Athearn F7a Repair Help Needed

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catnippertom

catnippertom

That Oregon Guy
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I recently snatched this SP F7a unit from my local train store. A few weeks prior I bought the b unit not knowing they had the A unit so once I saw it, I had to snag it. It was $25 which I thought was a good deal for what I assumed was a running loco. The loco did indeed run but only for a moment. I have been watching a lot of SMT Mainline on Youtube so I figured I would be able to repair it easily with some cleaning or something. I decided to dive into it while changing out the couplers to Kadees. Turned out the loco had some running issues. As seen in the pictures, what I assume is the driveline, disconnects after only running for a short amount of time. The front trucks still move and pick up power and the motor still spins fine but the connection to the rear is broken. I am not sure what I should do with it so I decided to consult the forum. I thought about using some super glue or something similar to lock it onto the motor output but I didn't want to do that unless that was the only fix. If anyone has any other better ideas than glue lmk.
 
catnippertom said:
I am not sure what I should do with it so I decided to consult the forum. I thought about using some super glue or something similar to lock it onto the motor output but I didn't want to do that unless that was the only fix. If anyone has any other better ideas than glue lmk.
Click to expand...
It is a friction press on coupling, that in the Athearn parts world is part of the motor. Part 84001. Glue might work.

https://hoseeker.net/assemblyexplosionAthearn/athearnf7gp9gp30gp35.jpg
 
Iron Horseman said:
It is a friction press on coupling, that in the Athearn parts world is part of the motor. Part 84001. Glue might work.

https://hoseeker.net/assemblyexplosionAthearn/athearnf7gp9gp30gp35.jpg
Click to expand...
Thanks for the info. I think I am just going to glue it. It comes off on the other end so I don't think it would do too much harm to the locomotive or working on it down the line. Also awesome diagram. I am definitely going to use that later down the line when I inevitably pick up more Athearn blue box locos down the line.
 


If this coupling keeps coming off, you need to look carefully to see if there is a hairline crack in it, which is likely.
CA Glue is OK as a stop gap measure, an Epoxy would work better, but if you've a hairline crack, that part will fail again.

You might as well buy new couplings, you can't get them singles unless your go on an auction site, but for your money better off getting a new pack, you will use them eventually.

I've maybe 40 locomotives I bought dirt cheap as non runners, couple of bucks of spares and some time and they now run beautifully.
 
Smudge617 said:
If this coupling keeps coming off, you need to look carefully to see if there is a hairline crack in it, which is likely.
CA Glue is OK as a stop gap measure, an Epoxy would work better, but if you've a hairline crack, that part will fail again.

You might as well buy new couplings, you can't get them singles unless your go on an auction site, but for your money better off getting a new pack, you will use them eventually.

I've maybe 40 locomotives I bought dirt cheap as non runners, couple of bucks of spares and some time and they now run beautifully.
Click to expand...
There aren't really signs of cracking but that is something to look for down the line if issues persist. But always having extra parts on hand now would probably help down the line.
 
catnippertom said:
There aren't really signs of cracking but that is something to look for down the line if issues persist. But always having extra parts on hand now would probably help down the line.
Click to expand...
True, in time you'll accrue quite an assortment of spare parts from all sorts of places like garage sales, and swop meets.
 
That part is a friction press on part however I don't think it came with the 84001 motor I found a few on line for sale and none had that part
If you look at the diagram for the DD40 or the SDP 40 they list the motor and part #90108 as seperate parts
I don't think you will find any So either auction site or some one that has one on hand ( I sent mine to Smudge617 ) and he's way over in England
Or a newer motor with flywheels and all new drive train $$$$ or like been said epoxy it

I don't think I ever had one crack but I suppose it could Motor mounts yes they crumble
After I thinned out my motive power all the DCC stuff went I probably still have 50 or so BB athearn engines

Here's the SDP 40 for reference
https://hoseeker.org/assemblyexplosionAthearn/athearnsdp40diagram1966.jpg
 
catnippertom said:
Thanks for the info. I think I am just going to glue it. It comes off on the other end so I don't think it would do too much harm to the locomotive or working on it down the line. Also awesome diagram. I am definitely going to use that later down the line when I inevitably pick up more Athearn blue box locos down the line.
Click to expand...
The HO seekers site is wonderful. There are about 8 variations of the Athearn drives through the years.
 
MikeGTW said:
That part is a friction press on part however I don't think it came with the 84001 motor I found a few on line for sale and none had that part
If you look at the diagram for the DD40 or the SDP 40 they list the motor and part #90108 as seperate parts
I don't think you will find any So either auction site or some one that has one on hand ( I sent mine to Smudge617 ) and he's way over in England
Or a newer motor with flywheels and all new drive train $$$$ or like been said epoxy it

I don't think I ever had one crack but I suppose it could Motor mounts yes they crumble
After I thinned out my motive power all the DCC stuff went I probably still have 50 or so BB athearn engines

Here's the SDP 40 for reference
https://hoseeker.org/assemblyexplosionAthearn/athearnsdp40diagram1966.jpg
Click to expand...
Mike, A-line still produce those don't they ?
 


From his pictures it looks like the correct part All the Athearn motors like that one the motor shaft is .12" The much older Athearn motors the shaft was .08 The only thing that looks the same is Proto 2000 and I don't think I have one to check opps I just looked at my list and I have some GP18 will take a look Still think maybe something with that part on his engine
update I forgot how much to take one of those apart Nope but the drive train does look kinda the same I just dought that's what he has
 
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Okay so on super close examination there is a crack that I can barely see starting to form so it looks like I will need a new part after all. Great...
 
Don't think you will find that part by itself you might have to get a doner engine for parts allmost any 4 axle Athearn engine will work
or the ones from A-Line all though you have to drill them out to fit the Athearn motor
Or like Smudge says CA glue maybe that Locktite Plastic Bonder its a two part made for hard to bond plastics
Good luck hope you get it fixed
Also if you look for a doner maybe one with flywheels and the newer style gold colored motor will run a lot better
 
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Took a look at that site not too bad but most stuff list price plus shipping
That gold athearn motor w flywheels $32.99 plus $2.99 shipping usually ships in 2-3 days
Same price on amazon free shipping and comes from Horizon Hobbies (Athearn) order today be here Friday
 
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