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Old August 28th, 2019, 15:46
frijolee frijolee is offline
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Join Date: Oct 2010
Location: Tustin, CA
Posts: 377
Re: Joel's multipurpose XJ build (rocks/boulevard)

Originally Posted by Evan03 View Post
Mild steel will wear much better than aluminum especially in a skid plate application. Aluminum will also stick to rocks more were steel will slide.

Very very nice fab work on it. You should sell them I think lots of guys will buy them for the coolness factor
It's all compromises. Weight is the biggest one for steel. With aluminum being 1/3 the density I can run 1.5x thicker aluminum while be half the weight of an equivalent bit of steel. Young's modulus (bending elasticity) of aluminum is also about 1/3 that of steel but since bending is a function of thickness^3, the 1.5x thick scenario above actually stronger than steel against bending. If you jump to 2x thickness it gains even more.

In my case I was more concerned with preventing damage than ability to slide on rocks (but the point about being less slippery is valid). If you wanted the best of all things, aluminum armor skinned in some replaceable UHMW would be pretty trick. I've seen that on a few Ultra4 rigs.

FWIW, material costs were higher with aluminum than most aftermarket skids retail for complete and out the door. As such, I suspect that price would be the issue that would determine viability at retail. I own a business selling car parts on the side already ( but doing Jeep stuff would be a big jump from our current markets.

I do think the aluminum armor has some coolness factor, but I built them for performance and they've work damn well for what I need. It's certainly different so I thought folks might get a kick out of it... Glad you did.

I'm glad to see more folks thinking through the compromises of material choices. Stinkyfab's High Roller WJ steering comes to mind.

Originally Posted by XJEEPER View Post
I've run 1.25" bolt-on billet wheel adapters for over 15 yrs on 2 different XJ's with zero issues. What exactly are you trying to avoid by using a longer stud and slip-on spacers?

Seems to me you've added risk of component failure.
Indirect load paths suck. Are bolt on spacers sufficient? Maybe, but it’s still a crap design. For one of the most famous examples I can think of, consider the 1981 Hyatt Regency walkway collapse.

No way I’ve made it weaker going direct, so why not?

Originally Posted by Jim Malcolm View Post
Try a plain ol' nitrile/Buna-N o-ring. Viton is a horrible material quite frankly, except where there's no other choice due to temperature or chemical compatibility.
Got any more detail on that? I was under the impression we mostly cared about service conditions and durometer... I don’t have nitrile in the right size at the moment, but it's probably worth a try.
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