Zona4r

So, as most of you may know, I've been looking at using UHMW polyethylene for light-weight skids. I've finally had some time to work on them today.

I have a 10' long x 2' wide x 3/8" thick piece. I test fit the whole piece and cut it (because I originally wanted to be able to remove sections and not the entire skid as i need). I now have a 3' long piece and a 7' long piece. The 3' piece runs from the front mounting point of the stock skid to just behind the steering rack. I intended to cut the 7' piece down to cover the remaining underbelly back to the 3rd cross-member.

I looked at it and the 7' foot piece is also long enough to run the entire length by itself. I'm now thinking of either running the entire 7' piece or cutting it into 3' and 4' segments (doesn't really matter). This will leave me with an additional 3' piece (what I originally cut). I figure I can use this extra piece to double the thickness of the skid and increase the level of protection if/when I need to.

So here's the questions: What is the more vulnerable area of the underbelly? I can double up in the front, middle, or rear. Keep in mind that I want this to be anchored to the vehicle when it's on, not simply bolted to the existing UHMW skid.

I also have a 8' x 2' piece of expanded metal to use as a backing/ stiffener if I need it.

Did any of what I said make any sense?

Thanks
Carl

SOAZtim

It made sense to me!
I think the oil pan seems to be a critical area.
Where are you at now in town? I'll come and grab that sheet. I hate to make you store it any longer!

hross14

will that actually hold up to a bashing on the rocks? Worried that though it might not break--what about the flex?

Elvota

I like the UHMV idea, but have read you'll need to back it up some how to prevent flexing, warping and possible failure. Not of the UHMW, but where it attaches. Like bolt heads pulling through for example.

If it was me, I'd look into a thin gauge steel for the backing, and try to break up the longer sections with additional support... maybe tube and brackets. Since I tend to go a bit crazy with stuff like this, I might try and figure out a way for the panels to all be mounted to a frame of sorts, and this frame would have a hinge on one side (or end). That way, I could un-bolt the fixed side, and drop down the whole skid for working under the truck if need be. That way, I wouldn't have to lift and re-mount the skid every time I needed to do some maintenance.

I'd try and cover the transfer case, split one of those and you'll be very sorry. It would be nice to get the exhaust and muffler out of harms way... even though that won't stop you on the trail... but as you know from riding with me it sure gets loud. Oil pan of course, and gas tank as well. Even if you don't put a hole in your tank out right, every dent looses capacity and in turn will reduce your range. Not to mention if you happen to hit where the fuel sender or level actually is.

My other concern with to much coverage would be water retention and even mud. Although that stuff is almost a non-issue in AZ, my hinge idea would allow you to open it all up and pressure wash on occasion. Preventing rust and such perhaps. Maybe some drain holes would make sense either way.

I'd really like to see what you come with when you are through.

Zona4r

Tim, I'm in Tempe now, Southern and Mill area. Storage ain't a problem. It's out of the way in a safe place.

UHMw should hold up, they use it on rock crawlers and i've seen on some other boards where people have used it with great success.

I got some expanded metal (1/8" thick) to run the entire length. I'm thinking that should be pretty good backing. If not, I can always throw in some stringers to shorten any gaps, maybe right along the t case. Now all I need is some metric grade 8 hardware. Drainage shouldn't be too big of a problem. The edges are flat so stuff can just run off.

I looked Jon's BudBuilt and it seems most of the hits come up front. If IU size it right, I can always move it around.

flyfishexpert

The one concern I have with using UHMW is it has a relatively high coefficient of thermal expansion. I have used UHMW extensively in the processing equipment and have seen it put on a piece of equipment in our shop and either expand and cause waves or contract and pull out rivets. One thing we do is fix one end and slot the holes that secure the other points that way as the plastic expands and contracts it will be able to move freely.

Zona4r

Beau

Good info. After researching, I understand the coefficient to be 0.00011. at 1000 deg F, the material would expand 0.11 inch? Is that correct?

flyfishexpert

38.9 ?in/in-?F or .0000389in/in-?F MatWeb.com
We built a set of conveyors here in Idaho in December and shipped them down to Mexico. The temperature difference between Idaho and Mexico was +80 degrees. With that we saw 0.003112in/in (80-?F*.0000389in/in-?F) and with a conveyor 20' long we had a gain of 0.74688" in length (.0.003112in/in*20ft*12in/ft). To calculate the expansion you multiply the coefficient by your change in temperature then by the length of dimension of the piece you are interested in. It also depends on your specific type of UHMW as to the coefficient of thermal expansion, we happened to be using one with a higher number.

Edit: the above shows ? when it should be a degree symbol

SOAZtim

Cool,
Headed to Ouray this weekend, but I might try and grab it next week. I was going to work on it in tucson next weekend.