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Newbie Trailer Build Questions

Provience

Provience

Kill!
Joined
Jul 8, 2009
Member Number
15
Messages
9,717
Loc
Gatesville, TX
Feeling a little extra poor right now, so I'm going to start planning rebuilding my trailer rather than spend much money actually doing anything :homer:

My trailer tongue decided to start ripping off after a long and abusive overloaded journey. Only problem is, the wiring is all pretty new, i've got a bunch of lights still to install, the tires are only a few years old....and the crossmembers have been heavily rusted for at least a decade and some decent rust holes along the main rails as well. So the plan is to build a new frame and reuse as much of the little stuff as possible.

80" wide deck, 20 feet long, tongue about 4' out from there, center of axles is at 9' from the rear. Currently, main rails are 2x6x0.120 and crossmembers are 2x2x0.120. Tongue is 2x6x0.120 and is but welded at the main beams (where it tore open). It likely held up for 30 years or more.

Attached is a weight per foot chart. Shopping online trailers, it seems anything from 2x4 thru 2x6 is common for main rails.

stick with the 2x6 tube for the main rails? go with 2x5 or 2x4 instead?

1x3 weighs as much as 2x2, but would be much stronger against vertical load however 2" U bolts are common, so i'm leaning towards sticking with 2x2x0.120 for the cross braces.

Do the cross braces need to stay at 24" on center or would 30" be fine?

For the tongue, I want to change the design and go with a 50 degree V under the main rails. Do these need to go all the way back to the spring hanger? If it does go back to the spring hanger, and i used 2x6, would it then be okay to use 2x4 for the main beams on the trailer?

Trailer Picture.png



Tube Calculator - Round, Rectangular & Square Pipes Capacity | Rogue Fabrication

www.roguefab.com www.roguefab.com

handy calculator for comparing relative rectangular hollow structural tube :homer:
 

Attachments

  • weight-per-foot.pdf
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Here is a picture with more dimensions and some totals. saving material means saving weight and saving costs, i'd like to save as much as I can within reason :rasta:

Trailer Picture.png


Wood is about 4lbs per linear foot @2" thick and a foot wide. so about 500 lbs of wood for a deck

Max est weight:

2x6x1/8" mains = 388 lbs
2x6x1/8 tongue with full wrap = 181 lbs
2x2x1/8 cross @ 24" O.C. = 174 lbs

Total = 743+500 = 1243 lbs

Min Est Weight

2x4x1/8" mains = 285 lbs
2x5x1/8" tongue with no wrap = 88 lbs
2x2x1/8" @ 30" O.C. = 136 lbs

Total = 509+500 = 1009 lbs
 
Last edited:
rockyota83 said:
cross members should be either 16" or 12" OC if you dont want a POS :flipoff2:
Click to expand...
current ones are 24" o/c and for the decade that i've owned it, they've been significantly rusted and full of holes and it's worked well enough.

12 sounds way excessive :confused: i'm not trying to go over 8k lbs, i've only got 7k lbs worth of axles handy
 
12" is mandatory for my trailers :laughing: they get abused regularly though and when i need to use a floor jack on the deck i can without worrying

ive seen broken deck boards on several different trailers with 24"
 
rockyota83 said:
12" is mandatory for my trailers :laughing: they get abused regularly though and when i need to use a floor jack on the deck i can without worrying

ive seen broken deck boards on several different trailers with 24"
Click to expand...
So what you're saying is 30 should be out:laughing:
 
Id call the cross braces stringers and make them out of angle. Id drill holes through them for bolting the wood deck before welding it up. Id make the frame rails out of C channel on 16 centers C channel and angle do not rust through like tubing. Going rate here for useable steel at scrap yard is .50 per pound. I would work design materials around what I could find on craigslist or at scrap yard.
 
ChiScouter said:
Id call the cross braces stringers and make them out of angle. Id drill holes through them for bolting the wood deck before welding it up. Id make the frame rails out of C channel on 16 centers C channel and angle do not rust through like tubing. Going rate here for useable steel at scrap yard is .50 per pound. I would work design materials around what I could find on craigslist or at scrap yard.
Click to expand...
What dimensions c and angle would you shoot for? 2x2 for the stringers still and 2x6 for the c channel as well?
 
Trailer Picture.png


this is what 16" for 20' plus a head and toe looks like.

For the C channel, C6x8.2 is about the closet dimension to 6x2 rectangle. However, 2x6x1/8" is only 6.46 lbs/ft. Other than shaping considerations, whichever I can come across cheaper is what i'd shoot for between the two, seems to be a push regardless and it's "only" under 100 lbs difference across the whole thing.


any thoughts on running the tongue all the way back or just part of the way back?
 
IMO unless you're gonna do a tilt trailer I'd build the tongue by bending or notching the main frame rails.

It's more materially efficient that way.
 
I'd run the tongue underneath like it is in your picture but extend the sides back to the front spring pockets and tie those together. All the "brick shithouse" built trailers I see are like that.
 
SLOWPOKE693 said:
Doing it that way puts alot of torsional stress on the tongue where the rails meet and tends to make the deck floppy vs the double frame style where the rails are stacked.
Click to expand...
That's easier to solve by throwing steel at it IMO but either way works fine if executed well.
 
arse_sidewards said:
IMO unless you're gonna do a tilt trailer I'd build the tongue by bending or notching the main frame rails.

It's more materially efficient that way.
Click to expand...
Only 2 issues are that it takes a big asset piece to do it with a 20foot deck , or having to scab together a splice somewhere in the middle of the deck.

And running it underneath, even just a little bit, will help prevent the bouncing what then did fatigue and fail the current one. Granted, took decades, but still :rasta:
 
ive worked on/owned a bunch and have never had a trailer where the deck boards were screwed to every cross member, everything from bumper pull to goose to horse to utility trailers

my 12" OC trailer has them every 3 cross members, and typically the 16" OC have them every other cross member, i have even seen one that only had them on two.

imo the more the better on a lighter weight trailer, make it a little stiffer
 
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