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Seeking Advice on a steam loco "chassis transplant"

LW Lee WillisOGR Forum Member

The two photos below show a “chassis transplant” project I am about to start.  I  am soliciting advice, tips, and suggestions, and particularly interested in hearing from anyone who has transferred drive trains, including valve gear, etc., from one cast steam loco to another, or made their own.  First the photos, then some explanation.

Recipient of new drivetrain and electronics, 2921.  Donor, 3759.

Slide1

Wheels and wheelbase look to be fairly good match. 

Slide2

 

I hope to transfer the electronics and running chassis from the lower of the two (Legacy 3759) into the upper of the two (very old scale MTH  that no longer runs).

The 2921 Northern shown is my favorite looking loco, period, partly because the 2900s were big and beautiful, and partly because MTH used the same boiler casting for this Northern and its 5012 (top in photo 1) so this loco is a bit longer than it would prototypically be – a plus in the looks department.  Note how much larger it is than the 3759.

The Legacy 3759 is one of two I have.  This one succumbed to a slight accident and lost its rearmost axle (back of the two under the cab).  Two new bearings/retainers would fix it completely – an easy repair that would take an hour to an hour and a half : I would not even order new bearing pieces, just make my own. 

What I intend to try is to transfer the entire running gear and chassis of the 3759 into the body of the 2929: perhaps best to look at it this way: transfer the body of 2900 to the 3759.   Given that works well, I would then transfer the electronics and speaker from one tender to the other.   There appears to be room for this to work.  I’ve done similar transfers on a slightly smaller scale in the past (i.e., WBB chassis into a Lionel Mogul). 

Keep in mind I run only conventional.  I have thought about other options and decided not to pursue them, including:.

  • I could buy another used PS1 2921 – and have another old, potentially troublesome loco with semi-obsolete technology. 
  • I could add a third party electronics board with sound and cruise to my 2921 or upgrade it to PS2 or 3 – but it would still be step behind the best Legacy, which has spoiled me. 
  • I could buy a 3rd Rail ATSF 2900 Northern.  Well, actually, I did.  It didn’t look quite as good (it is more detailed but prototypically accurate in length, so not quite as impressive), and rather to delicate to be a constant runner, and with its TMCC electronics it does not run nearly as smoothly as my Legacy locos. (No loss though, it’s in a display case at work where people love it!)

Frankly, I think it only 40% likely I can pull this off.  But to me, it is a bearable risk:  it’s a fun project, and maybe I can put 3759 back together and repair it if the transplant does not work, Butif it does, wow!

 

I appreciate all suggestions.  Comments that there are other options, that I am crazy, or that I spend or risk too much money on toy trains and silly projects will have no impact, however, as I already know these things.

 

 

Thanks,

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B BASEMENTBILLOGR Forum Member
Originally Posted by Lee Willis:

The two photos below show a “chassis transplant” project I am about to start.  I  am soliciting advice, tips, and suggestions, and particularly interested in hearing from anyone who has transferred drive trains, including valve gear, etc., from one cast steam loco to another, or made their own.  First the photos, then some explanation.

Recipient of new drivetrain and electronics, 2921.  Donor, 3759.

Slide1

Wheels and wheelbase look to be fairly good match. 

Slide2

 

I hope to transfer the electronics and running chassis from the lower of the two (Legacy 3759) into the upper of the two (very old scale MTH  that no longer runs).

The 2921 Northern shown is my favorite looking loco, period, partly because the 2900s were big and beautiful, and partly because MTH used the same boiler casting for this Northern and its 5012 (top in photo 1) so this loco is a bit longer than it would prototypically be – a plus in the looks department.  Note how much larger it is than the 3759.

The Legacy 3759 is one of two I have.  This one succumbed to a slight accident and lost its rearmost axle (back of the two under the cab).  Two new bearings/retainers would fix it completely – an easy repair that would take an hour to an hour and a half : I would not even order new bearing pieces, just make my own. 

What I intend to try is to transfer the entire running gear and chassis of the 3759 into the body of the 2929: perhaps best to look at it this way: transfer the body of 2900 to the 3759.   Given that works well, I would then transfer the electronics and speaker from one tender to the other.   There appears to be room for this to work.  I’ve done similar transfers on a slightly smaller scale in the past (i.e., WBB chassis into a Lionel Mogul). 

Keep in mind I run only conventional.  I have thought about other options and decided not to pursue them, including:.

  • I could buy another used PS1 2921 – and have another old, potentially troublesome loco with semi-obsolete technology. 
  • I could add a third party electronics board with sound and cruise to my 2921 or upgrade it to PS2 or 3 – but it would still be step behind the best Legacy, which has spoiled me. 
  • I could buy a 3rd Rail ATSF 2900 Northern.  Well, actually, I did.  It didn’t look quite as good (it is more detailed but prototypically accurate in length, so not quite as impressive), and rather to delicate to be a constant runner, and with its TMCC electronics it does not run nearly as smoothly as my Legacy locos. (No loss though, it’s in a display case at work where people love it!)

