New Frame/Axle - Fiberglass RV


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Old 05-21-2020, 11:53 AM   #1
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Name: Doug
Trailer: Casita
Texas
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New Frame/Axle

Hello all, this might be my first post on here. I bought a Casita for reasons probably most people do, lightweight, rot is generally not an issue, small, etc... Well I can't leave well enough alone, I want a little more exterior storage and ground clearance. My torsion axle is on it's last leg too. So enter a new frame and axle.

I'll talk more about frame design later, but I'd like peoples input on what they'd change/add on the frame if they could? Frame will most likely be 2"x3" rectangular tubing in appropriate thicknesses for area of the trailer.

For sure I'm going to add a couple of feet in front of the axle and possibly a raised area on the rear. Maybe something to hold a small propane grill and whatever else I'll need to offset the weight in the front. I'd love to be able to position the axle anywhere, but the wheel wells kind of dictate where the axle will go.

Axle will be a 5200lb Timbren "Axle-Less".

My background is metal fabrication, machining, and mechanical engineering. I've got a shop I can dedicate to this and all fabrication/machining equipment necessary.

Anyone have a 3D model of the shell of a 16' Casita? I'll use SolidWorks to model the frame, but would love to have the Casita shell to put in the model as well.

So, anyone have dreams of what they would add to their frame for convenience or other reasons?
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Old 05-21-2020, 12:49 PM   #2
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Name: Jim
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You might get some more good advise by posting this on the Casita
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https://www.casitaforum.com
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Old 05-21-2020, 05:13 PM   #3
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I like the look of that Timbren Axle-Less.
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Old 05-21-2020, 07:18 PM   #4
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Quote:
Originally Posted by WheelinAg View Post
Hello all, this might be my first post on here.

So, anyone have dreams of what they would add to their frame for convenience or other reasons?
Yes, it's your first post, welcome out from the shadows Doug!

While the 17' Casitas are typically very tongue-heavy, I've never heard that said about the 16' models.

We had a Casita 17 Deluxe and I worked up some conceptual plans for frame extension(s). One thing I found was that the additional steel in front could result in a substantially similar tongue weight while I had expected the additional leverage to lighten it up more significantly.

I looked at our needs holistically. While I considered building a "bike garage" with an aluminum weatherproof box on the rear, in the end I decided I liked keeping our folding bikes in the tow vehicle so that we could take them to different trailheads while the trailer was off the hitch.

Other things people commonly look at carrying on the outside include barbeques, towing gear and wheel chocks, rugs, canopies, generators, lawn chairs, etc. Sometimes they move the batteries around, increase or decease their propane capacity, add a mast socket for flagpoles / antennas / an elevated (rotat-able) solar panel.

Casita Greg has a pretty nice large poly box on a strengthened back bumper on back of his Casita. Jim Bennett had a custom box fabricated for the back of his fifth wheel; similar storage boxes are available commercially. Jim mounted his storage with two hitch receivers. Red Baron has a "bigly modified" Scamp you should definitely look at. I've also seen a Scamp(?) with a robust steel external frame that rises up to where you could add kayak racks over the roof.

You might add a bit of lift and possibly leave yourself some flexibility to shift the axle a bit if the balance doesn't work out precisely. One model Bigfoot had to add weights to the A-frame area as a recall to maintain adequate tongue weight. That's a no-Gouda.

Quote:
The 2003-2007 Bigfoot 21FB was recalled due to unsafe towing conditions with a light tongue. It appears to have been a poor design. The fix was a reinforced tongue section and 275# of ballast (weighted plates) that was added.
It's your world; what do you want to carry?
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Old 05-21-2020, 09:11 PM   #5
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Originally Posted by Civilguy View Post
Yes, it's your first post, welcome out from the shadows Doug!

Other things people commonly look at carrying on the outside include barbeques, towing gear and wheel chocks, rugs, canopies, generators, lawn chairs, etc. Sometimes they move the batteries around, increase or decease their propane capacity, add a mast socket for flagpoles / antennas / an elevated (rotat-able) solar panel.

Casita Greg has a pretty nice large poly box on a strengthened back bumper on back of his Casita. Jim Bennett had a custom box fabricated for the back of his fifth wheel; similar storage boxes are available commercially. Jim mounted his storage with two hitch receivers. Red Baron has a "bigly modified" Scamp you should definitely look at. I've also seen a Scamp(?) with a robust steel external frame that rises up to where you could add kayak racks over the roof.
Thanks for the response! I think I'm going to devote the rear to an "outdoor kitchen" and other outdoor equipment (Small grill, a couple of burners, and some kind of table). I definitely like the idea of some kind of socket for a flagpole!

