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frame stiffeners contribute to rust?

Crewdude007

NAXJA Forum User
Location
Bel Air, MD
I'm looking to add frame stiffeners to my rig, but I'm worried about removing the undercoating along the frame rails. Once this protection is removed, doesn't the frame rail start to rust? How do you prevent this?
 
I'm looking to add frame stiffeners to my rig, but I'm worried about removing the undercoating along the frame rails. Once this protection is removed, doesn't the frame rail start to rust? How do you prevent this?


Make sure they're 100% dry when you weld on the stiffeners, then re-undercoat the stiffeners when you're done. Anything that looks like a hole or a gap in the metal gets either JB weld, or a large amount of underbody coat.

...but maybe I should leave the help to people who have done it before...
 
Always use weld thru primer before you weld on your stiffeners, you also do not need to grind the entire rail down to clean metal, clean the area's you will be welding too, two coat's of weld thru primer on both your frame and the stiffeners. Ten as said, undercoat the crap out of it when you are done.
 
I wondered about this as I sat under my XJ looking at bare shiney frame rails with a stiffener in one hand and a welding gun in the other.... :banghead:

If it bothers you get some weld through primer. I've never used it but it would seem to be a good solution. I couldn't get it at the last minute so I just went ahead and welded mine on. Drill a few drain holes in the bottom of the sliders that match up to the factory holes and weld it up good.

The idea of sealing it up completely is do-able but you will need to account for EVERY hole in the frame that the stiffener will cover.
 
Stitch welding the perimeter with large gaps should leave plenty of room for drainage. Just primer them before and after welds, and then coat them with good underbody spray afterwards. Rust forms where water sits, and does not form when it runs off.
 
:lecture: Make sure it can drain and you will be all good. They make some really great underbody coatings that you can either spray or roll on--all of them do a fairly good job of rust prevention so long as you don't scrap the coating off on a rock or something
 
Stitch welding the perimeter with large gaps should leave plenty of room for drainage. Just primer them before and after welds, and then coat them with good underbody spray afterwards. Rust forms where water sits, and does not form when it runs off.

Why do my brake rotors rust if I park my Jeep for several months?
 
considering how many holes in the frame and all why not just occasionally pour a quart of used engine oil into each frame tube. That maybe coupled with a good bead of silicone along the top and the front should slow down any rust. Just don't park in your nice clean driveway for a day or so.
 
what frame?
The u shaped piece of metal that runs from the front to the rear of the cherokee that is fastened to / part of the body that while a lighter gauge than say a TJ frame still serves the same purpose. I believe that is what the stiffeners are welded to at least that what I welded mine to.
 
Why do my brake rotors rust if I park my Jeep for several months?

Atmospheric corrosion getting started on the ground iron surface. This picks up mainly because you don't heat up the rotors if you let them sit for a while (the heat from use burns off the moisture - problem solved.)

Fortunately, the milder the alloy (going from high-strength tool steels down to mild cast irons,) the more resistant to rust they seem to be. That's still not as good as a decent corrosion resistant alloy (10-17% chromium content,) but it's good if the part isn't structural.
 
Zinc primer


I work at Sherwin Williams and we carrie some sort of Zinc coating that you can spray on metal buildings.. it weights 95lbs for 3.5 gallons and its a 2 part epoxy and a kit is like 70$ a gallon if I can remember right.
 
I would think any kind of DIY weld will be susceptible to rust?

Even though water can drain, depending on the stiffener design, it could trap a lot of dirt and road salt.... doesn't sound healthy!
 
If water gets trapped in the welds then yeah it'll rust pretty quick. It's really a question of minimizing risk instead of eliminating it. Like, weld the front vertical edging so that water/muck can't get inside, and leave the rear vertical edge so that whatever moisture gets inside can flow out. Similarly, make longer welds on top so water can't get in as easily, and smaller welds on the bottom so that water can escape easily. Another option would be to just use bolts on the bottom, which might be adequate when combined with welding the top, depending on usage. Primer everything before and after and coat it all with underbody spray and you'll reduce the risk even more. If you're still freaked then best not to use a welded stiffener.
 
Really seems like I've heard a couple of good suggections.

1. Grind minimum amount of undercoating to make the stiffeners fit right.
2. Use some drain holes.
3. Zinc primer before and after the weld.
4. Use seam sealer along the top, leading and trailing edges.
5. Recoat with a quality undercoat.
 
If water gets trapped in the welds then yeah it'll rust pretty quick. It's really a question of minimizing risk instead of eliminating it. Like, weld the front vertical edging so that water/muck can't get inside, and leave the rear vertical edge so that whatever moisture gets inside can flow out. Similarly, make longer welds on top so water can't get in as easily, and smaller welds on the bottom so that water can escape easily. Another option would be to just use bolts on the bottom, which might be adequate when combined with welding the top, depending on usage. Primer everything before and after and coat it all with underbody spray and you'll reduce the risk even more. If you're still freaked then best not to use a welded stiffener.
Welding the front vertical is a bad idea, I believe it could lead to stress cracks, there are lots of posts about welding frame stiffeners, rosette welding a bunch of holes is often mentioned
 
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