Teardrops n Tiny Travel Trailers

by **Lgboro** » Mon Mar 28, 2011 4:47 am

Was wondering whether Stainless or Grade 8 would be a better choice to mount my cabin to the trailer. I soon need to test mount so I will be able to continue working in my small (10 x 20) shop out of the weather. No shop door big enough to get the trailer in my shop (5' door). I plan to install t nuts to allow me to almost complete the cabin inside my shop.

I know the Grade 8 is many times stronger than stainless and I could go to a smaller bolt without a compromise in strength. I built the cabin notched to fit inside the rails of a TSC trailer. It's a 4 x 9 framed out of cedar and joined with biscuits and dowel pins so I don't want to overkill with bolt size due to weight issues. How many bolts do you guys think will secure the cabin?

by **Shadow Catcher** » Mon Mar 28, 2011 5:26 am

Way too many variables as a question.
Grade 8 if it is truely that (lots of forgeries) is stronger less brittle.
However a good quality SS bolt will far exceed the strenght of the wood
http://www.ssina.com/view_a_file/fasteners.pdf
Note that figures for tensile testing are ksi, thousand pounds per square inch and 304 SS is 90 ksi.
Again buy GOOD quality fasteners! NOT the ones in the dangely packages at Lowes or...

by **john warren** » Mon Mar 28, 2011 7:42 am

unless you do someting really really wrong,,,say hit a bridge abutment.... any properly sized bolt is going to be plenty strong for a most .
i'd go stainless only for removability in some future repair.

by **Rock** » Mon Mar 28, 2011 8:22 am

McMasterr Carr to the rescue again. Best of both worlds - epoxy coated Grade 8 screws. 150,000 PSI tensile strength.

http://www.mcmaster.com/#catalog/117/3124/=bmnojj

I used these to attach my spring perches to my frame-less tear. Almost certainly massive overkill but I like to buy stuff from McMaster Carr. As a previous poster noted however my tear would shred to pieces before even Chinese grade 2 bolts broke.

Eric

by **Larwyn** » Mon Mar 28, 2011 8:35 am

I used six 3/8" galvanized carriage bolts to hold the TD body to the frame. That's two more than General Motors used to hold the bed to the frame on my full sized pickup. I'm often amused by how many bolts some use to hold the body on the frame.

As for bolt choice, I doubt that you would find grade 8 T nuts. Not much point in using such a strong bolt in standard T nuts.

I just used what I felt comfortable with.

by **eamarquardt** » Mon Mar 28, 2011 9:47 am

I've alway been amazed that the boats "floating" down the highway on their trailers are pretty much just sitting on the trailer with a couple of straps to hold them in place.

I think "mush metal" (what I call the typical hardware store nuts and bolts) would be plenty fine for bolting your box to your trailer. SS or a graded bolt is overkill IMHO.

Cheers,

Gus

by **Dale M.** » Mon Mar 28, 2011 10:25 am

Umm on bolt grades....

SAE Grade 0-1-2 (no marks on head) =74,000 psi.
SAE Grade 5 - (three marks on head) = 120,000 psi
SAE Grade 8 - (five marks on head) = 150,000 psi.

I can pretty much guarantee the weakest bolt (SAE 0-1-2) will hold cabin to frame because the attaching system (bolts ) are stronger than the wood base you are securing.... 8-10 3/8 bolts will probable still be on place long after wood is destroyed...

Any good quality cadmium or zink plated steel bolt is sufficient.

Most car manufacturers do not even use grade 8 bolts holding critical parts of your car together... (95-98% of fasteners on your car are grade 5 or less....

SS Steel bolts will not rust but its overkill (how may time are you going to take cabin off after trailer is complete)...... A little grease on treads of standard steel bolt and proper torque (tightening) will be more than sufficient to hold cabin to frame.

Dale

by **john warren** » Mon Mar 28, 2011 11:45 am

Larwyn wrote:I used six 3/8" galvanized carriage bolts to hold the TD body to the frame. That's two more than General Motors used to hold the bed to the frame on my full sized pickup. I'm often amused by how many bolts some use to hold the body on the frame.

As for bolt choice, I doubt that you would find grade 8 T nuts. Not much point in using such a strong bolt in standard T nuts.

I just used what I felt comfortable with.

think i used 8,,, because thats what i had in my box left over from another project. but six would have been plenty.

by **TimJones** » Tue Mar 29, 2011 3:21 am

Six 3/8 bolts from the orange store is enough. Mine is still on the frame

by **bobhenry** » Tue Mar 29, 2011 6:04 am

TimJones wrote:Six 3/8 bolts from the orange store is enough. Mine is still on the frame

Ditto !

by **Pottercounty** » Tue Mar 29, 2011 6:48 am

If you're worried about strength, I would suggest A/N bolts. (Army/Navy)

These are primarily used in the aircraft industry and thus are quite strong. I have a few left over from a Taylorcraft rebuild in 1/4" 28 thread but I'm sure you would want something more like a 3/8"s.

You can ususally find them on ebay much cheaper than you can buying from a aircraft supply house....

Good Luck!

by **Pottercounty** » Tue Mar 29, 2011 6:52 am

This is what I was referring to:

http://www.3rsales.com/an.htm

by **Steve_Cox** » Tue Mar 29, 2011 7:08 am

I just used a few of these Torx head self tapping trailer floor screws.

by **madjack** » Tue Mar 29, 2011 8:29 am

Steve_Cox wrote:I just used a few of these Torx head self tapping trailer floor screws.

I used the same...4 on each side, 2 in the front and 4 in the rear...they have a 500# shear strength so that adds up to 5000#s.......
madjack

p.s. stainless or grade 8 are overkill BUT, if they make ya happy....................mj

Teardrops n Tiny Travel Trailers

Stainless vs Grade 8 bolts for attaching cabin to frame?

Stainless vs Grade 8 bolts for attaching cabin to frame?

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