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Old 04-22-2019, 11:27 AM   #1 (permalink)
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Conveyor belting belly pan?

The subject pretty much says most of it, but here's the specifics.

I have a 2001 Dodge Dakota that is about to get a Mercedes diesel engine transplanted into it. I am looking at aero improvements, but don't want to lower the truck or add frontal area with an air dam unless necessary.

In thinking about what material would be best for a belly pan, I went through foamed PVC sheet, sheet aluminum, coroplast, and finally my brain lit upon the idea of rubber conveyor belting. It is tough, flexible, probably fairly easy to fit, and can be cut and solvent welded. And I can get it surplus.

The layout of the conveyor belt pan would likely be "as wide as possible" from the front bumper to the back of the cab, and between the frame rails the rest of the way back.

The belting wouldn't be the only element in the pan; I have a couple large sheets of aluminum for places that need to remain stiff all the time.

Anyone see any problems with this idea?

Thread TL;DR - even 1/4" conveyor belting is too darn heavy to hang off the bottom of the truck. The naysayers are correct.


Last edited by ThomCat316; 04-23-2019 at 01:58 PM.. Reason: ETA
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Old 04-22-2019, 02:07 PM   #2 (permalink)
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I have made two conveyor belt air dams (2005 Tacoma, 1994 Suburban) both work well and have stood up over time. I could see conveyor belting being very useful as a belly pan material between the frame and rockers, to allow for some flex.

I personally rather enjoy my air dams, they add a handling bonus that is noticeable. I sized mine at the point of the lowest obstruction under the truck (excluding the rear chunk) so I don't think I have increased my effective area. I have noticed a slight drag reduction at this height. I also drop mine lower near the sides, to act as a sort of tire spat.

My generic comments on belly pans is to not enclose the exhaust or you will create an oven. I also don't know about belting very close to the exhaust.
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Old 04-23-2019, 08:37 AM   #3 (permalink)
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My conveyor belt air dam is also standing up well. It hit one snowbank without damage.

I think a conveyor belt belly pan would work well. You will need many bolts around the edges to hold it without causing big wrinkles. I used stainless steel bolts for mine.
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Old 04-23-2019, 09:05 AM   #4 (permalink)
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I'm actually pondering an edge frame to prevent flapping, and high-zoot magnets to do the attachment along the frame rails and under the rockers. Probably bolting it on up front. Also thinking I'll build a hatch for oil changes.

The adhesive I found will bond to pretty much anything, so I don't have a lot of material constraints.
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Old 04-23-2019, 09:41 AM   #5 (permalink)
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Quote:
Originally Posted by ThomCat316 View Post
It is tough, flexible, probably fairly easy to fit, and can be cut and solvent welded. And I can get it surplus.
I have a conveyor belt air dam, material sourced from a Tractor Supply store.

It is 7-inches or so in depth (not very wide in other words), thick, heavy, flexible and there are easier materials to cut in my opinion.

Even when cost isn't factored in I can think of a dozen other materials I would rather use for a belly pan.

I don't know what sort of solvent you have in mind but might it make the joints more rigid and stiff?

Could be a good thing or bad thing depending on how you look at it. Personally I do not want to work with solvents over my head even if eyes, skin and hair are covered/protected.

The hot and cold cycles of weather plus vibration and impact concerns would force me to rely on mechanical fastening methods at all joints, but again that's just me.

Lap joints or butt joints, I cannot imagine how this concept is supposed to work. I've seen posted in the forum the metal lattice framework for belly pans, and it is a complex engineering proposition even with the most suited of materials.

In my opinion a better idea would be to trade or barter the conveyor belt material through the forum for other supplies better suited to this task.

Simpler yet, just build a conveyor belt air dam like others posting so far, we all seem to be happy with it.

https://ecomodder.com/wiki/Belly_pan

Quote:
Underside covers can be made out of many different materials, Some suggestions are coroplast (corogated plastic) or metal sheet. When choosing a material make sure it is strong enough to survive wet weather and being hit by small objects picked up by the tires.

The material used around the exhaust should be metal, coroplast will melt and deform. Metal can be used above the coroplast to ensure it does not touch the hot exhaust. The picture on the right shows an example of a frame that is used to mount coroplast to, it keeps the coroplast off the hot exhaust and keeps it generally flat. If a full frame is not used it is recommended to use either a metal frame or metal sheet just above the hot exhaust.

To install the sheet material drill and tap or pop rivet into suitable fixing points on the car. When screwing into the underside of the car check that sharp screw ends dont poke in through the floor of the cabin.

Note: Pop rivets work well when fixing to thin sheet metal areas like the floor of the cabin.
EDIT:

When trying to picture what lapping the joints would look like, I came up with a picture of clapboard siding.

https://www.finehomebuilding.com/200...bottom-or-both


An underbelly louver?



I first thought about butt joints going the length, but going across the width perpendicular to the flow might also work.

I guess the butt joints could work well if the lattice frame was wide enough and sturdy enough to take the heavy conveyor belt material.

Weight = Fuel consumption

At least for city driving.
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Old 04-23-2019, 01:21 PM   #6 (permalink)
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I think the conveyor belting is too flexible to resist gravity, and heavy. I'd suggest Polymetal.



Stiff as 5/8" plywood and 1/10th the weight and 1.5x the cost.
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Old 04-23-2019, 02:46 PM   #7 (permalink)
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I really hadn't multiplied out the area and figured out the weight. Y'all are right, conveyor belting is too damn heavy.

Freebeard, that signboard is very attractive stuff. How simple is it to form?

Back to the materials drawing board, or possibly to rethink air dam and skirts vs. belly pan. I had hoped to do a belly pan to avoid the truck looking like....a truck with bigass air dam and skirts. Skirts look like they would be 10", air dam 8-9".

Thank you for the reality check!

Last edited by ThomCat316; 04-23-2019 at 03:21 PM.. Reason: Spelink
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Old 04-23-2019, 04:33 PM   #8 (permalink)
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Well, thanks for asking.

I've only worked with the samples shown. It's used to make the big wings on dirt track race cars, that's all I need to know.

The pieces were sheared, braked and rolled on a tool with an 18" lever arm, by hand. That wouldn't be enough to flange the edge of a longer piece. The 90° bend ruptured the outer skin. A bead roller might compress the plastic core, but I haven't tried that.

It's available in 4x12 or 5x10 sheets and it's pre-finished.
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Old 04-23-2019, 06:03 PM   #9 (permalink)
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I came in to post "heavy", but I see it's been covered.
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Old 04-24-2019, 01:39 PM   #10 (permalink)
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A suspension lower than stock emphasizing handling & braking, (plus at least a 65-series tire), would only be improved by rack & pinion given IFS. And 4-whl disc.

This is pretty much what my ‘04 1T Dodge is.

Trucks can do okay steady state. It’s the transitions (any and ALL of them) where it gets murdered.

Driver has to plan route, sure, and while reduction of inputs is big

degree & duration of inputs are where the money is.

With trucks it ain’t about throttle use to save fuel. It’s about the brakes. Any other approach is backwards to what a work vehicle demands.

There’ve been a number of discussion about truck aero. Reducing ride height comes first. Crosswind stability & COG always matter.

One approach is using expanded metal as a pan from body edge inwards to frame. Leave center open.

How to “finish” the rear (the exit) is likely to be hardest.

At some point I’ll just try C-belting (Big Dave, etc) all around as it looks easiest. May also do the travel trailer.

If this is a straight-axle 4WD expected to also run the highways, might want to re-think that motor. (Percent of miles annually).

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