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I recently made it to a train show near Atlanta after a nearly 3 year hiatus, and lucked into a box of “stuff” for just $25. It was well worth it. Among the items were two F3 power trucks (front and rear) and two horizontal motors with spur gears on the ends. All of these parts were loose in the box, so I’m not even sure they are from the same type of F3, in fact I don’t think they are. After a good cleaning of the first truck and motor, I reassembled and found a sizeable gap between the motor’s idler gear and the truck’s worm shaft gear. It appears the two gears were maybe 50% - 60% engaged. I can see there would be a lot of factors at play here, and would like to hear from someone with a lot of F3 motor truck repair experience. Is this normal? And if not, what to look for?

Additional facts that may or may not be relevant

  1. Rear truck has no magnetraction and Front truck has good magnetraction – the rear truck may from a 2333 because it has the skinnier non-magnetic axles
  2. Both front & rear trucks have nylon idler gears and metal drive gears (at the end of the armature.)
  3. All gears appear to be in quite good condition, including the nylon idler gears – they show good shape on all teeth
  4. There is a fair amount of play on both idler gears
  5. A small amount of wear on both worm gears – they will be replaced
  6. Both trucks show the exact same issue, no matter how I mix and match motors & trucks, the gap is always there
  7. I will be ordering and replacing
    1. the idler gear assy complete with gears
    2. both worm gears
    3. At least one drive gear (inside of gear stripped, armature shaft still has good splines)


Original Post

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I can roll them by hand, and there's about a half-tooth worth of slack between the two. On the other hand, there is almost no slack between the armature's drive gear and the idler gear, although the idler gear seems rather sloppy on its shaft.

Their relationship is sort of fixed - the motor bolts directly to the truck frame, so there is zero adjustment I can make from the motor side (short of sanding down the motor mounts!), and on the truck side, the height of the worm shaft gear. The only way I can see that the worm shaft gear would be too low is if the worm shaft bearing was severely worn ... and its not - it's a nice snug fit.

If you look at the overall relationships, the drive gear mates with the idler gear which mates with the worm shaft gear. Three gears in a row that all have to mesh perfectly. Doesn't seem like a good design plan to me, but I'm not an engineer, so...

I did put one together and ran it, and it doesn't seem to behave badly, just a lot of slop between those two gears.

I read some articles on here earlier this week about someone who had repaired MANY of these in the past, @Jon G perhaps? I need to hear from someone who has seen many of these and knows if I'm missing something, or that's just normal.

thanks for your feedback!


Last edited by GeoPeg
@Jon G posted:

The idler bearing wears out due to lack of lubrication causing this slop in the gear mesh.  The idler is sold as an assembly; gear, bearing, rivet.  You just pry it out and press a new one in.

Thanks Jon, I'll be ordering parts tomorrow including drive gears, idler assy's, among other items. We'll see if that improves things.


Jon, do you have advice on how to change the worm gear without disturbing the axle bearings?  I have seen 622 wheel and axle replacement parts with the bearing already installed between the wheel and the knurling in the center of the axle.  Pushing the worm gear on the axle at the same time as pressing the axle bearing into the truck frame seem to be a challenge. I assumed that a shim was used between the wheel and the truck frame to get the axle bearing in the correct place.   The issue is having to press the knurling on the center of the axle through the axle bearing. This could score the bearing and could push it farther into the frame than it should be.

@Jon G posted:

If you are replacing the worm driven gears, be careful that you don’t push the bronze bushing into the truck block or the back of the wheel will bind on the block.

Thanks Jon, one of the first things I look at after pulling wheels is the backside of the wheel and how much of the bronze bearing is sticking out from the side of the block. Sure enough, this one had one wheel rubbing of the four.

Same as David Johnston above, I am curious as to your technique for magnetic axle replacement without scoring the new bearings. In the past, I have just shoved them in - the resulting scoring of the new bearing didn't seem to hurt anything, and it still rolled smoothly, but it goes against the grain to install new parts only to damage them during the process.

I have a non-scoring/damage process in mind, but it will require pressing the final bearing in with the axle in place. Special tool might be needed here. My first though is to grab my socket set and see if one will fit the bill. Appreciate hearing your thoughts?


Can say though that 2333/2343/2353 do not have any nylon gears nor our early switchers

623/624/ 6220 here at home.

What year they started with nylon not sure but OP mentioned rear truck may be from a 2333 which it did not come that way just so George knows what it is not .

Most of trains here in home are early postwar and prewar none of those have nylon in the gear train

Rob do you happen to know why they went to nylon was for cost savings or quieter operation or something else ?

@Dieseler and @ADCX Rob, my reference to nylon is one of guesswork. I suppose it could be made of some sort of plastic or even Delrin. I absolutely cannot attest to the age of these motors and trucks since that's how I got them, as just motors and trucks, 4 separate items. And this is really only the second time I have repaired a horizontal drive motor, the first being an early 2020 as I recall. IMG_5672

The pic above shows what I'm dealing with, I believe it is a 2343-196 gear and a 2343-187 Stud (Idler gear.) Although the gear teeth don't look too bad, the inside of the gear has a good bit of wobble on the stud mount. I have sourced the same white gear from Trainz, and the stud from both Trainz and Jeff, and a metal version of the gear through Jeff, although I forgot to ask about the thickness of his metal gear. This white gear appears to be thicker than metal gear, so I'll be asking him to take a quick measurement later.

