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Converting an Athearn GP7/9 Blue Box to Non-dynamic

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  • Member since
    May 2008
  • From: Miles City, Montana
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Converting an Athearn GP7/9 Blue Box to Non-dynamic
Posted by FRRYKid on Monday, September 10, 2018 11:17 PM

This may have been covered before but here goes: How hard/easy is it to remove the dynamic brake detail from an Athearn GP7/9 Blue Box shell? I am looking to add a non-DB one to my roster to echo a prototype from my favorite railroad on my protolanced layout. I have never seen one of those shells in person. (The only Athearn GP unit that I have worked with is a GP35.)

As usual, thank you in advance for any assistance that my forum friends can provide.

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
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  • From: Canada, eh?
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Posted by doctorwayne on Tuesday, September 11, 2018 12:02 AM

Duplicate post.

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Posted by doctorwayne on Tuesday, September 11, 2018 12:03 AM

It's been some time since I did these...

...based on a series of b&w photos taken of the real ones...

I simply cut out the fan for the dynamic brakes, and cemented a square of .060" sheet styrene into the resultant hole.  The intakes are snap-ins, and once removed, you can plug the holes with styrene rod of suitable diameter.

There's a Paint Shop article in the February 1980 MR outlining mostly the painting process.
 
I didn't really enjoy doing the work, though, as I did 51 of them (plus a couple in brass, which weren't equipped with dynamic brakes.  I also painted 15 Athearn SW7s in the same paint scheme, although they didn't need much in the way of modifications.

Wayne

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Posted by snjroy on Tuesday, September 11, 2018 7:04 AM

doctorwayne

(...) I didn't really enjoy doing the work, though, as I did 51 of them (plus a couple in brass, which weren't equipped with dynamic brakes). (...)

Come on Wayne, what was not fun about that? ☺

Simon

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  • From: Chamberlain, ME
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Posted by G Paine on Tuesday, September 11, 2018 9:14 AM

The dynamic brake blister on my Athearn BB diesels are a snap in part. I had a GP-40 that I wanted to be non-dynamlc and forund Athern Parts Dept had the non-dynamic part that replaced the dynamic brake part.

George In Midcoast Maine, 'bout halfway up the Rockland branch 

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  • From: Miles City, Montana
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Posted by FRRYKid on Tuesday, September 11, 2018 10:29 AM

doctorwayne

I didn't really enjoy doing the work

Sounds like the fun I had building my GP20s. I had to bend all the stanchions as they were adapted from Athearn ones. (Somewhere between 170-180 between the 8 engines. A few mistakes and breakage.)

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
  • Member since
    January 2004
  • From: Canada, eh?
  • 13,375 posts
Posted by doctorwayne on Tuesday, September 11, 2018 11:55 AM

G Paine
The dynamic brake blister on my Athearn BB diesels are a snap in part....

Yeah, the later BB diesels had a one piece snap-in part for either dynamic- or non-dynamic brakes.  The first ones I recall seeing were the SD40s.

The top of the Athearn GP7's hood was a little bit concave, which makes finishing the patch a little more work than would otherwise be necessary.  The torpedo tube air tanks are useful to disguise a less-than-perfect repair, and can be had from Juneco or Detail Associates.

Wayne

  • Member since
    May 2008
  • From: Miles City, Montana
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Posted by FRRYKid on Sunday, September 16, 2018 12:45 AM

Another question for the forums: Am I correct that the two oval structures on either side of the dynamic brake would need to be removed as well? (All the units I have played with before has always had dynamics.)

"The only stupid question is the unasked question."
Brain waves can power an electric train. RealFact #832 from Snapple.
  • Member since
    January 2004
  • From: Canada, eh?
  • 13,375 posts
Posted by doctorwayne on Sunday, September 16, 2018 2:42 AM

The dynamic braking feature, if I understand it correctly, is a method of allowing the traction motors in the trucks to act as generators, and the power thus created is fed through resistor banks in the long hood, thereby slowing the locomotive.

The resistors get hot, and the so-called "oval structures" on the sides of the hood are air intakes, through which the fan atop the hood draws air to cool the resistors.

The photos which I posted previously show both real and model geeps, none of them equipped with dynamic brakes - no such air intakes, and no fan between the two exhaust stacks atop the long hood.
The one model with the air reservoirs atop the long hood have them there because it's a passenger unit equipped with a steam generator in the short hood.  Water for the steam generator is stored in a separate tank next to, and appearing to be part of, the fuel tank beneath the frame of the loco.

If you look at the photo of the loco on the turntable and the prototype loco, both freight units, the ends of the air reservoirs are visible behind the fuel tank.  On the passenger unit, there's no room there for the air reservoirs, hence their place on the top of the hood.

Wayne

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