Rather than covering the how's and why's of the damage (that cat has been sufficiently flattened) I'll just share where I am in my current floor replacement project.
Most who do this elect to use heavier gauge steel tube and coating it. That's a good way to go; the factory installed .062" wall /16ga. uncoated tube is the reason why the floor structure is not going the life of the coach, the only two pieces of .125"wall/1/8" tube are the forward and aft most transverse pieces that bolt to the angle/bulkhead structure. Had they built all of it from that heavier wall tube most coaches would have likely got 40yrs+ of service before it rusted through. You can see in my pics that as bad as mine is rotted out the aft most (1/8" wall tube) is still in tack. I had no separation and no failed rolock fasteners. The only reason I found the problem at all is because I wanted to reconfigure my sewer dump.
As bad as the rotted steel looks, and yours
does look bad, it is still interesting that the damage was apparently not discernible under casual inspection. Your coach obviously did not break in half going down the road, and I assume the floors of the bays were not sagging under the weight of the contents. It is easy to understand how many owners (myself included) could have considerable hidden structural damage, and yet remain blissfully unaware of it.
Please keep us updated on your progress. We are all interested in these extensive reconstruction projects, even if we never actually get personally involved in them.
After finding the damage near the sewer dump and then seeing that I had "rust jacking" of the fiberglass belly skin under much of the tubes I peeled off the entire belly skin. Thankfully the heavy rust stopped about 10" behind the bulkhead just aft of the fuel/propane tank bay. Rather than creating another joint there, I just took the cutout to that bulkhead and created another bolted flange (now the forward section could be removed separately if ever needed). Gutting of the tank bays, water heater, batteries, inverter and aux compressor had to be done before the floor section was dropped.
You mention aluminum in the title. I would NOT mix the existing steel with aluminum.
Thicker steel, coated or painted steel-- just fine.
And, I am surprised that you could not get an idea of the damage by just looking at the FG underbelly. I would have expected the rust jacking to have significantly "pushed down"/"raised" the FG so that where the beams are is much more pronounced than toward the center of the coach where there is not water intrusion/rust jacking.
My background is working in marine aluminum structures/mechanical systems so rather than defaulting to heavier steel, I elected to replace my floor structure with thicker wall aluminum tube, it is far better suited to high moisture environments and even with increasing wall thickness/strength considerably, I will end up with a slight weight savings compared to the poorly executed original floor structure. Having said that; aluminum tube (3/16" wall) is more than double the price of 1/8" wall steel tube and requires considerably more patience for welding/fabrication.
One other plus of aluminum is that it allows me to work on my own safely as I can still pick up and move this entire 8ft x 10ft section on my own (though not as easily as when I was younger).
Post weld fit up test is where I am today.
Covered above...I'm entirely comfortable with my material selection.
That's why we don't drive in the rain if it can be helped. Yes, .125 wall is not going to add very much to the cost of the steel. How much trouble is it going to be to coat the steel? Not much. Nice to have removable panels under the coach so they could be easily pulled to inspect, modify, etc. As it is now, you really have to pull the bottom off to see how bad yours is. Bulging, etc only offers a guess at best.
That's why we will never visit the factory. Too great a chance of going Postal if several topics came up. 8)
Good photos. Bet some will not want to view before dinner! :D
Pierce
The key to attaching aluminum to steel is to create an effective barrier, I've already treated all the remaining steel with 2 coats of POR-15. I'll further coat the mating surface of the aluminum with zinc/chromate paint and then wet assemble the joint with a polysulfide sealent (avaition guys know it as "Pro-Seal").
One other thing I want to point out is the importance of cleaning up and sealing the upper backside attachment of the angle to bulkhead sheet, this is poorly attached with only 5/8" stitch welds and offers considerable gaps where the water splash off the tires will drain right down into the bulkhead/floor mating seam. I cleaned mine up and used a good urethane sealer...I'm probably going to add some more to the verticals as well..
My greatest disappointment was in the welding of the floor tubes, (beyond the crappy uncoated .062" tube) they only welded the vertical joints so that they wouldn't have to grind the horizontals flat for the skin application...just plain negligent. Even with no rust compromising it there would have been considerable flex...honestly I think they lasted as long as they did because the fiberglass and foam insulation held it all together.
Len. What type of covering will be going above and below the new frame and what kind of adhesive might you be using to attach it ??
still kicking that around...I'll probably use a urethane sealant but I'm considering plastics/FRP/aluminum sheets, leaning toward FRP panels now as they really are the best bang for the buck. I've done a lot of aircraft sheet metal work so I'll likely seal/rivet attach the panels in the open areas an then just use some type of threaded fastener for the areas were you can access the through bolts...
