Frameless Trailer/Torsion Axle Mount

[Sandino]

Hello All - After lurking for a while, I think I'm getting closer to beginning a build. Plans are for a 5x10, probably fiberglassed all over, including the floor/base - which leads me to the frame question.
It seems to me I have little need for a frame, given it will end up being essentially a unibody construction. So the simple way to proceed would be to bolt torsion axles to a wide plate (probably 12" x 1/4" thick), which would give me lots of bolting options for the trailer body, and the towbar could be welded to that plate, probably continuing to the back of the trailer to accept a bicycle mount.......sound reasonable?? or clear, for that matter?

[doug hodder]

Sandino...welcome aboard...check Jiminsav album...that's how he built his and it has worked out well for him. Whoops...I just checked his album and the pics are no longer there...Maybe he'll jump in with an explanation on how he did it...or drop him a PM... Doug

[dovaka]

i also decided i didnt really need much of a frame but i built a light one out of 1 1/2" angle steel just to make the box and tie the tongue and axle together but over all its still pretty light 2 people can pick it up fairly easily

[asianflava]

I'll stir things up and just start with saying that I'm not a fan of "frameless" designs. You are correct by saying that there is little use for them due to the unibody design of the trailer. The the frame serves 2 important functions, a positive attachment point for the tongue, and (as you've found) a positive attachment point for the axle. I'm not saying that it can't be done, it has. I don't want to say, "Uh, sorry officer, I thought it would be strong enough. I didn't think it would fall off an hit the guy behind me."

By the time you add the reinforcement plates and the mounting hardware, you will probably be close to what a minimal frame will weigh. There have been several designs posted. I remember one that was basically the axle attached to the tongue using a couple pieces of angle.

[Geron]

I'll agree with Asianflava,

I built a "frameless" for my second build and will put together a minimal chassis for my 3rd build.

There is an excellent thread on the "frameless design" with good input from Angib (I should say very valuable input).

Most likely I will at some point drop my tear onto a chassis of some type.

I honestly don't think it will ever in a million years come apart BUT there's that little "itch" that just won't go away.

g

[Alphacarina]

At a minimum, I would run the tongue back to the axle and weld it there and then triangulate it with a couple short pieces of welded angle iron and then bolt the trailer floor to every piece of steel it touches

The trailer may be 'unibody' and not need any additional support, but the unibody shouldn't also be expected to hold the running gear in line as well

Don

[angib]

By the time you add the reinforcement plates and the mounting hardware, you will probably be close to what a minimal frame will weigh.

Agreed. Going 'frameless' means you need to consider very carefully how you will attach the suspension and tongue/A-frame to the body - and really, the easiest thing is to attach them to each other to give yourself a 'minimal frame'. But there is no need to go beyond this - I think most people are thinking they need house foundations when they make their frames!

Here is a bolted-together 5ft wide minimal frame for a lightweight trailer:





I must get round to documenting these chassis plans and putting them on my web site.....

Andrew

[Nitetimes]

I'd like to point out one thing you should think about when deciding whether to use a minimal or frameless build. "LAWYERS".
Keep in mind that you are not a manufacturer with large quantities of liability insurance. It only takes one minor error in calculations and.....
Just a personal opinion on the subject.

[madjack]

...another, not a fan of "frameless" design here...while it can be done successfully. I would always be nervous, while towing it down the road...personally, a minimal frame, like Andrew has posted, would be the least I would accept.
Another consideration, are for attachment point for rear stabilizers and if you wanted a receiver hitch for bicycles or carry racks...how ya goona attach them safely and with peace of mind on a frameless design.....
madjack

[angib]

How do you guys NDT-test your welds? You've got a record of your welder certification, right? Your metal frame designs have been passed by a PE?

Metal frames, particularly home-made metal frames, are absolutely no guarantee of avoiding problems, as several posts on this forum will support. But they are certainly less likely to give you problems.

It's worth repeating that a frameless design is not something for the novice and requires a higher standard of build than a 'framed' trailer.

Andrew

[madjack]

...hey Andrew, a BFH(BIG friggin' hammer) makes an excellent "testing" device ..................

[Sandino]

Thanks all for the comments and guidance - this is exactly the kind of feedback I was hoping for. Soon after I posted the question, the matters of possible tongue box and rear jack placement came to mind - the first I think Andrew hit perfectly for me - really, the triangle frame suggested looks great. As to jack mounting, I'll just reinforce with f-glas. In an earlier post - probably an intro somewhere - I mentioned I built boats. There's been 35 or so of them, from 28 to 45 feet, some wood, but mostly fiberglas. And none of them have fallen apart yet - I've even managed to remain friends with the people I built for - so it shouldn't be too hard to support a tt. Thanks again - Kevin

[asianflava]

I just noticed the nav light color scheme.

[Geron]

I had outlined my "frameless" build earlier but the computer ate it

I'll try again.

There is a thread that has some good input on frameless builds.
http://tnttt.com/viewto ... =frameless

I think this is where angib first posted his A frame design which I bought into and modified.



Mine is not truly frameless but minimally framed.

When I got through with this outline I thought, This is truly a "redneck" build

You'll have to replace angib's axle with at 2x12 and half axle torsion axles.

1. The "axle" is a 2x12x5' epoxied to the floor of the TD (from Jim in Savanah) and screwed every 4" with 3" deck screws from inside and through the floor (5/8" ply)

2. A 24" 2x2x1/8 angle iron reinforces the side rails and is centered on the hub of the wheels (as per angib's drawing)

3. There are 6 bolts (3/8" grade 8 ) that hold the half axles in place on the 2x12 "axle". 2 of these 6 bolts go through the angle braces on each side rail. They all bolt from the inside and are reinforced with steel plates under the bolt heads to keep them from pulling through the floor. (of course the epoxy would have to give way before the bolts even went into action). There are 4 additional 3/8 grade 8 bolts (in addition to the row of 3" deck screws and the 6 bolts that hold the half axles on) that go through the floor and the 2x12 with metal plates serving as washers to keep the bolts from pulling through the floor if the epoxy ever failed.

4. I added to angib's design a 2 1/2 x 2 1/2 x 1/8" square tube Tongue that bolts to the 2x12 axle (with 2 bolts) and bolts to the floor in 2 more places (on the stiles or cross members) between the "axle" and the hitch. (carefully squared and aligned, of course)

5. The angle braces from the axle to the hitch are bolted to the middle bolt on the half axles then the angle braces are welded to the tongue just behind the hitch. These braces are also bolted to the floor with 3/8 grade 8 bolts in 3 places.

So you see it's not really "frameless" it's a "redneck" chassis.

Total TD weight empty is 780 lbs.

I was concerned about the flimsyness of the portion of the TD behind the "axle" before I got the walls on. The walls took care of those concerns.

I"ll most likely deconstruct and place on a factory chassis at some point.

HOWEVER, I simply cannot picture the thing coming apart. Everything is tied together with epoxy and grade 8 bolts.

Oh I didn't mention 4 6" lag screws -- Oh well. Live and learn.

g

[angib]

I just noticed the nav light color scheme.

In an earlier post - probably an intro somewhere - I mentioned I built boats.

So Kevin, you should visit John Blewitt's (name correct?) web site Tiny Tears and look at his Boxter trailer - frameless, vac bagged epoxy construction. And to please the frameless doubters, the axle ripped off on the first long journey because he made the schoolboy howler of forgetting that the peel strength of most composites is very low.

Andrew