Rather technical Atlas SD7/9 question

[daniel_leavitt2000]

Since I never owned an A/K or A/China SD9, I always assumed they were basically the same model, like the U25 and RS11. It wasn't until this week when shell swaps were brought up in another topic that I found out they had different widths.

So, now I am wondering, was there any commonality in the tooling? I know the trucks are interchangeable. What about the handrail sections? Did the shells share the same side slides? Or was this a totally new model?

[SP-Wolf]

I swapped out the old A/K side sills with the new A/China version. No issues what so ever.

The 4 units on the right are the old version - the one unit on the left is the current version. All I changed on the old units was the side sills. The hand rail portion is the old version.


Here they are assembled - in reverse order. The left 4 are originals with the current side sills/frames. The far right unit is a current one.


As far as I can tell -- the body shells are exactly the same. About the only difference is the new version is DCC ready - IE- drop in. So, the new unit has new side sills and a new mech. - That's it. All else is interchangeable.

Regards, - hope this helps
Wolf

[nickelplate759]

As far as I can tell -- the body shells are exactly the same. About the only difference is the new version is DCC ready - IE- drop in. So, the new unit has new side sills and a new mech. - That's it. All else is interchangeable.

Regards, - hope this helps
Wolf

I disagree.  The examples of the new body shells I have are narrower inside.  They don't fit on the old Kato mechanism.  I actually tried this.

[SP-Wolf]

I disagree.  The examples of the new body shells I have are narrower inside.  They don't fit on the old Kato mechanism.  I actually tried this.

Thanks, George

As all I did was change the side sills (I used the old hand rails and shells) -- worked great.

Regards,
Wolf

[daniel_leavitt2000]

I may have to buy a few to play around with. And compare to the B-mann and LL SD9. Gotta have some units to go with my new U25Cs.

I wonder if Atlas would sell me the old LL SD9 tooling cheap. 

Northeast Locomotive Works.... I like the sound of that.

[central.vermont]

No no no it should be called
the Leavitt Locomotive Company that way you could say it was an LLC!! 

Jon

[eja]

I wonder if Atlas would sell me the old LL SD9 tooling cheap. 

Sure they would, but it's probably stuck in that closed factory in China!

[daniel_leavitt2000]

Sure they would, but it's probably stuck in that closed factory in China!

Oh but it isn't! Walthers never used that factory.

Tangent: I wonder if this means we'll see an Atlas Evans X72. Bryan was trying to use Walthers original tooling back when he started work on his project, but they quoted him more than it would have cost to tool his own shell. If tooling hasn't begun work yet, maybe he can team up with Atlas.

Another tangent: I really think it's time we started some model comparison threads with high quality photos of the same prototypes. AC4400s, SD9s, F7s, GG1s etc. I love those face-off style threads.

[dmidkiff]

I was able to get a newer Atlas China SD9 to fit the old Kato chassis with some minor sanding inside the shell. From what I can tell, the exterior of the shells are identical. The interiors are a bit different due to the different chassis.

The older shells have a thinner wall across the center of the shell to fit the excess metal around the motor in the old chassis. The newer shells are the same thickness throughout with the addition of 4 tabs, 2 each front and back that fit with pressure on the chassis.  The picture below shows the two shell interiors; note that I have already sanded smooth the interior of the new shell and thinned it a bit around the motor.



Here are the two chassis', old Kato on top, new China on bottom. The metal area covering the motor on the Kato chassis is too wide to fit the new shell over. I took my Dremel with a drum sander and took some material off, then finished with a large bastard file to clean it up just a bit. You'll also need to chamfer the top of the chassis on both sides otherwise the newer shell with bulge even if it slips over.



You can see the chamfer on the top of the chassis in this photo.



Here is the shell sitting on the older chassis.



And with the sill.



I also found that the newer trucks do not work with the older chassis.  The little tabs on the chassis, forward of the pickup strips interfere with the top of the truck casting. I'm sure these could be removed from the frame, but I haven't tried yet.

Lastly, forgive me, but I did not take measurements on any of this work. I kept sanding and fitting until things went together smoothly. This should be a pretty simple process for those on this forum if they want to use the newer shells on the older chassis'.

Hope it helps.

Doug

[daniel_leavitt2000]

So the outside of the shell is still the same, making the newer models wide bodies?

[dmidkiff]

I measured each end of the hoods this morning, everything is 0.47", so the exteriors are exactly the same width.

Doug

[nickelplate759]

I measured each end of the hoods this morning, everything is 0.47", so the exteriors are exactly the same width.

Doug

0.47" works out to N-scale 6' 3.2".   That's within 0.02" (actual) of 6' (scale).