Now on to something I need help with. When I removed my wet tank it was/is full of loose rust (the other two are good to go) I replaced the drier right after I got the coach last year so the source of the problem is in hand...this is just left over damage. Is this configuration of tank still available?
I think Mike (Pamela & Mike) will answer that when he sees this thread. I know he has sources where he can order replacement tanks.
Well, I've only had my coach for 14 months and I found the issue about 6 months ago (just started working it in the past month on the weekends) and was just using it locally both before and after, I had no separation or sagging and monitored it closely after I found the problem.
I'm going to convert the front bulkhead connection to thru-bolting as well while I've got it apart.
First off that is a sweet job on the replacement floor. To the naysayers (owners of SOB that have caught us at a campground wanting to see the coach split in half due to misinformation) this shows how the floor is just a bolt on part and is fixable.
We have a Truck Parts World here locally that I have went out to and got a replacement tank or 3 from. Truck Parts World | Quality Parts Since 1987 (https://truckpartsworld.net/) They don't have the exact same tank but they have ones that will work. The bosses may be in different locations and you may have to drill a new mounting hole or 2 but they have always found one that would work. You just need to look around your area and find a good truck supply company and they can help. With us in the middle of the oil field we have several truck supply parts stores around to shop for parts at. NOW don't go in and tell them that you need a wet tank for a XXXX year model Foretravel as you will get the deer in the head light syndrome look. Just take the tank in and put it up on the counter and tell them you need one of these or one as close as possible.
Mike
Thanks for the lead, I'll definitely look into that; I'm also going to run my boroscope down in it and see just how bad it is...if not too bad I may try the old ball bearing/bb shake&swirl method to clean it out then poor a gallon of evapo-rust in it for a few days to kill the existing rust...of course if I can get a new tank for reasonable money, this one will be in the scrap bin..
I think I know the source of your severe corrosion issue.
According to the where is len.barron, you are located several miles west of San Diego.
Salt water will get you everytime. .
Tim
A mixture of 1/4" and 5/16" nuts work better than round objects. Works great on M/C gas tanks that have rusted inside.
How about welding tabs on the new structure so you could fasten the new covering on without drilling into the tubing?
Good article on steel treatment. Rust Protection (https://www.eaa.org/eaa/aircraft-building/builderresources/while-youre-building/building-articles/basic-construction/rust-protection)
Consider Tube Seal or boiled linseed oil for the interior of steel tubing. This is used in aircraft since the Wright Bros.
Pierce
Impressive fabricating Len.
The trusses running the length carry the weight, the boxes underneath prevent twisting.
Len,have tried both Rust Bullet and POR-15,Rust Bullet much better in my opionion.
Len good looking project. I'm sure you have addressed this but be aware to properly ground in multiple locations to prevent electrolysis from getting a start, separate from your attachments? Did you use 6061? Are you going to Alodine?
Scott
Nice looking work.
Scott,
Yes, Beyond the zinc chromate primer on the mating surfaces, I'm going to use MIL-DTL-85054 Amlguard Corrosion Preventitive Compound on the entirety of it (thanks for the PM offer, but, I have similar access to those materials as well). When reinstalling my converter charger I'll do a large bonding/ground strap system than will handle the structure to structure and case grounding of that component.
WOW!!! impressive work
Idea,next time someone with skills like that builds one as good as that,ask around,maybe could build an extra for someone with the same size coach.
I'm wondering about the difference in temperature expansion rates between aluminum and steel. Is it possible it might effect the glass lamination of the coach sides? Other possibilities?
Linear
Temperature Expansion
Coefficient
- α -
(10-6 m/(m °C))
Aluminum 21-24
Steel 10.8-12.5
The cost of aluminum is going to be a lot more than steel.
Welding is going to require more than a simple wire feed welder.
Corrosion resistance to water with winter treatment chemicals is poor. May be partially mitigated by treatment/coating.
Thermal Expansion - Linear Expansion Coefficients (https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html)
I do appreciate the excellent job done in the construction. First rate!
Pierce
Here are some good tips and a good read about steel and aluminum protection from the EAA. Quote:
Protect your freshly cleaned parts with a suitable primer to prevent further oxidation.
1. Epoxy Primers provide a durable surface that resists most chemicals and is also highly abrasion resistant.
2. Red Oxide Primer, as used in automotive circles, is excellent for use on steel components because of its fast film build, quick dry time, easy sanding, and its ready availability.
3. Zinc Chromate (specification Mil-P-8585A) is preferred by most homebuilders. My favorite corrosion preventative for both aluminum and steel is DuPont's self-etching Variprime™ because it is a good economical base for most types of paint finishes.
