Imperial Power Antenna Mast Repair

by Chris Middlebrook

Imperial Home Page -> Repair -> Accessories -> Antenna -> Chris' article

Symptom:

You can hear the motor when you close the ANT switch either in the up or down position, but the antenna does not move at all.

This may be because the leader is broken. The leader is the piece of flexible nylon cord inside the antenna mast, which when moved by the motorized reel, forces the antenna to telescope up or down.

Aside: Now you would think with the restoration craze of recent years, that this piece would be an easy find and fix. It turns out that no one has anything close. You can have the experts retrofit your radio from tubes to integrated circuits, AM to FM, XM, even MP3. However, if your antenna breaks, you are back to sticks and stones…

 

This repair requires patience, and anyone can do it in a couple of evenings. I will assume from this point forward that the antenna has been removed from the car. Different years have different configurations. For example in a ‘62 Imperial, the engineers cleverly placed an access panel on the passenger side wheel well for antenna access.

Not being familiar with antenna terminology, I will come up with some of my own names here for clarity. I call the very first antenna element (the thinnest one) the main mast. The whole piece with all of the telescoping elements I call the mast.

You will need the following tools for this job:

Wrenches:

¼", 3/8", 5/16", ½"

Center Punch

Dremel tool with cutting wheel

Drill Press

Vise

Soldering Iron

Drill bit:

1/8"

Screwdrivers:

#2 Phillips, flat blade

1. To begin, the crown on the mast has to be removed. It just happens that a ¼" wrench can fit around it. Before you start twisting on it though, you need to make sure that the main mast is firmly fastened to something that won’t mar it. When I did my repair, I used two pieces of rubber on a vise. If the crown does not twist off, you will need to apply some heat to the area. I used a soldering iron; this way I wouldn’t run the risk of dulling the nice chrome finish on the mast or crown with the heat from say, a torch. Nothing wrong with a torch mind you, just use it very sparingly for this operation if you must.

2. Once the crown is removed, you can now disassemble the body of the antenna.

3. Remove the ¼" bolts from the upper and lower support tube. This will free the mounting flange that attaches the antenna to the fender of the car and the mount where the antenna body attaches to the mast.

Caution: The antenna connector is still attached to the mast. Do not pull or twist the mast.

4. The connector for the antenna cable is attached by two ¼" bolts. Remove these, and carefully pull out the connector. There is enough slack in the cable to move the connector a small amount.

5. With a soldering iron, de-solder the cable from the antenna mast.

6. The mast should be free from the outer tube. Remove this tube. The only item that will keep the mast attached to the body of the antenna at this point is the leader. Of course, if the leader line is broken, the mast is now free!

7. The antenna body has one side with a cover held by two nuts and another with a hemispherical cover plate. The cover with the two nuts houses the armature assembly. The hemispherical cover houses the clutch and reel assembly. Begin by removing the two nuts from the motor cover. Once the cover is removed, you should see two Phillips screws on either side of the armature in the housing. Remove these two screws.

8. Turn the antenna body around to remove the hemispherical cover. This cover is held in place by dimples that have been struck on the main housing. Simply take a small flat-blade screwdriver and gently pry around the cover. With patience, it will come off. Make sure to remove the small gasket, and keep it in a safe place where it won’t tear. You have now exposed the clutch assembly.

9. The clutch assembly has a shaft with two nuts. Remove the first nut, and count the number of turns when removing the second nut. Keep this number handy since it is set to the proper torque when you put everything together again. Remove the spring.

10. A roll pin holds the clutch mechanism in place. Carefully slide it off, and keep in mind that the assembly has two ball bearings. Store these in a safe place.

11. You should be able to remove the reel assembly from the antenna housing.

12. To disassemble the antenna mast itself, simply push the main stem of the mast (the one that had the crown screwed on to it) towards the antenna body. I took every telescope piece off to individually clean them (and straighten a couple too).

13. You will notice that the main stem has a brass ferrule that crimps the mast to the leader. This has to be removed, and the way I did it was with a Dremel tool and a cutting wheel.

14. Living in a rural part of the country, I had to search high and low for something that would replace the leader line. The closest match was some weed whacker line – the largest diameter I could find. I hope that wherever you live can give you access to more options. The line works quite well, the only trick involves trying to connect it to the main stem to the new leader line. And quite honestly, I think no matter what you get will pose the same challenge. The way I did it is a little bit involved, but it works well. If you have a better method, please share it with us, and I’ll enter it here as an alternative. It takes a little bit over 70 inches of leader line to duplicate the same amount as the original. (Man those antennas were tall!)

15. If you look at the main stem, there is a slight recess around it where the ferrule was crimped to hold it snug. Take a center punch and put a good dent in the recess to prepare for drilling.

16. You will definitely need a drill press for this next step. With the main stem firmly fastened to a vise, take a 1/8" drill bit and drill through the main mast. Be patient and make sure you have the drill press running at its slowest R.P.M.’s. Do the same to the new leader line about the same distance from the end as the hole you drilled in the main mast.

17. Take a piece of heat shrink tubing (1/4" diameter or so) and slide it on the leader line in preparation for this next step:

18. Take a piece of 18-20 gauge steel wire and loop it from the main mast to the leader line using the holes you drilled as anchoring points. Use only one loop of wire or your finished assembly will not fit into the larger (next size) antenna mast.

19. Slide the heat shrink over the main mast and leader, making sure you cover the wire loop and drilled holes. Use a heat gun to evenly shrink the tubing. If you have no access to one, you can use a candle or a lighter, just don’t put the flame on the stuff or it will melt.

20. Reverse steps 1-12 to reassemble the entire antenna and motor assembly. Be mindful of the winding orientation of the leader to the reel. This is also a good opportunity to lubricate gears, antenna mast pieces, the armature, etc. Remember that the new leader line is not going to be as cooperative in the reel as the one you are replacing. So be patient. (this is the Pandora’s box portion of the project)

21. If you want to test your handy work outside of the car, you can connect a power supply (or 12V battery) to the antenna. Connect the negative terminal to the body of the antenna, and the positive to either the yellow or the brown wire, depending on whether you want the antenna to go up or down.


This page was last updated June 25, 2004. Send us your feedback, and come join the Imperial Mailing List - Online Car Club