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Skid Plate Bolts

HYDRODYNAMIC

HYDRODYNAMIC

Rock Stacker
Joined
May 20, 2020
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545
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Lost in the forest
What style bolt head should I use?
1/2” UHMW backed with aluminum.
3/8” bolt holes for all the tabs.
I can access all of the bolts from both sides.
Nylocks on the back side.

Hex counter sink?
Flat or slotted counter sink?
Regular hex head?
Button head hex?
 
I would go hex countersunk in I think. That seems like the least likely to get messed up long term and still be able to pound a socket on them to get them off. Flat heads work, but at some point you can't get an allen wrench in them anymore and you just weld a nut onto them to get them out.

I really like the idea of wrapping the skids around whatever structure you have so that the bolts securing them are out of harms way, but this is understandably difficult to do at times.
 
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Been using these for over 20 yrs. When the allen gets messed up I weld a nut on it to get out and replace with new. I've only had to do this a couple of times.
 
I used hex countersink on mine and welded the nuts to the chassis side.
 
Hex counter sunk on backer and plastic. Backer held to chassis to welded in threaded inserts. Backer is threaded for plastic to bolt to.
 
Tabs are already in and are through hole. I really don't like threaded tabs for guards or skids. The threads get loose and or hammered and the bolts back out. For body panels I was fine with the threaded insert tabs because some where blind. The skids can all be accessed from both sides.

1/2" UHMW is not really thick enough to counterbore for a hex head cap screw. 1/4" of bore leaves 1/4" of material and pull through is a chance. Plus the head would still be raised and would need a washer. Counterboring large enough to fit a washer and or socket width would be a pain as well.
Flat head hex Allen key screws are hard to get a key into once deformed which means cutting a slot with a zip wheel or welding a nut onto.
Thinking flat head slotted screws would be the easiest to hammer a screwdriver or coin into or clean up with a zip wheel if its really bad.
They also seem to be common and available. Going to give them a try.
Edit, most of the holes are 3/8” so dropping down to 5/16” screws for clearance.

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Plow bolts would be great, but you'd have to figure out how to machine the squares in the skid plate.
 
I've run 1/2" UHMW back by dimple die'd 1/8" steel for years (engine, belly, and boatsides). It's mounted using flat head hex allen screws (3/8") and has been fine for years. I've never had to weld a nut to any of them, I've been able to hammer something in the socket enough to get them out. I'd go the same route over again (though I'm entertaining AR550 instead).
 
Bebop said:
Lazer
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Yeah, or even a small carbide burr and file, or air file i bet would work if it's regular steel.

On my Jeep I just had countersank bolts with flat face Allens (whatever they are called). Had a few I had to hammer a bit into to remove after some years. Could even weld a "mound" so the bolt is resecessed if wanted to get real fancy.

Or a hex head in a pocket with adequate clearance for a socket. Though the skid plate would need to be pretty thick.

Some of the dozer and skidder belly pans I've worked on have that and that holds up to 20, 30+ tons of machine scraping on rocks and stumps. Those plates are usually like 3/4" thick though, or the bolt area is made much thicker to allow for the recessed bolts.
 
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Freerider15 said:
I've run 1/2" UHMW back by dimple die'd 1/8" steel for years (engine, belly, and boatsides). It's mounted using flat head hex allen screws (3/8") and has been fine for years. I've never had to weld a nut to any of them, I've been able to hammer something in the socket enough to get them out. I'd go the same route over again (though I'm entertaining AR550 instead).
Click to expand...
Yeah, my boatsides are 1/2" UHMWPE backed with 1/8" aluminum (5052 or 6061...not sure which now)...7/16" countersunk allen head screws. Never had to do anything special to get 'em out....
 
I had 2 hexes in my belly I tapped a torx into to remove. I actually use 3/4 plastic on the belly and sink the bolts in a bit so they don't get torn up right away.
 
My old work we used counter sunk Allen's, but found it worked best just to drill the holes straight and just tighten them until they were flush.

Edit: The holes may have been like 1/16" oversized.
 
this is the only way to do skid plates. the threads will collect dirt, when you undo them the threads will get wiped out or the hardware will seize from the debris in the threads. consider the clip on nuts disposable and life goes on. do not use fine thread.



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1/2" uhmw
1.75"x.25" bore, with a 1/2" hole all the way through
1/4" hole, with a countersink
stuff will get tweaked, this setup gives you room to adjust

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.25" AL washer, 1.25" diameter, counter sunk for 3/8 allen
3/8" allen got to the flat tab on the chassis that get unuts
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1/4" bolts get washers and nuts, they hold the two pieces together
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www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
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You guys are crazy thinking plow bolts won't spin in the uhmw after tightening and loosening them a few times. Or maybe just the first time.

Also having to tighten nuts on the backside would suck
 
YotaAtieToo said:
You guys are crazy thinking plow bolts won't spin in the uhmw after tightening and loosening them a few times. Or maybe just the first time.

Also having to tighten nuts on the backside would suck
Click to expand...
I was thinking a proper steel skid plate, not plastic.
Course I'm used to equipment so weight is usually a benefit.
 
Where can these be had for a 3/8" counter sunk bolt that are solid and not stamped? I'm not having much luck with the Googles right now.

I can find all kinds of stamped ones.

1720578851396-png.879947
 
SLOWPOKE693 said:
Personally I'd want captured or welded nuts on the chassis side so I didn't have to dick with an impact and fish a wrench all over the subframe to install and remove the skid
Click to expand...
A little big for this job but bed bolt kits are the shit for skid plates since you get something on the order of a 1/2 socket head bolt with a huge pan head and some big clip on nuts to go with it. Just gotta trim the bolts to length and clean up the threads.
 
gt1guy said:
Where can these be had for a 3/8" counter sunk bolt that are solid and not stamped? I'm not having much luck with the Googles right now.

I can find all kinds of stamped ones.
Click to expand...

not an off the shelf item.

have local laser house to cut circles, then countersink them or have them do it
 
After watching all the U4 cars, the U clip nuts are the only way to go IMO.
Once you strip them out or cross thread them, toss it and slip another in there.

BUT then all run allen head bolts too, I don't like that on a trail rig, they are too much of a PITA to remove on the trail.
If you're getting hung up on a 3/8 bolt head, you're doing it wrong.
 
I like having a bolt and a nut to hold my skids on. The skids usually bend all to hell and it's easier to get then back on instead of trying to line up threaded holes. Plus like others have mentioned easier to deal with stripped out fasteners that way.
 
HYDRODYNAMIC said:
IMG_5946.jpeg
Click to expand...

Ouch. I have somewhere around 100 bolts for all the skids.

I bought the stamped ss ones off McMaster not realizing they were stamped a while back. I'm wondering if I were to put a counter sink in the UHMW and crank down on the stamped ones, would they kind of reform into something following the UHMW. I think a test might be in order on some scrap.
 
welndmn said:
After watching all the U4 cars, the U clip nuts are the only way to go IMO.
Once you strip them out or cross thread them, toss it and slip another in there.

BUT then all run allen head bolts too, I don't like that on a trail rig, they are too much of a PITA to remove on the trail.
If you're getting hung up on a 3/8 bolt head, you're doing it wrong.
Click to expand...

How often are you removing your belly pan on the trail? Everything I need to access in my buggy can be gotten from the top. I can't think of a time where we needed to remove anyones skids to do a trail fix.
 
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