Full article at EAA site: Rust Protection (https://www.eaa.org/eaa/aircraft-building/builderresources/while-youre-building/building-articles/basic-construction/rust-protection)
Pierce
IMO. The aluminum part is the easy part. Everything else is quite a project. Bonding the lower skin, filling with pour foam. Vacuum bagging/ bonding upper skin. Len what type of welder are you using? Great project.
Scott
Note approximately .008 inch difference in 5 meters of length between aluminum and steel with 122 degrees temperature change.
Len,
I marvel at your skill and willingness to take on this project. The first guy I recall doing it is Don (acousticart) about ten years ago. When he first posted his plan there was shock and disbelief here on the forum. "Get that rig onto a flatbed and into the Foretravel factory! It can't be done! You'll be sorry! You're over your head!" He did it in the gravel in his driveway and it turned out better than the original by far. As our erstwhile Aussie member would say, Good Onya!
jor
I look at doing the job, and the hardest part would be taking all the stuff out from
above the bulkheads. Fuel tank and water,grey and black water tanks etc. I've read
Don's write up and it was and awesome job.
I get a .096 inch change over 20 feet with a 20 degree F increase in temperature.
Results
Material: Custom (α = 20)
Change in Length (ΔL): 0.096
Final Length (L + ΔL): 240.096
Thermal Expansion Calculator | Good Calculators (https://goodcalculators.com/thermal-expansion-calculator/)
© 2015-2021 goodcalculators.com
Pierce
So based on 5 meter long calculation and a 122F degree temperature change steel grows 3.25MM and aluminum is 5.55MM so a additional 2.3mm extra growth. I'm simply not going to worry about it. You could easily be off that in assembly or more and how could you ever measure anyway. Its also too hot or too cold to measure it . It will be fine.
Scott,
Yep, just not enough to matter. Many associate the increased speed of heat transfer (and relative movement) to mean that the movement/expansion to continue at that rate..and it just doesn't. Aluminum transfers heat (and moves) more quickly, but (in this application) not significantly more..
It was no mistake that I waited until after I had the new structure built before I posted it here; I've blazed enough vehicle project trails to know that whenever you go your own way, you are going to be challenged. Then everyone looks at it again, and again, and then someone else decides "he might be on to something"...then next thing you know it's routine..
I've also been installing 3M barrier tape as I access upper basement pa els to prevent fuel or water getting into places I don't want a chance of it happening. Photo is it on my slide till I replace bladder seal on order P/n 8663DL
Scott
3M™ Polyurethane Protective Tape 8663DL Transparent Dual Liner, 12 in x 3 yd... (https://www.industrialgeneralstore.com/3m-polyurethane-protective-tape-8663dl-transparent-dual-liner-12-in-x-3-yd-sample-1-per-case.html?gclid=Cj0KCQiAqbyNBhC2ARIsALDwAsD63RBUVDDGV6ADq9wsDo4XXHgcWlq7dq0reNCkjni5QUWsrVPWl8kaAtuwEALw_wcB)
We use the (very similar) 8681 erosion tape on the leading edges of our rudders on the LCAC Hovercraft..
Lol i have a roll of that also. Timed out of course but still good in my world
Put a little more time on it this weekend.
Beautiful work !
Looks great. Please keep the updates coming.
Looking great.
Nice job! 👍👍👍
What is the material held in place with the clecos?
Thx
Tim
Fiberglass Reinforced Plastic (FRP) Panels
Love the workmanship. Did you tig or mig weld? Also why aren't you reusing the original skin? I'll have to take care of this job at some point.
Looks great! I think I would of layed my FRP panels smooth side up, easier cleaning and will not hold in the dirt.
I just MIG'd them, no need to put in the extra time for TIG in this application, if I was building a fluid system component(or something cosmetic) I'd definitely have TIG'd it . Original skin would have required a lot of hours to clean, and it had some damage from both battery acid and some small impact damage (road debris) so new material was just easier..
I considered it, but decided the textured up in the wet bay would help wick moisture from under the fresh tank. The larger dry storage bay all gets carpet anyways so that didn't matter.
As long as you have it all open make a fill sized catch pan for the wet bay and have everything inside of it to catch any leaks. It can drain out through the bottom. Wet bay leaks seem to be the cause of most rust issues.
Outstanding work Len!
Yes, I agree with Roger. I made stainless steel pans with drain holes but any material that has sealed flanges will work.
I also did not put a single screw into the new floor which is another leak path inside to the foam and structure. I mounted things to the walls or let them float on top; for instance the water pump is held well enough by the water lines connected to it.
I also used 3M 5200 to caulk the joints between the new floor and walls. The factory used silicone but it doesn't last and once the tanks are in, it's impossible to see the condition of it let alone reseal it.
