All About Hog Troughs!

Known technically as "Underbody Sill Reinforcements" or "Torque Boxes", the hog troughs are an integral part of an Avanti's structural integrity. Before you buy an Avanti, always check the hog troughs for rust. Replacing hog troughs is difficult and expensive. You don't want to do it if you don't have to.

What are they exactly?

The Hog Trough is a part that runs under the door sill of the Avanti from just behind the front wheel well to just behind the back wheel well. It is riveted to the floor pan, bonded to the door sill, and bolted to the roll bar. Bolts also go into the hog trough from the frame as an additional way of holding the body to the frame.

What do they do?

The hog troughs add strength to the body, hold the body to the frame, provide mounts for the seats, provide support for the roll bar, and support the sill (or rocker panel) under the doors. During a side impact crash, the hog troughs also provide added safety to the passengers.

Why are they called "Hog Troughs"?

Roughly... that is what they look like. They are high gauge steel pressed into a trough-like shape. In the picture below, the Hog Trough is the lowest most part. The door sill is piece is shown above it.

What happens to them?

Hog Troughs can rust out. The trough shape makes them strong and adds great strength to the body of the car. Unfortunately, this shape also can retain water and rust. Hog troughs have drain areas, but if clogged or installed improperly, there is no drainage. Owners have been known to drill drain holes to prevent rust.

Rusty passenger side hog trough.
Notice how the metal is rusted away where the trough bolts to the frame.

How do I replace them?

Now you have to make a choice... There are several options of how to replace hog troughs.

• You can take the body off the frame and install original style hog troughs.
• You can make cuts in the fiberglass body panels from wheel well to wheel well and remove panels from 1/4 inch below the sill and down. This allows you to install the trough from the side without taking the body off the frame.
• You can use a hog trough that comes in several pieces. By being in several pieces, you can install the trough without removing the body from the frame or cutting fiberglass. After it is installed, you weld the separate pieces together.

So... you can get a one piece original style hog trough, a multi piece hog trough... PLUS if you want you can buy a one piece hog trough in stainless steel or fiberglass! (Fiberglass won't ever rust away again, but it is not going to do the job of a metal one either.)

Where do I buy them?

There are ads in the AOAI magazine. You can also order from one of the suppliers listed on the supplier page.

How much do they cost?

They cost $800 to $1000 a set. (There are two per car) It took me about 30 hrs to install mine. There are a couple cheaper versions, but they are not high quality and won't line up with all the rivet holes nicely when you install them.