Briscorvette

1978 Silver Anniversary is original and still has the original radio and CB radio combo in dash. The power antenna doesn't work. Its a Radio/CB radio combo antenna. I can find no one who sells replacements. Does anyone know someone who could rebuild an old one?

speedreed8

might give this place a call
http://antennamastsrus.com/

hugie82

In the back of the Hemmings book, I remember a few companies advertising radio service and refurbished units. That's a rare option, I think it's worth restoring!

Does the power antenna make noise or completely dead ?
They sell rebuilding kits for the mast and the motors can usually be brought back to life.

qwank

I just sold mine to a guy in Germany.

There's a member on here that might have one. I'll sure he'll chime in if he sees this thread

Briscorvette

The antenna makes noise, will not move. I can pull it up by hand.

hugie82

Then you need the rebuild kit for the mast. It's a thin flex able rod that pushes the antenna up and down. Over the years they break and you'll here a clicking noise. It's pretty easy to fix once you open up the antenna case. Most venders carry the kit.

Gordonm

I just finished up a complete rebuild of the exact one.it was a 79. You need the rebuild kit from the company listed above. The cable breaks inside and needs to be replaced.

KapsSA

Wrote this a while back for another thread...........................

You'll need the correct nylon repair kit, available from "AntennamastsRus" as linked above.

1978 GM AM/FM/CB FACTORY ORIGINAL power antenna repair
This style...................................


Remove the antenna from the car. Some guys feel it’s easier to remove the left side muffler. You can also remove the 4 bolts at the catalytic convertor and rear hanger and remove the entire Y pipe/muffler assembly.
I’ve found it easy to remove the antenna with the muffler in place, just have the car at a comfortable working height on a lift where you can reach straight in without bending and twisting your arm.
Disconnect the battery.
You’ll need to cut the green/gray/white wires as there is no connector between the factory antenna and relay under the center console.
Leave plenty of wire on the antenna. I like to remove the rubber grommet at the body and carefully slice it lengthwise to remove it from the cable/wires. That way I can resplice the cut wires and put the splices beyond the grommet inside the car body to hide them.

Antenna disassembly

Tools needed....
12 volt power source(car battery)
pliers
cutter
7/32" 1/4" drive socket
9/32" 1/4" drive socket

Power hookup for testing....
To raise
Green(+) Gray(-)

To lower
Green(-) White(+)

Remove the 2 bolts(9/32") at the base of the mast assembly and remove the assembly.
Extend the mast enough to grip the SMALL mast section just below the finial tip with the pliers.
Remove the finial tip, you can grip the small mast section just below it with pliers/vicegrips and try by hand or carefully with pliers if its the correct large round tip or a socket if it's ever been replaced with the smaller hex tip.
Only if there is no nylon cable sticking out the bottom that you can get hold of, take two small screwdrivers and insert them in the two screw holes at the base and carefully pry out the white plastic “plug” at the base.
Pull the small mast section out through the bottom and discard.
Take the new mast section/nylon cable and cut off the metal hook. Remove the felt and plastic seals. Discard the seals and hook.
Put a dab of grease at the base of the mast section at the joint with the nylon.
Reinstall the white plastic “plug” into the base of the mast tube if it had to be removed.
Insert the small mast up through the bottom of the mast assembly and reinstall the finial.
Set it aside.

Remove the 3 screws(7/32") and pry the cover off the motor. Clean off the old silicone sealant.
Carefully pull up the contact points holder and push it aside.
Remove the cam, I believe it’s red on a CB unit.
Remove the gear with the arm on it noting how the end fits on the stud in the motor housing.
Remove the large white drive gear.
Remove the steel wheel.
Remove the spring loaded pinch wheel and clean thoroughly.
At this point you should be able to access the broken end of the old nylon cable within the takeup pulley.
Pull the old nylon cable out of the housing.
Reinstall the metal wheel making sure it’s seated.
Reinstall the springloaded pinch wheel. If it looks worn you can recut the teeth with a small triangular file.
Reinstall the white drive gear making sure it seats onto the metal wheel.
Reinstall the gear with the arm on it making sure the end is on the stud.
Reinstall the cam.
Carefully reinstall the contact points set onto the shaft and cam making sure the arms on the points are not bent or twisted. When installed, make sure at least ONE set of contacts is closed.
If the two little plastic tabs break off at the top of the points holder then install a thin flat washer onto the shaft.
Temporarily reinstall the motor cover, screws finger tight.

Going by the “power hookup” specs, run the motor up and down a couple times ending with it in the UP mode(green +, Gray -)

Now with a helper manning the wires, insert the nylon cable into the hole on the motor and firmly push while the helper runs the motor in the down mode(green -, white +)
As the nylon cable gets pulled into the motor stop about half way.
Reinstall the mast assembly to the motor making sure the co-ax fittings point towards the armature housing, not away.
Now continue to run the motor in the down mode. Don’t worry if it doesn’t go all the way down. Now run it up and down a few times to fully reset it.

If for some reason you can’t get the motor to pull the cable in, you’ll need to open up the motor again. You’ll need to hold the pinchwheel open with a needle nose pliers while you feed the nylon cable between the two wheels and get it started into the takeup reel.

Remove the cover and apply new sealant and reinstall.

Reinstall the antenna and splice the wires.



