Coach Cage Frame construction

[Blue Skies]

The cage structure for these coaches is appealing and somewhat unique.

This enlightening forum and the Show Hauler website have some spec information but perhaps a review in this section is appropriate.

A summary might include the materials in the cage, and the specs of the metal used (thickness of metal, thickness of the tubes, spacing of supports for sides, floor, roof, etc).

What is the material and thickness of the skins and the underneath storage bays?

The insulation of the sides, floor and roof.

What is the welding process and how is the coach secured to the chassis?

How were those specifications and materials determined? Do they vary from coach to coach?

In other words, for a novice to the truck conversion world like myself, how strong is strong enough?

[Warpath]

Floor: 2"x3" 11 ga tubular steel, 16" o.c.

Walls: 1"x1-1/2" 16awg tubular steel, 16" o.c. where possible

Around slide-outs, the box corners & top hat: 1"x3" tubular steel 16 ga.

Bins: Angle iron, 1"x1-1/2" 16 ga. Enclosed with Galvanized steel 20 ga.

The interior steel frame is wire welded together, no screws.

Interior walls are sheeted in 7/16" osb Board to tie the frame together. Floor is 3/4" Plywood.

Exterior Skin: .063 Aluminum in 4' wide panels. Panels are attached by 3M VHB tape. (Note: I have used this product and you cannot believe the strength of this tape when attaching metal) No rivets

Roof Exterior: .030 one piece aluminum

Insulation Interior: adhesive bonded all walls and ceiling surfaces with a highly efficient bubble type insulation.

Insulation Floor: first joist are covered with .040 alum. with ¾ " Styrofoam.

Coach Frame is U-Bolted on Oak planks to truck frame.

All wiring is to ANSI A119.2 & NEC code, R.V.I.A. certified. All 120vac lines are hi-pot tested.

There is a start.

Bill

[Blue Skies]

Originally posted by warpath:
There is a start. Bill

That is a great start. Thank you for your thorough reply.

Was aluminum ever considered as a frame material given its tensile strength and favorable weight?

Any other methods considered for anchoring (or cushioning) the coach to the chassis?

How did those specs and materials come to be chosen oven larger or smaller sizes and distances? Was there a target strength calculation that needed to be met?

I admire all of the above factors that need to be addressed to make a durable coach including the many, many items that become apparent only to those who build these from the ground up.

John

[Gary Atsma]

That is WAY more than a start, Bill! While it is possible that a coach MIGHT not have to be built as strong as that, it can't hurt either. I'll take safe construction over glitz and glamour ANY DAY. Kingsley could learn many lessons from this forum. Are you listening, Ralph Dickenson?
Gary

[KAYE RIVERCITY]

.....I agree 100% with you guys.....today I was over at Stop Fure having extinguishers filled and tested [it's getting that time of the year again]I asked the owner about a system for coaches-he is looking into it.....course forman said " there is NO standards to follow so it ain't allowed" typical bullsh*t can't think that with out any laws against it it can't be done....frickin' idiots-no wonder they are poor hourlies.....Been in the box so long they can't think for themselves....any way I was thinking of a cylinder in a corner or on the ceiling that would activate due to rate of rise or flame-maybe dense smoke?.....working on it-will advise.....geof kaye

[Gary Atsma]

Keep us posted Geof, sounds like a hot item......
...sorta like a certain Kingsley Coach we've been hearing about....
Gary

[RICHARD PHELPS]

Bill;
The siding is attached with 3M VHB, and you are right, you better have it where you want it because it will require another truck to remove it.
I have been removing panels that have been on for 4 years plus and they are a bear, details later still.

[KAYE RIVERCITY]

.....I'll stick with the steel frame and Aluminum sheeting with the plywood interior.....should the thing roll over....bet I make it home-ugly, very ugly, but I should make it alive......geof kaye

Insulation Floor: first joist are covered with .040 alum. with ¾ " Styrofoam

For the sake of accuracy. Unless Showhauler has changed the constructiion since last May when was at the factory they are not using Styrofoam insulation in the floor.

They were using expanded polystyrene foam insulation "beadboard". This has a R value of R-4 per inch.

Styrofoam is the Dow Chemical Co brand of extruded polystyrene. It is R-5 per inch. It is not the same thing as beadboard.

Most of the RV industry uses beadboard even though many companies incorrectly call it Styrofoam.

[Blue Skies]

expanded polystyrene foam insulation "beadboard". This has a R value of R-4 per inch.

For clarification and comparison, what are the R values for the floor and ceiling?

