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

[3-Wheeler]

Originally Posted by k.civic.f4i

very impressive indeed. what did you use the GREAT STUFF FOAM for?

Hi k.civic,

The Great Stuff foam has a limited use for my foam/fiberglass projects, since it's density is too low, and it can only be used to fill shallow areas, since it needs air contact to setup properly. The sunlight also causes it to change shape for what seems like several weeks as it stabilizes.

The foam was used to keep wheel well water out of the outside body panels on the rear wheel area. The Insight has the 'flare' that helps the air flow around the rear tire, and the plastic panel that provides this shape is hollow, and likes to collect water and debris.

I first put some large foam blocks in that area, to take up most of the volume, then filled in the remainder using the Great Stuff foam.

Jim.

[3-Wheeler]

Originally Posted by MetroMPG

What are you using to glue the foam pieces of the puzzle together?

Hi Metro,

My favorite glue for holding things together is ordinary Elmers Wood Glue. And the favorite thing to hold blocks together until the glue dries, are long plaster board screws that you get from the hardware store.

For tiny pieces of foam glued together, I use sewing pins to hold things.

When using Elmers Wood Glue, one thing to consider is when the glue gets wet, it starts to reverse the gluing process, and the glue gets soft again. Because of this, the foam needs to be coated with something to keep water away from the glue, like epoxy resin or latex paint. Anything that will not attack the foam and also seals the glued surface will work.

Jim.

[3-Wheeler]

On some ways, the rear panels by the gas tank were harder to make than the front engine panel. This picture shows a shot from the rear of the car looking forward at several mounting points that were added.


Several more mounting points are shown here. The extreme left of the picture shows the area where foam blocks were added to flare in front of the rear tire, and where Great Stuff Foam was used to fill in the small gaps.

You can also see how much the thickness of the driver side panel varies. The panel wants to be as thick as possible for high bending strength, but not protrude down into the air stream under the car.



Here's another picture of the wood blocks used to stabilize the panel under the car.


This mount was added after the panel was almost complete in shape. The author just wanted to have slightly better mounting support in this area.


This pictures shows both panels in various states of completion.


Here weights are used to hold the layers of foam tightly together until the glue dries.


Now you can see the extra thickness from gluing large foam pieces to increase the thickness in various areas.


Various instruments are used to trim the foam thickness where needed.


About two weeks later, and after adding several coats of light-weight spackling, you get a glimpse of just how much sanding dust one can make when smoothing things out.


Whoops!! The sanding went a little too far towards the left and right most areas of this picture!! On the right side, more spackling is added, and on the left, another piece of foam.


It's hard to tell in this photo, but the entire back side of the panel has been painted with Latex based paint. The panel has already seen life on the car, and through several very rainy days.


Here is the reverse side after fiber-glassing.


Both rear panels side by side. You can barely make out the layer of wood in the thinnest area of the panel, which is about 1/4 inch thick. The wood is heavier than foam, but gives needed support in this area.


You can clearly see a portion of the accumulated road dirt in this shot. So far the panel has seen several weeks of rainy fall weather.


Here is a shot of the panels mounted on the car.


Another shot of the gas tank panels. You can see the cutouts for the exhaust pipe and rear brake cables. There is about a 1.0 inch gap on either side of the tail pipe in this area. There have been no signs of foam overheating is this area. Foam starts to degrade at about 250F or so, and it looks great in this area, so the tail pipe runs cooler than that here.

Of course my driving may have something to do with this, as my typical speed on the way to work is usually 45mph or so.




Jim.

[MetroMPG]

Thanks for the glue tips. I continue to be mightily impressed.

Any plans to add your car to the garage? (If only so it appears under your username to give all your posts some context.)

[3-Wheeler]

Originally Posted by MetroMPG

Thanks for the glue tips.

Hi Metro,

Actually, the *glue tips* regarding the use of Elmers Glue can go even farther, if done correctly. Take a look at the motorcycle fairing below...



Now take a guess on what type of *epoxy* is used to hold the glass to the foam core. Polyester resin? No. How about more expensive Epoxy resin? Sorry. Try again.

How about Elmers Glue!! Yes!!

All the glass added to this fairing, both inside and out was all added by soaking the cloth with Elmers Wood Glue. Obviously, it could not be vacuum bagged when the glue is setting up, but hey, it's a whole lot cheaper than other options.

As for longevity, this fairing has been on this same motorcycle for the last 15 years, and besides some scratches here and there, looks really good after 115,000 miles, through rain and shine.

Metro, you might want to try this approach on your boat tail project. The only caution is to make sure that all water can not come in contact with the glue, and this is easily done by *encapsulating* the glue with glazing putty to smooth out the rough edges, then later, spraying with primer and finally painting and clear coating. Sounds easy, doesn't it?

I hope this encourages you or others to give it a try.

P.S. I used West System epoxy resin exclusively on the Honda Insight under-body panels, since there is a higher risk of rocks and other debris *chipping* the outer surface of the structure. This could easily put the Elmers glue at risk, since the panels can not be viewed and monitored easily due to their location.

Jim.

[RandomFact314]

Hmmm, awesome, will you do my under body too?

[3-Wheeler]

Originally Posted by RandomFact314

Hmmm, awesome, will you do my under body too?

LOL.

If only it were that easy!!.

It's funny too, cause if you add up the cost of the supplies, like the foam board, and glue to hold the foam, it costs less than $100 for all the panels.

The big ticket items are the cloth at about $50 and the resin at ouch, $100.

If someone wanted to be *really* thrifty, they could...

1) Buy foam board
2) Purchase loose weave nylon fabric, similar to a 'breathable' wind breaker
3) Get about one gallon of Elmer's Wood Glue
4) Pickup some small pieces of wood, and attach to underbody at strategic locations
5) Using nothing more than a hacksaw blade, 1/2 round 1" wide rasp file, 60 grit sand paper glued to a foam block, and start cutting out foam pieces and...
6) Glue together
7) Shape and smooth, then *glue* the nylon fabric on the outside of the foam board shape

[RobertSmalls]

You mentioned somewhere that you've insulated your catalytic converter to keep underhood temps down. What kind of insulation did you use?

The stamped aluminium heat shields are falling off my cat. I want to upgrade them to something with more insulation than stock, because I plan to enclose the engine bay. However, unlike Lil' Red, my Zombie will be climbing hills at 75mph in 3rd gear.

[MetroMPG]

Thanks for the additional glue tips!

Did you also paint that motorbike fairing yourself? It's pretty darned shiny. (Having seen your attention to detail in the belly pan, I wouldn't be surprised.)

[discovery]

That really looks nice and healthy, keep up the good work, what are the MPG numbers?