Fifth Wheel Trailer From Scratch

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Lostranger
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Fifth Wheel Trailer From Scratch

Post by Lostranger »

We're in the process of going mobile full time, and I'm having a change of heart about how to do it. I had planned to replace our leaking and unreliable Flxible transit bus with a 40' MCI C3, but Sharkey's thoughts on building a trailer and pulling it with a road tractor are making a lot of sense. The MCI would require an engine and transmission transplant to get away from the 2 stroke Detroit and efficiency hog automatic transmission. That's a huge investment of time and money off the bat.

Small, single-axle, day-cab tractors are pretty cheap and not hard to maintain. Having the tractor would give us transportation options without having to pull a toad. I expect my wife will be living in this rig after I check out, and I don't want her having to maintain and operate a complicated and difficult to access power plant and drive train. She could always sell the tractor and hire some trucker to move her home when need arises.

I've looked at a lot of fifth wheel RVs, and they're all crap. I'm not interested in building a wood frame structure for the highway. The post accident photos of Wayzalot underscore my concerns.

Thanks to this site, I've been inspired by Rob Gray's Wothehellizat. I have adequate metal fabrication skills and facilities, so I think I'll build from the ground up. I'm thinking of using 2" mild steel square tube for most of the frame ribs and joists. Not sure if 11ga is adequate or if I should use 3/16".

I used 18ga cold rolled steel sheet to side my current bus, and I'll probably use the same to skin the trailer. The bus skin is affixed with Sikaflex 252 adhesive, but I've had an alarming failure rate. I plan to plug weld the trailer skin, 1/4" holes on 4" centers.

This machine will roll on two or three 6000lb Torflex axles. With welded steel skin on the frame of 2" square tube, the box should be pretty rigid. I wonder how much additional framing it should have underneath, other than enough rail to mount the axles. Maybe I need to frame it the whole way. I'm no engineer, and I'd love to hear from someone who is.

I can't find any internet info on this type of construction, other than a small house truck built on an Isuzu NPR chassis, but it feels like a good way to go. Any helpful feedback or links would be greatly appreciated.

Jim Huskins
Marion, NC
lostranger@mindspring.com

Mark R. Obtinario
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Post by Mark R. Obtinario »

I am wondering why you are trying to reinvent the wheel for this project.

If you are going to use a Class 8 truck, why not purchase a used reefer trailer for your basic platform--it will have axles that are more than adequate to the task, it will have air brakes that are a lot easier to maintain and will stop a lot better than any electric or hydraulic brake, many come with air suspensions which will ride much smoother than any spring suspension, it will be more than adequately insulated already, it will have more than enough space under the trailer to mount all of your mechanicals and tankage, and the frame of the body is already designed and built to withstand the rigors of highway travel.

And like used Class 8 trucks, used reefer trailers can be purchased for about what it is going to cost to build your own from scratch.

Think of the possibilities with a box that is more than 90" wide inside, inside height of over 8', and lengths up to 53' long.

It is your project so you will end up doing what you think is best.

Good luck.

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Post by Stealth Camper »

There are some here who have built trailers and it is a lot of work, but very rewarding. My first one weighs about 8,000 lbs, has two 6,000 lb torq-flex rubber axles with brakes and is SO overbuilt.... the frame design calculations say this little 20 foot frame would be good for 40,000 lbs. Nothing else would be, but the frame, yes.

I like the axles - they seem to be a "premium" way to do this, but even the biggest RV people don't seem to use them and I am puzzled why not. I have had my trailer rolling around for about 5 years and notice no degradation of ride or suspension problems. For given size, they are probably 25% more expensive, but just watching it travel, the ride looks very smooth. Any insights from anyone on rubber axles?????

Have been planning to do a fifth wheel and the following two sites have been of particular interest to me. I plan to make laminated walls using a vacuum bag and blue-dow foam panel insulation similar to what Nu-Wa does. Also will be doing something similar with the bus walls if it all works as well as I expect. I REALLY like the structural aspects of the stuff.

I have done a little personal experimentation with that stuff using 1/4" plywood and 1/2 foam from the Home Store Dime Stores. Works VERY WELL. Just like Nu-Wa says.

My preliminary frame design has led me to use 12" I beams (can't remember thickness - 19 lb, I think but maybe 16 lb per foot. Will check papers later). And a 32' to 35' length. Way overkill on the frame, with proper cross beams, but I want the depth(height?) for tank installation.

Have even thought about having the bus pull the fifth wheel with a dolly, but that occasionally just seems plain silly. And sometimes not....

