Bellypan question

[Rostam]

I have been thinking about addressing the bellypan since I bought our Avion more than 5 years ago but have not gotten to it yet. I'd like to come up with a plan and wanted to run the steps by the members to make sure I am not missing anything.

1) Remove the stabilizer jacks

2) Remove the gas line -- Question: If I detach the line from the appliances inside the trailer, can I pull the line out from the bottom? Would the lines need to be replaced if bent slightly?

3) Remove the belly pan

4) Remove the water tanks

5) Inspect the frame and floor and apply POR-15 to the frame.

6) Re-install the water tanks after cleaning them (and measuring their dimensions, in case I need to make a replacement)

7) Re-install the bellypan (possibly replace aluminium sheet if it has lots of damage)

8) Re-install gas line

9) Re-install stabilizer jacks.

Also, since this is a major project, I might do it in steps. I can do the uninstall part near the end of camping season this year, and start the re-install in spring. Would leaving the underbelly exposed create a problem? FYI, the trailer is parked in my driveway. My concern is mice. I plan to park the trailer on a couple of wooden boards to get more clearance. Is an extra 3 inch of clearance enough to drop the water tanks?

Thanks all for any feedback.

[Jason]

I am going through those same steps on my 79's floor replacement.

Breaking out the remove tanks steps might be helpful. Some of the jobs there can be somewhat large. Like removing the toilet and flange. Allot of people have had issues just rotating that flange.

I'd also measure the bay size and the tank size, in case there could be a savings of money or time for buying an off the shelf tank instead of a custom one.

[silverloaf]

Rostam-

I raised our trailer gradually until I got the frame roughly 12"-14" off the ground. I also targeted getting the tires off the ground about 1". This enabled me to remove them, work on the suspension & brakes and re-install them without a big hassle. Of course, you trailer might need different heights. .

Avion tanks are about 9" in depth. They are designed to fit into sub-frame pockets of the same depth. The tanks are as ornery to remove as well as re-install. There are built-in drain fittings on top of the tanks that protrude beyond the 9" depth.

I learned the hard way that the toilet flange actually threads into a fitting in the black tank. I didn't know this and cut the flange off with a sawz-all. It took me a while to come up with a scheme to reproduce the assembly.

The flange can be removed with a make-shift tool. Take a piece of wood and mark the centerlines of the toilet bolt inserts on the flange. Drill holes and install 2 bolts and 4 nuts in the wood. The bolt heads should extend low enough to engage the holes in the flange; the nuts lock the bolts into position. Then begin unscrewing the flange in a counter-clockwise manner. Use a rubber mallet to coax it along if necessary. It should come apart in a minute or so.

Regarding the gas line, I believe all of them can be detached below the floor before entering the interior. The only segment I replaced inside was the one for the water heater. The OEM routing was rather crude and unruly.

I did replace all the copper gas line under the trailer, including the steel leader where it connects to the propane tank. As part of the plan, I fabricated some 1" spacers to create a deeper pocket between the rear stabilizer jacks and the belly pan. This allowed me to run the line through the pocket and not under the jacks. It now sits snug against pan (courtesy of some isolators about 6' or so apart) and out of harm's way of getting snagged.

Pinched copper can sometimes be opened up using a small pair of vice grips and squeezing it at the widest point. When installing new lines, I used inexpensive spring benders that slip over the tube. The coils keep the lines from collapsing while bending it to desired shape.

One last thought. Our belly pan was not salvageable. In the process of measuring to have galvanized sheets cut to size, I noted there was a large spacing between the side-to-side crossmembers. I installed up some 16ga angle steel one across the trailer to reduce the centerline distances . This added tremendous strength to the final installation, as well as reduce the oil-can effect associated with large pieces of metal.

[Rostam]

Thank you both Jason/Silverloaf,

It seems the tank uninstall/re-install is its own major subtask. I've been avoiding the bellypan as I don't want my Avion to be offline due to repairs (I want to be able to use it). One thought is to hire a contractor to help me (this shortens the duration of the project).

Silverloaf, would you mind sharing the process for raising your trailer? I know wooden blocks are needed to secure it after it is raised, but not sure what is the correct way to raise the trailer without possibly damaging the frame.

Thanks,

[silverloaf]

Thank you both Jason/Silverloaf,

It seems the tank uninstall/re-install is its own major subtask. I've been avoiding the bellypan as I don't want my Avion to be offline due to repairs (I want to be able to use it). One thought is to hire a contractor to help me (this shortens the duration of the project).

Silverloaf, would you mind sharing the process for raising your trailer? I know wooden blocks are needed to secure it after it is raised, but not sure what is the correct way to raise the trailer without possibly damaging the frame.

