Body / Glass: Avanti Fender Apron

[GinettaG12P]

I relocated the voltage regulator on my 1963 Avanti R2 when I installed a dual-chamber master cylinder and a different brake booster. To hold the regulator in its new location, I drilled though the fender apron and installed nut-serts. Now here is the strange part. When I was checking grounds on the regulator, I discovered that the nut-serts are grounded. (Yes, I removed everything so that the nut-serts were isolated from any parts other than the apron.) A continuity test revealed that the nut-serts were connected electrically. That seemed weird to me so I got out a strong magnet and found that the magnet is attracted to the fender apron over much of its surface aft of the battery box. The magnet was not strongly attracted to the apron, but enough to overcome gravity on some of the less steeply slanted surfaces. I checked other metal parts that are attached to the apron and found that they, too, are at the ground state. This was a BIG surprise. Is there a metal screen or fabric within the fender apron?

[bezhawk]

No wire in the construction. Only the Packard Hawk hood had screening in the fiberglass. That was for radio spark interference.
Avantis had ground wires connected to the regulator, and most every thing that had power going to it.
Every bolt on the inner fenders had a metal nut plate riveted on the back side. That is what your picking up with your magnet.

[rkapteyn]

Set your meter to the lowest ohm setting and measure the actual resistance to ground.If it is set to the highest range it will read even a moisture layer.

[GinettaG12P]

No wire in the construction. Only the Packard Hawk hood had screening in the fiberglass. That was for radio spark interference.
Avantis had ground wires connected to the regulator, and most every thing that had power going to it.
Every bolt on the inner fenders had a metal nut plate riveted on the back side. That is what your picking up with your magnet.

Saw and avoided the nut plates. The magnetic attraction is diffuse.

[GinettaG12P]

Set your meter to the lowest ohm setting and measure the actual resistance to ground.If it is set to the highest range it will read even a moisture layer.

I used the 0-200 ohm setting on the VOM and the readings between the nut-serts (and other metallic objects attached to the apron) was 0.2 ohms. I know I'm dealing with fiberglass here, which is why what I'm finding is so difficult to understand. Also, even in areas where there is no obvious metal the magnet is attracted to the apron. Very strange. You don't suppose Studebaker toyed with the idea of making the fenders and firewall a Faraday Cage to eliminate radio frequency interference, do you?

[karterfred88]

That must be one super strong magnet!! I can't get one to stick to the apron even over one of the riveted in supports on mine !! You must have a one-off iron infused apron assembly!!
What type of paint/color is on the apron?? Maybe something in the coating is showing up.

[GinettaG12P]

That must be one super strong magnet!! I can't get one to stick to the apron even over one of the riveted in supports on mine !! You must have a one-off iron infused apron assembly!!
What type of paint/color is on the apron?? Maybe something in the coating is showing up.

The magnet is a cow magnet that I bought to put into my power steering reservoir. Yes, it is pretty strong. The interior of the apron is painted the same gold color as the exterior of the car and the exterior of the apron is undercoated. I thought that the undercoating might have metallic content, but ruled it out as the magnet is more strongly attracted to the interior of the apron than to the exterior - undercoated - surface of the apron. I tried a more sensitive VOM and measured 1.8 ohms between the engine and the isolated nut-serts. I also measured between the battery hold-down riveted to the apron and the engine and found 4.7 ohms. (There is no battery in the car.) It is just plain weird.