Plastic skid plates - HDPE and UHMW

HDPE or UHMW skid plates seem to be a popular DIY mod for people with vehicles that have fewer aftermarket options. But they also are cheaper than metal, easy to work (cut with saw, bend with heat), don't dent, are lightweight, and slide more easily over rocks.

Thread comparing the two plastics: http://bbs.zuwharrie.com/content?topic=84377.0
Xterra HDPE skid http://www.clubxterra.org/forums/showthread.php?t=10656
FJ http://www.fjbruisers.org/forum/index.php?topic=2033.0


Some potential XJ uses I'm wondering about:
- Bolt to the stock skid plates so they will spread force and prevent denting
- Gas tank skid that will protect the tank even without being rigid, by distributing impact to the tank itself. Maybe you could sandwich a layer of foam (like those interlocking mats) between the plastic. But how would this be attached?
- Differential glider. Diff pumpkins are supposed to be strong enough to take a hit, but why not distribute force and prevent gouging? It might be possible to mold warm HDPE to the shape of the pumpkin.
- Boat sides from the bottom of the uniframe to the pinch seam, instead of rock sliders

Viable ideas? The one I really want to try is a gas tank skid.

I could see on top of the skids, but not alone.

I would have to agree with srmitchell. Its a great idea used by many people but I dont think it is rigid enough alone. Maybe using the plastic with a skid that is not as thick as a normal one? The combination of a thin metal skid plate and the thicker plastic might work well. I wouldnt go any thinner than the stock skids though.

I've read on here that folks are using one or the other for quarter panel protection- you'd probably get better feedback from the folks who've actually used it.

MG2000XJ said:

I would have to agree with srmitchell. Its a great idea used by many people but I dont think it is rigid enough alone. Maybe using the plastic with a skid that is not as thick as a normal one? The combination of a thin metal skid plate and the thicker plastic might work well. I wouldnt go any thinner than the stock skids though.

Click to expand...

Yeah that's why I didn't suggest the plastic be used alone for a tcase skid or the front skid-- Too long to be stiff. But with a thin metal skid cut with a dimple die or with stamped ribs, like the stockers, the combination of stiffness and strength would work pretty well I think. As I understand the stock skids are already stiff enough, just susceptible to dents.

But what about the gas tank? Can the tank support weight? If so, a layer of HDPE backed by foam to spread the force evenly could be pretty good protection

I will be using something like this for my boatsides. I also want to try it on a gas tank skid, but that is far into the future.

winkosmosis said:

But with a thin metal skid cut with a dimple die or with stamped ribs, like the stockers,

Click to expand...

I didnt even think about dimple dies, that would allow for some very lightweight but strong skids, I will be paying attention to this thread for ideas.

I think it'd be great to reduce friction when used on cross members, sliders, and maybe diff center sections. But this would only work well when mounted on top of a solid skid.

Even my rear factory skid has gotten some huge dents.

There is more than one type of UHMW. I have seen it made with SS expanded metal in it. Made it very strong, hardly any flex, but very heavy.

Another type which I think would be best for us is Quicksilver. This is used in dump trucks to let the over burden slide out. This is very slick and comes in 1/4" to 1" thick. It also comes in widths up to 5'. This plastic is also weldable.

If you would drill and tap a skid plate and use counter sunk Allen bolts. Just drill and tap the skid plate. You could also use a router with a V cutting bit to relief cut the back side so you could make nice bends. 1/4" would be enough to add a layer of protection and reduce resistance while sliding over rocks.

There is other types that are oil impregnated and is also very slick.

I have made rails out of 2.5" with some 3/8" angle and a 3/8" sheet that goes from the edge of the rail to the frame. It works very well. I have jacked the jeep up on them, slid around trees and over rocks.

So the possibilities are endless.

Answers the question about making a turtle belly. I've been really concerned about the weight of 3/16 steel plate and the impact on long term gas mileage. One of these, reinforced, cut to fit rocker to rocker, bent, and you're gonna avoid most trail rash on a DD.

Those who add uniframe rail reinforcements now can "plate" them over and avoid all the snagging from the CNC punched holes. And mounting one up won't take two jacks and three buddies.

It works very well but you're not going to see much 'distribution of force' from it.

I use it on mine as a belly skid but it has a supporting framework behind it.

I looked in front of the gas tank and I guess that would not be a good place to attach a plastic skid. The two long bolts that the strap attaches to look like they'd break or rip out if you dragged the gas tank. That or the straps would break. I wonder how hard it would be to bend HDPE into a U shape, drill the flat sides of a hitch, and bolt to that. Upward pressure would still be transferred to the tank, but dragging wouldn't pull the tank backward.

What is the thickness of the stock skids? I'm wondering if it would be feasible to have a custom full belly pan made from thin metal, steel or aluminum, with dimple die cuts or some other method of added rigidiy, then cover it with HDPE myself. Is 1/16 steel too thin?

Found a pirate4x4 thread with discussion about UHMW backed by metal. One guy uses UHMW with aluminum http://www.pirate4x4.com/forum/showthread.php?t=610452&highlight=hdpe

The "plastic" provides lower friction for sliding, but little real "protection"...can't carry any weight. Now for gas tank skid, the issue is avoiding puncture...dent is acceptable, but puncture is not. In the gas tank situation, I'd think a layer of HDPE or Kevlar, or ??? would be good...distributes load and avoids puncture.

For t-case or transmission...not a good idea.