I have a new Atlas GP 40-2 Silver series, DCC ready 8 pin socket that I need to install a decoder in. I have a Digitrax DH 123 that I think will do the job ok.
My problem is getting the shell off, it has been a tough one to deal with. I did a Google search and found that I need to:
Remove the couplers (no problem)
Remove the hand rails from the cab, if possible… without breaking. (one came of easily, the others… forget about it!)
Remove the fuel tank. The instructions say it’s a hard job and I believe it, and why do you have to do this?
Then they explain the shell is held on via 6 tabs inserted into slots and to release a body tab it must be pressed inward away from the mating frame slot. Ok, got that… but it ain’t budging one iota.
Oh! The dynamic brake cover does come off but I don’t see a way to install a decoder that way, or am I missing something here.
You’re doing it correctly. The paint on shell tabs are probably sticking to the frame protrusions, which hold the shell on.
The easiest tab to dislodge is the one towards the back of the loco, since the shell can be squeezed easier there than the other locations.
You need to wiggle the shell as you pull up. Once the back breaks free, the others follow pretty easily.
You may also try a very thin but wide bladed screwdriver to help break the seal between the tabs and the frame nubbins, but be very careful since you do not want to break the tab.
You can also try to put a very small amount of 91% alcohol on a very small brush to wet the tabs. The alcohol will loosen the paint a bit. Again, be very careful to not spill any paint on the visible portion of the shell, since it might eat the paint.
BTW, the shell and the walkway are two different pieces, which are linked by the handrails that attach to the cab (the cab goes with the shell). That’s why you need to remove the handrails. When you gain experience, you’ll be able to pop off the shell, along with the walkway and handrails, off all in one piece. Also, you really don’t need to remove the tank, but an untidy grip may cause damage to the fine parts as you hold it to loosen the shell, so that’s why Atlas recommends it.
So, I do need to pop the handrails loose from the cab. I really didn’t see how I was going to get away without doing it since you can’t lift the shell out of the way if it is attached to the frame/walkway via the handrails.
I guess if I do break one I can CA it back in position.
I do not have the GP40-2, but I do have the GP38 ‘Silver Series’ and they should have the same drive. To install the Digitrax decoder, I removed the coupler mounting screws and the coupler pockets. You should not need to separate the body from the walk-ways. The entire shell(including the walk-ways) should lift up from the chassis. It may take some ‘rocking’ back and forth the remove it. Make sure you have an DH123 with the 8 pin NMRA harness so you can plug it in. I have Digitrax SDH164 sound decoders in my engines. You can use either the short(1") or long(3 ") JST to NMRA 8 pin harnesses in these engines.
The old Atlas engines with the dual mode decoders were accessed via removing the DB hatch. I still have 2 engines with that decoder(Lenz IIRC). My Trainman GP38-2 & GP39-2 engines are similar and take a standard NMRA 8 pin harness as well.
I remember that for my Atlas Dash 8 getting the shell of wasn’t too hard, the weights and metal frame seemed tight on the shell. Getting the shell back on was a nightmare.
Jim, maybe that’s the problem. There must be a couple of versions… one where the walkways etc. stay on the frame and one where the walkways are part of the body and come off as one unit. The only instructions I can find on the Atlas website instruct you to remove handrails from cab (and the fuel tank) then remove the shell leaving the walkways on the frame.
I have several other Atlas locos and, though some have been a little difficult, with a bit of rocking back and forth persuasion, they did come off.
I’ll look at this one closer today and see what I can come up with.
The walkway and sill is one piece that slides off the frame when the shell is removed. The shell is the long and short hood sections with the cab attached.
Flip over the loco and locate the two tabs that attach to the frame towards the back truck. If you can get those to release, the shell should begin to wiggle off with some effort. Yes, the first removal is the most difficult since the newly painted loco seems to stick together.
I think those two additional screws are there to hold the weight/speaker a-frame in place.
I’ve found that after a few disassemblies some of the rectangular tabs will break. At that point the entire shell and walkway assembly will come off together without having to remove the handrails. To separate the shell from the walkway, I think you really only need to disconnect the handrails from the cab. That’s the only place where the handrails connect both parts. I believe that the remaining handrails are suggested to be removed so that it is easier to squeeze the shell to release the tabs.
Here is a photo of the bottom of said locomotive, cab end is to the left. The online instructions say there are 6 tabs/6slots, two of them near the middle of the fuel tank. The tank has been removed in this photo. For the life of me I do not see two tabs in that position, or the other four. Is this a case of can’t see the forest for the trees? [:D]
I don’t know about 6 tabs. Which instructions are you looking at? I know that the Atlas C30-7s have 6 tabs, but I don’t know about the 4-axle units. The on-line drawing for the GP40-2 only shows 4 tabs: http://www.atlasrr.com/pdf/PartsPDFs/HOGP40-2Silver.pdf
Do you have a phase 1 or phase 2 loco, the parts diagrams are different and at least early phase 2 loco’s shipped with the wrong diagram(the phase 1 diagram). The GP40-2W has it’s own parts diagram as well.
I don’t have a GP40, on the GP38 and 38-2 the dynamic hatch is right above the PC board and the dummy plug you remove to put in your decoder. I thought I was told the GP40’s were the same. There are limits to what you can see from a parts diagram but it looks similar to the 38/38-2’s. Are you sure you can’t get to the plug from the dynamic hatch?
The tabs on the end are for allignment and do not have locking notches. the locking tabs are about 1/2 inch in from the ends. With stuborn tabs, I use 1/4" flat blade screw driver , inserting it between the metal frame and the sill/walkway just above the wheel next to the steps. Start pushing the screw driver in until it stops (about 5/16") while wiggling it back and forth, you can be firm.
To eliminate this issue, I cut off the tabs and glue the walkway to the shell (I use Ambroid’s ProWeld, formulated for ABS plastics (or Same Stuff from Micromart), Testors is for styrene and won’t hold well). The couplers will lock the shell to the frame and when you remove the shell, you just remove the couplers and slide the shell off and no messing with handrails. Proto 2000 glues their walkways to the shell on most of their models.
Thanks for the clarification and also the tip about gluing the shell to the walkway. I’m bookmarking this thread. I have a couple of these units and have been putting off taking them apart for some tuneup/servicing.
The tabs are located, from this angle, underneath the wheels to the farthest right. From this angle, the shell tabs are sticking up from the bottom of the shell and are grabbing the frame nubbins. Turn the trucks to see.
I don’t recall seeing the tabs that are near the cab side and I don’t think the tabs under the tank can be seen at all.
