ZR-1 Antenna Repair

SYMPTOM - The antenna does not fully extend or retract

DIAGNOSIS

Assuming that the antenna motor can be heard to run when the radio is cycled on or off, then;

1) If the antenna mast can be made to fully retract by cycling the radio on and off several times then the mast is probably dirty and binding through friction. Extend the antenna and clean. I recommend that the mast then be waxed to maintain a slick surface. Using oil or petroleum based products (even if wiped off) will lead to an earlier accumulation of dirt and friction again. Cleaning and waxing the antenna every time you wash or wax car would be good preventive maintenance.

2) If the antenna can be made to move only a short distance or not at all then either the nylon cable attached to the antenna has separated, the teeth may be stripped from the cable or the take-up gear in the motor may be stripped.

In the incident on which this is based the antenna stopped retracting about 4" above the deck. When cycled "on" the antenna fully extended. However on the next cycle "off" the antenna did not move. I was able to manually depress the antenna and it would then extend again. The nylon cable was found to have separated at the very bottom end of the mast. Thus, it would not pull the antenna home but would extend it since the cable was still fully engaged in the gear mechanism and moving through its full travel.

REPAIR

Order AC Delco part # 22535396 - Antenna Mast Kit

Note: The contact spring (actually a metal sleeve) in the kit and the plastic keeper probably will not match the one on your original antenna. The plastic keeper on my antenna had two flat shoulders and screwed down over the top of the motor while the repair kit had an integral plastic top (not removable) and a wedge shaped bottom that appeared to simply squeeze between the motor housing and the deck grommet to hold it in place.

The "tool" provided in the kit is to remove the bigger plastic or metal antenna base on something other than the ZR1. It does NOT fit the black retainer at the top of the mast!

PROCEDURE

Although the directions with the kit and the Service Manual indicate that the repair can be made without removing the antenna motor it is advised that you plan on doing it anyway as you will probably be unable to get all of the old cable out. If you do attempt this without removing the motor you will probably ruin the rubber grommet in the deck so plan on ordering it also.

1) Jack up rear of car high enough to comfortably lay on the ground and reach up into left rear quarter panel. Set on jack stands.

2) Retract the antenna as far as possible pushing manually if necessary. If it can not be retracted and you are reasonably certain the cable is broken I would simply cut the antenna off about 3" above the deck. This will facilitate withdrawing the unit and positioning it in step 4.

3) From under car at bottom of antenna motor remove two screws holding motor to mounting bracket. One also has a ground cable at the connection, note which side.

4) Slide the bottom of motor forward off the bracket and pull the unit down out of the deck grommet. There is another RF/ground wire connected at the top of the motor unit that will need to be removed before you can lower the unit further. At this point the unit will still have the radio antenna wire and power wires attached to it. These do not disconnect but are long enough to allow the unit to be lowered to the bottom of the fender lip in a horizontal position with the antenna pointing toward the rear.

5) At the very top of the motor housing (base of the antenna) is a plastic fitting. Upon close inspection you will see that there are two square shoulders on the very top 1/4" which will unscrew from the remainder of the black plastic fitting. It is possible that your antenna may have been previously repaired and in this case they may have used the squeeze fitting which will match the new kit. In this case you should be able to simply pull the old antenna mast out of the motor.

Remove the contact spring (actually a sleeve) off the old antenna by sliding it off the top end of the antenna. Clean the sleeve being careful not to bend the metal fingers which touch the antenna mast when installed.

6) The motor housing is covered with a fitted rubber weather boot. I was able to roll this up over the housing like a sock to expose the side of the gear case. My unit had three self tapping screws. Others have reported that theirs are held together with hot injected plastic fasteners. These must be drilled out for disassembly and then the case can be reassembled with self tapping screws. There is also one small nut at the center of the cover that must be removed.

Removing this cover exposes the take-up reel case. don't lose the two small washers that reside between the cover and the reel case.

7) As you remove the reel case you will find some or all of the white nylon gear strip which was originally connected to your antenna mast. You will also be able to inspect the nylon gear for damaged teeth. Note that the antenna cable feeds off the gear into the take-up reel case similar to an endless cassette tape. My case had white grease inside the gear box. This facilitates the spooling of the cable into the case. Clean the old gunk out as needed. Slide a lengthy piece of the gear strip down from the top to ensure that no other small pieces are still in the shaft.

8) Apply a nominal amount of grease inside the take-up reel case and reassemble. Replace cover with self tapping screws. Roll weather boot back down over unit and temporarily connect the bottom ground wire back onto the bottom of the unit.

9) Take the new antenna and extend it almost fully leaving about a foot of the nylon gear dangling out the end. At this point ask an assistant to turn the radio on. The motor will cycle to fully extended and then stop. Insert the end of the new nylon cable into the top of the motor as far as it will go with the teeth facing down. This assumes the motor is lying in a horizontal position with the gear case facing towards the right side of the car. Now have the assistant turn the radio off. Feed the cable into the shaft of the motor as it takes it up. The antenna most likely will not fully retract on this first cycle.

You now should be able to slide the bottom section of the mast into the housing. If not have the assistant cycle the radio on and then off once again while you hold the mast as close to the motor as possible.

10) Now slide the old contact spring and plastic retainer over the antenna. Tighten the retainer to the top of the motor. Ensure the antenna has room to clear the underside of the car and test by cycling radio on and off two or three times. The antenna should retract all the way into the motor housing.

11) Remove the ground wire again. The weather boot is longer on one side and will face forward. Reconnect the top RF/ground wire noting which side will face the rear when you reinstall motor into the holding bracket. The cable is not long enough to reach the front if you twist it around the shaft. Press the antenna tip up through the deck grommet and slide the motor onto it's bracket. Install the two bottom screws including the ground wire on the side which has an additional ground strap going up the side of the motor.