Minimalist Torsion Axle Frame

[Bogo]

If you need them, carriage bolts are available in grade 8 strength. Some farm implements use them. BTW, it isn't that hard to square a round hole in a piece of steel. Use a square file, and the job is a bit easier. There are also plow bolts which go into a squared or keyed bevelled hole. I'm not sure how you'd make the bevelled hole on the inside of a tube.... The strongest grade of T-slot bolts would also work, you want 150,000 psi or stronger strength. You would need to file your initial round hole into a slot to use them.

Wow, Fastenall only has one grade 8 carriage bolt. McMaster-Carr didn't have them, only up to grade 5. Hum, looks like Fastenall has them under "Shaker Screen Bolts". Very slightly different head shape than a typical carriage bolt, but they still have the square shank for locking into a square hole. Hum, I don't see any anti-rust coatings, so thread lock them to keep the moisture out of the threads, and then paint over them.

If I had reasonable access for a box end wrench to access the bolt head from the tube end, I'm not sure I'd use a carriage bolt. If for some reason the square hole gets stripped it could be very hard to remove the bolt. Grinding through a grade 8 nut and bolt is hard work. I bet most frames are only mild steel and not hardened steel or high tensile steel which I think would be a minimum for use of a grade 8 carriage bolt. That square shank is small and the area it bites against is also small.

 

[rowerwet]

I don't recall at the moment what kept the bolts from turning while securing the nuts, but it worked very well.

What I've seen elsewhere is using a carriage bolt and fitting a big square/rectangular washer under the head of the carriage bolt - a square hole for the bolt locks the bolt and washer together and if the washer is big enough, it can't turn inside the tube/chassis member.

the hitch for my '12 focus (same car underneath now) went on the same way, before you threaded the bolt onto the helicoil looking end of the wire you put the wire through the square hole in rectangular plate, this kept the bolt from turning, (this works better if the hole you drilled in the frame was slightly off center in the frame channel)

 

[alaska teardrop]

• Thanks guys for your ideas. In order to avoid complicated assembly when the original concept came to mind, I went out to the shop & tried it first before keeping with the idea. A couple of pictures that may show better of how simple it is to drop the bolt in place & hold it with the wrench:

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• If the body where not welded on the tow bar, but made of aluminum, wood or fiberglass, those same 2" tubes would be used to mount the body. The body bolts would go through the top of the tube in the same fashion as the axle bolts. This drawing is the genesis of the design showing the mounting bolt locations:

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• Fred

 

[alaska teardrop]

• These two pictures are of Stacie Tamakis' trailer with the steel portion of the cabin framing welded to the minimalist chassis.

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• In order not to get off topic, I won't go further with the building of her trailer in this thread. Stacie blogs about her trailer here: http://theflirtyguide.blogspot.com/sear ... 0-%20Build

• Fred

 

[KCStudly]

Oooh, that looks nice. I'm sure that Stacie is going to be very happy, and that things are going to work out best for her in the end.

Great design and, IIRC, it really does look like what Stacie said she wanted!

 

[deleted]

It is just what I wanted! So lucky to have met Fred here on the forum. Every email update with photos he's sent me is like Christmas morning. And not only will my trailer be fantastic, I get to see what the country is like east of WA, OR, and CA. It's going to be a great adventure driving out to Michigan to pick it up.

 

[alaska teardrop]

Oooh, that looks nice. I'm sure that Stacie is going to be very happy, and that things are going to work out best for her in the end.

Great design and, IIRC, it really does look like what Stacie said she wanted!

Hey, as Red Green says " If women don't find you handsome, they should at least find you handy".

 

[Fishingtomatoseed]

Both trailers look really nice.

 

[alaska teardrop]

• Thanks, Clint.

• Fred

 

[alaska teardrop]

• Except for some cabinetry that Stacie plans to install, her trailer is completed. It weighs 554# with a tongue weight of 82#.

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• More pictures in Stacie's album. gallery/album.php?album_id=2983

• Fred

 

[aggie79-HILO]

Very nice Fred! I know Stacie will love her new Teardrop. Thank you for showing details of your construction methods.

 

[KCStudly]

Excellent work there, sir! I applaud thee.

Stacie, "Road trip." - Otter & Boon, Animal House, 1978

 

[deleted]

I do, I do, I love, Love, LOVE it! Thanks so much Fred! The entire process has been an absolute pleasure

BTW, feel free to camp out in it in your yard if you'd like to before I come get it. To sleep you can put your feet in the tongue box since I suspect you are quite a few inches taller than me

 

[SamIAm-TNT]

That looks like a fantastic chassis design, and some great trailers on top of it.