I would be interested in learning any more identifying features of the motors, such as the use of this white gear, or even the hole used to punch the stud out of the block (both of my motors had this hole), the transition year from bronze sleeve bearings to ball bearings, the different brush plates used (mine are 2343-119), etc.



Images (1)
  • IMG_5672
Last edited by GeoPeg

Something is not making sense to me. The OP states these are horizontal motors. Lionel made F3s with this motor from 1948 through 1954. They switched to vertical motors in the F3s with the 1955 production. AFAIK, all the gears made during this time for the F3s were metal. There were no nylon, or other plastic gears. Nylon or plastic gears did not appear in Lionel production until the MPC era. And when MPC reintroduced the F3 in the 1970s, they went with the vertical motor, not the horitontal motor. Again, AFAIK, no horizontal motored F3s were produced after 1955. So MPC and follow-on entities would have no reason to make the idler gear, period. So it follows that the nylon gear in question is not original to the motor assembly. And it is not made by Lionel. So someone in the after-maket parts industry made it, as there is a need for this particular gear. I would be very curious what the hole for the stud looks like (is it worn or egg shaped?), whether the idler meshes well with both the drive gear and the truck gear, and how the gear compares with one from a low mileage 1949-1954 unit.



@lehighline posted: is not made by Lionel. So someone in the after-market parts industry made it..

The only online reference I have ever seen to the nylon gear is from Scott Griggs, both as a 2343-124 & 2343-196.  S&W has the -196 number on their parts list(and not the -124) but does not ID it as being nylon. The last F3s parts lists for the Southern show the metal -124.

Last edited by ADCX Rob

I took a look at the Lionel Engineering Standards to see what I could learn about gears. Nothing in this book is dated, but later items appear yo be in chronological order. I believe Lionel discontinued maintaining the Engineering Standards in the mid 1960s. For the 2333 gears, 2333M-14 and 2333M-17 were machined from cold rolled steel. The spur gear on the worm shaft, 2333-46, was machined from brass. An interesting point is that all of these gears have 14.5 pressure angle. All the 2343 gears have a 20 degree pressure angle. This would make the 2333 gears and the 2343 gears not compatible.   Lionel appears to have changed from the 14.5 to 20 degree pressure angle on all their gearing in about 1950  

The 2343 gears, 2343-124, 2343-111, and 2343-41, are all sintered.  I do not have access to the compositions of the materials used in the sintered process, but my guess is that -41 was brass and -111 and -124 are steel.  These are all 20 degree pressure angle gear profiles. Gear 2343-196 showed up late in the list. My guess would be late 1950s. None of the other 2343 gears show up again. It is made from Zytel #101 (nylon risen). Somewhere I read that the -196 gear was introduced to reduce the noise made by the horizontal motor F3 units. The sintered gears are not made with the precision of the machined gears and would be noisier.

Based on the sequence of the listings in the Engineering Standard, the first Lionel plastic gear would be the 1122-89, followed by the 2343-196.  These were followed quickly by the burro crane, track cleaning car, tie ejector, 68, 264, and lots of the accessories.   I do not see where any plastic gears were used in any locomotives other than those listed above.

Guys, some horizontal motors did indeed come with nylon drive gears.  The nylon gear extends ever so slightly beyond the bottom of the motor casting and is not interchangeable with motors with all metal gears.  If a truck came with motors with nylon gears you can't replace the motor with one with metal gears.  It won't mesh.  The metal gear will miss the brass spur gear on the truck.  Subsequently the nylon gear will bind the brass spur gear on the truck that came with metal geared motors.  A discovery I made while servicing/repairing.

Nylon geared motor on the left.  Even the motor casting is a bit different both on the top and bottom.

F3 MotorF3 Motor2F3 Motor3F3 Motor4


Images (4)
  • F3 Motor
  • F3 Motor2
  • F3 Motor3
  • F3 Motor4
@Johnsgg1 posted:

If a truck came with motors with nylon gears you can't replace the motor with one with metal gears.  It won't mesh.  The metal gear will miss the brass spur gear on the truck.  Subsequently the nylon gear will bind the brass spur gear on the truck that came with metal geared motors.  A discovery I made while servicing/repairing.

Very interesting - so the truck and motor must be matched.

Well if a decision can be made as to which motor I have based on the pictures above, then I would conclude I have the motor on the left, with a nylon gear. The rounded hump visible just below the field coil looks identical to mine.


Now as to matching the motor with the truck, my nylon idler gears do not bind with the brass spur gear on the truck when seated. Quite the opposite, they only engage about 50%-60% of the brass spur gear, what conclusion is to be drawn? My first thought was perhaps the nylon gear teeth are well worn. Although they don't appear to be worn, I believe that my eyes could be deceiving me. I guess I will know more when I get my new repro 2343-196 idler gears seen here from Trainz.

@Johnsgg1 do you know if Lionel assigned different part numbers to the matching trucks for metal idler gear equipped motors vs. nylon idler gear equipped motors?

And because the question was asked earlier in this thread about the hole that provides access to pushing out the idler gear stud, here's a pic. I wonder if that could be another distinguishing feature of a nylon idler gear vs. metal?




Images (4)
  • IMG_5674
  • IMG_5677
  • IMG_5680
  • IMG_5680_crop
Last edited by GeoPeg


Very interesting! Thanks for posting those pictures. Looks like I'm going to eat some of my words. You learn something new everyday. Do you know if the trucks are different, and if so, how to tell them apart? The rounded protrusion ahead of the armature makes it easy for the motor casting.



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