SP GP20 Build, 2023 Edition

jwaldo Feb 26, 2023

  1. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    You’re probably thinking, “this guy can’t be posting another drawn out SP locomotive conversion thread!” And yet I am. My first-ever ‘real’ N scale project was a GP20E, and every ten years or so I feel compelled to see if I can outdo myself. They’re great looking and VERY nice-running models, but bringing them up to SP’s oddball specs takes some work.

    First, here it is freshout of the box (but pre-owned and clearly well-loved):

    [​IMG]

    The bell is MIA, the wheels and gears are dirty, and there is oil everywhere. Someone painted the handrail ends white, but whatever they used didn’t really stick. And as nice as the shells are, the factory-applied red paint on the hood ends is disappointingly thick and prone to flaking off. So the shell went straight into an alcohol bath (and the frame went straight to get a DCC decoder):

    [​IMG]

    Step one is making the changes to convert the LL Phase-1 GP20 to a later Phase-II model. These have different side sills more similar to later Geeps, so I’m filling in the cutouts, thinning the side sills above the fuel tanks, and reshaping the area around the fuel filler.

    The Phase II GP20s also had lower-profile 48” radiator fans instead of the flared fans on the LL model. For my previous GP20s I’ve dealt with this discrepancy by ignoring it, but this time I feel up for the challenge. The front fan top on this model was only partially glued on, and as seen above my attempts to remove it without damaging anything were partially successful. But I’ve ordered some 3D printed fans, there should be something in the set to replace it.

    [​IMG]

    What’s more, I have found prototype photos of a single Phase II unit (#4075) that has a flared-top rear fan. That saves me from having to pry off the second fan OR agonize about the choice of road number!

    [​IMG]

    Once the Phase II conversions are complete, the light packages will be the next order of business, along with coupler conversion and adding the rectangular cutout in the side of the nose. Every GP20 I’ve seen has it, but LL omitted it. Anyone know what it actually is?
     
  2. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

    67,560
    22,735
    653
    Now you have made me curious, too! :D
     
    308GTSi, BNSF FAN and jwaldo like this.
  3. M&E Alco

    M&E Alco TrainBoard Member

    145
    237
    23
    I suspect it's simply a step for climbing onto the short hood on low nose models of the time. I've seen photos of factory GP-9 low hoods with this recess. There's a hand grab on the hood just above, which would support the theory.
    Cheers
    Steve
     
  4. SP-Wolf

    SP-Wolf TrainBoard Supporter

    2,585
    13,693
    74
    Thanks,
    Wolf
     
    Hardcoaler, BNSF FAN and jwaldo like this.
  5. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    A step seems like the likeliest, if slightly anticlimactic, explanation. Luckily I have a rectangular cutting template that's just about the right size.
     
  6. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    It's slowly becoming one of those "spot the differences" puzzles:

    [​IMG]

    The shell in back was originally intended to be a parts donor, but if I can find a mechanism at the upcoming local train show, this might just become a two-locomotive thread :LOL:

    On the other hand, I have barely enough left in my dwindling reserve of Sunrise detail parts to complete the one loco. I'm not looking forward to the day I run out.
     
    308GTSi, freddy_fo, Sumner and 8 others like this.
  7. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    I am slowly but surely transitioning from cutting stuff off to adding stuff on. Just a few more grab irons to go.

    [​IMG]

    Now that I'm down to my last precious Sunrise SP light bracket, this loco is getting a scratchbuilt one. And even in the heyday of detail parts I never found the right EMD handbrake in N, but this is the first time I'm actually taking a shot at making one instead of ignoring the problem as usual :whistle:
     
  8. eposte12

    eposte12 TrainBoard Supporter

    392
    1,998
    35
     
    jwaldo and BNSF FAN like this.
  9. alister

    alister TrainBoard Member

    733
    1,196
    37
    Have you ever thought of making a mold of your remaining sunrise detail parts and casting them in resin? This would ensure that you had the means to keep making new SP models. Just a thought.
     