I'll definitely be putting solar on the roof as I'm ditching the almost 20 year old fridge. As an engineering dork, I love the theory behind a 3 way ammonia absorption refrigerator, but don't like the performance. I'm going to switch to a refrigerated cooler. I'm losing sleep at night thinking about how to make a 2 way slide heavy duty drawer slide so I can remove the old fridge and have the cooler slide into the Casita and outside the Casita. Sliding outside would be one of my last priorities before our trip. Getting rid of the old louvered vents and coming up with a trap door will be time consuming...

Oh and I'm going to look at cleaning up the gray/black water plumbing and moving it for better ground clearance. I've already ripped the gray water plumbing apart before on the beach... I'm glad I had done the Hepco shower conversion previous to that trip.

What's prompting all this craziness is my wife and are seriously thinking about a 3-4 week rocky mountain trip in 2-3 months.

I'll be going down to 1 propane tank and adding a Honda EU2000 on the front. Although I'm used to humid, hot Texas weather. I probably don't need a generator in the mountains...
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Old 05-21-2020, 10:27 PM   #6
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Quote:
Originally Posted by WheelinAg View Post
What's prompting all this craziness is my wife and are seriously thinking about a 3-4 week rocky mountain trip in 2-3 months.
Another thought is where the spare tire might end up. I have seen a few mounted under the frame behind the axle with the crank-down hardware common to that style. Someone makes a "ladder rack" that gets installed underneath and sort of hinges on one side of the trailer; it might be a dubious approach if you're parked on a sloping shoulder.

Just for fun, here's an offroad Scamp 19 and a couple of Scamp 19 bumper-pull conversions. I'll post some pictures of an offroad a UHaul separately. People get creative.
Attached Thumbnails
Scamp 19 off road 001.jpg   Scamp 19 fifth wheel bumper pull CasitaClub post-11457-0-84891000-1367750209.jpg  

Scamp 19 tandem fifth wheel bumper pull Frank Glugla.jpg  
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Old 05-21-2020, 10:30 PM   #7
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Uhaul offroad conversion with kayak rack.
Attached Thumbnails
UHaul offroad 20180512.jpg   UHaul offroad 20180511_202341.jpg  

UHaul offroad 20180511_202054.jpg   UHaul offroad 20180511_202021.jpg  

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Old 05-21-2020, 10:48 PM   #8
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2"x3" frame sounds good. That is what we used to build the new frame for my Trailswest Campster. The original 2"x2" frame had bent upwards just behind the tongue area. Added in some diagonals as well to reduce stress at some of the major 90 degree intersections of the framing members. Also gusset plate added in at the weld where the angle changed from the frame for the body to the angle for the tongue. Plus a long diagonal 1x2 square tubing strut to tie those pieces together as well as a 1x2 cross bar Of course not the identical trailer design to yours but some of the concepts might be of interest to you.

Photo shows some of the improvements for the transition at the tongue area to keep it stronger and stable without making it too heavy in weight. I don't have a heavy duty tow vehicle and the heavier 2x3 frame meant I had to keep any overkill tendencies for an extra beefy frame under control to keep the overall weight compatible for my tow vehicle capacity. It will be getting a mounts put across the tongue for a tongue box for my little generator but I don't have that box yet so that will happen later this summer.
The replacement frame was designed in the 3D CAD program Ironcad. Took measurements from the original frame and then modified it in the CAD program. I am trained in Solidworks but Ironcad is a lot more fun to design with so I don't own a copy of Solidworks for my personal use.

