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1994 C4 ANTENNA MAST ASSEMBLY REMOVAL AND REPLACEMENT

PREFACE
After an exhaustive search on how to remove and replace an antenna mast assembly; I found that this topic was not covered comprehensively in any forum. I saw the need to share with the Corvette community how to diagnose and fix the problem. I have lots of photos to share which are just as important as any written instruction. In this posting I will offer advice, instructions, opinions, and diagnoses. All numbered bullet points are directly from the Factory Service Manual Reproduction (FSM); Helm Incorporated, 14310 Hamilton Ave., Highland Park, MI 48203. Photos can be referenced and found in My Gallery (member profile) titled “Antenna Mast Assembly”. I am happy to share my knowledge, experience, and photos with all rights reserved. Thanks and gratitude to those who help me navigate this forum.

EQUIPMENT AND SUPPLIES
Portable shop lights
Assorted screw drivers
¼”drive metric socket set with extensions and swivels
8”-10” long 3/8” socket extension
Needle nose pliers
Shop solvents/cleaners
Silicone Grease/Lubricant
Miniature wire brush

PROBLEM AND DIAGNOSES
The antenna mast will not fully retract and remains up approximately 3”-4”. Other forums have suggested that a portion of the mast nylon ribbon has broken off and is creating a stoppage. I suppose that that this is possible and has occurred. But in my case, the root cause was the white lithium grease in the gear housing drying and hardening; and thus binding and causing a stoppage. I have observed this same issue in other applications and have ceased using white lithium grease all together. I overhauled my unit by completely disassembling; pressure cleaning the gear box; re-lubricating with Silicone grease/lubricant and reassembling.

GETTING STARTED
The expected project time is 6 ½ to 8 ½ hours; depending upon whether you overhaul your mast assembly or replace it with a new unit. Previous mechanical experience is a plus. Difficulty on a level of 1 to 5 is about a 3. Review the instructions several times prior to beginning the project. Remember: take your time; have everything planned out. Wear a long tailed shirt and let it hang out to prevent your belt buckle or steel buttons from scratching the side of the car.

INSTRUCTIONS: Remove or Disconnect, (review photos in “My Album”)

1. Release hatch

2. Negative battery cable
a. (do not skip this step, it’s not worth frying a computer or tripping the airbag)

3. Hatch rear trim panel

4. Left rear speaker enclosure grille

5. Reposition hatch left side trim panel

6. Luggage shade latch
a. (Remove luggage shade assembly as well)
b. (use needle nose pliers to grasp spring loaded plastic end cap)
c. (pull until released from detent and remove unit)

7. Rear carpet retainer and sound insulator

8. Reposition carpet to gain access to antenna cable

9. Antenna cable

10. Electrical connector from antenna relay
a. (skip step 12)
b. (alternate way to gain access to inner body area, MUCH EASIER)
c. (reposition left reverse light assembly)
d. (remove both outer tail light assemblies)
e. (mark location of wire harness with tape and tuck wires inside of rear fascia)
f. (note: needed to replace tail light housings because plastic mounting studs were split)

11. Push rubber grommet, electrical harness and antenna cable through body hole
a. (this is not easy, the grommet is hard to get to and is dry/hard)
b. (if possible, lightly lubricate interior side of grommet)
c. (using long 3/8” extension, push outward on grommet face)
d. (simultaneously reach through tail light opening, grasping outer grommet face to assist)
e. (grab only the grommet, not the antenna wires or cable)

12. Raise vehicle
a. (skip, not required)

13. Body ground strap and antenna from bracket
a. (do steps 15 and 16 first)
b. (then step 13)
c. (then final bracket bolt adjacent to ground strap bolt)
d. (then step 17)

14. Antenna from bezel
a. (grommet that is on upper left body panel)
b. (requires no action, is part of antenna assembly removal)

15. Screw securing ground plane terminal
a. (gain access through tail light opening)

16. Screw securing antenna ground strap to bracket
a. (gain access through tail light opening)

17. Antenna
a. (the assembly will exit towards the ground)

INSTRUCTIONS: INSTALL OR CONNECT
A. Install or connect in reverse order
B. Reinstall fasteners to same locations (FSM)
C. Clean ground strap terminals and terminal surface with wire brush
D. Lubricate terminal and terminal surface with silicone grease
E. Position strap terminal under mounting screw correctly (FSM)
F. Terminal orientation is not to exceed 90 degrees to antenna mast (FSM)
G. Lightly lubricating antenna cable grommet with silicone grease will aid in reinstallation into body hole

Hope this is helpful and best of luck,
 

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1994 corvette antenna replacement

Read a ton of reviews on how to do this. One review suggested to remove the license plate and tail light housing to get to the motor. Great idea. That's what I did. Super easy procedure for antenna replacement. Only issue is that the taillight housing screw inserts break. I was able to epoxy the broken pieces and re-use the housings. New ones cost around $50. Found them for $21 on ebay. Only had to remove the back finish plate to get to the wiring. No need to remove the tire and wheel housing. A little tight but still able to access the the mounting screws and remove the motor and reinstall.
 
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