trailer build question

marty79

marty79

Well-Known Member
Joined
Nov 24, 2013
Location
Newton, NC
finally bought some good material and gonna build a legit car trailer once and for all!!
My question is:? do you put a slight bow in the trailer frame like 18 wheeler trailers have so when you're loaded you're sitting flat?
I bought 2x4x1/4" tubing for frame, front and back pieces, and got 4x4x1/4" for the braces in between. Tongue will be same 2x4 since i got 4 20ft sticks.
Just trying to figure out if you're supposed to keep it perfectly level or put a very slight bow in it...might be overthinking it but doesn't hurt to ask since I'm building one for real this time lol, no more camper trailers haha. thanks.
 
No. Keep it straight.

tractor trailers have a MUCH larger spread from axles to pin to create some preload on the frame. A car trailer is set up much different where most of the weight is carried by the trailer axles, which is mostly centered under your load. Preloading the frame won’t help on a car trailer.
 
rockcity said:
No. Keep it straight.

tractor trailers have a MUCH larger spread from axles to pin to create some preload on the frame. A car trailer is set up much different where most of the weight is carried by the trailer axles, which is mostly centered under your load. Preloading the frame won’t help on a car trailer.
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cool thanks, couldn't really find any info on that.
 
Why tubing? Wood or steel floor? Floor over on top frame and crossers?
By the length and number reference sounds like you plan on the exterior frame and tongue area to be separate framing members and weld to one another?
Deck over or fenders?
Are planning on a 20 food deck plus tongue? Applied to axle placement.
Tongue length?
Also applies to axle placement.
Tandem axles?

So many variables and questions......
 
WARRIORWELDING said:
Why tubing?
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why not...lol
don't wanna get into "proper materials" for car trailer...been there,done the search and I was convinced with 2x4 over C-channel...that's that
18ft with 2ft dove tail(20ft total), dual axle, brakes, 4ft tongue, 84" between wheels/fenders,
 
marty79 said:
why not...lol
don't wanna get into "proper materials" for car trailer...been there,done the search and I was convinced with 2x4 over C-channel...that's that
18ft with 2ft dove tail(20ft total), dual axle, brakes, 4ft tongue, 84" between wheels/fenders,
Click to expand...

marty79 said:
finally bought some good material and gonna build a legit car trailer once and for all!!
Click to expand...

:D

Another build I can't wait for!
 
marty79 said:
why not...lol
Click to expand...

Why not?
Extra weight without equal added strength.
When it comes time to attach lights and such not as convenient.
 
YotaOnRocks said:
Make sure you get your axle placement right so your not constantly fighting too much or too little tongue weight. Can probably get by with just grabbing some measurements off a factory manufactured trailer on a lot.
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This... I had a home built trailer that the axles were too far forward by about 1"...... What axles are you planning?
 
I am sure this thread will be as the rest. :popcorn:
 
It really needs to have a 3/16" per foot bow, but only from the hitch to the front of the spring mounts. Then it should be straight across the full length of the spring mounts for better tracking. Finally it should have a 1/8" per foot reversed arch from the back of the spring mounts to the back of the trailer so that it has proper trilateral hexagonal diffusion when loading and unloading.
 
jeepinmatt said:
It really needs to have a 3/16" per foot bow, but only from the hitch to the front of the spring mounts. Then it should be straight across the full length of the spring mounts for better tracking. Finally it should have a 1/8" per foot reversed arch from the back of the spring mounts to the back of the trailer so that it has proper trilateral hexagonal diffusion when loading and unloading.
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I did this with the last car carrier I built. Towed great!
 
Have you done any weight calcs on this trailer? Sounds like you're going to have a very heavy frame for the stiffness. 2x4x1/4 is 8.81 pounds per linear foot (table value).

Both 2x6x1/8 and 2x5x1/8 are upgrades for stiffness, and significantly lighter per linear foot (I think 2.3 and 3.2 lbs less per linear foot, respectively). My point is that you could probably save a few hundred pounds of steel, and make a stronger trailer at the same time.
I'm not a structural engineer and didn't do any math, I'm just making quick assumptions from a few table values compared to the 2x4x1/4.

Or channel. Hmm. C5x6.7 channel looks really similar to 2x6x1/8 (stiffness, weight, everything), as long as you can control the twisting so you don't have a buckling failure.
C6x8.2 would be about the same weight per linear foot (8.2lbs) but much stiffer and stronger, also assuming that you can keep it from twisting/buckling.
 
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marty79 said:
why not...lol
don't wanna get into "proper materials" for car trailer...been there,done the search and I was convinced with 2x4 over C-channel...that's that
18ft with 2ft dove tail(20ft total), dual axle, brakes, 4ft tongue, 84" between wheels/fenders,
Click to expand...
Good luck sounds like you got a plan. Hammer down. I expect you'll be done in a day or two.
 
@marty79
I am going to disagree with the masses.
I think arching the trailer is actually a good idea to increase weight carrying capacity.

How would you go about that?
 
Arching is way more important for a bumper pull trailer. It wont transfer as much movement to the hitch and increase front tire life by reducing the yaw and ackerman angle.
 
all i got to say is i got a trailer that is right up your alley, you got the steel to cut it and lengthen it to whatever you want. already has axles breaks, i even got brand new lights and 7 pin plug to wire it all up.
 
shawn said:
Y'all are a bunch of assholes.

But you know that already.
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What the hell are you referring to? The trailer I built pulls wonderfully. And it's a convertible from bumper to gooseneck to 5th wheel.
 
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