Anyone know about thumbwheel radio repair?

[jeryst]

1969 Roadrunner.

The pushbuttons and tuning wheel did not work on my thumbwheel radio. I found a tutorial that allowed me to get the pushbuttons working, however I cant find any info on the thumbwheel tuner.

If I put slight pressure on the tuning gear and turn the thumbwheel, the needle moves, so everything is working together. It just seem as if the shaft that the gear is attached to, is very tight, and the thumbwheel is unable to move it on its own.

Anyone know how to fix this? I would really like to fix it myself snd dont want to ship it off someplace when it might be an easy fix.

 

[gkent]

WD40 ... seriously !

 

[Mike Szadaj]

WD40 ... seriously !

Hold off on that. There is a small plastic gear that transfers the turns from the thumbwheel to the tuning mechanism. I have seen many of those gears break. I have glued them back together and to the axle they turn with. I use two part epoxy such as JB quick weld. If the axle that the thumbwheel rides on is frozen, by taking off the metal faceplate, you can pull out the thumbwheel and clean/sand it.

 

[Mike Szadaj]

First pic. This is the plate you must take off. The two small bolts at the bottom are inset, and hard to reach. I took a Hex bit holder and ground it down to get them out.
Second pic. This axle must be taken out. You can only push it towards the thumbwheels on the other side.
Third pic. Axle out, then thumbwheels come out. In the middle of the wheel on the right you can see the little white plastic beveled gear that often breaks.
Fourth pic. This other gear, when turned, moves the dial pointer back and forth.

 

[Mike Szadaj]

This is the type of magnetic bit holder I am talking about. Grind down the diameter of the end that the bit goes in. About an inch. After it is ground down to the point it will fit into the recessed area the small bolt is in, just use it with one of the drivers that you put the small hex bits in. It is the correct size for the bolt. Here is another view of the gear attached to the tuning wheel that often either cracks or comes loose from the wheel. Can easily be glued, just don't get glue on the teeth.

 

[threewood]

@Billccm

 

[coronet68mx]

 

[Mike Szadaj]

You may have to oil part of the tuning mechanism. There is a clutch that disconnects the thumbwheel when you use the buttons (that is why the tuning thumbwheel doesn't turn when the buttons are pushed). So if the buttons work, but not the thumbwheel, the problem is probably in between that clutch and the thumbwheel.

 

[Billccm]

Mike has the right fixes. I've had so so luck with the glue.

 

[jeryst]

This is the type of magnetic bit holder I am talking about. Grind down the diameter of the end that the bit goes in. About an inch. After it is ground down to the point it will fit into the recessed area the small bolt is in, just use it with one of the drivers that you put the small hex bits in. It is the correct size for the bolt. Here is another view of the gear attached to the tuning wheel that often either cracks or comes loose from the wheel. Can easily be glued, just don't get glue on the teeth.

View attachment 789568

I noticed that if I push one of the buttons in until the clutch disengages, the tuning wheel will move the needle just fine. The large gear that is part of the tuning mechanism is extremely hard to turn using my fingers, so I was thinking that maybe the clutch mechanism is binding or something like that.

Anyway, thanks for the great info. I'm going to try what you suggested tonight. Never had much luck with using glue on pieces that are subjected to any type of stress. Is there any type/brand glue that you recommend?

 

[Mike Szadaj]

As I mentioned earlier, I like to use a two part epoxy, such as JB Weld. I prefer the quick set version. If everything is free to move as it was from the factory, the torque needed to move the dial pointer with the thumbwheel is not very much. Even from the factory, the gear on the thumbwheel seems to be just a press fit. After you take off the volume and tuning thumbwheels, you will be able to see if the gear is still attached to the thumbwheel. If it is, your problem lies elsewhere.

 

[Mike Szadaj]

I noticed that if I push one of the buttons in until the clutch disengages, the tuning wheel will move the needle just fine.

