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Aluminum gas tank skid

802 views 10 replies 6 participants last post by  441119 
#1 ·
Hello all.. I'm normally on the TJ thread (since around 2005), but I bought a 00 Cherokee last week. It's completely stock now and I'm putting a shopping list together now.. I'm a big fan of aluminum armor for several reasons and I'm looking for a few items now. Do any of the vendors make an aluminum gas tank skid for the XJ? How about bumpers and such?
Thanks for any help..
 
#2 ·
Not that I've ever seen, and I have looked plenty.

However I have seen some company selling a bumper mounting kit for mounting any TJ bumper on an XJ. You could use that kit to mount an aluminum TJ bumper on an XJ.

There are no aluminum gas tank skidplates that I know of.

However, Tomken makes a 1/8 inch thick steel gas tank skidplate that is strong enough and light enough.

Genright makes aluminum gas tanks that have a built-in aluminum skid plate. So I there's an aluminum skid plate for XJs. An added bonus is that it holds more fuel. It's for overlanding trips when you're far from a gas station.

That's as aluminum as it's going to get for an XJ, unless you fabricate your own aluminum skid plates. The good news is that XJs are light-weight because of the unibody construction. Even with steel skidplates, my XJ is still 800 pounds lighter than my LJ Rubi was.
 
#3 ·
I've looked around and not found anything either. Your best bet would be making something yourself or going with a thinner steel option if concerned about weight. I would worry about the aluminum losing it's strength at the joints though. The strength loss is pretty substantial with your typical 6061 after welding, assuming you don't heat treat it afterwards.
 
#4 ·
Another downside to any basic aluminum alloys is the softness - if you wheel in areas where there are plenty of sharp rocks, aluminum will stick itself onto the rocks pretty damn hard.

Weight- savings on aluminum vs. steel are substantial, but on the other hand a steel gas tank skid doesn't really need to be that thick at all. As long as the mountings are strong, high- grade .120" thick steel is plenty enough. IMO, 1/4" what many of the skids are is way overkill. Especially if you have a plastic gas tank, minor dents on the skid don't matter a thing :)
 
#5 ·
I've bought aluminum skids from steel armadillo, but I don't see an XJ on their site. They have quality stuff (I've bought quite a bit), and it's a shop, not a store, so just because it isn't on the website doesn't mean anything. Send him an email or call him up and ask if you makes what you want. FMJ is another custom fab shop that I'm working with to make a custom rear winch mount bumper. They were very happy to customize, and aluminum was one of my options.

The steel armadillo skids are nicely made, and thick, but aluminum is aluminum and steel is steel. Steel is much harder to gouge, and moves a little before it tears. Aluminum is stiffer and softer, so it's easier to tear a chunk out with a rock. My first few offroading trips, which didn't include any rock crawling, already put some badges of honor on the aluminum. I was going for light weight, and want to see how these hold up long term. I'm under budget on my build, so if I rip up the aluminum and switch to steel next year, that's okay. If they last for years, I would probably just replace them with aluminum again.

If you're dragging over rocks on purpose, you might want to go with the lower cost steel which will take more hits. The general engineering rule of thumb, subject to hardness and composition, is that the same strength in steel is twice the wieght, but 1/3 the thickness of aluminum. Again, aluminum varies greatly, just like steel, but the ratio is useful as a first comparison (before looking up numbers on the steel or aluminum alloy you are choosing).

Fatigue strength, and work hardening are much better in steel, meaning if you're going to bend something and bend it back, don't use aluminum. When aluminum bends, leave it bent, or plan on it cracking. If you have to bend it out of your way, bend it as little as possible and heat it if you can. Aluminum is very subject to stress concentrations, like sharp corners or cracks. Crack propagation in aluminum is brutal compared to steel. If you see a crack in aluminum, at least drill a smooth hole just past where you can see the crack end (with a bright light and magnifying glass), but you should replace it if failure would be costly.

Steel is easier to repair pieces of it, and even an amateur weld can be very effective. Amateur aluminum repairs can be very dangerous.

So, if cost is less important than weight, and you don't need a long life of beatings out of this part, then aluminum is a great way to go. If the skid plates are for "just in case" or the hits are softer materials like mud and sand, then aluminum is even more attractive.

Try steel armadillo or FMJ offroad if you want something made. In fact, the custom winch mount bumper that FMJ is designing and building for me was about what a catalog bumper costs without the winch mount.
 
#6 ·
Thanks for the replies and information fellas.. I'll look into some of the fab shops.

