I wanted to keep the original T&C radio as close to original as possible. When I got the car, the radio would come on but no sound (broken speaker wire), and the tuner wouldn't move the dial (not to mention the seek functions didn't work well...kind of hit and miss).
On the Motorola radio that is in my 1955 Thunderbird when I would turn the tuning knob, sometimes the pointer would stop mid-way and you would have to use the station selector buttons to get it to operate again. The problem was that the clutch material had deteriorated from age and was no longer adhered to the clutch plates. After removing the clutch assembly from the radio it was disassembled; cleaned, lubricated, and new friction material was made from gasket paper. After cementing the new friction material to the clutch plates, the clutch assembly was reassembled and installed back in the radio. Now the tuning control was functioning as designed.
Here is an article that I wrote on how I repaired the Motorola radio in my 1955 Thunderbird.
1955 - Motorola - 5MFS8 - Radio Repair This winter one of my projects was to try to repair the original AM radio from my 6 volt, 1955 Thunderbird. When I purchased the vehicle the radio never played, except for an occasional loud static sound from the speaker. Since the push button that controls the on/off switch would only stay in the on position, I had no way of turning the radio off. I also noticed that when I would turn the tuning knob, sometimes the pointer would stop mid-way and you would have to use the station selector buttons to get it to operate again. With the help of fellow CTCNO club member Frank Barone, I removed the covers from the radio, and performed a complete cleaning and inspection. During my inspection, I discovered that the lever that engages into the slot of the on/off push button had too much clearance. This was the reason that the push button would not stay in the off position. By slightly bending the lever and with some light lubrication, I was able to get the on/off push button to function again.
ABOVE- The lever that engages the on/off push button in the on position after the adjustment was made
The tuning control is an interesting design. It utilizes two clutch plates that connect the tuning knob to the tuner carriage. When you turn the tuning knob, the gear on the end of the tuning shaft rotates the first clutch plate. Since the clutch is engaged, the second clutch plate turns the gear that is on the end of the spline shaft and moves the tuner carriage. When you depress one of the station selector buttons, the clutches disengage the tuning knob shaft, allowing the tuner carriage to move without rotating the tuning knob. These clutches are also designed to slip, to prevent damage if you continue to rotate the tuning knob after the tuner carriage reaches the end of its travel.
The problem with tuning knob on this radio was that the clutch material had deteriorated from age and was no longer adhered to the clutch plates. After removing the clutch assembly from the radio it was disassembled; cleaned, lubricated, and new friction material was made from gasket paper. After cementing the new friction material to the clutch plates, the clutch assembly was reassembled and installed back in the radio. Now the tuning control was functioning as designed.
ABOVE- Tuning Clutch Assembly Installed
ABOVE- Tuning Clutch Assembly Disassembled
ABOVE- Tuning Clutch Assembly Assembled
After testing the vibrator and replacing 3 defective tubes, it was time to see if the radio would play. To my dismay I was only able to received one station, and it was a very weak one at that. Upon further inspection I discovered that the top of the movable core (A8) of Oscillator
Coil (L4) had broken away from the adjustment rod, and the movable core was not moving with the tuner carriage.
The broken core and adjustment rod was removed from the radio, and the top of the core was squared on a lathe. The center of the core was then drilled and tapped to match the thread pitch on the adjustment rod. To keep the movable core from turning on the adjustment rod, a lock nut was used. After reinstalling the repaired movable core (A8) back into the Oscillator
Coil (L4), I was able to receive a much stronger local station.
ABOVE- Tuner Carriage with the Coils
ABOVE- Repaired Movable Core (A8)
Before I could epoxy the adjustment core rod to the tuner carriage, I had to adjust the Oscillator
Coil (L4). Since I did not have the proper test equipment required to make the adjustment, I identified the strong local station I was receiving to determine the frequency that it was broadcasting on and to see how close it was from the indicated frequency on the dial. Leaving the movable core (A8) stationary, I adjusted the tuning knob to get the indicator to the frequency of the station I identified and then I applied epoxy to the adjustment rod.
After the epoxy had cured, I was able to tune into five local stations. Some were strong, however most were not. Since I was performing this alignment procedure on a bench in the garage, it will be interesting to see if I get better reception with the antenna mounted on the fender and the radio installed back in the car. I guess the real test will be when I take the car out in the open. Due to the Ohio weather, I’ll have to wait until the spring.
doug7740
1955 Thunderbird Blue
It works well, and even has a USB charging port so I can keep the phone going indefinitely. It does tend to drop the BT connection after starting the engine about half the time, but it's a minor nuisance to reconnect.
www.customautosoundmfg.com
www.retromanufacturing.com
