LifeLike GP18 GP20 Atlas GP7/9 Interchangeability & Performance

[pjm20]

All,
  I have been doing some research online and in the forum archives and want to address some questions I have in one topic that hopefully others can use a handy reference in the future. The goal for me is to model a Phase III GP9 using the LifeLike GP18 shell with the GMM detail etch and get DCC/Sound fairly easily. From Spookshow's reference Walthers came out with a newly tooled chassis in 2004. My first questions are: is the tooling in terms of detail that much improved versus the previous versions? I understand the cab and short hood? became a single piece and that the pilot was closed, but how about the molding for the detail on the shell, any significant improvement?
  From what I have been able to gather, there has been a 2004, 2007, 2009, and 2011 release of the GP18 with the newly tooled shell, with the 2007+ being DCC ready. For my next question, these releases all have the same shell that are swapable between releases? A 2004 shell is no different from a 2009 shell?
  Spookshow notes that the 2007 release with a DCC ready chassis for the first time has some noise in the chassis, with the subsquent releases this has been addressed. I have also read the late release GP18 is one of the best 4 axle locomotives ever to be produced. Is there a fix for the 2007 chassis noise? Is the later release DCC ready GP18 chassis that good when compared to a "modern" mechanism?
  My next set of questions involve shell swapping the GP18 shell onto other Geep chassises. For shell swaps I have read that a swap with a Atlas GP7/9 mechanism is fairly straight forward, with some material needed to be removed from either the Atlas chassis or GP18 shell. Is this accurate? Would you swap the frame as well or just the GP18 cab and hoods onto a Atlas GP7/9 chassis and frame? LifeLike also made a GP20, which apprarently shared the mechanism with the later GP18s. Atlas has rereleased the LifeLike GP20, would a GP18 shell fit onto the Atlas GP20 chassis, along with if the frame is from the GP18 or the 20? Given the statement on how well the late GP18 chassis ran, is there a point of swapping the GP18 shell onto another chassis? I would imagine the immediate benefit of the Atlas GP20 swap, if feasible, would to get a chassis that is DCC ready or equipped with sound.
   If you have made it to this point, thank you for the help. The GP18 is starting to get somewhat harder to find in later version, so I would like to see if being particular about a certain release is necessary or not.

[jwaldo]

I also have a Phase III GP9 on my workbench right now. It’s one of Southern Pacific’s low-nose units:

[ Guests cannot view attachments ]

I’m using the 2011 DCC-ready version of the GP18/GP20 mechanism released by Walthers. It really IS a fantastic runner*. The shell is a mix of LL Gp18 and GP20 parts, plus GMM details and an Atlas GP9 fuel tank.

Things get messy when you bring Atlas parts into the picture. The LL/Walthers GP18/GP20 shells have scale-width hoods. The Atlas GP9 (whose shell still dates back to the 80s) is several inches wider. This means that 1) the LL and Atlas hood and cab sections can’t be interchanged, and 2) the only way to fit the LL hood on the Atlas GP7/9mechanism would be to mill the sides of the Atlas frame down. But if you leave the Atlas shell out all of the LL/Walthers shell parts are all interchangeable except for needing minor modifications of the tabs that hold the parts together, and the resulting Franken-shell fits on the 2011 mechanism perfectly. The Atlas fuel tank required both sanding and shimming to fit on the Walthers mechanism, but that was easier than trying to find a DCC-ready GP18.

Presumably the new Atlas GP18/20 mechanism is designed to fit the LL/Walthers shell tooling, and they didn’t redo the entire shell from scratch. But the new Atlas  GP20s seem to be rarer than the Walthers version, which is already rarer than unicorn farts.

*The DCC-ready GP18/20 mechanism is only the second best running 4-axle loco I've ever encountered. The best one is still the original pre-DCC LL GP20. With a little TLC and tuning my old GP20s will creep along at <1 scale MPH.

[u18b]

Noise:

Remove the inner bearing blocks.

