Trailer Frame Feedback Request

[bemerritt]

Would love to get some feedback on the design below.

Constructed with 2" steel tubing, 1/8" wall everywhere except the tongue, which would be 2.5", 1/4" wall.

Overall plan will be a pretty fully loaded expedition trailer, 40 gallon water tank, RTT, kitchen, batteries, etc.

Right now Timbren 3500 axles is the plan, but would love to make a custom independent suspension, but that seems like to big a bite to chew right now. There's always gen 2, right?!

My main areas for comment are:
1. Tongue length and overall construction of the frame.
2. How to predict where to put the axle line without fully mocking it up with weights. Is there a general rule of thumb? I kinda eye balled it based on commercial offerings.
3. How to predict ride height with the timbren. Plan is to have it be on matching 285 70 17 tires.



Rough mock up of the body



Tow rig 2015 Land Cruiser

 

[NatersXJ6]

Tongue might be too short to operate your swing outs? Double and triple check this before you build.

Typical trailer frames do not make a 90 degree triangle at the front. Check a coupler catalogue, but I believe a 50 is commonplace. I don’t know precisely why, but suspect it has to do with hitting yourself when you jackknife the trailer, I believe your current design would hit most vehicles.

I think that 60/40 tongue/rear is a common trailer axle layout.

 

[bemerritt]

Great input on the swingouts. Im trying to keep the length down while still accommodating larger RTTs, so i'll look into the 50 degree angle.

edited to add, the tongue was designed to be a 2" ID, so i guess i can extend it as needed and keep it short for storage.

 

[1000arms]

Would love to get some feedback on the design below.

Constructed with 2" steel tubing, 1/8" wall everywhere except the tongue, which would be 2.5", 1/4" wall.

Overall plan will be a pretty fully loaded expedition trailer, 40 gallon water tank, RTT, kitchen, batteries, etc.

Right now Timbren 3500 axles is the plan, but would love to make a custom independent suspension, but that seems like to big a bite to chew right now. There's always gen 2, right?!

My main areas for comment are:
1. Tongue length and overall construction of the frame.
2. How to predict where to put the axle line without fully mocking it up with weights. Is there a general rule of thumb? I kinda eye balled it based on commercial offerings.
3. How to predict ride height with the timbren. Plan is to have it be on matching 285 70 17 tires.

View attachment 593744

2" square tubing, .250" wall, for a spine you can weld a receiver hitch tube to the front and the rear, allows for the changing of hitches in the front and bike rack/receiver rack in the rear (or tug point with a decent spine to the front). You could run a ball hitch on the road and switch to a pintle set up off-road.

A longer tongue combined with a pintle hook and pintle ring combination could allow you to jackknife the trailer to less than 90 degrees from your tow vehicle without any contact. Quite useful for maneuvering.

Trailer handle: Weld two pieces of two inch long 2" square tubing to the spine, on top, and just behind the front receiver tube for the first, and about 18" back for the second. Then weld a piece of 1" square-wall (.120) to the top of each of the two short pieces of 2" square-wall. You'll have a handle you can grab with both gloved hands and easily move the trailer.

Plan on putting your batteries and water tank as close to the axle as you can, but remember that you can figure the weight of the batteries in to trailer tongue weight balance, but the water tank will change from full to empty, so put it right over the axle, so that full or empty, it won't change your trailer balance.

You might want a bit more room for the tires in case a rock or branch/log tries to jam in there, and/or you want to be able to run chains on your trailer as well as your tow rig. Chains are good for ice and often mud too, but an unchained trailer whipping around when chains on the tow vehicle grab is dangerous.

 

[CampStewart]

The A frame design of the tongue is going to limit tight manuvering, if you determine than it is necessary with your materials than upgrade them and get a straight tongue. .125 wall tubing is overkill and unnecessary, go with thinner tubing. 60/40 is standard for axle positioning but that doesn't mean it is best for your application.

 

[bemerritt]

The A frame design of the tongue is going to limit tight manuvering, if you determine than it is necessary with your materials than upgrade them and get a straight tongue. .125 wall tubing is overkill and unnecessary, go with thinner tubing. 60/40 is standard for axle positioning but that doesn't mean it is best for your application.

Well, tight maneuvering is pretty high on the importance list, thanks for the input. seems chopping that A frame off is the way to go. Just keep a little area for a tongue/battery box possibly.

 

[NatersXJ6]

[QUOTE="1000arms, post: 2800498, member: 192011"

Trailer handle: Weld two pieces of two inch long 2" square tubing to the spine, on top, and just behind the front receiver tube for the first, and about 18" back for the second. Then weld a piece of 1" square-wall (.120) to the top of each of the two short pieces of 2" square-wall. You'll have a handle you can grab with both gloved hands and easily move the trailer.

[/QUOTE]

This idea isn’t bad, but use caution with a tow vehicle that has swing outs. On mine for instance, the swing out comes across about 3/4” above the top of the hitch, so you have to run a pretty deep drop hitch and lower the trailer or lift the tow rig to clear anything sticking above the top of the trailer tongue (chains, light wiring, tongue jack, etc) and if the trailer is uphill from the tow rig you really can’t get in the back without disconnecting. A handle might make this condition worse if not well designed. Think before welding or you will have a grinder in your future!

