Hallmark Frisco N Scale GP7 Rebody using Atlas DCC Equipped GP35 Chassis

Discussion in 'N Scale' started by jmoore16, Jan 28, 2017.

  1. jmoore16

    jmoore16 Member

    Hello Folks -

    I recently acquired two Hallmark GP7 locomotives and one F7B in our familiar Orange and White paint scheme off this site but, unfortunately, the GP7s have been sitting for a while since my layout was DCC. The F7B was pretty easy to convert due to its plastic body.

    The brass frame and metal chassis of the Hallmark diesel GP7 scared me but I decided to take the plunge. I will lead you through my discoveries, mistakes and eventually a video.

    First step, a look at a stock Hallmark GP7 Diesel Locomotive...

    Notice the lack of flywheels. These flywheels will keep stability and smooth motion even if the locomotive finds a dead spot or other reason that would not normally upset a modern N Scale locomotive. What you don't see are antiquated electrical pickups and gears which do not meet the standards that we expect out of a smooth running locomotive from the major manufacturers. This is something I learned after installing a Digitrax DN136D onto the Hallmark frame...
     

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  2. jmoore16

    jmoore16 Member

    This is the original Hallmark GP7 converted to DCC using the Digitrax DN136D. Luckily, this conversion was surprisingly easy if you can solder.

    And if you don't shake...

    I do. In the process of soldering the gray wire from the DN136D to the motor lead connecting the brushes underneath the electric motor, I accidently soldered the plastic driveshaft to itself and froze up the motor. I finished the DCC install and, with the use of 1/16th heat shrink in lieu of the now faulty driveshaft to the front truck, I was able to get the locomotive running on a temporary basis. Forward and backward under its own DCC power.

    I could buy a replacement driveshaft, but running forward and backward, I realized that this thing will sound and run like a Model T on a freeway full of new Ford Fusions. I did a search on the internet for what it would take to replace the antiquated Hallmark running gear for something more modern from Atlas, Kato, Bachmann or anything.

    The only thing that I could find came from the N Scale Yahoo group. I was pointed to the webpage http://www.spookshow.net/loco/hmsd2426.html which tells the story about an effort by Hallmark to put a non-DCC ready Kato SD7/9 mechanism underneath a brass Hallmark SD24/26 body. It was a success/failure, but I thought that I could do the same thing using a DCC equipped Atlas locomotive chassis.
     

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  3. jmoore16

    jmoore16 Member

    I decided on the Atlas GP35 because I had two DCC equipped frames that could be used and the centerline of the trucks on the Atlas GP35 mechanism matched the GP7 from Hallmark. The trucks also matched. Only thing that would be difficult is the GP7 tanks and reservoirs in lieu of the GP35 tank. Shown here is the finished modified GP35 and the stock GP35 in the background.

    Now the details...
     

    Attached Files:

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  4. jmoore16

    jmoore16 Member

    First off, I had to cut off the front and rear of the GP35 frame with a Dremel cut-off wheel far enough to leave a portion of the nylon nut and bolt holding the halves together.

    I learned from a previous project to remove the trucks before you cut and not to let the frame get to hot when you cut. Keep in mind, nylon plastic melts a lot quicker than aluminum! The trucks are held in with two small tabs that fit into a pocket in the frame. Extra heat in the frame will quickly melt the tabs off the trucks. Remove the trucks!
     

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  5. jmoore16

    jmoore16 Member

    Next step was to disassemble the GP35 and reassemble just the 3 nylon spacers, nylon nuts and bolts. I then used a Dremel sanding wheel to remove enough metal to fit the locomotive bare frame into the brass GP7 shell. I had to sand off material from the top (near the DCC board) and both sides except the fuel tank and electrical pick-up tabs/mounting features. I made the mistake of removing two of the four little tabs that help hold the brass strips in place when they contact the trucks.

    Don't do this. I'm ok, but I know I would have a more reliable prototype if I left them on...
     

    Attached Files:

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  6. jmoore16

    jmoore16 Member

    I had a resin GP7 fuel tank from another project, so I flipped over the frame until the GP7 tank that I found on EBay fit underneath the GP35 frame. One issue that I had using the resin GP7 tank was the lack of side support of the brass pickups. Other than that, the tank fit but didn't attach. When everything was finished, I put two small tabs of CA glue under the tank. I can snap it off if I need to work on the locomotive. On to the problem with the lack of brass pickup retention by the tank...
     

