I'm planning on fabricating a skid plate for the transmission/transfer case area under my Gen III. I haven't been able to find any aftermarket support for this except through some businesses in Australia.

I'd like to know if anyone has a suggested thickness for the overall plate and if you'd recommend placing stiffing "ridges" on it as well. The plan is to use the existing cross-members for attachment points.
Thanks

Thickness required depends on your usage and expectations. Most folks won't need any more than 3/16", good for general underbrush and some light rocks. Not good for heavy rocks or resting the entire weight of the truck on. If you are seriously going to use them, I'd say 1/4"-3/8" would be sufficient. 1/2" if you want to get crazy...

The designs I've been working on use some 3/16" for some parts, all the way to 1/2" for real crucial areas. The trouble is making it modular enough to facilitate trail repairs, yet solid enough to make a difference...

I don't do any serious rock-crawling, but I do frequent trails with some extended rock sections where I've wished I had more undercarriage protection.
Thanks for the suggestions. I like your idea regarding the modular plate with varied thicknesses. I was thinking about 1/4-3/8'' thickness, but if I could use 3/16'' in "less vital" places it will reduce the overall weight a bit...all the better.
When using the 1/4'' or 3/8'' I don't image needed any stiffing ridges...true?

All depends on their span and projected weight carrying. 3/8" should be able to bear the load over a foot or so of span without stiffeners. It'll show the effects, but it'll hold. Draw up your design and post it. Some of the folks here have alot more experience at this than me, so I'm sure they'll chime in...

If it helps an illustration for the undercarrage is usually contained in the FSM. I know it's in the gen I fsm anyway. <img src="/forums/images/graemlins/kewl.gif" alt="" />

1/4" T6061 aluminum usually does a good job. We were using 5/16" for the front skid plate replacement but that turned out to be a waste of metal. If the un-reinforced square area isn't more than say about 2'x2' 1/4" works fine even for heavy bashing. If you're not planning on slamming the weight of the vehicle on it it will certainly work. You can go to 5/16" or 3/8" for larger square areas but at that point you really need to consider supports and mounting more than the metal thickness.

For what you sound like your doing I'd do 1/4" 6061. It'll save weight. Just my 2 cents.

Edward

On mine I didnt go any over 3/16th" anywhere......and that includes the rear. What most people fail to realize in my opinion at least is that skid plates need to flex and deform because if they dont to a certain extent then that "Force" is tranfered somewhere else and that is usually not a good thing.

So in my opinion I wouldnt go above 3/16th" and then use some 1-2" angle in certain spots to reinforce it. I have only reinforced my gas tank skid cause it takes the whole weight of the vehicle. Under the oil pan and transmission i just left is flat and it has held up to LOTS AND LOTS OF ROCKS hitting it. After 4 years I finally needed to replace my oil pan one. Anyhow hope this helps.

Thanks so much for everyone's advice and suggestions!
I'm going to start looking into materials soon...

Icysyrup, did you mount your plate for the trans/transfer case from the cross-member? Did you install mounts for the attachment towards the rear?
Is there any way you might be able to post some pics of your handy work?

On the rear skid under the transmission pan I ended up drilling two holes in the rear crossmember and running a long bolt through with big washers to hold it. Has held up fine that way and then in the front of that plate I used the mounting tabs that were there. Here are pics of the front skids that I built. Nothing spectacular but they work great and were cheap out of 3/16" All built to utilize the current mounting points that were already in place.

Hey Icy,

How did you bend the front skid? Do you have access the a brake? <img src="/forums/images/graemlins/cheers.gif" alt="" />