I thought this was a pretty good discussion of steel vs aluminum armor.
https://rockchucksummit.com/aluminum-vs-steel-skid-plates-and-armor/
https://rockchucksummit.com/aluminum-vs-steel-skid-plates-and-armor/
Armor - Steel vs. Aluminium
- Thread starter StG58
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I don't see any mention of which type of aluminum they are using for the comparison. As @mrblaine pointed out to me today, some types of aluminum are stronger than others.
I agree, it was an article that was worth reading. I've decided to use exclusively Savvy armor on mine, which as you know is aluminum.
Let's put it this way... if those guys down in Johnson Valley (which is arguably some of the toughest wheeling on the planet) are using Savvy aluminum armor and not having any major issues, then I think that speaks for itself.
It's lighter, it doesn't rust like steel, and it has a number of other advantages. I really see no reason not to use aluminum armor... as long as it's the right type of aluminum for the job.
I ditched everything on my TJ that I could and replaced it with the Savvy aluminum... including the Rokmen armor.
Let's put it this way... if those guys down in Johnson Valley (which is arguably some of the toughest wheeling on the planet) are using Savvy aluminum armor and not having any major issues, then I think that speaks for itself.
It's lighter, it doesn't rust like steel, and it has a number of other advantages. I really see no reason not to use aluminum armor... as long as it's the right type of aluminum for the job.
I ditched everything on my TJ that I could and replaced it with the Savvy aluminum... including the Rokmen armor.
After reading I wondered whether the higher steel numbers of steel were necessary for what we do with our Jeeps, or if the AL is sufficient
I'm guessing that the answer is "it depends ". For what I do and where I wheel (and what I wheel) some aluminum seems to make sense. It's like the aluminum winch plate I've spec'd out. Saves weight where I need it most, and it's plenty strong for the application. Same with the skid plate. Shaves a couple of inches and a few pounds where it'll do the most good. I don't crash rocks, so it should work fine.
Steel will slide where aluminium will gouge and dig in. As for weight, at equal thickness aluminium is lighter but to equal the strength of steel aluminium must be thicker. Depends on your goal but I'd always use a high strength steel for skids and bumpers unless I really wanted, needed to save weight. But with a 4.0L weight is likely not a big factor.
How much steel is enough? I'd have to throw calipers on the stock TJ shovel, but it looks like formed 10 or 12 gauge. The shape probably gives some stiffness, but it's not that stout in the grand scheme of things.
It does make you wonder...how much is enough for your use? And we all have different environments we deal with.
It does make you wonder...how much is enough for your use? And we all have different environments we deal with.
Folks that don't understand armor and aluminum always point out that fallacy. It isn't true in the least and I've posted these pictures enough times over the years that one would think by now it would have become common knowledge.
This is my aluminum belly skid which has spent most of its life in JV getting drug over rocks. Pay attention to the length of the scratches. If aluminum didn't slide, they wouldn't be as long as they are.
No, you wouldn't use high strength steel because you won't afford it. You'll use the regular steel alloys and none of the post manufacturing processes like heat treating to bring up the utility at considerable expense.
The stock TJ belly skid is actually very well designed for the amount of material used and the stiffness and resistance to bending the design generates. The aftermarket will never do anything as strong with that small amount of weight.
Which winch plate? What material?
Generally though, you are correct and the wrong question is asked which is which is stronger? Steel is always stronger. The correct question is whether or not aluminum is strong enough and the answer is when it is done right, yes it is.
Exactly the point I was driving at with post #6. Strong enough for our rigs under punishing use is the issue. Can we get stronger material? Sure. But at what cost and for what purpose?
The article strangely kept saying that to get Aluminum as strong (general term for whether shear forces or hardness or whatever is in view) as Steel the thickness of the Aluminum would wipe out any clearance gains. Maybe if you're trying to get it as strong as Steel in all departments. But if you're trying to accomplish what is sufficient, it's not necessary to make it that thick and the clearance loss is so minimal that with the weight savings it is virtually nil and certainly easier to handle for the average DIY garage
The problem with aluminum is very few understand how to use it correctly and design around its properties. A lot of companies simply took their steel designs, substituted aluminum and cranked them out. It generally doesn't work that way and the product will fail.
Tera did it with the CRD diff when they saw that Currie was developing the aluminum Rock Jock. They didn't design it in aluminum and it failed in very short order. I'm still running an aluminum RJ 60 rear axle.
A few well known belly skids have failed due to similar practices. The big one is welding to fab. You can't weld aluminum in the high strength alloys and have it retain strength like steel does. It has to be heat treated as a unit and no one will pay for that.
Another thing in the article that shows lack of experience is the reference to the strength of the structure. I build a lot of engine skids out of aluminum. I don't brace them down the sides because it is impossible to get enough strength in them to prevent bending. I use a flat plate and let it flex up into the oil pan under high loads and when the load it removed, it flexes back and doesn't stay bent up. We've had several issues over the years with steel skids getting bent up, staying bent, and then dirt mixed with oil stay in place and the engine vibes sand a hole in the oil pan.
I sold the gas tank skid. I posted it up for sale a while back and even tagged you in it. I think you responded and said you didn't need it at the time
I am going to start by saying that aluminum skids are NOT a bad product. But they do corrode. Not even close to as fast as steel. Water is the enemy of aluminum. If you live in a dry climate they are great. Attached is a video of the types of corrosion that can be found. As a aircraft avionics then a sheetmetal guy for the past 10 years i have seen most all types. Keep in mind most planes i work on are 30-50 years old.
Again aluminum is not a bad product.
Again aluminum is not a bad product.
There are some of us who have folded the stock skids. They really aren't strong enough for moderate wheeling.
I'll start by saying that I spent almost 25 years working with aluminum. A couple years in extrusions, a couple in anodizing and many in machining with a couple of those years in engineering.
Then I'll say that I know aluminum will corrode but I don't even know what this guy in the video is saying. I'm not saying he's wrong, it just seems like more details than I could ever get a grip on.
Makes sense to me. Of course, I have a minor in Chemistry, so I can just barely keep up...
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