New and better belly pan
 

A new and better belly pan (lots of photos)

Today I fitted a replacement undertray to my car. Previously it was made out of two pieces of 4mm acrylic. The old one was a bit of a patchwork job, and only went about halfway.
http://i4.photobucket.com/albums/y14...407_090207.jpg

I purchased a single sheet of 1.5mm ABS plastic to make the new one.
http://i4.photobucket.com/albums/y14...407_090508.jpg

So here's how it went down!

It was on for about 3 months, and one of my concerns was the exhaust melting it. So after I removed it I gave it a good check for melted bits.
http://i4.photobucket.com/albums/y14...407_091229.jpg

The only damage was where the exhaust muffler touched the plastic and it melted a little and got worn down.
http://i4.photobucket.com/albums/y14...407_091241.jpg

The new one is longer and a little wider, not to mention a couple of pounds lighter:
http://i4.photobucket.com/albums/y14...407_092159.jpg

The old version didn't cover all of the wheel arches, so this one goes right into the corners. The research paper of that Audi A2 from Coventry university saw some improvements from filling these gaps.

Old fitting:
http://i4.photobucket.com/albums/y14...407_090152.jpg

New fitting:
http://i4.photobucket.com/albums/y14...407_113851.jpg
http://i4.photobucket.com/albums/y14...407_113838.jpg
http://i4.photobucket.com/albums/y14...407_114042.jpg

There are a few panels fitted to the middle at the factory, but the rear end is a mess.
http://i4.photobucket.com/albums/y14...407_103550.jpg

So I cut the new sheet to be a nice tight shape.
http://i4.photobucket.com/albums/y14...407_103535.jpg

I left the rear a bit longer this time, so I could leave a small diffuser lip. Then I used my heat gun to tilt it up a bit:
http://i4.photobucket.com/albums/y14...407_113626.jpg

The front has a neat engine tray from the factory:
http://i4.photobucket.com/albums/y14...407_115708.jpg

But just behind it is another mess:
http://i4.photobucket.com/albums/y14...407_115717.jpg

So I rescued a piece of the old tray, and cut out a filler piece. You can tell it's rescued, cos it's filthy!
http://i4.photobucket.com/albums/y14...407_120308.jpg

And that's it! The new undertray is done, and much improved on the old one.
http://i4.photobucket.com/albums/y14...407_121842.jpg
http://i4.photobucket.com/albums/y14...407_105322.jpg
http://i4.photobucket.com/albums/y14...407_113759.jpg

Looks great! I'm inspired to start work on mine now.

nice job!!! I have just started to look for abs plastic sheets here in NZ with no luck so far but it is early in my search. I was wondering if this stuff comes in different thicknesses, sheet sizes, range of colours and what price you paid for a sheet of this stuff in America. cheers fk

I got this from a supplier here in England who does small pieces coated in a carbon fibre effect. He sold me one of the big sheets he starts with for £38 delivered.

Very nice job. Do you plan on doing any testing to see what the benefits are?

I've never done any proper testing on my mods, so I don't have a good measurement of the "before" and I don't plan on taking all that stuff off again any time soon!
I did have a little bit of a coastdown test which gave me 25.1 seconds to go from 60mph to 40mph in neutral. Since then the car has been lowered and this new floor on, so I suppose I could do it again.

Coroplast is the preffered product because it is much more rigid. You don't have as many mounting points. Abs will tend to vibrate. With a much smaller surface area you'll be ok. I had to use 2 4x8 sheets of coroplast on the Q45!
But that looks nice.

ABS can be easily stiffened by heat forming a few channels using nothing more than a heat gun and scrap wood or even reinforcing rod. I've been recently working with it extensively on a car with all ABS body panels. It's easily obtained through any Grainger or Mcmaster. Call the local branch for availability. If it cracks or breaks it can be repaired with more ABS and MEK solvent.

McMaster-Carr

Search abs sheet - Grainger Industrial Supply

Sweet pan! I might just do the same thing.

those are great properties.
But why would you use an inferior product for the task at hand?
It's heavier (not much but it is)
will not hold a straight.
requires more mounting points.
more expensive.
does not provide a more superior result.

In the UK we can't get large sheets of coroplast, not without spending a small fortune. We can't even pinch them from politicians advert boards :P