A trunk lid question I'll bet nobody has asked...

[ae5dw]

OK, bear with me. Some of you might find this horrendous but here goes anyway.

As an amateur radio operator it has killed me not having my ham rig in my 300. The reason is that I've not wanted to hang big heavy antennas on the aluminum trunk lid. I've decided that I'm going to put a relatively small antenna back there and install a VHF-UHF ham rig.

Here's the odd question about the trunk lid: Does anyone know why it is not grounded to the body?

Since the sibling Charger has a police package, and some 300s have been pressed into law enforcement service, I know trunk lid mounted antennas are used on those. I'm wondering what the designers were thinking when they isolated the trunk lid above ground. The 2-way antennas (most, anyway) require a good ground plane to work properly.

I had one other car that had a non-grounded trunk lid. That was a 1980 Dodge Challenger made by Mitsubishi. It used the trunk lid as the AM-FM antenna. It actually had a spade lug and a wire coming from it to the stereo. The 300 uses an imbedded grid antenna on the rear window for that so I'm stumped as to why the trunk lid is not grounded.

Anyone?

[OoTLink]

Aluminum sucks at conducting electricity, for one, and for another there's nothing electric on the trunk lid.

[LAYN300]

Originally Posted by OoTLink

Aluminum sucks at conducting electricity, for one, and for another there's nothing electric on the trunk lid.

wow.. aluminum is an excellent conductor...power lines contain aluminum wrapped around steel.... its better to keep your mouth shut and have people think your a fool then to open it and confirm the thought

[LAYN300]

oh and also, why are there wires running into the trunk lid to the release if nothing is electrical

[ae5dw]

Originally Posted by OoTLink

Aluminum sucks at conducting electricity, for one, and for another there's nothing electric on the trunk lid.

As the above poster said, aluminum is an excellent conductor.

I know there is nothing electrical on the lid besides the trunk release solenoid. Many newer cars have electrically released trunk lids. Fewer and fewer cars have keyholes in the trunk. So why go to the trouble and expense to put plastic bushings in the mounting holes to keep the lid from being grounded to the body?

Thanks anyway.

[LAYN300]

Originally Posted by ae5dw

As the above poster said, aluminum is an excellent conductor. I know there is nothing electrical on the lid. So why go to the trouble to put plastic bushings in the mounting holes to keep the lid from being grounded to the body?

Thanks anyway.

my best advice is to get rid of the paint between the hinges and car body and make sure everything is clean metal where you attach your antenna....granted i know nothing of ham antennas installation

[OoTLink]

*ducks* All I knew was copper made a better conductor than aluminum, tried to look that one up before saying it (and I'm 100% positive some idiot in the car audio forum posted it) - my apologies for making a fool out of myself :P

[ae5dw]

LAYN: Oh I know how to ground it much easier than that... a short piece of wire braid and a couple of sheet metal screws, one in the hinge where it attaches to the body and the other on the trunk lid underside. It's super easy to bond body panels to ground. I'm just wondering WHY it's designed like this. I checked for continuity between the trunk lid and the negative post on the battery with a multimeter. No connection to the lid but the hinges are a dead short to ground.

Oot: No harm no foul. At least you tried.

Take a look at these pics of the antennas on my Grand Cherokee. These are the ones I was going to put on the 300. Obviously I'm not putting the big antenna on the 300. It's huge, heavy and ugly. The smaller one is the one I'm using. Just so you have an idea of what I'm doing.

Yes, I know most of you will cringe at the thought of putting antennas back there. It's my car, not yours. I wouldn't dream of doing some of the mods I see on this board, so to each their own.

Thanks guys!

[srt8danno]

Well I have no idea why they wouldn’t have grounded the trunk unless the bean counters somehow thought it would cost more to do. That smaller antenna shouldn’t be that obtrusive. Ham radios are very cool and I would have loved to take up the hobby. So go for it and enjoy it in your 300…..as you say it is your car.

[robaustin]

Just a thought. Connecting dissimilar metals can create a galvanic (like a battery) voltage across the connection if there is moisture involved. Isolating the aluminum trunk lid from the steel body might reduce the possibility of corrosion, especially up here in the "rust belt".