MTH motor gear puller recommendations?

I use the great plains gear puller.  The pins are too short, so I buy drill rod from McMaster and sleeve it to fit the threaded shaft on the puller.  If the gear is too close to the motor housing, but the motor is trashed, I just hammer the opposite end to drive the gear and shaft out of the housing a little so the plate fits under the gear.

Pulling the worm off the motor is not an easy task.  It will require considerable heat and force.  I use the Great Planes Pinion Gear Puller for 2-5mm Shafts Hi-Strength, and it's not always up to the task.

Thanks Guys!

GRJ, I have that puller. The shafts supplied with mine, didn't fit. As you know, the opening of the outside of the gear is larger than the actual diameter of the pinion shaft. So, for me, a couple of cranks, and the puller's shaft is at the point where it's where the opening is smaller. The pinion shaft is somewhere in the neighborhood of 2.20mm, the puller's shaft won't reach on the puller I got from them? As for the puller, yes a little heat from a jeweler's torch, and the gear would remove nicely.

Thanks Jon G., I have some drill rod ordered, I've already fabricated a sleeve, so now it's sit and wait for the rod. I'm pleased to hear you've suggested, exactly what I have planned to do.  -Joe

@Jon G posted:

I use the great plains gear puller.  The pins are too short, so I buy drill rod from McMaster and sleeve it to fit the threaded shaft on the puller.  If the gear is too close to the motor housing, but the motor is trashed, I just hammer the opposite end to drive the gear and shaft out of the housing a little so the plate fits under the gear.

Typically, if I'm trying to remove the worm, the motor is shot, so I don't care what happens to it.

I have successfully replaced several worms in SD-type MTH products.  I have two steel plates machined so they can nestle under the gear, long enough to rest on vice jaws, and bolted together with two more steel plates and machine screws.

It is really important to minimize shock to the motor, so I create a bed of rags about a half inch below the motor, big enough to catch it.  Then I heat the worm with a torch - doesn't take long for it to get to maybe 400 degrees - and pop the motor shaft with a nail set and a hammer. "Plump."  Don't heat the rags.  If it doesn't pop off with two hammer blows, re-heat.

My experience with impacts to the motor shaft is it frequently slides the commutator assembly on the shaft and kills the motor.

I have modified my Great Planes puller to push off gears from 385/365 motors…..on the advice of Pete, ( Norton ) I cut off the smaller pin end ( the one that always wants to bend) and bored that insert to accept drill bit blanks. So far so good with a little heat ….So far with this new tooling, I haven’t run into a gear I couldn’t push off all the way…..

Pat

Thanks one and all!!! I'm pleased with the informative replies and creativity!!! Thank you!!!

So I took a hollow square stock steel, machined a thin groove in the bottom, slotted length wise.  Drilled a threaded fne pitch hole on top side, machined a bolt to accept proper sized drill rod.  Slide motor worm up into slot, place in vice, screw bolt down, push motor off worm.

If motor is bad, you could just cut shaft off with worm.  Then easy to place worm on vice with gap, and punch out shaft.

If motor good and worm is bad, I use a dremel and cut a slot along worm gear where it attaches to shaft without going all the way through into shaft.  You can do both sides.  If you get it just right the worm might even crack along the cut from the stress.  Even if it doesn't it is now much less force to push it off the shaft.

Pressing an item is always less dynamic then hammering punching something off.   G

@harmonyards posted:

I have modified my Great Planes puller to push off gears from 385/365 motors…..on the advice of Pete, ( Norton ) I cut off the smaller pin end ( the one that always wants to bend, and bored that insert to accept drill bit blanks. So far so good with a little heat ….So far with this new tooling, I haven’t run into a gear I couldn’t push off all the way…..

Pat

I tried my GP puller with my new pin that you made for me on the first motor, and the worm slid right off with a little heat.  I think it's a keeper.

@gunrunnerjohn posted:

I tried my GP puller with my new pin that you made for me on the first motor, and the worm slid right off with a little heat.  I think it's a keeper.

Very good John, glad it’s working in the field…..I was curious how well it would work in another shop, so hopefully this can be a repeatable solution…..the technique I do is once you get past that initial “ it’s moving “…….don’t stop!…🤣🤣🤣🤣

Pat

Yep, once I feel movement, I just keep cranking.

@harmonyards posted:

Very good John, glad it’s working in the field…..I was curious how well it would work in another shop, so hopefully this can be a repeatable solution…..the technique I do is once you get past that initial “ it’s moving “…….don’t stop!…🤣🤣🤣🤣

Pat

I ordered one of the pullers.  Can we get a picture showing the modification?  I think I've got some dead motors in my junk stash to try practicing on.

Jim

@Jim Sandman posted:

I ordered one of the pullers.  Can we get a picture showing the modification?  I think I've got some dead motors in my junk stash to try practicing on.

Jim

You pretty much need a lathe. Easiest to take one of the existing punches, cut off the end at the larger diameter that fits in the screw, then find a drill bit the same or close to the same size and drill a hole in the shank you just cut the end off of and cut the drill bit shank off and put it in the hole. Optionally find some bits the same diameter as the screw hole and turn down the drill bit shank to size. A carbide cutter will cut high speed steel.

The most useful size will use a drill bit slightly smaller than the Mabuchi 385 shaft size.

Pete

Pete is correct, ain’t happening without a lathe operation,…..the modification requires a good centering, and parallel to the threaded arbor,…..if it’s crooked, or wobbly, you won’t get a straight push, as some of those gears are on there with plate tectonics force….this is what the altered tool looks like, and another shot of it doing the deed….those that have this tool, and need it set up for Mabuchi 365’s, 385’s etc,….may contact me via profile and we can go from there….

Pat

Wow! Exactly what I did, even before seeing these commendable results! Something like "good minds think alike", or I was just lucky!!! -JoeC

Some great posts on what looks like may be not so easy of a  job. Working as a mechanic for years especially in rust country. The coming apart was always the tough part. The new parts went on with relative ease.

Once you have the worm gear off and the new motor in hand. How do you install it on the new motor ?

@Dave_C posted:

Once you have the worm gear off and the new motor in hand. How do you install it on the new motor ?

1 ton arbor press.

@Dave_C posted:

Some great posts on what looks like may be not so easy of a  job. Working as a mechanic for years especially in rust country. The coming apart was always the tough part. The new parts went on with relative ease.

Once you have the worm gear off and the new motor in hand. How do you install it on the new motor ?

Perfect bore for slip fit, counter bore for set screw, …..both the gear & the flywheel,…

Pat

@harmonyards posted:

Perfect bore for slip fit, counter bore for set screw, …..both the gear & the flywheel,…

Not happening with my tools, so I'm happy to be able to pull them off and press then on with my press.

Admittedly, I was reluctant to post my question on the "gear puller", however with the collection of replies, the posting is a winner!!! Personally, as many of the group members are, I'm an old-time mechanic! Back in the day, we used to refer to two classifications of mechanics; Ones that "actually fix things", and "part changers"!!! I can see that most, if not all of the contributors to this posting, are "actual fixers", like myself!!!   Enjoy!!!  -JoeC