All:

Replaced masts in our '83 and '84 300SDs last week. Both OEM Hirshman units.

One (toothed) was balky despite oiling often didn't retract fully, other (smooth) had a broken nylon actuator and didn't go up.

If your actuator motor/mechanism is working correctly, replacement process is straightforward if nylon actuator is intact (5 minutes), and if broken inside the antenna mechanism, it's only a few additional steps to repair it (maybe 30 minutes). :y

When antenna is down/radio off, unscrew the antenna retaining nut and turn on radio - now quickly as antenna extends, keep pulling on it until the antenna and all of internal nylon actuator pulls free from antenna motor mechanism inside fender.

Now you'll see if you have the 1) toothed actuator or the 2) smooth one. You'll need to specify the type (toothed/smooth) you need from your parts supplier. Our '83 has a smooth actuator, the '84 had a toothed one. We got our replacement masts from importec.com (Dallas, TX) for ~ $21 smooth aftermarket and $29 toothed OEM Hirshman.

If as in the case of our '83, the nylon actuator broke and part of it remained inside the antenna actuator motor mechanism, you'll have to remove the motor/actuator from the inside trunk fender area and disassemble the unit to remove the broken remaining piece(s) of the nylon actuator.

Not hard to do - just pull back the molded carpet in trunk and remove a handful of screws and the fender top retaining nut, and disconnect power/control cable, to remove from car and open up the antenna mechanism case and remove actuator piece(s). This is also a good time to lube the internal gears etc.

Installing new shafts - once old antenna shaft has been removed, turn off the radio (assuming it was on, otherwise turn it on wait a few moments for it to “extend” then turn it off… ) and quickly insert the end of the new antenna mast nylon actuator down into the fender top antenna mechanism opening and let the mechanism pull the actuator down into the automatic antenna unit. I wiped the extended shafts with a light machine oil and plan to keep them clean to avoid future malfunctions.

Now enjoy your new correctly operating automatic antenna on your classic Mercedes!!! :zoom:

DRG

Here's an easy way to tell if your MB uses a toothed or smooth nylon mast. Take a look at the antenna grommet. If you have the black one, you're going to have to use a toothed mast, if you have the chrome grommet, you'll use the smooth mast. I think 1983 was the last year for the chrome grommets. But, you may come across a pre-83 MB with a retrofitted antenna, so you know if it's a black grommet, then it is toothed.
-Joe

__________________
'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

HELP.....

The retaining nut on my unit is broken - Previous owner must have tried a repair. The nut has broken away from the threaded insert.

Any Ideas??????????

Thank You

Stephen

__________________
98 K2500 Suburban 6.5 Luxo Barge

"We cannot change the wind - But we can adjust our sails"