I'm humbled by the outstanding work shown on this post. Great examples for others to follow.
Pierce
I have wet bay envy, wow!
Very nice John.
I'm right there with you John. Fewer holes in the floor.
John , you know that 5200 stuff is FOREVER. I used it on our dash to front cap repair and nothing up there even budges now.
Kinda like Shoe Goo. :))
Floor is back in (for good this time). I must have done something right because all the bolts (all 49 of them) went in without any drama. I was also very grateful to have used aluminum, this thing got pretty heavy by the time it was insulated/paneled and sealed. I still have a lot of edge/fastener sealing to be done so what you are seeing is not a finish product. I did include a picture (rv31) of the aft bulkhead where I trimmed the 16ga. sheet up 2" and welded it to the angle. It seemed foolish to me to have that continue down to the bolted flange, it is now fully welded across the width of the coach. I'm using "body plugs" to fill the fastener access holes, they'll do double duty as fastener access and drainage/inspection ports if the need ever arises. I'm also going with a much larger open pass through for my shore power and sewage connection, and I'll be rerouting my fresh water overflow to dump out there as well (eliminating another hole to be drilled).
I'll be out of town for a few days for Christmas but will have some time next week to start repopulating the bays.
Love the FRP board. Tough stuff and very user friendly! Beautiful job on your rebuild as well. Quality and professionalism shows!
Very impressive, this forum never ceases to amaze me! We're blessed with many talented folks.
Looks fantastic, nice work on a difficult job. I can't wait to see it all come back together. Thanks for all the great pictures! Have a great Christmas :)
Keep the pictures coming, I love looking at great work.
Finally got to working the project that started this whole mess; new sewer dump setup and new battery tray and cables. I'm making a two piece aluminum expanded metal grate cover for the opening and some remounting/reconfiguration of the drain valves...fresh water tank overflow will also run to this opening.
Also, part of my plan was to just replace the water heater, I had/have the old Atwood GH6-4E which is Propane and has the Engine Heat Exhanger option...it had "issues"
Turns out Atwood/Dometic have discontinued all the versions of the GH6 (-4 thru -10) and even the propane only versions are out of stock everywhere...changing to a different model would have required an outer cover change and on my coach the paint stripes run right across that...so I decided to pull it apart and attempt a mini "refurb". I hydro'd the tank (which thanfully was good). Then the "heat exchanger" which is just an aluminum tube (that was corroded through in about 5 spots). I cut off the existing aluminum heat exhanger tube and welded on a new one (bought from mcmaster carr...forgot to get a pic of it). I cleaned up the face panel and all the parts, installed new temp switches and thankfully google how to install new swage rings (it's not hard if you bevel the tube and have a proper sized sleeve to drive them on). Also replaced the old cardboard and fiberglass insulation with the molded styrofoam. Overall, I'm happy with it, I've got about $100 in materials and probably more hours than I should but it works...and it no longer leaks.
Len, all of that fabrication and labor, yet here I am complimenting you on the water heater restoration: Nice job!
I am also in awe of Len's water heater refurb. I didn't realize such a thing was even possible.
Our '93 U280 is still operating with the original factory installed water heater. I have always assumed it must be getting close to end-of-life, but now there is a glimmer of hope that it could be saved!
nice work on everything you have done
I was happy that it lasted from 88 until now (and still made good hot water) and would have been good with retiring it had I been able to find a replacement that didn't require changing the outer panel. I found that a lot of tanks had been replaced due to poor winterizing so the parts support to do the work was there. I was also pretty surprised at just how simple the "heat exchanger" was...I had thought it must be a coil inside the tank or at least something more elaborate than just a tube welded to it...I guess simple saved the day on that..
Also, lots of problems if the tank isn't flushed regularly. Here's the original from my 95.
jor
Jor, Do you have an album of all of the parts of your coach? You seem to have a picture of every part of a coach.
Forgot to post up that I completed the project(s), new basement floor from the bulkhead just behind the fuel tank all the way to the aft most bulkhead (10ft), converted the remaining floor to through bolt configuration, cleaned and POR15'd the remaining floor, refurbed the water heater, replaced the tank/sewer dump system, new battery mount tray, replaced the chassis battery (house batteries new from PO), replaced all the battery cables and added HD Blue Sea disconnect switches.
Total budget (materials only since I provided the labor) was $1970. Could have been done for about $300 less in steel.
Coach is back in service and we had it out a couple weeks ago..
Len,
You set a high bar for those of us who try to do our own work on our coaches. AFAIK, only Don (Don & Tys) has attempted such a complex floor reconstruction project using mostly his own skills and not employing a "professional" RV repair shop. You show us all what is possible. Congratulations on a awesome project well done!
ENJOY !!