One of my projects is to convert a USAT GP38-2 to a GP40-2. Last week I bought an SD40-2 shell and frame because … Well just because it was $50 and I figured I could do something with it someday. Today I’m looking at the shell and think “the body sure doesn’t look much longer than a geep when the porches are off.” So I place it on a GP38-2 frame and Whoah!
Looks like if I cut about 18mm off behind the cab, I’ve got a pretty close representation of a GP40-2! Anyone done this before?
Hi Dan,
I thought about this, too, for sometime, but being I have several Aristo GP40s, I did not pay much attention to it. Since Aristo is out of business, it now will make for a good project that you can pursue with the excellent skills you have.
Pictured below is a prototype Canadian Pacific GP40-2, albeit without dynamic brakes, that may be of help.
One exterior item that may distinguish the GP40-2 from the GP40 is the “Electrical Cabinet Air Filter” (that I call the “Dog House”) located behind the left side of the cab, prevalent on the SD40-2 and the GP40-2 pictured above. I just completed rebuilding my UP SD40-2 from just a shell & chassis purchased sometime ago. Its Dog House is shown below.
When I last checked with Mike at USA Trains parts, the Dog House is not available. Coincidentally, the Dog House was missing on my friend, Colin Camarillo, SD40-2, so he is currently in the process of doing the 3-D print of that part.
-Ted
Ted Doskaris said:
Hi Dan,
I thought about this, too, for sometime, but being I have several Aristo GP40s, I did not pay much attention to it. Since Aristo is out of business, it now will make for a good project that you can pursue with the excellent skills you have.
Thanks Ted. After making the Comfort cab for the GP38-2, I started working my way back and made the dynamic brake for the GP40.
Now I think I’ll cut the SD40-2 shell and make a GP40-2LW so I can use the Cab and also make a large fuel tank (better sound)
One exterior item that may distinguish the GP40-2 from the GP40 is the “Electrical Cabinet Air Filter” (that I call the “Dog House”) located behind the left side of the cab, prevalent on the SD40-2 and the GP40-2 pictured above. I just completed rebuilding my UP SD40-2 from just a shell & chassis purchased sometime ago. Its Dog House is shown below.
When I last checked with Mike at USA Trains parts, the Dog House is not available. Coincidentally, the Dog House was missing on my friend, Colin Camarillo, SD40-2, so he is currently in the process of doing the 3-D print of that part.
My shell did not include the dog house either but it seems the CN GP40-2LW’s don’t have them. Instead there is a low cabinet. I Also noticed the Dynamic brake on the SD has 2 fans so maybe I’ll use the one I created instead!
The prototype GP40 and GP38 frames might be different lengths as well. I don’t know off the top of my head.
Craig Townsend said:
The prototype GP40 and GP38 frames might be different lengths as well. I don’t know off the top of my head.
Craig,
Both have an overall length of 59’-02" so I assume they are the same frame. However, The frame is higher on the GP40-2LW to accommodate the larger fuel tank so I’ll need to do something about that especially since the USAT model is low to begin with. I do have NWSL replacement wheels which should help.
-Dan
Dan,
I agree the more realisitic NWSL wheels would seem to be the best method for raising up the loco like a prototype, but the trade-off is the loco would run a little faster and slightly less torque at the railhead like a car with a tall differential gear ratio.
Admittedly less elegant, I used a spacer between the trucks and chassis in the GP38s I have to raise it up.
-Ted
Ted Doskaris said:
I agree the more realisitic NWSL wheels would seem to be the best method for raising up the loco like a prototype, but the trade-off is the loco would run a little faster and slightly less torque at the railhead like a car with a tall differential gear ratio.
I’ll admit I hadn’t thought of that but would it really make that much difference? Knowing what I know of you from LSC posts, I take it you have tested pulling power of the USAT GP38-2 stock vs NWSL 36" wheels?
Admittedly less elegant, I used a spacer between the trucks and chassis in the GP38s I have to raise it up.
I’m thinking of putting the wheels on first and if I need more I’ll print a new truck mounting bolster.
Dan,
I did not get NWSL wheels at the time I worked on my GP38s because at that time, to my recollection, the ownership had changed and things were in a disarray. Maybe today it’s different.
-Ted
GP9 with NWSL wheels, pulls 32 cars up 4% grade, wet rail, 150’. 33 cars, slipping, 34 cars stall. Tested back in the day on TOC’s layout during ops clean up one night during the rain.
Same motor blocks as the GP38.
I would be more worried about having to modify the brake shoes than tractive effort.
Craig, Was weight added to the GP9?
I use track power, and track is stainless steel on the outdoor part of the layout.
On my layout with its approx average 2.2 percent double helix grade, my GP38 (no traction tires) pull about 9 cars up the helix. Wheel slip can occur, particularly with more cars, and the loco would stop with wheels turning more so on the straighter portions of the helix. I prefer wheels to slip as a fail safe to protect the motors from drawing excessive current since back emf is present under that condition. A video can be seen of two GP38s pulling 18 cars on my helix before I added weight to the locos at a later date and when the layout was still under construction.
Another video at a later date with 6 Rock Island locos pulling 44 cars up the helix. (I put the two USAT Rock Island GP38s on the train for appearance sake. I think just using the heavier 4 Aristo GP40s would have pulled the train up the helix)
-Ted
Ted,
The only weight added would be the batteries, but I can’t remember if I removed the USAT weight.
Aluminum rail, mostly all Bachmann cars.
As a point of reference, TOC regularly used the Bachmann Shay to clean up. We added the shay after it started slipping.
Thanks Craig,
Did the GP9 wheels have traction tires? If so I did not know that NWSL wheels fitted on the GP9 were offered with traction tires.
-Ted
So I don’t believe I’ll lose tractive effort and I’ll gain about 1.75mm in height. Also a wee bit more weight where it counts most. Which makes me wonder if anyone has tried replacing the top/bottom covers on the truck with something heavier?
Ted Doskaris said:
Thanks Craig,
Did the GP9 wheels have traction tires? If so I did not know that NWSL wheels fitted on the GP9 were offered with traction tires.
-Ted
Nope, no traction tires at all, just the NWSL wheels. I want to say they are stainless steel? I was quite surprised myself at what I could pull. Haven’t done it since, so lucky once? Or add that Dave’s rails are so old they have more grip?
