Re-motor NOISY Plymouth MDT

[bpickering]

Hello again, and happy holidays,

I've got an ancient HO-scale Plymouth MDT, made by (I believe) AHM in the late 70s (estimate from my memory of getting it in my early teens.) Cute little bugger, and would be nice to use doing industrial switching on both the layout I'm building now (small time-occupier while waiting for co-engineer to be old-enough to help out with building a larger layout) and the bigger layout I'm planning for the future.

After cleaning off the wheels with a wire brush, I'm not getting the sparks as it runs along the rails (yes, they were THAT dirty... sitting in poorly-sealed storage boxes for 20 years does that, I guess) and it runs smoothly, even over insulated frogs at relatively slow speed- pretty-good for only four-wheel pickup. [:)]

HOWEVER... the thing has always been more than a little noisy- this is easily the loudest of all my engines. Since I'm planning on installing sound in as many locos as possible, having this electric-razor-sounding engine will be a serious breaking of the Fourth Wall. [V]

I've never jumped into the re-motoring biz before, so don't know all the questions to ask. It would help if there is anyone out there who has already re-motored one of these little buggers. I expect that with the plastic worm-gear/pinion drive, it's never going to be as silent as my P2K & Atlas engines, but I would like to get it down to something less than a dull roar. [:D]

Leaving adequate space inside for details would be nice, of course. The existing motor is a quite large open-frame motor, occupying most of the cab space, so I wouldn't be surprised if it was possible. A quiet one-for-one size-wise replacement would still be preferable over something that sounds like an airplane engine revving up. [:D]

If this works well, my next re-motoring project would be the Spectrum Doodlebug, which is almost as loud.

Brian Pickering

[Anonymous]

Not sure how to go about remotoring it, but here's a few tips that might help with the existing drive system. Try cleaning the commutator of the motor with a track-cleaning block - I did this with a couple of locos recently and they were transformed - just hold the block gently against the commutator while the motor is turning to clean it. Also worth checking is that the worm and gear are properly meshed. Finally, try adding a little grease to the gearing and a drop of oil to each motor bearing - this will often solve a lot of noise problems.

[bpickering]

QUOTE: Originally posted by Railroading_Brit

Not sure how to go about remotoring it, but here's a few tips that might help with the existing drive system. Try cleaning the commutator of the motor with a track-cleaning block - I did this with a couple of locos recently and they were transformed - just hold the block gently against the commutator while the motor is turning to clean it. Also worth checking is that the worm and gear are properly meshed. Finally, try adding a little grease to the gearing and a drop of oil to each motor bearing - this will often solve a lot of noise problems.

Good points.

I tried some of the basic maintenance prior to considering the re-motoring:

• The commutator is VERY hidden inside a plastic frame that surrounds the motor. It's unlikely I'll be able to do much about that with the motor running.
• The gears appear to mesh fairly well, and there isn't any play in the worm/motor mount so that it would be moving around.
• I already did some of the lube work, after cleaning out the CAT HAIRS wound around the axles (in my teens, I was completely unable to convince Ki-Ki that there were other ways to get to her favorite perch than across my layout...) I haven't done anything about grease, though... IIRC, I've seen recommendations for light silicone grease for this type of application here on the list?

I'll do a little more investigation into more lubrication, but as I said, this thing was loud out of the box. Even several years of use didn't make it any quieter.

Brian

[mcouvillion]

Brian,

Is this a 3 pole or 5 pole motor? My guess is that it is a 3 pole. You can improve it some but it will not run as well as a 5 pole motor. The noise you describe (electric-razor sounding) is confusing to me. Is there any auxillary device on the engine that is powered, such as a smoke generator or uncoupler or something like that. It sounds like it would be a coil for a relay or something.

Anyway, try to carefully disassemble the motor to get to the commutator. You will have to remove the brushes and springs. If you have a piece of very fine sandpaper (600 grit or finer), cut a strip the width of the commutator and several inches long and loop it around the commutator. Rotate the armature while putting a slight tension on the strip of sand paper. This should poli***he commutator and help remove imperfections. Ideally, you would like to polish it with an even finer grit so that it shines. Clean out the groove between the sections of the commutator with the tip of a pin or a sharp hobby knife, but do not scratch the commutator.

While the brushes are out, check the end-play of the armature. It should NOT have a bunch of movement along its axis. It should rotate freely. If there is end-play, you will need to shim the end of the armature to take out the slack. You want the brushes to follow the same path on the commutator when going in either direction, preferably down the center. I have used Kaydee 0.010" and 0.015" shims with a small "V" cut out with diagonal pliers. The shim(s) can be pushed in place with tweezers over the shaft but won't easily come off by themselves. Again, the shaft must rotate freely. Lubricate the motor bushings (I use transmission fluid rather than oil since oils gum up over time.) Replace the brushes and springs and run it in on the bench, varying the speed and direction until it runs smoothly and uniformly in both directions. Place the motor back in the engine.

If the motor tune-up doesn't stop the noise and improve performance, I don't know what you would need to do to quiet it down. Now if the noise begins after putting the quiet motor back in the engine, that's another thing altogether. Good Luck.

Mark C.

[rrinker]

I have one of those. Yes, they are VERY noisy - they are noisy because they aren't really geared down at ALL and the motor runs very fast. It's the only HO engine I've seen that can do a Lionel imitation and roll off the tracks on a curve. Even an Athearn Hustler doesn't run as fast as this thing.
And therein lies the clue to repowering it - I beleive Proto Power West or someone once made a repalcement drive for the Athearn Hustler, it was the whole mechanism, you just reused your original body. The Plymouth body might also fit on this chassis.
I don;t really know how else you'd go about this, the motor sits vertically over the rear drivers, and the worm directly drives a gear on the rear axle. The axle gear is TINY - I think the drive is around a 1:1 ratio! Perhaps scratchbuilding a new chassis to fit the body is the way to go.

--Randy