screws holding shell to frame

[Sue and Henry]

I'm replacing a little over a fourth of my burro floor due to dry rot. On the burro the floor is attached to the frame and then the shell is attached to the fiberglass enclosed floor. I'g getting ready to remove the large screws going from inside floor down through the frame. They are screws, not bolts. Is that normal? It seems like that would be weaker than bolts. If it i normal, then can I reuse the holes or will I need to relocate to new spots? I don't want to weaken the frame with unnecessary holes if possible.

[mary and bob]

Maybe they are the floor screws as used on the wood floors of freight trailers and box trucks. Those are generally a self tapping screw. I've seen them in 1/4-20 thread, and others in some odd thread that no nut will fit. They were probably used to speed up production, less time than installing a bolt and nut. You will have to see if they are reusable, good threads, but I would use bolts myself

[Sue and Henry]

Originally Posted by mary and bob

Maybe they are the floor screws as used on the wood floors of freight trailers and box trucks. Those are generally a self tapping screw. I've seen them in 1/4-20 thread, and others in some odd thread that no nut will fit. They were probably used to speed up production, less time than installing a bolt and nut. You will have to see if they are reusable, good threads, but I would use bolts myself

Thank you Mary and Bob,
The Burro is 33 years old now and the screws look original and tired. Bolts it is
Sue

[mary and bob]

Those are not the floor screws I was thinking of. Uhaul campers, which are very similar to your Burro, used an "elevator" bolt to hold the body to the frame. Similar to a carriage bolt but with a bigger and flatter head. Available at the big box hardware / lumber stores, they are also commonly used on roll up (overhead) doors on box trucks and freight trailers

[Sue and Henry]

Originally Posted by mary and bob

Those are not the floor screws I was thinking of. Uhaul campers, which are very similar to your Burro, used an "elevator" bolt to hold the body to the frame. Similar to a carriage bolt but with a bigger and flatter head. Available at the big box hardware / lumber stores, they are also commonly used on roll up (overhead) doors on box trucks and freight trailers

Okay - so I looked online and found this. It gives a choice between split washers and flat washers with the nut. Does one have an advantage? I am going to use locknut goop in hopes that the bolt doesn't shake unscrewed.

[mary and bob]

That's about it, although odd color. Here's what I use most of the time, the two nuts to the top have an attached star type lock washer, commonly referred to as a "keps nut". I've seen them under another name that I don't recall. The nut at the end of the bolt is a nylon lock nut, or nylock. Good, but used in your case once the nut got on the bolt to the nylon lock part then most likely the bolt would turn in the floor. Either use the keps nuts or the common split lock washer. We used the keps nuts and elevator bolts all the time on roll up doors when I worked in a truck shop, so that's what I'm used to.

[Sue and Henry]

Mary and Bob,
Thank you so much. This was not something I wanted to screw up!
Sue

[mary and bob]

If body bolts are in storage areas, not on the part of the floor where you would walk, you could use a regular bolt with a "fender" washer under the head. Fender washer is a large diameter but small hole, available for various size bolts.

[Sue and Henry]

Its about 50/50 - floor/storage. I am going to put a second layer of plywood (not fiberglass covered) over the walking area on the shell lip that screws into the fiber covered ply. Since the heads won't be against the final floor finish, would the big washers add strength (is that why you gave me the option for the storage areas)?

[mary and bob]

The big washers would give slightly more surface area but then you would have a bolt head sticking up, as opposed to a flush to the floor head with the elevator bolt. You would only use a bolt and fender washer in the storage areas where it doesn't affect the "living area" flooring. I have some fender washers that are 2" diameter with a 1/4" hole. Elevator bolt head is 1 1/8" diameter

[Sue and Henry]

Oh - that is plenty of surface. Thanks

[ThomasE]

I replaced all the lag screws (your first picture) on my Burro with galvanized 1/4" carriage bolts and lock washers/nuts. You could also use a regular washer and nylon locking nuts. I priced out stainless parts and it was pretty pricey and less available than galvanized stuff, which should last longer than the original lag screws. I got all my stuff from home depot or lowes, don't remember which. It was pretty easy to do, I did have to drill out each hole in the frame a tiny bit with a 1/4" drill bit.

[Sue and Henry]

Originally Posted by ThomasE

I replaced all the lag screws (your first picture) on my Burro with galvanized 1/4" carriage bolts and lock washers/nuts. You could also use a regular washer and nylon locking nuts. I priced out stainless parts and it was pretty pricey and less available than galvanized stuff, which should last longer than the original lag screws. I got all my stuff from home depot or lowes, don't remember which. It was pretty easy to do, I did have to drill out each hole in the frame a tiny bit with a 1/4" drill bit.

Thanks Thomas. I think I am ready to start the fiberglassing then bolt the thing together. I just really want to go camping and this process is so slow with me at the helm!
Sue


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