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This is a recent acquisition from “mowingman” who happens to live just 30 minutes away. It’s a “in need of a total restore but fabulous engine and tender combo”. Probably a 47 or maybe a 48. Not quite sure but mowingman thought the earlier. In the transaction I got to actually meet in person a fellow forumite and tour his setup to boot. My train efforts pale in comparison to him as well as to most of you!  Great fun.

The engine has some wear but I think it will come out real nice.  Still barn fresh. Missing a couple of hard to find items (boiler front and steam chest) but after checking with the TrainTender and others I found TrainWorx In Pennsylvania had both after a referral from Harry Hennings. The boiler front is a new repro hard casting that TrainWorx is just starting to crank out. I’ll share that when I get it.

Photos below. At this point I’ve completely torn down the engine.  It did not run. It was so gunked up the brushes were stuck up in the tubes. Did not seem to be oil on the brushes but was fouled with carbon black.  They cleaned up nice.

Test runs smooth as can be.  This is the loose bearing variant 671m-1 I think.  Anyway it had 11 bearings total.  I reassembled it and then remembered I had a leftover bearing cage with five ball bearings from a 726RR rebuild.  So I redid the setup with 11 bearings in the rear and the bearing cage in the front.  It seems to run better with more bearings. Fit up really well and with one extra shim on the front it has a hair under 0.01” axial play.  Much better than my other motor.

NOW MY QUESTION and the reason for the post: on both of these engine rebuilds I have not been able to completely remove the armature.  I see in other threads that it can be done.  For me the shaft end with the worm is always too large in diameter and it simply cannot pass through the front oilite bearing.  What is the proper procedure?  

In the end feel fine with my result as I thoroughly flushed the rear with oil.  Same with the oil hole and front bearing.  Then reloaded the shims and loose (rear) and caged bearing (front) with grease.  Any thoughts welcome...I thought about spinning it under power and hitting the worm with a 600 grit wet-o-dry sandpaper but in the end got lazy.

The first photo used with permission from Jeff Thomas, all others mine.

lionel 726 plus 2426w side1FD845AD-FA12-4C62-BF99-C2B19747C8DA07A667FC-05BA-4399-BB60-6FD04381E09400461099-65B3-44D1-B783-EE69BEB862A9


Images (4)
  • lionel 726 plus 2426w side
  • 1FD845AD-FA12-4C62-BF99-C2B19747C8DA: 70+ year old dust!
  • 07A667FC-05BA-4399-BB60-6FD04381E094
  • 00461099-65B3-44D1-B783-EE69BEB862A9: I’ve always felt this style engine is a work of art.
Original Post

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On your 671M-1 motor, I checked some of the parts in the Lionel Engineering Standards. The rear bearing is 671M-20 and, by design, has an ID of 0.191”.  The front bearing is 2020M-20 and, by design, has an ID of 0.1875”. The armature is 671M-6 and has shaft 671M-7. The design of the worm on this shaft shows a Do (maximum diameter) of 0.186”. So the worm should fit through both bearings, but the front bearing is tight. You may want to examine the worm to see if it has developed a slight bur or lip at the edge where it slides on the worm wheel. If so this could be cleaned up with a fine flat file.

The balls that belong in the motor for the thrust bearing are 671M-21. They have a diameter of 0.0625.  The caged thrust bearing is 681-121.  The balls in this bearing are 0.062” in diameter.  These parts should be interchangeable if the OD of the cage fits in the housing. With these tiny balls wear is possible.  When I work on a motor I like to change all of them to be sure they are all the same diameter and will share the load. Mc Master Carr carries precision balls in this size for a very reasonable price.  

Wow.  Thanks for the detail David.

So first thing to confirm I used all the original loose balls in the rear and one could assume they are all the same size... BUT on principle, proper maintenance practice would be too replace them all, correct?  If so I may do that.

They are really old course so it makes sense.  (I wrench my own vintage bike builds and rarely don’t always replace old bearings).

Your data gives me confidence to clean up the shaft just enough to let it pass.  I will go with loose bearings.  More balls to carry the load (also my practice with bikes!).  Thanks.

ADD: I can feel a small raised edge on the side of the groove on the shaft that was cut for the e-clip.  Just a quick deburring with a fine file should do it.  Amazing what you can see if you look.

Last edited by Obuckler

Success!  So glad I did this. You can see all the gunk that came out after I thought I was done.  Now for new bearings.  And I need to flatten the commutator face per David’s instructions I found from 2016 or so in an old post. So double thanks David. I am doing this because my test runs clearly showed some skipping of the brush contact and you could feel an edge of the commutator segment was higher than it’s adjoining segment.  Now to drill a hole in a chunk of metal and find my extra fine garnet sandpaper.  Thank goodness I’m also a woodworker. TOO MANY HOBBIES :-) !!396063AE-99F3-4421-A68B-DDA1821AFCC7


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  • 396063AE-99F3-4421-A68B-DDA1821AFCC7
Last edited by Obuckler

B478E196-46D3-4895-8401-016C319A482DThanks Jeff.

I am currently in a holding pattern. The motor will remain unfinished because I decided the brushes were oil-fouled not carbon dust dirty.  So I still have the tender to take apart to make a list of any needs there before I place one parts order.  In the meantime I refurbed the e-unit which just needed a tear down and cleaning.

And back on the motor I did one last final polish on the commutator.  It shines now for sure.  


Images (1)
  • B478E196-46D3-4895-8401-016C319A482D

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