 

[john61ct]

No need to chop off your A-frame

just make it receiver tube sized, maybe extend to to the next rearward crossbar

and slide an extendable standard sized tube inside.

You'll likely prefer travelling with it extended somewhat, better stability & handling

also give some ball weight-balance flexibility

and can extend it fully for when radically tight backup maneuvering is required

 

[john61ct]

And add the receiver at the rear too for carriers

Having a decent spine (not overkill receiver all the way)

allows you to go a bit lighter and still have good lateral strength / integrity

 

[CampStewart]

No need to chop off your A-frame

just make it receiver tube sized, maybe extend to to the next rearward crossbar

and slide an extendable standard sized tube inside.

You'll likely prefer travelling with it extended somewhat, better stability & handling

also give some ball weight-balance flexibility

and can extend it fully for when radically tight backup maneuvering is required

What loads do you think will be imposed that makes you think the A frame is necessary? Have you ever been in a position where you were trying to turn around very tightly and when backing you hit the A frame with your vehicle long before you would have with a straight tongue? I see lots of wasted structure and extra material at the front of that trailer for no real reason.

OP In my area sticks of receiver tubing with no inside seam are impossible to get and need to be ordered. shipping would make it impossibly expensive. I buy 4ft sections from E trailer and get free shipping. I will typically sleeve the receiver tubing inside a larger diameter thin wall tubing like 3 inch in the center of the trailer. Id recommend extending the receiver tubing a few feet in front of the box and then 2x2x1/4 tubing inside of it.

 

[john61ct]

With a long enough straight extension, and a normal angle A-frame, best of both worlds.

I've never even seen a live-in unit with only a straight tube, single point connection to the front-most crossbar?

Not for me. . .

 

[jmnielsen]

I used the 60/40 rule when I built my trailer. I would extend that tongue out farther if I were you. Others have mentioned making it so you could insert different lengths, That's really not a bad idea and could make garaging it for storage easier.

I think .125 wall is good for the main part of the frame, but you could scale it back for the rest of it. I used .125 wall 2x2 for the main (outer part) of my frame and I think 14 gauge 1x2 for the rest to keep weight down.

 

[bemerritt]

And add the receiver at the rear too for carriers

Having a decent spine (not overkill receiver all the way)

allows you to go a bit lighter and still have good lateral strength / integrity

seems like you and user 1000arms suggest doing something like this for the tongue (and rear receiver). Think that is a great idea, thanks for the idea. Do you think having the 2" spine running hte length of the trailer is overkill?

 

[john61ct]

Well if you are trying for minimum weight, then you should take advantage of the added design-strength

to lighten up in the other beams.

Just strong enough is what you should be shooting for.

 

[1000arms]

seems like you and user 1000arms suggest doing something like this for the tongue (and rear receiver). Think that is a great idea, thanks for the idea. Do you think having the 2" spine running hte length of the trailer is overkill?

View attachment 593910

You are welcome.

I suggest you use shorter receiver tubes at the front and rear. Just use 2" square-wall tubing (.250" wall) for the spine, and weld the (shorter) receiver tubes to the spine, without needing to integrate the receiver tubes in to the rest of the framing. (The photo you posted has the front receiver tube attached to more than just the spine.)

Although the spine will hang a bit lower (2"), you could "hang" the spine below the rest of the frame. This would cut down on cutting, aligning, tacking, and welding. It is what I did.

... A longer tongue combined with a pintle hook and pintle ring combination could allow you to jackknife the trailer to less than 90 degrees from your tow vehicle without any contact. Quite useful for maneuvering. ...

Part of my reason to use the 2" square-wall .250 wall spine is to have a long enough and strong enough spine/tongue to combine with a pintle hook and pintle ring for maneuverability.

... Trailer handle: Weld two pieces of two inch long 2" square tubing to the spine, on top, and just behind the front receiver tube for the first, and about 18" back for the second. Then weld a piece of 1" square-wall (.120) to the top of each of the two short pieces of 2" square-wall. You'll have a handle you can grab with both gloved hands and easily move the trailer. ...

This idea isn’t bad, but use caution with a tow vehicle that has swing outs. On mine for instance, the swing out comes across about 3/4” above the top of the hitch, so you have to run a pretty deep drop hitch and lower the trailer or lift the tow rig to clear anything sticking above the top of the trailer tongue (chains, light wiring, tongue jack, etc) and if the trailer is uphill from the tow rig you really can’t get in the back without disconnecting. A handle might make this condition worse if not well designed. Think before welding or you will have a grinder in your future!

Something to think keep in mind while planning your trailer.

I made my trailer for use behind my Jeep Wrangler TJ. I used an adjustable pintle hook (where I bolted the hook to the plate/hitch) to adjust to match the trailer height, and had welded a homemade swingout-tire-carrier/roofrack to my bumpers, but I didn't have any issues with my rear Jeep "door" or the tire carrier.

... Plan on putting your batteries and water tank as close to the axle as you can, but remember that you can figure the weight of the batteries in to trailer tongue weight balance, but the water tank will change from full to empty, so put it right over the axle, so that full or empty, it won't change your trailer balance. ...

If you are using much for battery/batteries, closer to the axle is better than out on the tongue.