Frankly, I think it only 40% likely I can pull this off.  But to me, it is a bearable risk:  it’s a fun project, and maybe I can put 3759 back together and repair it if the transplant does not work, Butif it does, wow!

 

I appreciate all suggestions.  Comments that there are other options, that I am crazy, or that I spend or risk too much money on toy trains and silly projects will have no impact, however, as I already know these things.

 

 

Thanks,

 

Hi Lee, first things first. If you don't want another calamity to happen to these fine engines, please, please, get some more support under your shelving. If your pictures are any indication of what you're using to support what must be many pounds of die cast metal, you definitely need something stronger. And, I think this will be a very interesting thread. Look's to be quite the ambitious project. Keep the pic's coming. Bill

Gilly@N&WGilly@N&WOGR Forum Member DIGITAL SUBSCRIBER

I can see the transfer of electronics as very do-able.

 

Assuming you're a master machinist, the next part is only slightly more difficult. As for the mechanicals, strip both engines to their bare frames. Laser scan and/or make detailed CAD drawings of both frame assemblies. Maintain the perimeter dimensional data (engine shell mounting) for Engine "A" and drivetrain dimensional data (motors, axles, etc) for Engine "B".

 

Setup your CNC Machine and cut a new frame section from piece of billet aluminum; integrating the appropriate dimensions from both frames. Polish, hard anodize the completed piece, and reassemble. Piece of cake....

 

Even with this scenario, you risk damaging both engines beyond repair. If the plan is to fix your dead engine, I'd suggest sending it to JDS Ltd and just stroking Jeff a check. They do some pretty cool stuff and IMHO can meet or exceed Legacy features/capibilities. You could even sell the Legacy "donor" on the Buy/Sell Forum to pay for it....

 

Gilly

 

I'm not 100% sure on this, but I'd expect dimensional accuracy needs to be more on the order of 0.005". You may get by with 0.010", but I'd be extremely surprised. 

Last edited by Gilly@N&W
LW Lee WillisOGR Forum Member
Originally Posted by Burlington Route:

Ok, I'll ask...what officially died on the MTH engine- Electronics{big shock, there}...motor{easy repair}...gearing{tricky but do-able}...? I'd like to see you keep "both" running.

Well, the electronics died twice in the last eight years.  Second time it would not even given the three clanks of death - completely gone - so I installed a rectifier and at least it would run forward.  It's mechanicals are old - it always had an amazing amount of play and "slop" in the drivetrain but ran okay.  Lately it makes ominous grinding noises from underneath so I have stopped running it. 

Burlington RouteBurlington RouteOGR Forum Member

Hmmm, for the electronics you could go ERR for command or a simple E reverse board for both directions......for the gearing you could try MTH for new gears or possibly north west shortline for better ones or even a whole new gear drive{box}.

I'm playing with a MTH K4 with no board at the moment and am trying to decide whether it's going to be my Aeolus project or for the armored war train{probably a diesel for that}.

If you could somewhat easily swap drives, what are you going to do for 3759 - new drive for that?

 

Last edited by Burlington Route
TS Ted SOGR Forum Member DIGITAL SUBSCRIBER
Lee, IMO Gilly is right it will be very difficult to get the mounting points from the Lionel chassis to line up with the MTH boiler shell.  I never liked the gear ratio MTH chose for these big, high drivered 2900's.  My thoughts- just build a new chassis for the MTH model from scratch.  Use a nice big flywheel and a proper gearbox from NWSL.  Bob Turner posted a series of articles about chassis building in OSN 48/ft magazine circa 1999.  He can be found on the 2-rail scale forum if you have any questions.

Once you have a mechanically sound chassis it wont matter what electronics you use.  Depending on how it's geared you might not need speed control.  My $.02.  -Ted
LW Lee WillisOGR Forum Member
Originally Posted by Ted Sowirka:
Lee, IMO Gilly is right it will be very difficult to get the mounting points from the Lionel chassis to line up with the MTH boiler shell.  I never liked the gear ratio MTH chose for these big, high drivered 2900's.  My thoughts- just build a new chassis for the MTH model from scratch.  Use a nice big flywheel and a proper gearbox from NWSL.  Bob Turner posted a series of articles about chassis building in OSN 48/ft magazine circa 1999.  He can be found on the 2-rail scale forum if you have any questions.

Once you have a mechanically sound chassis it wont matter what electronics you use.  Depending on how it's geared you might not need speed control.  My $.02.  -Ted

Thanks, its a good option, if necessary.

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