    BoxcabE50, BNSF FAN, MK and 2 others like this.
  10. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    I've got a few of the Shapeways light sets, but as far as I can find nobody offers the blank bracket with no lights. And all of SP's GP20s either had their rear signal lights removed at some point, or were delivered without them.


    One of these days I intend to cast or 3D print my own details, but for now the startup cost, learning curve, and limited workspace are prohibitive. One of these days, though. One of these days...
     
    badlandnp, SP-Wolf, BoxcabE50 and 2 others like this.
  11. Glenn Butcher

    Glenn Butcher TrainBoard Member

    167
    306
    9
    Waiting for another project's glue to set, I modeled what I think is a close approximation of the SP light board, sans lights:


    Look at the script, at the top are the dimensions, N scale inches, kinda approximated from my Atlas GP-9. I tried to upload the .stl, but the forum won't take it.
     
  12. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    Glenn, thanks! Having dimensions will come in handy. SP experts, were the angled tops of the prototype brackets open or closed? Models seem to be evenly split both ways.

    The local train show turned up lots of gems, including yet another GP20 in the Unspeakable Yellow Railroad colors for a bargain price. The mechanism from that will go under the no. 4058 shell, and after an alcohol dunk the shell will become a donor for fans, hood doors, etc.

    IMG_3583.JPG

    I also received some Trainworx grab irons and MU hoses. I'm curious to see how they stack up against their BLMA counterparts.
     
  13. SP-Wolf

    SP-Wolf TrainBoard Supporter

    2,585
    13,693
    74
    Here is the rear light bracket from a GP9 (Can't imagine it would be different) - Closed makes sense. Keeps out rain and other foreign objects.

    upload_2023-3-26_5-44-30.png

    Image borrowed from: http://espee.railfan.net/espee.html

    Thanks,
    Wolf
     
  14. Glenn Butcher

    Glenn Butcher TrainBoard Member

    167
    306
    9
    Closed; I'll modify my model when I can get to it.
     
    SP-Wolf and jwaldo like this.
  15. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    Thanks Wolf, that's pretty definitive. I suppose there could be some prototypes with open tops too, after all SP was deathly allergic to consistency!

    I had never seen a LL GP20 whose fan tops weren't VERY permanently glued on, but the fan tops on the UP unit popped right off without damaging the shell. With the fan conversion having basically taken care of itself I chose that hood for my second SP unit, leaving SP 4058 to become the part donor. A section of its hood doors are being converted into number board doors for the remaining two locos.

    [​IMG]

    Another batch of detail parts is on its way, which should give me some time to get the second unit caught up with the first.
     
  16. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    Another day, another brush with catastrophe. While gluing on lift rings, the glue applicator spat out a gob of CA glue that wicked down the inside of the shell, around the dynamic brake housing, and onto the outside of the shell.

    [​IMG]

    A quick hail-Mary application of lacquer thinner and a lot of careful scraping got most of the mess off. Unfortunately, a bit of the dynamic brake grill ended up mangled. And I can't even swap in the DB from the spare shell because this one is now VERY securely glued in place. Unless someone makes a photo etched DB grill, I'm just going to have to live with this, and keep my fingers crossed I don't make the same mistake on the second unit!
     
    308GTSi, SP-Wolf, badlandnp and 4 others like this.
  17. MK

    MK TrainBoard Member

    3,496
    4,798
    82
    Weather the grill and you won't notice it. :)
     
    BoxcabE50, BNSF FAN and jwaldo like this.
  18. jwaldo

    jwaldo TrainBoard Member

    694
    2,902
    54
    That's my plan, but no matter what I'll know it's there! At least until a few projects down the road once I have other newer mistakes to keep me up at night!
     
  19. tehachapifan

    tehachapifan TrainBoard Member

    1,859
    859
    46
    I think the grill looks good as-is!
     
    BoxcabE50 and BNSF FAN like this.
  20. Sumner

    Sumner TrainBoard Member

    2,798
    5,837
    63
    If you don't mind sharing what is your procedure for stripping a shell to repaint it? Thanks, I need to get brave and try one.

    Sumner
     
    308GTSi likes this.

Share This Page