My uses for this particular rig will be mild trails in the mountains. It's going to be a camping/trail rig for me and my grandson. The hardest thing it will see will be going in to Coyote Lake which is similar to Dusy-Ershim. I have axles, gears etc all planned and am working out details for suspension that will work with 33 in tires. I'm thinking a lighter steel GTS will do.. I was really hoping for aluminum though as my Savvy unit on my TJ is a work of art and extremely functional.
Thanks again.. And if I find one I'll post it..
 
#7 ·
There are strong hard grades of aluminum and ways to weld it without weakening it. Mr Blaine's Saavy TJ aluminum bumpers are hard and strong. Mr Blaine knows how to make a hard strong aluminum product.

The problem is most fabricators don't know how to fabricate a strong hard product using aluminum. It's beyond the typical fabricator's skills.
 
#8 ·
Seriously, most skid plates aren't all that heavy, except for a belly skid and gas tank skid which are heavy. Well, gas tank skid is heavy if it's 3/16 thick. A 1/8 gas tank skid doesn't weight much (and I think it's still strong enough for most people).

However, as I said, you can buy a good Tomken 1/8" thick gas tank skid for a reasonable price and it's strong enough for an XJ (which is a reasonably light vehicle). Also, a little weight in a gas tank skidplate is a good thing for an XJ because it puts some weight behind rear axle, which helps ride quality, rear wheels traction, and overall vehicle balance. i.e. - XJ (or TJ) is front heavy. A steel gas tank skidplate helps even out the weight distribution. However, Tomken 1/8 gas tank skid is relatively light compared to a 3/16.

IMO, the only skid worth the cost and trouble of making of aluminum would be a belly skid, and it's worth having aluminum bumpers too. I already explained an easy way to have an aluminum TJ bumper on an XJ.
 
#9 ·
From the factory XJ's weight is distributed ~52/48 (slight variance by year and equpment), which is quite good. So heavy gas tank skids would only have value balancing it if you need to counterbalance a large winch bumper or some such and aren't carrying around enough weight in tools, spares and a spare tire to offset it like many of us are.

Otherwise I pretty much agree with the other comments.
 
#10 ·
IME, a little extra weight in the rear helps rear wheel traction a lot on any surface, and helps prevent or reduce fish tailing on Winter roads.

I remember driving on very uneven terrain and my 96 XJ (that I had at that time) tipped way forward and to the side whenever a front tire went into a deep dip or hole, and the opposite rear tire would raise way off the ground. It felt like we were going to tip over.

Now with a little extra weight in the rear, my 99 XJ is more balanced in those conditions.

BTW - if you have a rear hitch, that is another thing that adds some weight to rear.
 
#11 ·
IMO, a cheap and effective alternative to aluminum bumpers is to keep stock bumpers and add some 1/8 or preferably 12 gauge sheet metal for backing material behind the stock bumper to act as a interior hidden bumper inside the stock bumper. This could also be used to create a boxed bumper. It'd look stock, but be reasonably light and strong.

My version of that that I plan to do is to add 12 gauge boxes behind the outer portions of my stock bumper. That would make the outer portions of my stock bumper stronger while remaining light. I don't plan to beef up the center portion (between frame rails) because it's strong enough for my purposes.

Before anyone jumps in saying how weak stock bumpers are. IME it depends on the situation. Stock bumpers are weak for tension. i.e. - they aren't made to be pulled on. You can't hook a strap to them and pull another vehicle out of the sand or mud because the stock bumper would pull off easily.

However, stock bumpers have reasonable compression strength, IMO. They can take a reasonably hard hit between the frame rails and stand up to it reasonably well, IME. If the stock bumper is hit hard enough to bend between the frame rails, then be thankful it absorbed some impact so you didn't have to. The stock bumpers are weak to taking a hit on the end portions outside the frame rails, but that's why I suggest boxing the ends by adding material in that area.

I know from miserable experience that stock bumpers can take a reasonably hard hit in the part between frame rails because I was rear ended (40 mph hit) hard enough to break my neck and total the Honda Civic that hit my 96 XJ. All I had to replace was the rear bumper and bumper mounts. Really, all I needed to replace was the rear bumper mounts. The rear bumper was still usable, but was ugly - so I replaced it too.

Whether or not beefing up stock bumpers would be strong enough for your needs depends on your intended uses. It is a way to have light bumpers that look stock, but are a bit stronger than stock (for hits anyway, not for pulling). But you can use tow points for pulling. You don't need to use bumper for pulling.

Before anyone gets critical of what I said above, please remember he's looking for LIGHT weight strength improvements over stock.

A better, but more expensive solution would be a Savvy aluminum bumper mounted using that kit that allows mounting a TJ bumper on XJ.
 
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