Help with MTH Motor

There’s a pair of similar motors on that certain auction site right now that appear to have that same gear, but different flywheels .....perhaps you can change them out as the pair to get you going?...this way the flywheels will be the same size?....I looked in my stash and I don’t have anything like that.......sorry.............Pat

I tried that already.  The gears a a bit shorter, so don't quite work.

Frank Timko can pull the gear off and put it on a new motor.

Timko Repair Depot

Its unusual to not be able to free it up by lubricating the bearings. If a magnet had separated from the case it wouldn't turn at all. Is there a space between the flywheel and case? You should be able to at least slide a business card between the flywheel and case.

Pete

What are the letters/numbers for motor identification?  looks like ** 3812?  That is the first clue.  Second, measure the length and diameter of the drive gear ( in millimeters).  That is how you can identify a replacement motor. Do not try and remove the drive gear from the motor.  It is virtually impossible.  Flywheels can be removed and replaced if you have a good gear puller.  

If all else fails, you can get intouch with The Motor Doctor, in Ohio, Albert Garlatti, 513-399-4035, motordoc@themotordoctor.com.  I had to do this for a Railking Mountain because a correct replacement could not be found.  Only drawback is it cost $70.00.

Good luck,

Bruce

Pete, I have one in captivity that has the same issue.  Don't know what happened originally, but it just turns hard and obviously gobbles tons of power.  I used oil, liquid wrench, etc. on it, nothing worked.  Flywheel and worm spacing looks fine and matched the new motor I got from MTH as a replacement.  It also had no rubbing on the armature like a magnet separated, don't know what happened to it.

Pete, yes there is space, with a little play.  It is even hard to move it up and down.  I have tried all kinds of cleaners, penetrating lubricants etc, but it is just really tight.

I can let is just sit there and run, but it gets pretty hot.

Any suggestion on the best lubricant to try.  I tried PB Blaster, WD 40, and some others.  They don't seem to do much.

Well that stinks.....ok, contact Perry at the Toy Exchange in Mt. Airy Md......you can find him on the web, shoot him an email (best way to get up with him) and see if he has what you need....he has a lot of older MTH parts...and I mean a lot!.....I won’t be going back up to see him until the fall, but I usually pop in 2 or 3 times a year and hunt for parts....it’s a real treasure hunt, ..........if push comes to shove, you and I can get together via email and give me the dimensions and I’ll hunt you one up next time I go....sad part is, I was just there a couple weeks ago......but like I said, if all else fails, I’ll try and hunt one at Perry’s............Pat

Any of those should free it up if lubrication was the issue, at least for a little while. I have gotten gears off while just about destroying the motor. Then drilling and tapping for set screw and drilling the bore for a sliding fit. But if Frank Timko can swap out the gear I would try him. I doubt he would charge 70 bucks for this.

Pete

Thanks all, I will give Perry at Toy Train Exchange before trying to get the gear pulled.

FYI:  The gear length is just under 24mm.

Bob,

Gear diameter is needed also (mm)

bruce

Gear width is 8.2mm, length just over 24mm, 23.70mm best I can guess.

Two DIY methods that you can try but have be careful with:

1. Place the motor can in a vise or clamp with the gear facing upwards. Take two flat blade screwdrivers of roughly equal size and place on either side of the vise with the blades up against the shaft and pry downwards on the screwdriver handles with equal pressure to try and lift the gear up.

2.  Place the motor can in a vise or clamp with the gear facing upwards and, if you have a small torch, like a plumber's torch, heat the gear until expands enough to remove it from the shaft.

No guarantees, but either method is potentially capable of working. I always try the heat method first and sometimes try #1 after the gear has been heated up.

I tried method #1 to remove the gear from a possible replacement motor, and it just pulled the interior bearing out so that there is too much play in the motor shaft, and the gear didn't budge.

I have been thinking of pulling out the torch and try method #2, so may give it a try later today.

If you use a gear puller and the heat method, you might have succeeded.  However, pulling on the gear shaft and securing the motor is about 99.999% sure to fail, I've sure never seen it succeed!  Even pulling the flywheel off without a wheel puller is a loser, and they're usually very easy to remove, the worm gear is REALLY on there.  I suspect they may have used a retaining compound to secure the worm, which is probably 75% why heat will help, it breaks down the retaining compound grip.

Even with heat, they’re a nightmare to try and remove....one false move and it’s toast....like John said, that gear is on there tight!.........Pat

The heat idea didn't do it.  Good think it was a motor that was already toast.  Guess I have to hope to find a loose motor out there somewhere.

It takes a lot of heat and a good puller. Thats why its near impossible to get off without destroying the motor.

Pete

I’d be willing to bet Perry has a chassis with those motors in it...if you say an SD9 is the same as......I do remember seeing boxes of full of chassis's there.....Perry is a super great guy, he’s just busier than one legged man in an *** kicking contest....I have no clue where you live, but if you’re anywhere near his proximity...it’d be worth the drive for spare parts.........Pat

Like I said, find the proper motor, regardless of the worm.  Sent it to Frank Timko and it'll come back with the worm on it without destroying the new motor.

Most of the time the press fit of the gear on the shaft is too tight to remove it without damaging the gear or motor. I've talked to Frank about this. The high current draw may be caused by deformation of the bottom of the can motor which cocks the lower bearing which will cause the shaft to bind. A couple of taps with a hammer near the mounting holes will bend the can and either align the bearing with the shaft or make it worse. It's a trial and error proceedure.  Another possibility is a loose magnet, but you typically hear it scraping on the armature.

I do have a motor with similar worm dimensions, but different flywheel that came from a DL-109, but the worm pitch typically isn't the same for steam and diesel, so fit isn't guaranteed.  I do all the repairs for Perry and have most of his individual parts.

Jon G posted:

Most of the time the press fit of the gear on the shaft is too tight to remove it without damaging the gear or motor. I've talked to Frank about this. The high current draw may be caused by deformation of the bottom of the can motor which cocks the lower bearing which will cause high current draw. A couple of taps with a hammer near the mounting holes will bend the can and either align the bearing with the shaft or make it worse. It's a trial and error  Another possibility is a loose magnet, but you typically hear it scraping on the armature.

I do have a motor with similar worm dimensions, but different flywheel that came from a DL-109, but the worm pitch typically isn't the same for steam and diesel, so fit isn't guaranteed.  I do all the repairs for Perry and have most of his individual parts.

May I contact you off-line Jon?....Id like to see if you have a few goodies I’m looking for....thanks........Pat

Jon, awesome advice!  A few lucky taps and the motor spins with ease!  THANKS!

Also, the Steam Turbine is the massive C&O Coal turbine, a steam/electric, so the Dl-109 motors might just work.  Will keep you posted after I install my 'fixed' motor.

Interesting about the motor being deformed, I'll have to keep that in mind!  Nice tip!

All is well again, the engine is up and running!  Thanks for all the help!

Does the end of the motor/bearing area get deformed by over tightening the screws that hold it in place?

No, usually a hard drop during shipping causes the damage.