What would be the possibility of having the tear portion removable, with the 6 or 9 bolts that are shown in the various designs, with a utility box that could be bolted in it's place? What dimensions of steel would I need to use to have a rough capacity of #2200lb gross (the likely TV's capacity)?

Thanks

 

[alaska teardrop]

• The design allows for different widths, cabin length and tongue length. The torsion axle is the main chassis crossmember. It assumes a cabin with torsional integrity. The #3 tie together parts are 1/8" flat bar. The #2 parts are 1/8"x2" square tubes for the coupler and axle mounting. The weight and tongue length of the trailer determine the #1 main rails. With a 36" tongue for example, the gross capacity would be 980# using 1/8"x2"x1" rectangular tube. 1341# using 1/8"x2"x1-1/2" rect. tube. 1701# using 1/8"x2"x2" square tube.

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• Sam,

• A drawing of the design & an estimated weight of the trailer that you have in mind would be helpful in answering your questions. If the #1 frame rails are 3/16"x2"x2" square tubing, the capacity would be 2240# for a trailer with a 3' tongue.

• Fred

 

[SamIAm-TNT]

• Sam,

• A drawing of the design & an estimated weight of the trailer that you have in mind would be helpful in answering your questions. If the #1 frame rails are 3/16"x2"x2" square tubing, the capacity would be 2240# for a trailer with a 3' tongue.

• Fred

[/quote]

Hi Fred,
I was just up in Alaska a couple weeks ago, and enjoyed the trip- mostly around Anchorage.
Here is an image of my version of your frame.

I hope that the teardrop/trailer combo would be 7-800 lbs. I would construct the tear with a torsion box floor, with foam walls and roof covered in Canvas in the Foamie tradition, and from what I've read, this would be a torsionally strong tear. I would like to be able to take off the tear, and put on a utility frame, likely made out of angle ironor square tube, and have a gross capacity of 2400lbs (Subaru Forester TV.) I don't have a truck, or easy access to one, so having a utility trailer would be nice to pick up sheet goods from the lumber yard or doing landscaping stuff, and if I can make one trailer do the job of two, that would be great in my books. I would be sure to use lockwashers or nylock nuts on the attachment bolts, and use grade 5 or higher.

A couple notes on my drawing:
I put 2x3x1/8 for the main members- According to angib's link here (http://www.angib.pwp.blueyonder.co.uk/t ... tear84.htm) it is stronger, but lighter. I am not sure if I should use it for the axle attachment points as well or if 2x2x1/8 would be sufficient. Also, I initially put 2x3x1/8 for the rear member, but I wonder if I could go with 1.5x2.5x1/8 instead.
The axle attachment points would have holes drilled every 2 inches to allow for some adjustment of the axle position for balancing.
I would use a Flexiride or Dexter axle
Attachment points are marked with an x
Thanks for your feedback,
Brendon

 

[alaska teardrop]

• Hi Brendon,

• I lived in Alaska for many years, however I no longer live there. I do miss it at times. You're lucky that you don't have so far to travel.

• Must say that by using this layout for a heavy trailer, you are taking me into a realm that I hadn't considered.

• Good catch on the 2x3x1/8 tubing. According to Andrews chart, that gives you a 2670# tongue capacity with a 42" tongue. Also, by using the 2x3x1/8 for the coupler & axle mounts everything will be in the same horizontal plane for easier & proper welding.

• Now, here is where I question the dual use trailer idea. To get a 2400# gross weight capacity you would need a #10 Dexter w/brakes (or Flexride equivalent). You might try calculating the steel & axle weight and costs to see where you're at verses buying a utility trailer for your heavy loads. The other problem with the dual purpose idea that I see, is that a 7-800# teardrop on a 2400# axle would be like having no suspension at all.

• Fred

 

[SamIAm-TNT]

Thanks for the feedback Fred,

I know I may be overshooting my goals with the dual purpose, or at least dual purpose with such a wide weight range. Perhaps if I halved my target weight for the utility trailer to 1100# I would be better off, and the majority of the use the utility would get would be under that weight, yardwork likely being the only victim to a reduced trailer capacity. Up where I live, trailers are quite expensive- the low end is $1200 - $1500, so purchasing a second one is a major thing (and I'd rather buy a new table saw for the same amount!) No Harbor Freight or Tractor Supply as a source of cheaper trailers. I've got all summer to plan, as I won't start building until the fall, so I can contemplate the advantages and disadvantages of each course of action.
Thanks again for the advice,
Brendon

 

[alaska teardrop]

• You're welcome Brendon,

• That sounds like a very good compromise. At 1100# you could use the #8 Dexter and have safe & smooth ride for the teardrop. Back to your original question. 2x1-1/2x1/8 rectangular tubing would have a tongue capacity of 1150# with a 42" tongue. You of course, should run your own calculations.

• Keep on designing. Fred