Belly pan how-to

[brucepick]

This is a thread for belly pan how-to information. I don't have the information, which is why I'm asking for it here! This thread would warrant a sticky, imho.

For anyone who has built a belly pan, can you please post some details and hopefully pics?

Here are the issues and questions I have, as I consider how to build one for my Civic:

1) Any vehicle likely needs a frame to support the belly pan from above. Has anyone built one that attached directly to the car's underbody?

2) How to attach framing and sheet material? Rivets? (aluminum or something else??) Sheet metal screws? Rubber well nuts, aka expansion plugs?? Something else?

3) What framing and sheet materials did you use? What worked and what didn't work?

4) How did you deal with the engine bay, between radiator bottom support bracket and the firewall?? Were you able to put a panel over the area, or at least over part of it?

5) How did you deal with the exhaust area? I'm considering leaving mine uncovered (it goes down the center till it gets near the gas tank) but what did you do? If car has a rear muffler, did you cover it over?

Thanks!

[3-Wheeler]

Well, here's one way of doing it....

Honda Insight Under-body Smoothing Panels (custom belly pan / undertray)

Jim.

[brucepick]

Originally Posted by 3-Wheeler

Well, here's one way of doing it....

Honda Insight Under-body Smoothing Panels (custom belly pan / undertray)

Jim.

Wow. Tremendous job.

[saand]

you can also have a look at the various forum links in the wiki
Belly pan - EcoModder

to answer your questions directly
Frame for belly pan: I have not used or required a frame, i am using coroplast which is fairly rigid, screwed or pop riveted at multiple points to the car body, front grill

How to attach material: I am using screws (wood screws however metal screws should be used in my case im just too cheap to get them) I am also using squares of aluminium with a hole to act as a large washer which gives more surface area to hold the coroplast to the body.

What materials used: just coroplast, aluminum squares and screws. I have also joined multiple coroplast sheets together using hot glue which works very well. (its very hard to find a really big piece of coroplast.

engine bay area: I have put belly pan material over the whole engine bay area, except where the exhaust is as it melts through the coroplast. This results in my front grill block/cover flowing straight onto the belly pan.

Exhaust area: I have left it uncovered at the moment as it would melt through the coroplast. If you are really eager you could use sheet metal over the exhaust area as it will not melt. Note: if you have any exhaust issues and any holes in your cabin area you risk having exhaust gasses feed into your cabin, you should smell that very quickly though.

[tjts1]

All you really need is coroplast and zip ties.
Volvo 850 coroplast wonder

[BamZipPow]

Here's what I've been doing with my belly pan on my Toyota T-100 truck...

[Weather Spotter]

saand, you beat me to the wiki link

From my partial belly pan here is what I found. get under car and look, you should be able to see where you need one and where to attach.

[basjoos]

1) Any vehicle likely needs a frame to support the belly pan from above. Has anyone built one that attached directly to the car's underbody?

The belly pan is attached directly to the car's frame.

2) How to attach framing and sheet material? Rivets? (aluminum or something else??) Sheet metal screws? Rubber well nuts, aka expansion plugs?? Something else?

Used machine screws drilled and tapped into the metal frame and the underside of the plastic bumpers. A few attachments points in the wheel wells are screws, washers, and nuts attached through the rubbery fibrous materials used for parts of the wheel well interior wall.

3) What framing and sheet materials did you use? What worked and what didn't work?

Coroplast for most of the underside, aluminum flashing for the parts near the exhaust system (from front bumper down the length of the central exhaust tunnel with a bend following the exhaust pipe over to the rear right wheel).

4) How did you deal with the engine bay, between radiator bottom support bracket and the firewall?? Were you able to put a panel over the area, or at least over part of it?

Engine bay totally covered, used aluminum bar or angle to provide support across large gaps (engine bay, gas tank) where the car's metal frame wasn't available).

5) How did you deal with the exhaust area? I'm considering leaving mine uncovered (it goes down the center till it gets near the gas tank) but what did you do? If car has a rear muffler, did you cover it over?

Aluminum flashing covers the extire exhaust except for the underside of the muffler where I bring coroplast to within a inch of the muffler's surface.

[Niner]

I have not gotten anywhere near ready to put a belly pan on my car, but I do have one product that may help. For another project, I found some self-tapping metal lathe screws at the hardware store. They've got a nice drill-style head and did fine piloting their own holes in 1/8" thick angle iron. The heads are wide and low profile, good for holding coroplast without an additional washer. They are apparently for holding fine metal lathe against the side of a house before applying stucco.

[puddleglum]

Here is the link to the belly pan I made last summer. Some of it is attached directly to the subframe, but I attached wood strips and some metal cross braces to the subframe as well for extra support. A couple of the cross braces were old curtain rods. They worked but are not heavy enough. The first coroplast pan I made warped so I reinforced this pan by gluing pieces of foam board to it. This was a must for the sheetmetal pieces to keep the noise down. Panels are all attached with screws. I had to leave the exhaust open and put some fiberglass and tin flashing around the converter and front muffler to keep it from melting my pan. I haven't done a rear pan yet. Don't be afraid to spend some time laying under your car coming up with a plan. Also, don't forget to leave yourself some jacking points exposed. New belly pan