 

https://u18b.com/wp-content/uploads/2019/10/Bearingblock09.pdf

[nickelplate759]

All,
  I have been doing some research online and in the forum archives and want to address some questions I have in one topic that hopefully others can use a handy reference in the future. The goal for me is to model a Phase III GP9 using the LifeLike GP18 shell with the GMM detail etch and get DCC/Sound fairly easily. From Spookshow's reference Walthers came out with a newly tooled chassis in 2004. My first questions are: is the tooling in terms of detail that much improved versus the previous versions? I understand the cab and short hood? became a single piece and that the pilot was closed, but how about the molding for the detail on the shell, any significant improvement?
  From what I have been able to gather, there has been a 2004, 2007, 2009, and 2011 release of the GP18 with the newly tooled shell, with the 2007+ being DCC ready. For my next question, these releases all have the same shell that are swapable between releases? A 2004 shell is no different from a 2009 shell?
  Spookshow notes that the 2007 release with a DCC ready chassis for the first time has some noise in the chassis, with the subsquent releases this has been addressed. I have also read the late release GP18 is one of the best 4 axle locomotives ever to be produced. Is there a fix for the 2007 chassis noise? Is the later release DCC ready GP18 chassis that good when compared to a "modern" mechanism?
  My next set of questions involve shell swapping the GP18 shell onto other Geep chassises. For shell swaps I have read that a swap with a Atlas GP7/9 mechanism is fairly straight forward, with some material needed to be removed from either the Atlas chassis or GP18 shell. Is this accurate? Would you swap the frame as well or just the GP18 cab and hoods onto a Atlas GP7/9 chassis and frame? LifeLike also made a GP20, which apprarently shared the mechanism with the later GP18s. Atlas has rereleased the LifeLike GP20, would a GP18 shell fit onto the Atlas GP20 chassis, along with if the frame is from the GP18 or the 20? Given the statement on how well the late GP18 chassis ran, is there a point of swapping the GP18 shell onto another chassis? I would imagine the immediate benefit of the Atlas GP20 swap, if feasible, would to get a chassis that is DCC ready or equipped with sound.
   If you have made it to this point, thank you for the help. The GP18 is starting to get somewhat harder to find in later version, so I would like to see if being particular about a certain release is necessary or not.

There are two slightly different GP18 bodies.  The early bodies have open end sills (because of truck-mounted couplers), and the later bodies have solid end sills with body-mounted couplers and finer railings (especially noticeable on the ends).

[sizemore]

For the Wallyworld/Life-Less split frames, may consider switching to Atlas GP Blomberg trucks. I did this with some split-frame BL-2's and it really improved the locomotive pickup as well as the Atlas truck is slightly taller which fills the frame void so it doesn't look like a 4x4. Been contemplating this for the two GP-20's in my paintshop.

The S.

[atsf_arizona]

Some years ago, I put an old open-pilot Seaboard Air Line GP18 shell, on one of the old non-DCC-ready Atlas GP7/9 mechanisms.

Here's some notes I made, regarding how to get that LL GP18 shell to fit on that Atlas mechanism.

=========

---  what I did:

-----  Purchased old LifeLike GP18 with the plastic mechanism, so that I could have the SAL #406 GP18 LifeLike shell

-----  Put a older 1995 era Atlas GP7 mechanism under the LL GP18 shell. 
Swapped a 2014 Scale Speed motor into the 1995 era GP7 mechanism, to
speed match the mech with my other Scale Speed Atlas Seaboard diesels.

=========

NOTES:

Needed to grind out a bit on the LL GP18 shell under cab end, and in a few other
   spots, to get the LL GP18 shell to fit nicely. 

Ground off the "nubs" on the Atlas mechanism (these nubs would hold the Atlas shell onto the Atlas mechanism).   Since the Lifelike GP18 shell was on the
old LifeLike plastic frame mechanism (see https://www.spookshow.net/loco/llgp18.html for details), this Lifelike GP18 shell didn't have any molded-in spaces for the "nubs".

Ground down side of the mechanism under the cab.

Ground down top of mechanism under long hood.  Maybe didn't have to do that but did it anyway.
   
To mount Micro-Trains, I used MT 1166 adapter.  I used MT underslung 2002 coupler to get right height on the coupler.

With these mod's, the old LifeLike GP18 shell fits nicely on the Atlas mechanism.
I ended up with my LL GP18 shell being a good press fit with proper coupler height.

Re-used the GP7 fuel tank / air tanks.  Not exactly correct but close enough.

Engine black paint on some of the GP7 mechanism that shows under the LifeLike GP18 side sills.

===========

I trust this will help a little bit .

[pjm20]

All,
  Thanks for the replies. For the LL chassis, I'm assuming that some chassis itself would need to be milled for a speaker if I wanted to go the sound route? It looks like there are  drop in DCC board replacements from TCS and ESU.

[amato1969]

I cross-kitted Atlas hoods onto Life-Like chassis for my Lehigh Valley geeps:



Full build thread here https://www.therailwire.net/forum/index.php?topic=36505.0