Boxing a 47-53 1/2-Tips, Parts

[duwem]

I want to coat the inside of the frame rails (prior to boxing) and the backside of the boxing plates with some sort of paint.

It appears weld through primer is what I need.

Is this what you guys would use? What Brand (seeing 3m, SEM, U-POL)?

Just blasted the frame Sunday and want to get it covered before the summer humidity starts to rust it.

[jimig1]

Weld through primer is what you'll have to use. normal paint will burn and contaminate your welds. I use SEM it is cheaper then the 3M stuff and the paint store said SEM is a good brand. I plan on using it where I box the frame then use Internal Frame Coating from eastwood

[NICK51]

I did exactly what jimig1 said.. I used weld thru primer on the inner part of the frame rail, and primer then got some eastwood internal frame coating and hit it with that as well. You can prime the bigger part of the frame rail (vertical part across from where the boxing plate is going to go) that side won't get hot enough from the weld to do any damage to it, if you take it slow.

1. Primer big side of frame rail
2. Weld Thru Primer on top and bottom of frame rail
3. Weld
4. Internal frame coating all the frame rail

[sevt_chevelle]

I use epoxy for any of my personal projects coming out of my shop.
No matter what you use its gonna burn away from HAZ.
Weld thru primer no matter what brand has very poor adhesion and very limited corrosion protection properties as well.

Epoxy the frame rail, then grind it bare about 1/16 of inch around the welded areas.
Weld your pieces in place and spray more epoxy into the interior of frame rail. Tape over any holes, turn the fan pattern down on the spray gun and spray way, this will create a fog and coat the entire frame rail.

How you prep a welded joint after welding is far far more important then what you do before welding. I certainly would not use weld thru primer to coat the entire inside of that rail, I wouldn't use it all, as epoxy will do a far better job...Eric

[Lextech]

Why not box the frame the entire length but, inset the plates about 3/8"? That would stiffen the frame and still allow you to run the lines on the outside where they are accessible, but still protected. Then you could triangulate some tubing under the cab. Wouldn't that be the best of all 3 worlds?

Jeff

[El Campo]

I know this is old thread but had some questions on it. If boxing the frame has little to no impact on twisting how come before I boxed mine I could lift one frame horn up 8 or 9 inches (with all the crossmembers in) and the frame horns on the other end wouldn't move off of the jack stands because there was so much flexing. After boxing could only lift frame rail an inch or two without lifting other end? I did weld the plates to the crossmembers though would that explain why there is not much flexing? Took me 40 hours to do with an acetalene/ox torch and a Miller arc welder and some plate steel that I got at the welding shop. Only welded one inch at a time. Also I ran my braided stainless line through the frame rails but did as was suggested and had no fittings in the rail and has worked just fine so far. Same with brake lines. Just be certain that wherever there is a fitting that u have an access hole really close by and a way to remove the whole line in case it malfunctions. Again, I am no expert but this has worked for me FWIW.
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[duwem]

I agree 100% that the frame will get stronger when boxed.

I'm almost done filling holes on the one side of my frame, then its off to the other side, then I can get some plates and weld them in. Still concerned about all the stuff that needs to be figured out before you box the rails, but I think some of it can be made to work afterwards. Going to weld nuts on the backside for all the stuff I know I need, stuff I forget I will hole saw out a plug, weld the nut to it and then weld the plug back in.

[mknittle]

Originally Posted by michaelnolimit

We don't recommend boxing in the entire rail for a couple reasons. First the rail doesn't flex that much, Its the stuff between the rails that allows the rails to flex. Second boxing the rails pushes all of your brake and fuel lines closer to your exhaust. Heat does not help fuel or brake systems. An x in the center of the chassis will reduce flex more than boxing the rails. We usually put an x under the cab and two pieces of tubing that create a triangle out back just in front of the rear suspension. A triangle cannot change shape unless one side is shortened or all three angles change. A square or rectangle can easily change shape without shortening one side, all you have to do is change the angles in the corners. A triangle is much stronger than than a square. An x is basically two triangles. But everyone is entitled to there opinions. This is my thought on the subject. Let me know how you guys feel. Happy cruising. Or building. Whatever stage your at, enjoy it.
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P.s. do you have any pics?

I am am going to box a section for support of suspension x members and triangulate the rest.

[El Campo]

O yea by the way I Don't know how you are doing it but worked really well for me was clamping my 3/16 by 6 inch sheets of flat to the rail and then just running a torch along the top of frame rail to cut it to size perfectly. Then hit it once with a grinder to clean all slag off and then put a little bevel on the plate and the frame rail and welds go on BEAUTIFUL! If you use your head which i am sure you are on the straight sections of frame you only have to cut one side of the plate. I think total weight added was no more than about 30 or so pounds.
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