Swap Atlas Classic U25B shell onto Atlas/Kato U25B mechanism, or vice versa?

[atsf_arizona]

Hi,

Has anyone swapped Atlas Classic U25B diesel loco shell onto the older Atlas/Kato U25B mechanism, or vice versa?

Do they fit without any problems?   Or any "filing modifications" needed?     

I am contemplating buying an older Atlas/Kato U25B (to get the fast speed-motored mechanism), and then swapping the shells between the Atlas Classic mech and the Atlas/Kato mechanism.

Basically, I want to swap Atlas Classic U25B SP Bicentennial shell onto the older Atlas/Kato mechanism, so that I can (in DC), MU the SP U25B Centennial with my Con-Cor U50, thus have two locos with approximate same speed mech's.


Thx   

-----------------

Note:   (if you happen to be getting out your calipers out to check for me)..............

I have noted from Spookshow's loco encyclopedia and my own investigation, that the Atlas Classic U25B shell has these
"tabs" that fit into the "notches" in the mechanism. 

Thus when removing shell, now that you know those tabs are there, you should *very carefully* use a small screwdriver (i.e. the "toothpick technique")
to spread the Atlas Classic shell (and I suspect the Atlas/Kato shell) in such a way as to to avoid breaking the tabs or damaging the shell when removing it.

When you are doing that, be very careful about not bending the Atlas Classic long brass wipers that go from the mechanism to the trucks (don't ask how I know that):



I.e., work carefully,  I did just "tap the ends of the shell off", but I did it carefully, knowing about these tabs and releasing them gently as I worked the shell off.

-------------

It appears from the photo above, that the underside of the Atlas Classic U25B shell has the flat surfaces needed to sit on the Atlas/Kato mechanism "lip":

Atlas/Kato U25B mechanism: 

Atlas Classic mechanism: 

---------------

Thx again for any experiences / advice / tips.

[Lenny53]

 

I am contemplating buying an older Atlas/Kato U25B (to get the fast speed-motored mechanism)

  As i remember the original U25Bs were not that compatible with the speed of other Kato drives at that time as they had different gearing that caused them to run slower.

[rrjim1]

If your just looking for a faster running mechanism, than IMO it would be much easier to just replace the scale speed Atlas motor with a high speed Atlas or Kato motor.  You would just need to use the original flywheels with what ever motor you choice to use.

[mecgp7]

The Atlas Classic shell and Kato shell are interchangeable without modification. I've done it many times.
With a tune-up my Kato versions run better and more quiet than my Classics.

[SecretWeapon]

Hey John!!  I've done it also. But if IIRC, the handrails were the problem. The Kato version is a great runner.

[atsf_arizona]

Thank you, all, for the excellent input.

[Albert in N]

On the Atlas/Kato mechanism, the lights are small push in to slots on front and rear.  This is similar to many earlier Kato, as well as Atlas/China diesels.  Both Atlas and Kato parts are out of them.  Does anyone know where new clip-in bulb assemblies can be purchased?  I still run DC using conventional MRC Tech4 powerpacks. Otherwise, is there a source for small bulbs to replace burned out or dim ones in the clip assembly?  Ideally, there would be replacement clip in LED bright light assemblies.  Look at ATSF_Arizona's Atlas/Kato assembly photo (the one with Rapido couplers) to view the clip-in  bulb assemblies at front and rear (two separate units, one at each end).

[SecretWeapon]

There's a guy that sells old parts. soo much stuff. he has a store on ebay.

[atsf_arizona]

Tips on removing the shell from the Atlas/Kato version of the U25B?

The "lip" on the Atlas/Kato version of the U25B prevents me from getting in to release the shell retaining tabs that my U25B Atlas Classic photo shows.

Ron Bearden's tips on doing this from Oct 2013:  https://www.therailwire.net/forum/index.php?topic=30702.0  ....... trying them, but the shell won't budge.  Still mysterious to me.

Atlas parts diagram for this Kato-made loco here, isn't much help either, tried following instructions..... still mysterious to me:   http://www.atlasrr.com/pdf/N%20GE%20U25B%20Loco-Japan.pdf

Thx for any tips.

[johnb]

John, the pickup on the Kato chassis sucks, get a motor and swap it out.

[atsf_arizona]

OK, I managed to get the shell off.   When I get some time soon, I'll take and post some pictures, so that we have documented, what the inside of this shell looks like, where the mounting tabs are, what I had to do to get the (very tight fit) shell off.

The mechanism is also noisy, so per the following thread:  https://www.therailwire.net/forum/index.php?topic=40758.0   I'll see what I can do to quiet the mechanism down.  While I'm at that, I'll take some pics of the mechanism laid open, and post so we have that documented as well. 

In the process of getting the shell off,  I managed to have the rear truck drop out and fall apart.  So, the truck wiper mechanism that's referred to above, as well as dis-assemble and re-assemble these trucks, I'll take pics to document them as well.   Stay tuned (it'll take me a few days to get to taking/posting the pics).