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Welding new frame rails over the old rusty ones?!


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I am about to purchase a set of Bad Dog frame rails.. however; I feel uncomfortable welding the new rails over the existing rails!

 

It seems if the old rails are rusty, they will continue to rust all the way through up to the floor and beyond.

 

Is there a process to strip the rust off the old rotten rails before you overlay the new ones?

 

Thanks guys

 

Ryan

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Use any method at hand to remove rust - sandblast, I prefer flapper discs if no sandblaster is available. Wire sheels for hard to reach areas sometimes.

 

Once the rust is mostly gone, I would use OSPHO to get microscopic rust and then paint wherever you are not welding to prevent future rust.

 

For paint I would use Zero Rust.

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  • 1 month later...

Just some advice. Look at both frame rails very closely before you start work on one or the other. I started working on replacing my driver’s side with new floor pans and used the Bad Dog frame rail caps and the driver’s side came out very nicely. However when I started to work on the passenger side I ran into a small problem, what frame rail! The frame rail was pretty much gone all the way to the T/C bucket when I started to clean out the old rust.

 

DSCN1714Medium.jpg

 

The reason it looked this bad is because of the work a body shop did on the car years before. They just covered up all of the rust with a tin cap and put in enough undercoating and filler to make it look like there was a frame rail there but after removing the undercoating and filler look what I found or did not find!!

 

So in the end I had to ditch the bad dog frame rails and build custom 2X3 frame rails to replace both sides.

 

DSCN1752Medium.jpg

 

So I had to redo work that I already did, not fun. But in the end it worked out for the better and the car stiffen up nicely! Hope my pain helps someone in the end!

 

Check both sides before work on one!!

 

HB280ZT

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The BD rails are sized to fit over the existing rails and in alot of cases, doing so just temporarilly hides the problem. If your rails are just beat up from jacking ect... capping them is fine.

 

If theres bad untreatable rust, cut it out, media blast or wire wheel any surface rust and por-15 the area prior to installing the new rails. While your at it, por the inside of the new rails too. After everythings welded uo, you could drill some access holes thru the floor pan and spray some undercoating into the rails and then snap in some rubber plugs to cap the holes.

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Well the stock sub frame connectors are 2" - 2.5" wide depending upon where you are measuring. I'm using 1" X 2" X 0.083" tubing to replace my frame rails. At the same time I'm replacing the floor pans with 18ga metal. I'm also doing a full cage, so you might want to go to thicker material on a non caged car.

 

Justin

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I'm in the same boat, also, but I'm going a little extreme with mine.

 

I'm going to be just use a spot weld remover bit and take out the rails (and hopefully, not half the floor).

 

I would say to tack weld a frame in there, before removing the rails, just to be safe

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You can unbolt the fuel/brake lines. I'm not sure if they can be pushed far enough to one side to weld the passenger side sub frame connector. Maybe it would be best to completely remove the hard lines when welding in the passenger side rail.

 

Justin

 

Hmm, it'll be tough; particularly at the back of the car. You may be able to disconnect at the front and rear and simply swing them over to the side. Pushing them over is not really going to work, but then again, it's all in how close to fuel lines you feel comfortable welding. :-)

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