[KAYE RIVERCITY]

....should be using R-7+ 1" polyisocynate Board .....though it is $9.00 a 4X8X1 currently as opposed to $4.00 a sheet of bead board.....sure would be worth the extra insulation value over the years.......also filling the cracks with spray can foam and staying away from bubble wrap would make a big differance......geof kaye

[KAYE RIVERCITY]

should be a 3 to 1 anotherworks 3 times the insulation value in the ceiling as the walls.....though glass windows is just a hole in the insulation they should be at an maximum of 10% of the floor space.......though some people are phobic and have to have air and windows open.......geof kaye

[cjc]

Several of you have sung the praises of the 3M tape system of attaching the aluminum skin. I'm currently up here in Elkhart to have repairs done to my coach which is 2 yrs old and has almost 40,000 miles. Among the repairs is a fix to one of the panels that came loose. This is the second time that I've been back because of a popped panel and it has been two different ones on opposite sides. Has anyone else experienced this? I also have two areas of corrosion to the aluminum skin located at the extreme back end of the coach. Not good considering the expensive paint job that I had applied. I live in Florida and my truck only saw snow on one occasion during a return to the factory for repairs. It's also garaged during non-use times. Has anyone experienced either of these problems?

[KAYE RIVERCITY]

.....Florida weather is worse than acid rain if you ask me....I used to leave a car in Fla. for the winter months.....it depreciated faster than a car up here in Ohio.....damn thing rusted in the garage and the paint turned to chaulk inside of the garage....sun through the garage windows and sea air with salt in it-as per the insurance company.......was not as bad when I moved off Sanibel but still a problem in Ft. Myers......lawnmower lasted 3 years and was shot as well.....no paint can survive the sun and there is not a metal portectant what will stop salt water rust that I know of and I've tried them all....I stop in Atlanta and use a spray car wash and a truck wash to get the salt spray off before heading back to Cincinnati....costs about $45.00 but it's worth it......geofkaye

[cjc]

I agree with you in regard to the sun, but my coach is garaged-and there aren't any windows for the sun to beat down on it. The corrosion is not rusty steel, but aluminum corrosion. My guess is that it's due to contact between dissimilar metals, ie: steel framing and aluminum skins in full contact. The only place that the corrosion exists is the aluminum covering wrap at the extreme back end of the coach. Showhauler ends the framing with what appears to be a piece of 3" x 3" steel square tube and then it's covered with aluminum. Other steel to aluminum has the tape in between the two metals. Add any stray electricity to the mix and you have a battery. Anyway, this is just an educated guess and the question was, is anyone else having this experience or am I the only lucky one?

[KAYE RIVERCITY]

....now that you have explained it.....I'd better take a closer look at my trailer.......geofkaye

[Warpath]

Hey cjc

On my 03 I had 2 grounds break loose. The first one was off of the entry step and the other was near the back of the coach.

I would creeper the whole under side of my coach every month or so and spotted it pretty quickly. Even so the entry handle screws corroded so quickly that I did need to replace them.

I did replace those grounds with some high quality SS screws. Never did have a issue after that.

Anytime you have dissimilar metals and some stray current you can start electrolysis. In my case I ran my rig in the winter and the street salt definitely expedited the process on those entry screws.

It is so critical to crawl all over these rigs inspecting every potential area for problems.
Bill

[cjc]

Since you brought up the topic of 3M tape for the adhesion of aluminum panels to the steel framing, I would like to ask a question of anyone that has owned a conversion built with this system. Have your panels ever popped open? My Showhauler is now just over 2 years old with 42000 miles and I've been back twice for repairs to the aluminum skins. Both times it was because of popped open panels. First, the last panel on the right side and recently the panel immediately behind the slideout on the left side had to be reglued.

[Jimm]

Ehhh...what exactly is wrong with rivets?

Mine was factory made in '88, riveted aluminum skin, tube steel frame. Still holding tight as hell, original paint still looks OK...couple of minor chips and scrapes, a couple loose rivets (easily fixed) down in the galvanized steel lower bay area but nothing anywhere that smells of manufacturing defect and it's held up VERY well. The only thing that actually dates it as older is...well, it's on a Ford F450 frame so it's got a giant pickup for a nose/cab .

But the rivets have held up perfectly for...God, 17 years now and you'd never guess it was that old unless you knew Ford medium trucks real well.

GLUE!? What the hell?

[James]

For the most part, money and time. And time is money.
Rivets are expensive and labor intensive compared to the glue and the 3M tape.
Then, to a lesser extent, appearance. Most folks prefer a smooth surface on their RV's. Rivets have an industrial look to them.
It's also more difficult to do surface prep for a paint job on riveted panels. Do a bad prep job and your paint's going to pop. Normally right on the rivets.
Now, for the tape/glue, if done correctly, it should take an air chisel to seperate two pieces of bonded metal. Problem is, you have to be in an almost sterile environment to get perfect adhesion. Any dirt or moisture on either of the bonded surfaces or the glue or tape and you'll get a weak bond.