Bolt advice?

[musigenesis]

I'm rebuilding a section of my floor, and since I don't completely trust my welding skills I'm going to be using nuts and bolts in a number of places in the new frame. I want to make sure these don't work themselves loose, but after researching this a bit, I'm unsure of the best way to do this.

Split-ring or toothed lock washers (according to some sources) don't work unless the material being bolted is softer than steel. Grainger has a big confusing section for lock washers: https://www.grainger.com/category/f...?attrs=Dia./Thread+Size|3/8"-24&filters=attrs and I'm not sure what would work best for me. Loctite is a possibility although I don't know how long-lasting that is. I was also thinking I could weld the nut to the bolt and the material, but I'm not really sure how well that works (can that compromise the strength of the bolt?).

Thoughts on how best to do this? I'm planning to generally use 3/8" Grade 8 bolts here.

 

[2kool4skool]

Our BB uses a lot of prevailing torque nuts.

 

[musigenesis]

Our BB uses a lot of prevailing torque nuts.

Just straight-up with no loctite or anything else?

 

[DawgBüs]

Nylon lock nuts would be plenty to stop the threads backing out from vibration. You're talking about bolting down the plywood? Or the sheet metal?

 

[MacC-SKO]

Frame bolts and frame lock nuts. I was a parts mngr for Freightliner for years, years ago. They had great frame bolts and nuts and a good price. They attached suspension components to frame. Its been 18 years but I think the part number is 23-11011-bolt length. Like -125 or 225 or 300. Example 23-11011-175 is a 1/2x1-3/4 bolt. I can't remember the number for the nut. It is a USS thread. Its been years, so there could easily be multiple number changes. But they can take that number and get the latest and greatest number. Hope this helps. Grade 5 I believe. I think they used grade 5 on suspension because grade is to brittle. On suspension you want the bolt to bend not snap. But bolt head and nut have a washer built into them. Very nice bolts. Freightliner has great prices on brass, bolts, belts, the consumables kind of. Don't forget the part where I said it has been years. But I ordered parts for 15 years there with a 1.5 million dollar inventory not counting core values.

 

[musigenesis]

Nylon lock nuts would be plenty to stop the threads backing out from vibration. You're talking about bolting down the plywood? Or the sheet metal?

No, the replacement frame for my floor is made from 3" angle steel (3/16" thick) pieces that I'll be bolting to each other as well as to the chair rail. So this usage will be load-bearing as opposed to just attaching wood or sheet metal. (I will be welding some of these pieces together as well)

 

[musigenesis]

Frame bolts and frame lock nuts. I was a parts mngr for Freightliner for years, years ago. They had great frame bolts and nuts and a good price. They attached suspension components to frame. Its been 18 years but I think the part number is 23-11011-bolt length. Like -125 or 225 or 300. Example 23-11011-175 is a 1/2x1-3/4 bolt. I can't remember the number for the nut. It is a USS thread. Its been years, so there could easily be multiple number changes. But they can take that number and get the latest and greatest number. Hope this helps. Grade 5 I believe. I think they used grade 5 on suspension because grade is to brittle. On suspension you want the bolt to bend not snap. But bolt head and nut have a washer built into them. Very nice bolts. Freightliner has great prices on brass, bolts, belts, the consumables kind of. Don't forget the part where I said it has been years. But I ordered parts for 15 years there with a 1.5 million dollar inventory not counting core values.

That is interesting about using Grade 5 instead of Grade 8. What you're describing sounds like exactly what I need.

 

[MacC-SKO]

That is interesting about using Grade 5 instead of Grade 8. What you're describing sounds like exactly what I need.

I don' remember 3/8 base number. But they have them. Hope it helps. finally I contributed!! lol

 

[EastCoastCB]

That is interesting about using Grade 5 instead of Grade 8. What you're describing sounds like exactly what I need.

I think they use grad 5 for the seats in buses, fwiw.

 

[2kool4skool]

Just straight-up with no loctite or anything else?

Correct....

 

[banman]

Super easy to google strength charts for sae bolts (grade 2,5,8 ect).
Learn yourself the difference between sheer-load, and tension.

Simple things to know: for any given size bolt, fine thread will be stronger than course thread.
Split ring lock washers act like a kind of spring to provide tension to resist loosening -- not dependent on the material being bolted together being softer than the bolt.

All bolts are 'springs' and the fastening strength is a result of the proper torque on the bolt. If you over tighten a bolt you will stretch it, and weaken it, and it will not stay tight...

loctite is a simple, permanent chemical bond. It works in the absence of air, this also makes it a good rust inhibitor. The chem bond is broken when heated to 400'F should you want to unfasten something later...

Nylocs are pricy and will loose all their hold if used near exhaust or engine heat.

Go to a farm store like Tractor Supply where they sell grade 5 and 8 hardware by the pound at a very decent price. Then load up on all the sizes /lengths you might want with the correct equal grade nuts and washers.