And if you get anywhere near Chanute, KS, you can take a tour of the factory. I did and it was very interesting.

http://www.nuwa.com/

http://www.glen-l.com/campers/glenlrv.html
Last edited by Stealth Camper on Thu Dec 09, 2010 5:11 am, edited 1 time in total.

Stealth Camper
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Post by Stealth Camper »

Almost forgot - must (!!) use polyurethane glue for laminating the walls to blue foam.

Sharkey
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Post by Sharkey »

Well, first of all:

OMG!!! I had no idea that the Wayzalot trailer had been destroyed! What an awful blow for the owners! More photos on the Wayzalot site: http://www.wayzalot.com/end%20of%20wayzalot.html . The good news is that they were not injured significantly, and that the vintage tractor that they used to exhibit with the trailer was not involved.

As for your project, I have a few thoughts. Yes, Mark is correct, using a freight trailer would kick start your project, and all the rolling stock would be DOT approved, engineered, etc.

I can also see the appeal of building custom. I've lived for the last 35 years inside a rectangular steel box, and it has it's drawbacks, most of them aesthetic. If you build from scratch, you can insert your own custom touches, round some corners to make it less boxy, get rid of the flat roof (never again!).

If you do decide to use steel to sheathe the walls, be sure to insulate with something that doesn't hold moisture. My Housetruck would be set for another 35 years of use if it wasn't for all the rust that condensation from the inside of the living space started.

I do rather doubt that the Wayzalot accident would have turned out a lot different no matter what material was used for construction. Getting slammed by a semi is going to hash any living space.

Here's an old favorite trailer construction site, although the house part uses wood framing. The running gear part is shown in some detail on some of the sub-pages: http://www.digital-starlight.net/projec ... house.html . Don't know what ever happened to this rig, the builder never completed the web site, so I don't know if it got finished or not.

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Fifth Wheel Trailer From Scratch

Post by Lostranger »

Mark R's suggestion about converting a semi trailer has merit, and it's one I've thought about. I love the thought of air brakes and commercial axles, but some other issues stand in my way.

First, I don't want our home to be so high in the air. A drop deck trailer would mostly solve that concern but at the expense of large wheel wells in the living area. I know from experience with our Flex transit bus that wheel wells are a major issue. I will consider starting with a semi trailer and maybe setting the box down on Torflex axles and notching the body for the fifth wheel.

Second, we may want to occasionally put this rig in travel parks. The design I have in mind would blend better in that context than would a commercial semi. This is not a big issue with us now, but I am trying to plan for what my wife will be able to do as a widow. She may find that a park is the best setting for her.

Thanks for the good comments and info that are coming in.

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Fifth Wheel Trailer From Scratch

Post by Lostranger »

Whether I build from scratch or start with a semi shell, I plan to use spray foam insulation. Seems to me that will protect the shell from condensation.

As far as the customizing aspects of building from scratch go, I do like the idea of having full control. I envision an unadorned exterior (probably white) with few visible amenities that shout "RV". I'm hoping people will either not notice it or be unsure whether it's a commercial trailer or a camper. I'm not talking about a full "stealth camping" rig, just something that won't attract a lot of attention — positive or negative. I know this is the opposite goal of many housetruckers, but it's what we're going for.

Sharkey, your comment about no flat roof is well taken. The leaking, flat roof on my Flex has been a bane of my existence. I plan on building this roof with a slight arc.

I'd love to hear from anyone who's had success mounting solar panels to a mobile roof. I want to avoid penetrating this roof if at all possible, and I want to avoid mounting systems that seriously muck up the air flow.

Jim H.

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Fifth Wheel Trailer From Scratch

Post by Lostranger »

I forgot to mention that the INSIDE of this trailer will bear little resemblance to a tacky RV. Yellow pine paneling and oak floors. Brass and copper fixtures. Not a microwave in sight. We love to cook and to preserve good food. Our kitchen will be larger than most.

This will not be a small rig. Our favorite current drawing shows 38' feet total length including bedroom over the hitch. No porch on this one.

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Post by Stealth Camper »

Looked at the digital starlight site and the beams he is using are exactly what I plan on.

Axles are still up in the air - I really like air brakes and that pretty much puts me into the Eaton or Meritor world.

Another thing I plan is to go ahead and put the axle at the back to get rid of the wheel well problems - they can go under the kitchen area or maybe put the bedroom back there. Not sure yet.

