and seal it tight.  It gets inside the rails and everything.  Just make sure they do a good job of letting the first dip drain.  I've heard of them not draining the rails will and having solution dripping well after it was coated.  I learned this all from a guy in the Chicago area.  He uses a company in Milwaukee to do it.  He swears by them but I'm sure there are many across the country.

I've heard of this process but cannot find anyone in the Houston area that does this(seems strange for this size of city.)  Does anyone know of a vendor in the area?

[runningman]

Hey,I plan on useing this stuff called por-15. I'm told it can be sprayed with a udercoat gun and if you follow the instruction it will not rust.So I'm told.

The zero-rust or any of these types of products does seem to work well.  If you use a straw attachment when using a spray can it really helps to get into the seams.  I sprayed it into the outside and the inside as well.

[mopar73]

I replaced part of a pax floor pan and cleaned up the rails with wire wheels and then brushed por 15 on the whole works.  I put the replacement pan on and marked the holes, took the pan off ground the por 15 off in those spots and squirted some weld through primer on them and welded away. 

[FLG]

por15 has been found to do NOTHING!

From what ive heard its garbage, and they say not to use it on anything but rusted metal..not clean.

[Ghoste]

Why is it okay on rusted metal and garbage on clean?

[FLG]

Its supposed to only work properly on rusted metal 

But if you search around from what ive been hearing its no good on anything.

Maybe its people who dont know how to use it?? POR (Paint over Rust) your not supposed to use it over clean metal.

[hemi-hampton]

Its supposed to only work properly on rusted metal 

But if you search around from what ive been hearing its no good on anything.

Maybe its people who dont know how to use it?? POR (Paint over Rust) your not supposed to use it over clean metal.

Funny, Seems I said the same thing in here last year & I was pretty much told (implied) I was crazy  & did not know what I was talking about LEON.

[plum500]

POR-15 is incredibly picky if it is anything but rusted metal. Mind you, on rusted metal, the stuff does certainly behave like it says. On clean metal, I think many people simply ignore their recommendations for prep. I did, and it certainly doesn't stick well to un-rusted metal that has not been prepped. Degreasing with a cleaner that leaves no residue is one thing, but their metal etch is what I think most people skip -- and the reason it doesn't stick. I found it sticks really well to previously painted surfaces -- really well, tough as nails. But, if you have any part that has not been done correctly, and therefore doesn't stick -- it's a real PITA. The stuff peels right off -- and trying to work that spot, fix it, blend it to that which IS ok, is a pain.

[lexxman]

I've only used a little bit of the por 15 so far.I was told by the guy at the shop too follow the instruction to the letter or it wouldn't work correctly.He also said on bear metal I should ruff it up a little.

[green69rt]

Whenever I have a floor up for replacement...Media blast all the interior of the frame rail to remove all rust and scale.
Then heres a trick I use.  Once the new floor is drilled up for the spot welds.  On the last fit check. I'll mark the frame rail at each spot weld point.  The I use those small adhesive paper circles...The size of a dime..from any office supply joint. Pull the floor out after final fit.  Put the circles over all the marks for your spots.  Then epoxy prime the sh** out of the inside of the frame rails. Once dry...pull you circles.  Prep solve the adhesive off. 
Now you have a fully sealed frame rail with bare metal weld spots.  Quick blast of weld primer over each bare spot.  Lay in your new floor and weld away.
Promise you will never have rust in that frame rail again.

Thanks to all for the advice.  I've decided to go with the quoted process and not worry about it afterward.  I have used POR15 on most of the underside, and it does take some extra work.  The metal preparation is time consuming but the finished product does seem to hold up well, I've had a hard time getting it off the places I need to weld up.

For future reference here's what I did.
1. Coated everything with POR15 STRICTLY according to the instructions.
2. Strip off the POR15 where the pan sets on the frame(marked the pan on the underside so I will know where to drill the holes.
3. Drill the pan for the plug welds then put it back in (4th time, lots of time fitting it up.)
4. Mark through the holes onto the frame with a sharpie.
5. Bought some garage sale tags (3/4 inch circles) at Office Depot and placed them on the sharpie marks.
6. Painted over everything with another coat of por15.
7. pealed off the tags.
8. Painted the bare spots and the underside of the pan where it will attach to the frame with Eastwoods weld thru primer (3 coats).
9 Put the floor back in (5th time!!)

I'll let you know how it turns out.  Hopefully I'll start welding this weekend.  I'll post pictures.