I am confused by this statement. What are you referring to as the tuning wheel? If you are talking about the thumbwheel, the tuning thumbwheel should have absolutely no effect on the dial pointer when a pushbutton is in. Before you disassemble the front, take off the top cover of the radio. While one pushbutton is pushed in, turn the tuning thumbwheel. If the gear I am pointing to in the first picture turns with very little effort on the thumbwheel, the gears and thumbwheel are probably ok. If it doesn't turn, that little gear on the thumbwheel is probably broken. If that checks good, pull that gear toward the middle of the radio. that will disengage the clutch. Try to turn the wheel I am pointing to in the second picture. It should turn easily, and as it turns the dial pointer will move. By finding out which of these tests takes excessive force to accomplish, this should tell you if your problem is before or after the clutch. An appropriate fix can then be made based on which test shows a problem.

 

[jeryst]

As I mentioned earlier, I like to use a two part epoxy, such as JB Weld. I prefer the quick set version. If everything is free to move as it was from the factory, the torque needed to move the dial pointer with the thumbwheel is not very much. Even from the factory, the gear on the thumbwheel seems to be just a press fit. After you take off the volume and tuning thumbwheels, you will be able to see if the gear is still attached to the thumbwheel. If it is, your problem lies elsewhere.

Okay, I took it apart, and the gear is still attached to the thumbwheel, but there is one crack in the gear, which is good because it still has a lot of integrety, but bad because the crack is very tiny and trying to glue it is going to be tough.

I do have some questions, though.
1. The gear looks really fragile. What is the best way to get it out?
2. Will the tuning knob and gear from any other Mopar thumbwheel radio work? I see thumbwheel radios in different configurations for Cudas, C-bodies, A-bodies, etc. My wheel has some chrome missing, so if I can kill two birds with one stone, all the better.
3. Should I glue the crack in the gear and then press it back onto the wheel, or can I just glue the gear right to the thumbwheel? It seems the wheel and gear operate as one unit anyways.

 

[Mike Szadaj]

1. I don't know. Whenever I have found bad gears they just came right out. They are fragile, but I have glued gears back together that were in two parts.
2. All that I have ever seen were all the same design. The problem with replacement is what shape is it in?
3. Glue the gear to the thumbwheel.

 

[Billccm]

I believe @JimKueneman used superglue and wire to tighten up the crack on his radio tune gear. Search here for his fix:
https://www.forbbodiesonly.com/moparforum/threads/1968-coronet-500-project.114333/

 

[Billccm]

I noticed that if I push one of the buttons in until the clutch disengages, the tuning wheel will move the needle just fine. The large gear that is part of the tuning mechanism is extremely hard to turn using my fingers, so I was thinking that maybe the clutch mechanism is binding or something like that.

Anyway, thanks for the great info. I'm going to try what you suggested tonight. Never had much luck with using glue on pieces that are subjected to any type of stress. Is there any type/brand glue that you recommend?

Did this get fixed? I just did a 1968 Dart Thumbwheel radio over the weekend. Let me know if you still need help.

 

[jeryst]

Did this get fixed? I just did a 1968 Dart Thumbwheel radio over the weekend. Let me know if you still need help.

Yes, I did get it fixed. I didnt use any glue. I just took a super thin piece of wire, wrapped it around the gear twice, then tightened it by twisting. Works great now.

 

[speedbanana1977]

I just found this post today—it’s very helpful. The tuning wheel doesn’t work on my 1969 Coronet AM radio (Bendix 9BBCC) so using your pictures, I took it apart and found that little plastic gear was broken in half and one half was missing. Any idea where I can find a replacement gear? I have tried looking for similar radios that might have a good gear but most aren’t cheap. Thanks in advance.

 

[Hemihead2]

Does anyone happen to have either a thumb wheel (second one in on left) or a gear for the indicator wheel? I bought a radio that is completely missing the tuning gear on the wheel. Thanks