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Old 05-22-2020, 07:46 AM   #9
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Name: JD
Trailer: Scamp 16 Modified (BIGLY)
Florida
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I built a new front frame for my 16' Scamp using a Flexiride axle that allows for repositioning the arm to raise and lower the trailer. If you add the square tube between the two Timbren units there is no real gain, I have no idea about the cost differential.
The arms and the spindles of the Flexiride are replaceable if needed. As to the 5200 lb axle rating, if you make it higher than the trailer weighs you will increase ride harshness and beat everything inside to pieces. Since my target weight for my Scamp was 2800 - 3000 lbs I had the Flexiride built for 3000 lbs. I also changed the wheels to 14" D rated tires.
If I were to do mine again I would extend the rear as well as the front of the frame. I extended the front about 18" to give space for the mini-split heat pump outside unit.
I would extend the rear frame probably 2' to give a high strength "back porch" for generators etc. Since our heat pump, while much quieter than a roof top unit, does make some noise, more during heating than cooling.
It is important to balance the weight fore and aft and also best to keep the weight near the center (and low) for better handling. I installed my batteries just aft of the wheel well to keep that near the center with venting to the outside. The electric compressor (12 VDC /120 VAC) is mounted just forward of the wheel on the other side with the convection/microwave above.
We have camped for months in our Scamp and would not change much in our layout.
We have 300 watts of rooftop solar panels attached with aluminum angles and to the top of the awning case.
I have considered adding a rear carrier for extended traveling, but I am not sure what I would put on it. Perhaps my dual fuel generator that weight 45 lbs, but we have not found that many times we have needed it. In our case we towed with our Touareg with limited storage space and carried the generator (no gasoline in the tank) in the back. We have water proof totes for extra clothes in the car and other gear, but have been able to make do so far with months of travel at a time.
The biggest irritation we have experienced was the noise from the old Norcold swing compressor, but switching it out for a late model took care of that.
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Old 05-22-2020, 08:00 AM   #10
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PS.
On that generator I carried a genuine Harbor Freight Predator 2500 and while it worked OK it was heavier and only ran on gasoline. Carrying gasoline has always bothered me so I did not take the generator very much as the use is restricted in many places.
Also there is a problem with not using them often enough and the gas gumming / corroding the carburetor. To get past these problems I went to a Pulsar 2200 watt LP/Gas dual fuel generator. I have used it a fair amount, but never put gasoline in it. I added a second LP tank which gives 20 hours of use The 2200 watts (less on LP) runs everything in FrankenScamp, not necessarily at the same time. The inverter heat pump it easily runs and the microwave as well, but not with the coffee pot heating.
Look into keeping the second LP tank and getting either an LP converter for the Honda or a Pulsar dual fuel.
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Old 05-22-2020, 10:04 AM   #11
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Hip hip hoo-RAY...a Timbren build at last!

Quote:
Originally Posted by WheelinAg View Post

Axle will be a 5200lb Timbren "Axle-Less".

I'll follow this thread with great interest, thanks for starting it. We're backcountry campers, the rougher the road is the better we like it but clearance under the trailer can be a problem. I've been thinking for years of adding a Timbren for the extra clearance allowed by the absence of the pesky axle so am eager to hear/see what you do.
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Old 05-22-2020, 11:02 AM   #12
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Name: Doug
Trailer: Casita
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Civil Guy, I like that rack! I've got a nice tubing bender from my old offroading days, but I'm not sure my wife will go for it. However, the ability to put our kayaks up there interests me. I've thought about building an aluminum rack on the top, but not connecting it to the bumpers. It would make a handy place to attach items though!

Corbin, nice looking frame!

Red Barron, I definitely will pay attention to weight distribution with relation to tongue weight. I've towed some badly loaded trailers before and have the pucker factor of trailer sway... There is a 5k lb scale on amazon for $350 that I'm thinking of buying.

Regarding axle weight rating, I'd rather err on the high side then low. When I was young I smoked a trailer axle to the point of destroying the spindle and it wasn't a fun experience. At some point I might throw 2 dirt bikes on this as well.

Francesca, have any ideas for outdoor storage of "outdoor" equipment? Popup canopies, propane burners, etc...

Here's the outing I ripped off the gray water plumbing... This is 15 miles down PINS (Padre Island National Seashore)

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Old 05-22-2020, 03:33 PM   #13
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If you put 5200 lb "springs" under a 3500 lb trailer it will be way too stiff.
would not worry about the bearings as they are loafing at this weight.
As to
Axle less" either the frame must be reinforced to carry the twisting loads from the wheel contact outside the frame. With the high spring rate there would be a good bit of twisting "shock" loads and a carry through is called for in the instructions or a good bit of reinforcement. If you add the carry through as in section 6a then you might as well use an axle with an axle.
http://timbren-wpengine.netdna-ssl.c...-Rev041515.pdf
If you run a bolt through the rectangular tube be sure to weld a reinforcing tube for the bolt to pass through or the loads will just collapse the relatively thin tubing walls. The tubing most used will crush with 165 lbs of torque on the through bolts with the normal "Heavy duty" 1/8" wall thickness like I used.
If you are worried about the spindles etc the Flexiride has replaceable arms and spindles. I doubt I will ever have to replace mine, but if I ignored greasing the bearings for a couple of hundred thousand miles and burned out a bearing and is seized and spun on the spindle I could replace it.
My Flexiride axle carry through tube is right nest to the floor of the Scamp and is maybe not the lowest point on the trailer. It is a 2" square tube and is basically 2 " lower than the bottom of the frame. You can clock the trailing arm to adjust ride height.
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Old 05-27-2020, 12:10 PM   #14
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What year is your 16’ Casita. I have a 2000 16’ SD. Tongue weight on these is on the light side. My trailer weighs in at 2800 lbs., almost empty. If you’re adding timberen axleless suspension, you might want to spend some time on the Casita Facebook Pages and forums, but especially www.expeditionportal.com where this subject is addressed. Somewhere I read that the fiberglass shell may not do well in off-road environments, especially without the structure and support of the axle. Since you’re talking about an all new beefed up frame, may not be an issue. Just giving you a heads up to do some research in the Casita specific areas. Expedition Portal had some pics of other fiberglass trailer brands too. Good luck with your project! Can’t wait to see how it turns out!
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Old 05-27-2020, 01:49 PM   #15
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A lightweight fiberglass shell trailer does not need a 5200 LB Timbren Axle less suspension installed on a new frame. I am a great supporter of the Timbren products and will once again be using their suspension product in a new trailer frame build. Look at 4000 LB max and give that some serious consideration as being on the high side.

