Level of difficulty to fabricate a bellypan?

[vanster]

Is 3003 cheaper than 5054 or more expensive?

[crisen]

Generally 3003 is very slightly cheaper but you should really pick the alloy based on what it to be used for. When the time to fabricate is considered, differences in material cost are minor.

[vinstream]

Having done many Belly pans on both early 60's and mid 60's trailers with clean, tight, correct installations, I have learned a few things. First the type of aluminum is first and foremost key to success. 3003, 5052 are too soft types of aluminum and are very, very easy to crease in the critical corner areas of the belly pan. SO, you must use 2024 that is very hard to crease, but also hard to work with, but in the long run the most forgiving... The second thing I have learned is working upside down is hell! So if you can, assuming you are doing a full body off install, and can flip over the chassis to work on it, (like it was done in the factory) life will not be so simple. The third thing I have learned is using the old belly pan as a pattern will get you 90% (yours is gone so who cares) too the original belly pan but 90% is not close enough. As these trailers age and function they work themselves out of shape, hence one of the reason(s) the belly pan failed. Forth the .020 or .025 aluminum thickness that was used is not fun to work with and again is one of the reason(s) the belly pan failed and who wants to replace a belly pan twice on the same trailer knowing how hard it is to do, so I have found .040 works the best. Lastly the corner transition, and area of frame intersections are the hardest part and why the old belly pan is only 90% correct. SO to answer your question yes it can be done, the challenge is do you have the right tools, know how, and extra Aluminum because your first time around will become the templet for the second and depending on how picky you are may become the templet for the third... but like they say third times a charm!

[RankAm]

Originally Posted by vinstream

Having done many Belly pans on both early 60's and mid 60's trailers with clean, tight, correct installations, I have learned a few things. First the type of aluminum is first and foremost key to success. 3003, 5052 are too soft types of aluminum and are very, very easy to crease in the critical corner areas of the belly pan. SO, you must use 2024 that is very hard to crease, but also hard to work with, but in the long run the most forgiving... The second thing I have learned is working upside down is hell! So if you can, assuming you are doing a full body off install, and can flip over the chassis to work on it, (like it was done in the factory) life will not be so simple. The third thing I have learned is using the old belly pan as a pattern will get you 90% (yours is gone so who cares) too the original belly pan but 90% is not close enough. As these trailers age and function they work themselves out of shape, hence one of the reason(s) the belly pan failed. Forth the .020 or .025 aluminum thickness that was used is not fun to work with and again is one of the reason(s) the belly pan failed and who wants to replace a belly pan twice on the same trailer knowing how hard it is to do, so I have found .040 works the best. Lastly the corner transition, and area of frame intersections are the hardest part and why the old belly pan is only 90% correct. SO to answer your question yes it can be done, the challenge is do you have the right tools, know how, and extra Aluminum because your first time around will become the templet for the second and depending on how picky you are may become the templet for the third... but like they say third times a charm!

Vinstream, could you provode some explanation of what the second photo above shows us? Thanks, Hank

[vinstream]

RankAm or Hank,
The second photo you are referring to relates to the reshaping of the corner area of the belly pan. Below I have posted additional pictures detailing the steps to help better understand how to create a nice tight fitting corner without causing gaps between the channel and the outer skin or in many cases the skin rip that you see on many trailers even from the factory at the time.

So the first photo you will see lines scribed on the part. These are reference lines from the curve of the trailer that you are replacing the belly pan, not from some other trailer. There are two parallel lines... One at a lose fit the other tight fit. The lose fit is the scribe line you made from your trailer the other, tight fit is about a 1/4' in and this is where your bend will happen.

Next in the picture you will see several holes drilled to 1/2" in size. The placement is critical, the outside radius is about 1/4" from the bend line. The holes do two things they prevent the aluminum from cracking past this point and for an area for the aluminum to go. When you bend aluminum it wants to go some place and with out the holes the aluminum wants to crease.

The next picture you will see "v" cut out of the aluminum toward the whole you cut. This will create the tab part that will be sam-witched between the "c" channel and the outer skin. This is one of the keys to make a tight fitting belly pan with out creasing or splitting of the aluminum.

The third picture the one you were referring too it using a planishing hammer to create a nice tight 90 degree bend in the aluminum. This creates a 1/4" lip that will be covered up by the outer skin, and make the fit up a snap. If you did not do this step it would have to be done by hand with a hammer on the trailer fit up as you went like they did in the factory, but also leaves many dings and scrapes from the tooling. I place PVC on the aluminum before I do this to protect the part.

The forth picture shows the finished part, pre-formed and ready to be riveted and sealed into place.

The finished product when installed correctly shows no creases, no rips in the aluminum that the rub rail in many cases covers up, but does not properly seal from water.

Hope that helps..

[RankAm]

Vinstream, thanks for your informative post. Very impressive techniques!

I do not have access to a planishing hammer, but the other techniques will be helpful when I put the belly pan on my 1956 Flying Cloud.

Do you do any V cuts along straight edges (where the belly pan joins the straight curb side or the street side)?

Also, would you please explain how you scribe the two lines (the "loose fit" and the "tight fit")?

Thanks again for all the very informative posts!

Hank

[55AS]

I have found a very inexpensive source of belly pan material in 4ft x 8 ft sheets. $32 per sheet with no minimum order and if rolled, UPS Ground shipping is very reasonable.
5052 Aluminum Sheet - Aluminum Sheet
You need to call to get sheets larger than 48" x 48".

[NavyCorpsman]

Thanks Guys. A ton of great info here. My rear bellypan was grounded and needs replacement too. What works best to hold it up while drill/riveting? A sheet of plywood on jack stands perhaps?

[robwok]

dang Vinstream, that's some impressive thought process. Bravo. If my wife lets me do another after I sell my current, I'm sure I'll have to do some belly pan work. Getting a 50 year old trailer with a perfect belly was first time luck and I don't expect it again.

Rob

[rugjenkins]

What's your source for the aluminum in Mississippi?

[HiHoAgRV]

Originally Posted by rugjenkins

What's your source for the aluminum in Mississippi?

I have used Speciality Metals in Jackson.

[rugjenkins]

Thx. I'm headed to LA this weekend. It helps a lot