Skid plate: steel vs aluminum

I’m not offended at all so don’t worry about that. All my tests are real world with my personal vehicles and vehicles I’ve built and wheel with on some of the toughest most unforgiving trails around. Nobody uses 5052 for a main skid and people that do and wheel hard quickly find out it’s not up to the task. It has its place but that shouldn’t be under a heavy vehicle and rock crawling. If you’re doing dirt trails and don’t encounter rocks then it’s not as big of a deal. I couldn’t put a number on the force of the hits my rigs see. It’s kinda like the forklift test on rock sliders that everyone does, That doesn’t prove anything at all. You drop off rock and slam that slider it’s far more force that lifting up half truck with a fork lift.

 

Short answer... we can discuss a lot more if you want...
A skid plate will probably 'fail' in bending, like a simple beam (Assumption 1)

We will only discuss linear (elastic, no plastic) deformation (assumption 2)

We will call E for steel to be 30 Mpsi, and aluminum 10 Mpsi and assume steel yield strength to be 30ksi and aluminum 15ksi, (highly dependent on alloy.)(Assumption 3)

Comparing .25 alum to .19 steel

In flat plate bending, the stiffness is ratio'd by thickness ^3 (cubed) times modulus... for comparison calcs ONLY

Steel bending stiffness .19^3 * 30E6=206k
Alum bending stiffness .25^3 * 10E6=156k

So, the steel is about (206/156) 32% stiffer than aluminum in flat plate bending (.19 vs .25)


Strength, is ratio'd by thickness (^2) squared times stress allowable, so

Steel bending strength .19^2 * 30E3=1.08k
Alum bending stiffness .25^2 * 15E3=938

So the steel .19 is about 1080/938 =15% stronger than the aluminum.

But, the aluminum .25 weighs about 43% as heavy as the steel. If you make the aluminum as heavy as the steel, the aluminum will be much thicker than the steel, and much much stronger and stiffer.

Here are some quick 'off the hip' comparisons.

https://www.tacomaworld.com/threads/why-no-titanium-skids.575684/page-5#post-19053198

(This discussion does not examine rock skidding ability nor energy absorption)

Edit 9/16/2020, noticed a typo in % strength comparison

 

This is going to take some time digest. Lol

 

Nice rig. Gotta sk did you go witht the square main tube? I think it's an option, they say stronger, for a nominal cost. I'm tempted to pay for the single step w/TRD logo, and go w/the square main tube.

 

I highly doubt Aluminum would have stood up to this repeated desert abuse

 

No, didn't feel like I had the need for it. Mine is mostly to prevent trees from smacking my cab and bed side in the tight trails we have here.

 

I've been going back and forth on this myself and when it comes down to it, I think steel makes the most sense. You get a stronger product and you're only talking about a ~60 pound weight increase. Plus, you get to keep like 300 dollars in your pocket. Just kick your girl out of the truck here and there and you will make up the fuel economy

 

I'm debating between the TRD skid plate and the RCI front steel skid plate. Weight is not an issue for me since I don't have any added weight on the truck. For better protection I'm leaning towards the RCI but wanted to check if it would decrease my ground clearance, looking at pics I see the front hanging a bit low and since I'm stock I don't want to lose any ground clearance. Any input would be appreciated, I'm looking to replace the stock OR ones since mines are already damaged from my last trip.

 

I would get the steel one. You are unlikely to damage it to the point that a sandblast and fresh paint won’t make it nearly good as new. Aluminum will protect the truck but eventually it will get dented and torn enough that it goes in the metal recycling bin.

 

That's why I'm leaning towards the steel one. Any input on ground clearance from aftermarket skids? Thanks

 

I recently purchased a powder coated steel RCI engine skid plate after twisting up the stock tin pan.

I want a full RCI package but after reading this thread, I'm wondering if I should go aluminum on say...the gas tank? The idea of a hybrid skid sounds interesting but not sure if it's worth paying more for a minimal weight increase compared to the aluminum option.

MPG is a slight concern for me but I'd rather have a capable truck for the tracks and climbs I'm getting into.

Oh the decisions!

 

Update, after a few years of full RCI skids, I'm seeing a lot of powder coat flacking and some rusting. Wire brush and rattle can for the fix, but may take that into consideration of the final cost. Might turn out better to coat it yourself

 

Install this weekend (steel)

 

After doing a lot of reading on this forum and a few other ended up going with aluminum skid just because where I live in Nc there isn’t many times the truck ever even hits anything.

hopefully they last me at least 2 years before needing to be replaced. I feel like at 500ish bucks per 2 year’s of use that’s pretty good.