The only time I weld nuts to a part is when I'm making my own weld nuts, nut-plates, etc. Like on my build -- several items will be modular -- I will probably repurpose several of the bus seats into horse-shoe shaped sitting areas. I will have nut plates welded to the floor below them so the seats bolt in from above with no need to hold the nut from below -- makes it an easy one person job.

If you think you might want to reconfigure your angle iron framing down the road just use two bolts at each juncture, no welding. Or maybe part of this sub-frame could block future required maintenance -- make that section of sub-floor modular for easy removal and reinstallment.

 

[musigenesis]

Super easy to google strength charts for sae bolts (grade 2,5,8 ect).
Learn yourself the difference between sheer-load, and tension.

Simple things to know: for any given size bolt, fine thread will be stronger than course thread.
Split ring lock washers act like a kind of spring to provide tension to resist loosening -- not dependent on the material being bolted together being softer than the bolt.

All bolts are 'springs' and the fastening strength is a result of the proper torque on the bolt. If you over tighten a bolt you will stretch it, and weaken it, and it will not stay tight...

loctite is a simple, permanent chemical bond. It works in the absence of air, this also makes it a good rust inhibitor. The chem bond is broken when heated to 400'F should you want to unfasten something later...

Nylocs are pricy and will loose all their hold if used near exhaust or engine heat.

Go to a farm store like Tractor Supply where they sell grade 5 and 8 hardware by the pound at a very decent price. Then load up on all the sizes /lengths you might want with the correct equal grade nuts and washers.

The only time I weld nuts to a part is when I'm making my own weld nuts, nut-plates, etc. Like on my build -- several items will be modular -- I will probably repurpose several of the bus seats into horse-shoe shaped sitting areas. I will have nut plates welded to the floor below them so the seats bolt in from above with no need to hold the nut from below -- makes it an easy one person job.

If you think you might want to reconfigure your angle iron framing down the road just use two bolts at each juncture, no welding. Or maybe part of this sub-frame could block future required maintenance -- make that section of sub-floor modular for easy removal and reinstallment.

Thanks for the info. I think I'm just going to use loctite since I don't intend to ever disassemble this new framing. I am going to be bolting the insulated center units in place, though, since I want these to be removable if I ever need top access to the rear axle again. For those bolts I think I will use nyloc nuts.

 

[MacC-SKO]

All bolts are 'springs' and the fastening strength is a result of the proper torque on the bolt. If you over tighten a bolt you will stretch it, and weaken it, and it will not stay tight...




Don't forget some bolts like u-bolts are meant to stretch it gives the nut its holding power. U-bolts don't use locking nuts. This why you never re-use a u-bolt. By the way the Freightliner bolts I have been speaking of might have the serrations for holding power on frame. I just don't remember.

 

[Native-SKO]

I get all my substantial nuts and bolts from the local Freightliner dealer. They always have what I need and at a very good price.

 

[kidharris]

Super easy to google strength charts for sae bolts (grade 2,5,8 ect).
Learn yourself the difference between sheer-load, and tension.

Simple things to know: for any given size bolt, fine thread will be stronger than course thread.
Split ring lock washers act like a kind of spring to provide tension to resist loosening -- not dependent on the material being bolted together being softer than the bolt.

All bolts are 'springs' and the fastening strength is a result of the proper torque on the bolt. If you over tighten a bolt you will stretch it, and weaken it, and it will not stay tight...

loctite is a simple, permanent chemical bond. It works in the absence of air, this also makes it a good rust inhibitor. The chem bond is broken when heated to 400'F should you want to unfasten something later...

Nylocs are pricy and will loose all their hold if used near exhaust or engine heat.

Nice, concise, interesting assessment of locknuts, thanks.

 

[o1marc]

LocTite makes thread lockers for different applications. Some are good for locking fasteners that only need hand tools to loosen, some are good for more strength that require heat to loosen. Choose the correct product for your application.

 

[TheHubbardBus]

LocTite makes thread lockers for different applications. Some are good for locking fasteners that only need hand tools to loosen, some are good for more strength that require heat to loosen. Choose the correct product for your application.

Exactly. They've got green (for non-permanent friction) for small fasteners, blue (242) for non-permanent use on larger fasteners, and at least two versions of the high-strength red (don't remember the numbers)... one for large fasteners that shouldn't require heat to remove, and one that WILL need heat to remove if you ever desire to. For your application, one of the two reds would be the way to go. Which one depending on how permanent you want to make it. I don't see either one letting go, though, unless you're making it happen. Loctite is great stuff.

 

[banman]

LocTite makes thread lockers for different applications. SNIP....

Exactly. They've got green (for non-permanent friction) for small fasteners, blue (242) for non-permanent use on larger fasteners, and at least two versions of the high-strength red (don't remember the numbers)... one for large fasteners that shouldn't require heat to remove, and one that WILL need heat to remove if you ever desire to. For your application, one of the two reds would be the way to go. Which one depending on how permanent you want to make it. I don't see either one letting go, though, unless you're making it happen. Loctite is great stuff.

You can always go to the source for complete info...

https://us.loctite-success.com/en/solutions-guide.html