Build Your Own GP20; 2017

What's the best way to section the short hood?

You might want to graft on the short hood from the MTH GP20 shell.

Yep, that is what I do.

I would. Except that the Railking hood is a scale foot too wide and at least a foot too short. 

Yikes. And with the odd shape, shaving out of the center isn't that practical. And I think the short hood on the Lionel GP20 is even wider, though it might be the right length.

 

Now I have to re-examine my plans on correcting a pair of MTH ATSF SD24's (ATSF took delivery of them with GP20 cabs and short hoods).

Stupid question.  But why did you not use a Lionel GP20 It is also scale or at least suppose to be.  I plan on doing something similar. Matting a MTH SD24 with a Lionel GP20. The intent is to create a low nose ATSF SD24.

Not a stupid question.

I measured, and I was off a little. The MTH short hood is only 5" too wide. Not bad.

But, it's two feet too short.

To make it the same length, the MTH can is two feet too long compared to the legacy cab.

Yes. The Lionel short hood is closer, but my original plan was to detail the MTH unit, right up until I put it next to the Lionel. So, now it's cut down the high short hood...

       
       


Picture...

I see two options and remember that all depends of the placement of the forward Can motor if your going to keep it. 

 

1. Section the GP20 shell Cab forward and graft ( add 2ft at the graft point).

 

2. After sectioning the Cab forward. Section it again where hood meets cab and then add 2 scale Ft using styrene to the short hood and reattach to the Cab.  

 Matt,

 I remember you talking about this a while ago. It might work using the MTH GP 20 Cab and hood forward. Same issue placement versus the can motor. Since I now have a SD24 Shell I can hack up instead of screwing up my ATSF SD24 shell, Once the kids are back at school( next week thank god). I have time to start the project.

This is going to be a good thread and I will be watching.

The plan of attack on this was to take the short-hood motor from the powered unit and place it under the long hood on the non-powered unit, install counterweights under the short hoods to balance them, and wire them together since they run as a pair anyway. The other thought was to re-engineer the chassis to re-position the motors, which has been part of the delay on working the project (between all the other stuff that flies into the queue). A third thought was to convert the powered unit to an SD24B (ATSF bought a couple from UP), but research indicated they immediately converted them into slugs. Going to be interesting.

Matt

 

I am assuming with that said you haven't started yet. Since I have 3 pieces of the puzzle to work with no loss ( MTH SD24 Shell, GP 20 Shell and SD24 frame from dummy unit) to work with. I will actually be able to do a test fit. Any way I don't want to high jack Mario's thread but it sounds like their are similar issues at play.  

Here's some pictures for you to reference...

 

I was so excited to see that the Railking nose had a separately applied grab iron on the nose, and would have made my conversion easy, just adding the three more grab irons.

 

In the picture, the blue and red lines are the same size in the top and bottom; the shells were stacked.

 

oh well...

 

Thanks,

Mario

 

 

No hijack... It is going to play out quite similarly.

Glad to hear that many of us are working on the same things, roughly.

I look forward to seeing the concurrent projects evolve. Only one way to do it and that's dive in!

Thanks,
Mario

What about the MPC GP20 nose? That MTH GP20 resembles no GP20 I've ever seen, MPC misses the boat with that stamped metal frame / handrail combo.

I couldn't tell you. I sold my Lionel GP20 when I went scale.

It looks right. 

The MTH handrails are light years ahead of the Lionel PW style stamped frame/handrail combo.

I have a Lionel GP20 shell I picked up somewhere. As I recall, the hood was too wide. I had really wanted it for the cab and had planned on grafting it to the MTH hood and onto the SD24 long hood. I'll take another look at it.

I pulled the Lionel GP20 out of my parts bin. It looks like I will have to add about 5mm to the length of the long hood end of the SD24( Separate the Cab and High hood) Same thing with the GP20. 5mm between the long hood and the GP20 cab and low nose. Width appears to be a match.  I think this will work.

The issue as always are the placement of the can motors. MTH sacrifices length of the short hood to make it work.

 

Now I wish I didn't get rid of my GP20...

Should easy to find at a train show.  attached are pics. no science here.

 

 

Just a heads up that is a GP38 and the short hood is a different style than a GP20

Your right. Their was a reason I didn't use that shell. Funny thing is the nose has a distinct slope in it.  Maybe with modes?  Another thing to remember is that the SD24 is bigger then the GP20. The low hood nose is similar to the GP20 in designed but not the same. In fact now that I am looking at it, the conversion will be easier with less cutting..   

I'm not sure about that. The story on the ATSF units was they used GP20 cabs and short hoods on their units. Here's a pretty good profile photo of an ATSF unit and the slope on the short hood is pretty pronounced.

 

Now, while we're on the subject of cosmetic surgery on SD24's, has anyone thought of doing an SD26? ATSF rebuilt their SD24's when they started having problems, upgrading the diesels from the 567 to the 645, replacing the electrical and upgrading the air filtration system. Notice the relocated air tanks and the "hump" behind the cab.

 

 

 

One thing wrong with the Lionel GP20 nose is thatit is sloped all the way from the tip, where as the real noses don't start the rise until after the sand fill cap. Here's a shot of the nose from a GP18 And a 20.  

 

 

Don't be so nosey...

 

 

Hot Water, I calculate the short hood to be 62.5" tall at the nose, and a 5.55 degree slope on the hood; does this sound correct?

 

 

 

??

 

I really had no idea, and don't have any drawings of the GP20 low short hood in my collection. Maybe you could contact the Western Pacific Museum, out in Portola, California, as they have a beautiful, fully restored & functional WP GP20. Maybe someone there could photograph and measure the front nose.

Thanks...

 

Anyone have ideas on a fuel tank?

I was looking at drawings last last night. From the way it looks is they essentially cut the high nose down. Same as GP20 level and then angles up after the sand dome. Cab is the same as the GP20 only without the high nose. I may have found an easier route. The MTH SD24 shell dissembles into three sections.Cab, Nose, and lower body panels. use a wire saw to remove the top section of thigh nose. The draw a line with the angle and use the wire saw to cut again.  Mario could do the same thing with the nose from the GP. or he could use his printer. 

The Western Pacific GP20 at Portola is a high nose.  The MPC GP20 has a lot of slope to it and is longer than the MTH version.  Firemanchris was making a low nose GP18 and has some ideas in his thread.  I searched GP18 to find it.

I remember the SVC board. 

I really had no idea, and don't have any drawings of the GP20 low short hood in my collection. Maybe you could contact the Western Pacific Museum, out in Portola, California, as they have a beautiful, fully restored & functional WP GP20. Maybe someone there could photograph and measure the front nose.

The WP GP20's had high short hoods. Link.   GN's GP20's did, too, and were operated long-hood-forward; most of these had their short hoods "chopped" and were converted to short-hood-forward operation by BN.

 

I am prepping the nose for a reduction (nose job?)... and the Lionel shell is in 3 pieces as well...

I saw that too researching GN GP20s. It looks like the same nose as the GP 9. 

Oh well. Thanks, as I didn't remember that the WP units had the high short hood, sorry.

Here are some pictures of the assembled nose...

 

If anyone would like a O scale-sized drawing like the one I use, just print the attached full sized on an 11"x17" sheet, or let me know and I could mail you one.

 

 

Thanks,

Mario

Looks good. Once the kids are back in school next week, I will be starting on the SD24. How did you scale down the drawing?