Thanks,

Rostam-

You are taking on a pretty big job, considering you are dropping the tanks. You could well run into other issues that need to be addressed while the bottom end is open.

How long are you preparing to keep the trailer off-line for any work? I don't see any way of removing and re-installing the belly pan (including putting the trailer up/down on blocks) for short bursts of time.

What is your vision for all the logistics?

[Salty]

Having replaced nearly all of my bellypans, I can tell you it is a big job. At some point in my trailers life, the bellypans had all been removed and secured with sheet metal screws, so there were no rivets for me to remove and I just went back with sheet metal screws and coated them with POR-15 and topcoat
The worst part was removing the belly pan in the axle area. At this point the job developed a bad case of mission creep and I redid the entire suspension - but I digress.
If you're going to go back with Aluminum, Ryerson is a good source for sheet aluminum. I went with Aluminum b/c is was less weight than galvanized. I did not use anodized aluminum on the belly pan. Rather I used 5036-H32 and gave it a coat of paint for added protection.
Are you going to put any additional insulation on the underside of the floor?
The grey and black tanks on mine were held in place with hat channel. The fresh water tank is held in place by plywood.
Your sequence of events for disassembly looks good, I might add disconnect the brake wires, as they pass through the bellypan.

[silverloaf]

Well stated, Salty. I went with galvanized mainly because I couldn't get aluminum without sacrificing my first-born. . Odd that I lived in the Motor City but couldn't get it reasonably.

I remember having to strategically re-arrange the wood ramps & piers and jack stands to remove the belly pan. There was a lot of dried "silly putty" to remove around areas like the cutouts for the spring shackles.

Rostam-
I chose the area fore and aft of the front and rear tires, respectfully, to locate the wood piers. I determined this was the best point to keep the trailer relative stable. I used the trailer's electric jack on the front and jack stands under the frame extensions for the rear bumper to keep the trailer from teetering/bouncing.

My piers consisted of 5-1/2" wide x 12" segments of dimension lumber ranging in thickness of 1-1/2" to 5-1/2". I went through HD's cull rack to find lumber at fire sale prices. They were arranged in pairs (12" wide) and crisscrossed as they were built up. I added a sheet of ply/osb after each 2 pair to keep a uniform load on the group. This was really important to me; I didn't want the blocks to roll over on their edges if there was ever a weight shift.

I worked from one side to the other, using bottle or floor jacks positioned ahead (front) or behind (rear) from where the pier would be located. I recall unloading the jacks and changing sides after installing 2-3 layers. Once again, I checked the electric jack and rear jack stands for minimal clearance. In the end, I put 2 additional jack stands just before the frame blends into front V.

My target height was getting the tires about 1" or so off the ground so I could remove them to work on the suspension and brakes. The allowed my belly to clear the belly. The concrete segments in our driveway were not uniform in height. I added wood pieces to each pier to compensate. Also, I did my best to keep the trailer level. I found this helpful as another reference point while fabricating parts under and inside the trailer.

Salty was absolutely correct about the complexities of removing and installing the belly pan. I was an Avion newbie at that time. Hopefully, you will be able to craft a sequence that is efficient for you and keeps you safe!

[Razorback]

Thanks to all who have provided these good tips. That's a job I need to do on our Avion.

[Rostam]

Thank you Silverloaf and Salty for your input. It seems this job is more involved that I initially imagined (I had a hunch, hence, my delay in starting it!).

Since I do not want my trailer to be offline for too long due to bellypan repairs, I am thinking of a divide and conquer strategy. I will do the bellypan project in 3 years. Year 1, I fix the front. No water tanks there. Should be the easiest (just use electric jack to raise the trailer and put wooden blocks underneath). Getting it done hopefully gives me more confidence to do the more complex sections. Next year, I could do the rear. Only fresh water tank there. And the third year, I will do the middle. Gray and black water tanks there. I think this makes it the tasks more manageable. Do you guys think this is a plausible plan, or am I being naive here?

Alternatively, I could wait on this project. It's very important, and I definitely want to address it at some point, but it does not stop me from using the trailer.

Thanks,

[silverloaf]

I would want to build some substantial ramps ( 6" or more high) before using the electric jack as a lifting mechanism. With that steep an angle, your wood blocks would not sit square to the frame. You want the bearing area of the wood blocks to be perpendicular to the frame.

I would recommend a minimum 10" (9-1/4" nom.) width for the ramp. You don't want the ramps rolling over on themselves should the trailer shift.

Your plan of attack seems perfectly logical to me. Keep us posted!