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Discussion Starter #1
I'm in the process of installing a Hirschmann electric antenna in the right rear on my Alfetta GT. I bought it new eons ago, but that is neither here nor there.

It is as quiet as can be...when not installed. However when installed, and I certainly understand why, it makes a rather loud droning sound when going up and down.

It is very near the rear of teh car on the narrow flat edge. My plan as of now is to liberally coat the inside of the right rear fender with undercoating. Has anyone solved the issue by doing this? Or am I the only one who is bothered by the sound? I like the idea of nice smooth humm - so I know it is going up and down - but not when it makes a sound like an electric fuel pump on its last legs.

Admittedly, since it has only been partially installed, I've only heard it go up/down while standing beside it.

Any better solutions? I'm not big on the sound deadening stick on stuff since I've found it falls off when you don't want it to, but sticks like crazy when you want to remove it.

Biba
 

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Discussion Starter #3
Darren, I don't want to raise it up anymore on the outside but using one on the inside is a good idea. I did spray on a couple of coats of undercoating on the inside figuring it can't hurt. My hope is that it will cut down on any vibrations from the motor in the sheet metal.

Biba
 

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Biba, I can understand your dilemma.

A washer made from a slice of innertube would be quite thin giving around 1/16" or less increase in height/protrusion on the outside once tightened down. Granted it wouldn't be as effective at damping as a full on rubber washer, but it would be something at least.

Any thought to mabe putting a support arm/brace/strut near or on the very bottom of the assembly to support and mabe suck up some of the drone that's now centered on the only mounting point?
 

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Discussion Starter #5
Darren, I do have a thin rubber (?) gasket under the exterior base. I also have a brace/support on the bottom of the interior unit. Unfortunately the nearest/most convenient place to 'bolt' it is also on the fender.

Right now my plan is to attach it as planned, but with the addition of some rubber from underneath, then see how it sounds from inside. I also have the rear seat cushions removed, so once everything is in place, that will be the true test of how noisy it really is. Plan B is to partially plug the hole I've already drilled, make a subframe for the unit, then have just the end of the antenna sticking up outside. This also has its drawbacks since the opening has to be large enough for the lower section of the mast to go through.

Hopefully I'm making much ado about nothing. I do appreciate your comments in any event.

This is really goofy (not to mention anal) but I'm considering buying a Radio Shack decibel meter ($50) so I can check before and after sound deadening improvements. I've always had a noisy front section on my transaxle unit, but boy does it sound horrible with the rear seats out. I have a fresh/rebuilt (including new bearings) transaxle ready to drop in when I have the time. No, not quite looking to have my Alfetta GT to be as quiet as a Rolls Royce, but I find the current racket inside the cabin to be really wearing.

Biba
 
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