Back axles won't be a problem 'cause I plan to use at least a medium duty truck or bigger to pull it with. Like the bus? Pickups just don't cut it, and the mileage on a DT466 w/ automatic is at least as good as the 10 on the Dodge pulling a heavy load.

I can usually get 8 or 9 out of a class 8 with a modest load (< 30,000 lb), so may just go that route, too. I know - am getting a little bit crazy here. I will stop now.

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Post by Stealth Camper »

Oh, wait! I forgot!

One more thing - BIGGER WHEELS and TIRES!!!!!
As big as you can get. That's the reason to look at class 8 trailer axles!

Jones'n4chrome
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Post by Jones'n4chrome »

Lots of good ideas posted so far.

Mark's idea does have merit, but so does Sharkey's. My currant bus is based on a Crown postal/TV truck. It's about as good as it gets for a bus conversion. Yet often times when I'm working on it or designing around an obstacle, I find myself thinking "Why didn't I start from scratch?"
You can waste a lot of time solving design problems when working with something that was intended for another purpose.

Long ago before I had my bus, I almost bought a 1970 IH tractor with a DT466 engine and 10 speed trans. The drivetrain was in very good condition, but the body was rusted badly above the glass. I was going to replace the body, then build a lowboy trailer where all the tanks, pluming, storage, batterys would be inside an insolated basement with access doors to the exterior. After you enter there would be a few steps to climb, but the floor would be above the wheelwells and everything else.

I chickened out though. I didn't know if I could trust my fabrication skills. looking back now I know I could have done it, but I just didn't know it then.

Here is the style I would build. These are made to carry much more weight, but if you build it you can make it any capacity you need.

http://www.buyatruck.net/Trailers_for_Sale/Lowboy/

tamangel
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Post by tamangel »

how about a Tiny House on the above mentioned low boy or flat bed trailer.. with a classic White 3000 tractor..best of both worlds..

check this thread also:
http://www.mrsharkey.com/forum/vwtp.php ... highlight=

almost a megabyte download here, keep you busy looking at options for a while :):
http://www.tinyhouseblog.com/tiny-house ... ory-v3.pdf

Mike

a link to GL for Mil Surplus trailers.. Have to look thru to find one for your needs, lots of different kinds.. Cheaper than commercial and more sturdy maybe?
http://www.govliquidation.com/auction/e ... unged=7588

dburt
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Post by dburt »

Hey LostRanger- how about starting with a step-deck flatbed trailer as used for HD semi-towed highway loads? They offer a low deck height except over the king pin area which is usually about 10 feet long or so. (You can put your bedroom site there?) You would have a large flat floor to build on, you would have the better large HD 22.5 or 24.5 tires, air brakes, air ride, etc. Then you can build up from there to your own wall height and do your domed roof. But you don't have to build the basic trailer, and you will have room under it for your water and holding tanks, generator, propane tanks, storage, etc. (I think I have even talked myself into a new project....... :roll:)

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Post by Truckingturtle »

OK...OK...it's time for me to break my usual silence and speak up since the idea of a tandem trailer has been mentioned. I brought this subject up about 5 years ago (under the thread "re-formatting an old housetruck to pull a housetrailer" May 2005) so thought I would repost what I said back then so here it is again with the drawings I made:

I have been dreaming about what my next home on wheels will look like. Here are a couple of drawings I have done. This will be my fifth housetruck project and I plan to use my previous experience on the road to make it my best ever. I want to start with a good foundation-a 35' step-deck tandem-axle commercial hauling trailer-allowing easier access since it is lower to the ground, and able to take the weight of a wooden house on it.

Image

My fourth housetruck sets behind my cabinet shop right now, and I have come up with a plan where I would shorten it and convert the housetruck into a sleeper cab. Since it is illegal to have passengers in a trailer on the highway, the sleeper cab will give me the extra room I need for other passengers, and a place to sleep so it can be used for short joints away from the housetrailer.

Image

The lure of being out on the open road again is something I think about often. There's nothing like being able to go and see all those wonderful places that you can drive to, and still "be at home" in your own house! It's the mobile lifestyle that housetrucking is all about, not being parked in the same place all the time, or where it was built.

Roger (truckingturtle)

tamangel
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Post by tamangel »

there are several states that allow passengers in a fifth wheel trailer. The requirement for the passengers to be able communicate with the driver is necessary (intercom or ?)...whether a good idea or prudent is a question..seems the movie, a long, long, trailer illustrated this quite well..

here's a list of towing laws for each state..

http://www.towingworld.com/articles/TowingLaws.htm

Mike

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