Building the perfect H3 Hummer

[SuperBuickGuy]

my next sliders are going to be made of aluminum - right now, aluminum is cheaper than steel. If I really get ambitious I'll fasten stainless or other super-hard alloy to the bottom so it doesn't scar the aluminum too badly.... I'll also use either 5150 or 5056 alloy so I can weld it easier.

 

[Schwarttzy]

my next sliders are going to be made of aluminum

Man your brave in my eye's, I just don't have the trust in the strength of aluminum to do that.

 

[Sethmark]

I'm curious.... What expectations do you have of skid plating?

 

[Schwarttzy]

I'm curious.... What expectations do you have of skid plating?

Expectations... I'm a little confused by your question and probably won't answer it properly without some further in put.

Basically my goal was to not flinch at the thought of statically dropping the entire weight of the front-end of the hummer on to a rock without destroying the skid plate from a height of one foot. I still flinch, but it should survive from the testing I've done. I also had this idea from a really bad snow fall that if I had independent suspension and a wide enough skid plate that I could in a sense, hydroplane on top of the snow and possibly deep mud too that went into the design. I haven't had to much experience with snow or mud yet, but I found out the idea works the same with rocks and that section of mud in the center of deep ruts better than I could have guessed. It was really surprising to find out just how much I can slide right over, despite not having enough ground clearance. In testing I did bend a small potion of one of my plates, but have since added a bit of metal that should prevent it on production skid-plates, however this is mute point because it really didn't reduce the ability of the plates to protect my Hummer.

Does that answer your questions?

 

[Sethmark]

The reason I ask is your material choices are pretty heavy. Beyond anything I've ever built or seen spec'd.

That's not a criticism. Just an observation.

My expectations of skids are much lower.

 

[Schwarttzy]

The reason I ask is your material choices are pretty heavy. Beyond anything I've ever built or seen spec'd.

That's not a criticism. Just an observation.

My expectations of skids are much lower.

The thicknesses I decided to go with just feel right to me.

 

[SuperBuickGuy]

I build a lot of stuff with that very formula :thumbs:

That said, it's all about weight, and the calculations required to right-size something is pretty easy to do. rules of thumb (aka known as the stuff that really irritates mechanical engineers such as my wife)

4x the mass is what you need to stop - Steel, cold rolled, nothing special from the yard has 75,000 psi yield (that's 1" thick steel).... so you have a 5000lb H3 * 4 = 20,000 lbs force. round down, that's 1/4" steel round up, that's 3/16" steel to do what you want to do (of course, with tubes there's 2 walls, so you cut that number in half 1/8" wall or 3/32")..... 6000 series Aluminum has 45,000 psi yield. Again with the math, I need 1/2" of aluminum.... a lot, no? actually, no - that's 1/4" wall tube to get the same strength as 1/8" wall steel tube. The nice part about 6000 and up series aluminum is it has less deflection compared to steel (it's more brittle, or less plastic) so I can put it closer to my rig without fear of it whacking the plastic side panels


Which is why I use 1/8" stainless as a skid plate under my H3. It's tied between two rails so the math gets a bit more complex; but rule of thumb, I could have used 16 ga stainless for a skid plate - of course, 1/8 is what I had, so it's what I used.

 

[Schwarttzy]

Which is why I use 1/8"

That is entirely to thin, you wouldn't want to follow me where I go and what I do. Have a look a Genright their plate is just as thick as mine and on much lighter vehicle which is why I offer it in 5/16 inch.

 

[Sethmark]

If its properly reinforced and ribbed you can get away with a lot less steel. Add a simple 90* bend to the ends and run an FEA.

I think you're doing a great job of bringing some interesting products to the market and with some key additions you can add tons of strength without the weight penalty.

Drawing on your trail experiences is great. It's real world testing and the only place that all the talk matters. That's how buggies developed their popularity.

 

[SuperBuickGuy]

That is entirely to thin, you wouldn't want to follow me where I go and what I do. Have a look a Genright their plate is just as thick as mine and on much lighter vehicle which is why I offer it in 5/16 inch.

You build some great stuff, I was simply illustrating the calculations. The skid plate I built is bolted to both the cross members, so the material is held in tension - thus making it stronger. Same with my transmission skid bars - I didn't do a plate there because of transmission heat.... again, it's all about the design. And, as you point out, where/how you wheel.