Trailer Design

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Trailer Design

Postby RexInTheCity » Mon Dec 01, 2014 6:57 pm

I'm in the process of designing my not so tiny travel trailer. I'm modifying the Weekender to be used for a group of 2-8 people. My current plan is to provide enough room for 4 people to sleep inside and to store enough gear for 8 (cookware, sleeping bags, backpacks, luggage, chairs, etc).

I think I've settled on a 5x10 trailer that will hold a ~6x12 camper. I haven't had much luck finding a used trailer for a decent price so I'm going to contact a couple welders and fab shops to get quotes for a custom frame. I've taken DMcCam's frame design and modified it for my dimensions.

The camper walls will be built using 1x2s, 1/8th plywood, and foam board. The floor will be 1x3s, 1/2in plywood, foam board, and linoleum.

TV is a 2011 Silverado 1500 4WD w/towing package.

Reference Material:
http://www.vulcaniavolunteers.com/TEARD ... _FINAL.jpg
viewtopic.php?f=35&t=35097&start=45 (2nd to last post contains frame pictures)

My design:
2x2x1/8th angle for the cross members, 2x2x1/8th square tube for frame and tongue.
Image

Where I'm stuck:
1) Axle placement.
I haven't been brave enough to try the spreadsheet method of figuring out where to place the axle. I've used the 40/60 rule. How critical is axle placement, do inches matter or is a ballpark good enough? It seems like a lot of people just get the HF kits and go with the stock setup so I don't think it is too critical.

2) Stabilizer selection and mounting.
After reading the forums a bit I think I've settled on BAL Light Trailer Stabilizing Jacks (http://norcoind.com/bal/products/consum ... jack.shtml) 2 in front and 2 in back. Is that too little or too much? Should these be mounted directly to the front and rear frame or at a 45 degree angle like on DMcCam's design?

3) Tongue Jack placement.
Most of the trailers I've seen here have the jack mounted on the side of the A-Frame (vs inside the frame directly behind the coupler). Is there a reason for this or is it just preference?

4) Crossmember and body brackets.
I added another cross member and 2 more body mounting brackets when I scaled up the design. Are these overkill?

5) A-Frame and Tongue
I completely guessed at this. I made it 4ft long and added some brackets for possibly mounting a storage box. Are there any critical measurements in this area?
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Re: Trailer Design

Postby KCStudly » Mon Dec 01, 2014 10:55 pm

2) Generally the consensus is that putting the stabilizers at kitty corner angles provides the most stability.

3) From what I see you have the option of a swivel tongue jack or a fixed jack. The swivel ones provide more ground clearance when raised but must be placed further back to accommodate the swivel feature; outside the frame provides easier access to operate the swivel lock pin and makes mounting easier. Whereas the centrally mounted fixed jack is usually incorporated into a std. 50 deg coupler.

4) With angle xmbrs, why not just drill thru those and leave out some of the tabs? That's what did/am doing.

5) Going by angib's info (http://www.angib.pwp.blueyonder.co.uk/teardrop/tear84.htm) for my smaller build, lead me to use 2x2x3/16 thk tube for the A-frame and front xmbr (target weight 1500 lbs or less, braked, off road usage, std. A-frame design). Standard A-frame couplers are based on a 50 deg angle. I used this as a default even though I am using a custom coupler. My thought is that it would be a lot easier to convert later if need be. Yours looks more like 40 deg's. I'm not a fan of the little straight tongue member sticking out at the front. It creates a weak point at the join with the sides of the 'A'. If you need the added length or vehicle turning clearance, or are just partial to the straight style of coupler, I would rather see that straight member extending back to a small xmbr under your tongue box, or better yet, back to the main frame or second main xmbr as shown in the link above. Other's may have different opinions here, but for a "not so tiny trailer" I would rather see a triangular coupler.
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Re: Trailer Design

Postby bobhenry » Tue Dec 02, 2014 7:37 am

Tongue failure is the single greatest accident waiting to happen. It leaves you with no alternatives but to go find a welder that makes house calls.

I would forgo the front levelers and place a center reinforcement for the tongue. The "X" indicates where you could mount a flip up jack. Here it will be centered thereby avoiding the twist incurred when mounting to one of the A points.

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A good jack and a anti scoot dog food bowl is all that is needed to support the front of the trailer.

Dog food bowl :oops: you ask......

Yep a good rubber rimmed steel dog bowl! Just drop it in place and run down the jack the trailer will not and can not walk around with the wheel trapped in the bowl.
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Re: Trailer Design

Postby RexInTheCity » Tue Dec 02, 2014 7:27 pm

Thanks for the suggestions. I think I'll go with a bolt on tongue jack for now so I can try some different locations.

I've redesigned the tongue to be a 50 degree A frame with a center tube that extends out a bit. I'm trying to keep the tongue somewhat long to make it easier to back into my garage. I have alleyway access so trying to get a trailer in the driveway can be a challenge.

Also added a spare tire mount to the rear of the trailer to keep the weight in the rear. Any suggestions for what kind of metal bar to use for the tire mount? I'm not too familiar with what is readily available.

Image
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Re: Trailer Design

Postby bobhenry » Wed Dec 03, 2014 11:21 am

How about a continental kit :twisted:

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Re: Trailer Design

Postby RexInTheCity » Wed Dec 03, 2014 11:24 am

That's a very interesting use of a spare tire! Maybe I'm being too paranoid about it being stolen if it is mounted in plain sight.
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Re: Trailer Design

Postby Nansplace » Wed Dec 03, 2014 2:00 pm

I love the idea of the continental kit. It looks nice as well as being useful. Very clever idea. ;)
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Re: Trailer Design

Postby ctstaas » Wed Dec 03, 2014 9:56 pm

Hi RexITC I agree with Bob. I like a center pull tube Mine runs all the way back to the axle tube. I have a receiver in the rear. The axle should be from 50-66 % of the cabin length. Too close to the center interferes with the door placement. My perimeter frame is 1 1/2"xx 0.065" square bolted to the floor. Why do you need extra cross braces? Oversizing of the tongue and axle tube is good but the rest needs to be how strong? Joining of the cabin to the frame makes both components stronger.
Enjoy, Chris
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