Extra step for MOST 78 FACTORY ORIGINAL AM/FM antennas(non CB)

Non CB antennas require a different procedure to remove the finial tip from the mast as it is crimped on, otherwise same procedure.
Tip removal and reattachment.....
Remove.......
Take the mast tube and look at the underside of the tip on the end. It's usually crimped on if original, not screwed(AM/FM). You'll see a collar between the tip and mast section. If it's like this, you need to pop it off. Take a pair if cutters, I use a big lineman's pliers. Cut the mast section about 4" from the tip. With a vise open enough to let the collar through but not the tip, hold the cut mast section with a vicegrips with the tip above the vise, mast and grips below. Whack the visegrips with a hammer. Tip should fly off. Then spend 5 minutes looking for it on the floor! Slip the collar off the mast and you'll see how the mast is tweeked.

Tip reattachment....
New nylon/mast already inserted up through the other mast sections.
With your cutters(only if the tip was crimped on) clip off the threaded end. Insert the collar onto the mast section. Take the very tip of the mast and squish it in the vise like the old one was. Just a little crimp is all that's needed, but crimp a little extra and then grind the excess off. With the vise closed to allow just the mast section to slip through and the collar against it, tap the tip onto the mast with a plastic hammer or block of wood.

edit.....lately antennamastsRus has been supplying a new screw on tip with their repair cable so recrimping the original tip on won't be necessary.

keevel

Anyone know when in 1978 they switched power antennas from 1978 model to 1979 model ? The kits I've seen are said to fit "Late 1978 and all 1979. I'm pretty sure I'm out of luck with a low number Pace Car Replica.
Keevel

KapsSA

The 79-82 "kit" works fine for the 78.
Just cut off the hook and toss the seals.

Dodosmike

Thanks for this info. It's going to come in handy.

The stud coming out of the bottom. Is it a stud? Mines broken. Haven't had a change to play with yet to repair.

Does this look right?




Original to my '78 , non cb car.
Hopefully tomorrow I can check to see if the motor is good or not. Fingers crossed.

Dodosmike

KapsSA

As you can see from the date it isn't original to your 78.
The part no on the motor is a service part no. Over the counter replacement.
Ideally that red cam should be a white one for non cb units. Slightly shorter duration. Shuts off a little quicker rather than running under tension(cb antenna is longer). Replacement motors often had the red cb cam as non cb antennas WILL work with the red cam but cb antennas won't work with the white cam.
Are you talking about the stud coming out of that "boss" on the bottom? For mounting on the lower bracket.

Motor looks clean inside, wires look good. If the armature was burned up the wires would be a little toasted. Bet it runs.
To test it....
Up
Green +
Gray -

Down
Green -
White +

Dodosmike

I had no idea that was a date code. Who knew? Lol

Yes the "stud" coming out of the bottom. Can't quite see it in the photo.
Its broken off.

Might be able to free it up, or I'll have to drill and tap it. Hope not, doesn't look like there is much room for error. Not much "meat" to work with there.


Dodosmike

Dodosmike

Well after some trial and error on my part, it'll go up and down. Up was easy. Down, I tried to go by memory what was written above. Didnt work. Realized I need the white wire to make it work.

Cycled up and down a few dozen times. I ended up filing the stud off flush, drilled a pilot hole and increasingly larger holes until I was able to tap a 1/4" hole for a bolt. I'll need to fab up some kind of spacer go between the bolt head and the lower bracket.

When I was taking it apart I noticed the ground was long gone. The ground strap was coming off the stud at the bottom, but where should it be grounded to? Bumper bracket? Not much else close to ground it to.

Thanks for the help.

Dodosmike

diverrick

Ok, Been reading this thread very carefully as I am there right now. I managed to get the unit out by lowering the exhaust muffler (I could not get it off, so I rotated it) after about 8 hours of fussing with it to get the muffler loose, This is a factory pace car with true 2000 miles on the odometer and has never seen any type of weather, So she is clean as a whistle, But the muffler connection was a bitxh!!. Once I got the unit free I took it in to the house and dissembled it carefully. Of course I found that plastic drive broken in two places and arthritic as hell.. I also noticed that the white part with the points also is missing the two tabs( isuspect they are anti rotation tabs to hold the points in place), I found one half inside stuck in the grease, the other half is no where to be found. I removed everything down past the gear and the steel thing below it, but I am now looking at another grey wheel, That appears to be held in by one of the motor screws that is pointed at the bottom and two rivets, Not sure how to proceed. My new part has a 90 degree turn on the end that should fit into the wheel, but I see no way to install it., and does not look like it will fit at all. Tried to remove that grey wheel, but the screw for the motor refuses to let go and is starting to strip. I figured I better stop and check in with you guys. I am also looking for a three wire plug to splice back the wires that had to be cut. At this point if I could find a drop in unit, I'd take that and just replace the whole damned thing. This has so far been much harder than I expected. Mine has the AM/FM/ CB if that matters. I think I need a very specific part. TIA

diverrick

Correct me if I am wrong but if those tabs break off, the points would not close at the correct spot to stop the motor, and would break the plastic drive cable in time, if not the first time.

KapsSA

The 2 plastic tabs are just to apply a little tension on the gear assembly.
Not really important.
I installed a thin washer on the shaft if the tabs were broken off.

You don't need to remove that last piece you're trying to get off that the nylon cable winds up in(it's riveted on). As long as you got the old broken nylon out of it. Cut the hook off the new cable and insert the cable through the guide holes between the motor and mast, past the spring loaded pinch wheel and into the takeup reel(not really a reel, cable just rolls up inside it).