[alby]

This is the inside of my old fender. Does anyone know what that piece inside is called? What is it used for? It's very rigid and appears to be attached with some type of micro pins.

Both fenders and bedside quarter panels have them.

Old Fender:

That's where rust destroys our fenders and quarter panels! To be honest, I'm not sure if Fluid Film can protect our trucks in this case because moisture may find its way between those parts. It feels like planned obselescance.

I am replacing this rusted fender with a new one. However, my new fender doesn't come with that inside piece. Does anyone know if that inside piece is necessary?

Rust!

The new fender doesn't have that piece.

 

[4mula1fan]

Probably for rock ding protection.

 

[alby]

Yeh. Our panels aren't all metal. I noticed that when I was repairing my quarter panel last year.

The construction appeared to be something like a plastic, encased between 2 super thin sheets of metal. Actually, the sheet metal itself was as thin as a t-shirt.

 

[Clint]

Is it a sound deadening material?
Something to make the panel more rigid?

Clint

 

[alby]

Its not acoustic insulation. I think it helps support our weak panels.

 

[JimObel]

Weak panels? Which weak panels?