The idea of a new frame will give you a great solid foundation for a nice trailer as the factory frames are barely adequate particularly with all the upgrades people with to make to their trailers these days and all the CRAP they think they need to haul around with em!
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Old 05-28-2020, 03:41 PM   #16
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Ok, easy everyone, the axle weight capacity is the easy part! Lets talk about the pain in the butt part that gives me nightmares, separating the egg from the frame!

tdhess, I've been on expedition portal for a long time! I've got an M1010 military ambulance that I was going to build into an offroad camper, but life got in the way. That's a story for another time...

As far as the cracking issue, I'm aware. The main goal of the frame rebuild is to have storage areas front/rear. The much smaller reason is to gain some height so I don't rip off plumbing while going getting to more remote places. I have no illusions of taking this down any kind of trails. In my offroading days I wheeled a K5 blazer. The body had enough flex that you could hear the spot welds popping when the suspension was twisted up!

Ok back to the horrible issue of accessing all the self tappers. I'm sure I could get the majority of the "furniture" out in a day. This will probably have to happen anyways to do floor repairs. I'm fairly sure I have damage from the previous owner being oblivious to one of the cabinet rivets leaking. What I won't be excited about is removing the shower/bathroom. I've though about leaving that portion of the frame and tying into steel around it.

I've gone down these roads before though and you can spend more time and do more damage than if you'd have just done it right in the first place. Meaning just taking the bathroom out.

Taking the Casita to Matagorda in a couple of weeks and then I'll start tearing the carpet up to discover how much of a rot issue I have...
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Old 05-28-2020, 04:26 PM   #17
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Quote:
an elevated (rotat-able) solar panel.
I ran across some pictures of the "flagpole solar" setup I had mentioned earlier. The pictures are from Ron in BC's trailer; he's on the Escape forum.
Attached Thumbnails
Ron in BC Solar - 26-12-2014 4-45-28 PM1_resize.jpg   Ron in BC Solar - 26-12-2014 4-45-28 PM4_resize.jpg  

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Old 07-27-2020, 03:13 PM   #18
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Name: Doug
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Ok, getting back to this... I may not have time before our trip to go crazy on the frame/axle, but I definitely need a fridge.

Has anyone ever cut the belly band between the vents of the fridge? I'm not sure how structural this is, but fairly concerned because the door is directly adjacent.

I'm wanting to use a fridge/cooler and be able to slide it into the Casita as well as pull it out through it's own door and access it outside. To keep it at a reasonable height for both application, I'd need to cut the belly band. The cooler fridge will slide on heavy duty drawer slides or linear rails.

The cut will be the red lines. Also, I'm talking about something like a Dometic CFX 55 or Engel or ARB, not a regular cooler.
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Old 07-27-2020, 04:06 PM   #19
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Trailer: Scamp 16 Modified (BIGLY)
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It will weaken the structure . You could do it, but you would have to add a good bit of reinforcement to the shell.
In my case I actually filled that area in with fiberglass from the internal fiberglass partitions. However you could do what I did was add bulkheads on either side and bond them to the shell and then bond a horizontal shelf above that area. I would also bond the floor to the shell and add some stiffness in every area I could.
The standard fiberglass partitions, pop riveted to the shell would not add stiffness. I used 1/2 and 3/4 inch plywood screwed and bonded to the fiberglass to make the entire shell stiff and less flexible.
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Old 07-28-2020, 11:42 AM   #20
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Quote:
Originally Posted by WheelinAg View Post
The cut will be the red lines. Also, I'm talking about something like a Dometic CFX 55 or Engel or ARB, not a regular cooler.
It certainly sounds like an ambitious undertaking.

Cutting the belly bend will eliminate the shell gusseting provided by the band at that location, right next to that giant void space in the shell represented by the door. So, yeah, glassed in or epoxied reinforcement would be in order. Using pultruded fiberglass members or some carbon fiber would earn bonus points for elegance.

The weight of the rails and fridge and the contents of the fridge will add up to quite a load, so the rails and their hardware will have to handle the tension load holding down the opposite end of the rails when the cooler is cantilevered out.
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