    Attached Files:

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  7. jmoore16

    jmoore16 Member

    I had already purchased a bottle of Liquid Tape from Lowe's, so I used the plastic packaging to cut 4 shims the internal width of the fuel tank. I reassembled the entire GP35 Atlas running gear including DCC board and pickups into the modified frame and cleaned the entire frame and internals and did quick maintenance. Then, I glued the tank in place and slid the shims (2 on each side) between the inside of the tank and outside of the pickups, successfully holding them against the frame. I then used a Dremel cut off wheel to cut off the shims to the height of the top of the tank. This picture shows the shims in place, but they haven't been trimmed to fit yet so they could be seen in this picture.
     

    Attached Files:

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  8. jmoore16

    jmoore16 Member

    Next comes the modifications to the body. I actually modified the opening of the walkway around the locomotive first so I could test fit the modified frame into the brass body. I cut all the way to the end of the short and long hoods, but I learned later that this was unnecessary. You only have to cut off to the mounting screw which attaches the lower brass frame to the hoods. Also, and fairly obviously, I also had to cut off the two brass body mounts which are on the side of the long hood.

    After the Atlas locomotive mechanism with DCC board installed was test fit into the brass Hallmark body, I realized I needed to remove the rear body weight to clear the DCC board. Also, there were flanges from the cab that extended into the body which had to be sanded back to the long and short hoods to clear the front of the DCC board. After all these mods were done to the body, I applied 2 coats of Liquid Tape to the inside of the brass body and let it dry.
     

    Attached Files:

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  9. jmoore16

    jmoore16 Member

    While the shell was drying, I ran the modified Atlas GP35 for 30 minutes on a loop, 15 minutes going in forward and 15 minutes in reverse. That way, if there was a problem after the shell was mounted, I knew it was a body short from side to side of the GP35 mechanism through the body.

    I then dropped the Hallmark brass shell onto the Atlas DCC mechanism and everything worked like a champ. Incredible, smooth and able to pull as much as any other locomotive in my Frisco fleet of diesels.

    Now if I can just figure out what number should go on the cab...

     
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  10. jmoore16

    jmoore16 Member

    Sorry for the little video tribute (shrine???) to my dad at the end, but maybe some of you recognize him???
     
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  11. klrwhizkid

    klrwhizkid Administrator Staff Member Administrator Frisco.org Supporter

    Nicely done, John.
     
  12. pbender

    pbender Member Frisco.org Supporter

    John,

    An Atlas GP7 frame would have saved you a little work. At a minimum, you would have been able to use the GP7 fuel tank.

    Not sure I will do this on the one I still have, but it's nice to know the work required.

    As for number, use one that started life with a steam generator. The fuel tanks on one without the steam generator do not go all the way to the frame.

    Paul
     
  13. jmoore16

    jmoore16 Member

    Agreed Paul, but I happen to have two more DCC equipped GP35s. I picked up a custom painted GP35 725 that I will rebody with one of the chassis and I am very tempted to leave the other Hallmark GP7 in DC stock from the factory just for the collection. I'm really disappointed in the 725 as it uses the small FRISCO script (switch engine size) on the long hood. Who would make that mistake?

    10-4 on the number...

    Thanks Paul -

    JFM
     
  14. pbender

    pbender Member Frisco.org Supporter

    I saw a custom painted Frisco SD45 at a show once with an incorrect number. The painter was working the booth and he quickly put that locomotive away when I pointed it out...

    On that 725, be sure to use the right trucks. She was part of the group riding on trade in trucks from an FA1 or FB1. You can get the trucks from Atlas. Use the for their U25B ( or RS1 and RS2, I think they are all the same ).

    Paul
     
  15. jmoore16

    jmoore16 Member

    Great call on the trucks Paul. What about the trucks on 704 and 705? I'm lazy and thought I look it up on Encyclopedia Bender instead of pulling the books off the shelf!

    Haha!

    JFM

    PS - And I enjoy hearing from you guys...
     
  16. pbender

    pbender Member Frisco.org Supporter

    704 and 705 had torpedo tubes ( roof mounted air reservoirs ).

    Paul
     
  17. jmoore16

    jmoore16 Member

    721-731 rode on ALCo trucks? My 704 and 705 have the correct Bloomberg trucks.

    I need to remove the nose mounted coonskin herald (only 651, 911, 912 and 915 had herald) and replace the smaller switch size FRISCO on the long hood before I'm comfortable with running this locomotive.

    JFM

    20170206_112930.jpg
     
  18. pbender

    pbender Member Frisco.org Supporter

    Yes, that is right about the trucks.

    I actually might run that as is. It looks decent to my eyes, even if the font is wrong ( and we can't see the nose herald from the side.)

    I have a pair of E8s that I bought from a dealer custom painted in orange and white. The only problem with them is the white herald on the nose is too big. I just run them ( separately ) as the 2nd unit in a 2 unit consist, with the nose up against the first passenger car.

    I'm probably the only one here in Columbus who even knows they are wrong.....

    Paul
     

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