How to replace the drive gear of an MTH tinplate locomotive?

Can either the worm and/or the spur gear be removed on your new set, if so I would drill out the old shaft to removed the old spur gear and then cut the old gear shaft out.

Once the bearing are clear and clean, I would slide the new shaft into place and reinstall the gears.

Otherwise you will have to cut the frame to release the bearing and shaft.

Good luck

Totrainyard, I might end up doing that. The only problem is that the gears seem to be permanently attached to the shafts. I have heard that metal gears can be removed from the shaft if you heat them up with a blowtorch, which I unfortunately don't have access to at this time. I tried using a soldering iron instead, but that didn't work. I'll have to find another way to heat them up. Anyway, thank you for the suggestion! 

The early drives on these locos aren't easily replaced.  You have to cut the shaft with a dremel and remove the pieces.  Replacements available from MTH come with the cross shaft, side drive gear and worm driven gear that is secured with a set screw.

Jon G, do you know where I can buy one of those replacement gear assemblies? The MTH website has a parts search, but I can't find the option to buy a specific part. I was able to find this part, which appears to be similar to what you described, but the sizes of the gears don't look like they match the ones on my blue comet. Is there a different part I should be looking for?

The complete motor for the #263 is available from MTH, $114.  I added it to my cart and it said it was available.  Since I don't really need one, I removed it from my cart.

https://www.mthtrains.com/part/TP-OE00042

John, I think that that part is for the version of this engine with an AC motor built into the chassis and with a mechanical E unit. The one I have uses a DC can motor with an electronic E unit in the tender. I'm not sure if it will work. 

Well, you're right, it was the only part number I found for the #263 motor.   Findi ng those gears will likely involve getting MTH to assist you, maybe call Midge and see if she can track it down.

I hate to be a PIA, but have you determined why the gear stripped in the first place?

If not, the new gear might get stripped also.

@Blackjack4935 posted:

Jon G, do you know where I can buy one of those replacement gear assemblies? The MTH website has a parts search, but I can't find the option to buy a specific part. I was able to find this part, which appears to be similar to what you described, but the sizes of the gears don't look like they match the ones on my blue comet. Is there a different part I should be looking for?

The part you identified is for Std Gauge ProtoDrive motors.  They have both the individual O-gauge worm driven gears and the whole assembly.  Once you replace it with the new version, the worm driven gear will be easily replaceable.  Deb had a bag with those new gear assemblies and there is a part number assigned, but it may not have been posted yet.  Still furloughed, so I can't help with the part number, but Midge can check with Deb if you email her.

As for why it wore out, it's sacrificial so the worm gear on the motor doesn't wear out.  But, it's Chinese brass, so don't pull heavy loads, don't run it in a museum setting and keep it lubricated (not the easiest thing to do).

Roy, I'm not exactly sure what happened, but my theory is that the grease that was on the gears got old and started to harden, thus damaging the gear. When I took the locomotive apart, the motor's worm gear was almost completely submerged in thick grease which had turned green. I've removed almost all of the old grease, and I plan on doing a more thorough cleaning before I put in the new gear, so hopefully this doesn't happen again.  Jon, I had a feeling that the gear I was looking at was for standard gauge. I'm glad I didn't buy it right away! I contacted Midge about this a while ago, but I don't think I ever got a response. I'll definitely contact her again, now that I have a better understanding of what to do.   

As Jon says, that gear is a very common replacement part in many of the tinplate locomotives.  I've done a few of them in both STD and O-gauge.  I haven't seen the locomotive represented here yet, but it does look like you have to cut the old one out as Jon says.

I did that one quite a while ago.  PITA.  I think I had to press it out.  Press gear off new shaft, and press back on.  G

So I went back and looked at my notes.  First, you can press the shaft off.  Gears are pressed onto a splined/swaged shaft.  I have replace gears on diesel trucks and other engines.  The key in reassembly is location of the new gear and using spacers to ensure it gets positioned correctly during installation.

The new part assembly MTH came up with is now TP-OE00147.  This is a complete shaft and gear assembly that will not require pressing.  I have one in stock if you needed it. 

To get the old shaft off, you could press out on the side opposite of the idler.  Use a spacer to keep the damaged worm gear from moving as the shaft is driven out.  G

@GGG posted:

So I went back and looked at my notes.  First, you can press the shaft off.  Gears are pressed onto a splined/swaged shaft.  I have replace gears on diesel trucks and other engines.  The key in reassembly is location of the new gear and using spacers to ensure it gets positioned correctly during installation.

The new part assembly MTH came up with is now TP-OE00147.  This is a complete shaft and gear assembly that will not require pressing.  I have one in stock if you needed it. 

To get the old shaft off, you could press out on the side opposite of the idler.  Use a spacer to keep the damaged worm gear from moving as the shaft is driven out.  G

G, thank you for the information. Do you think I could remove the old shaft with a hammer and punch instead? I don't think I have access to a press of any kind.

You tend to deform the frame if you try to press/punch it out without proper support, and due to the design it is difficult to support.  I had better luck cutting it out and then flushing out all the debris.

I was wondering about that Jon, looking at those pictures, I couldn't see a good support for pressing it out.

Sockets and vise.  While I had a lionel press I never used it.  I do all my work with the bench vise and various sockets and broken drill bit to press wheels, and gears.  Punching is not the method to use.  I do use the flywheel and wheel puller that Timko makes, but the internal gear swaps and such are just basic tools and the vise.  C clips and flat steel can be used as spacer if needed.  G

I don't pound things out unless there's no other way.  I do have a press, and I use it for stuff like this is there's a way to brace the surface to avoid bending anything that I don't want bent.  Looking at this one, I'd probably go with Jon's method and chop it out with the Dremel.  Since the replacement doesn't need any pressing, that avoids any possible damage to the motor frame.

OK, dremel it is. It may be a bit of a challenge, since the frame might get in the way, but I'm sure it can be done. G, how much would the replacement part cost?