Noise issues on Tomix Shinkansen Dr Yellow

[PanAmShay]

We recently acquired a Tomix Shinkansen Dr Yellow 7 car set from a fellow club member.  It never ran great when converted to DCC with a Digitrax DN136, so it wasn't run very much in the last 14 years.  When we fired it up a couple of days ago, it sort of ran, with lurching/surging at slow speeds and surging at high speeds.  We installed a ESU Lokpilot V5 Micro in the power car, and after diagnosing some poor pickup,  it runs really well--it turns out one of the truck collector springs was too short on one side of one truck.  On a linear speed curve with a max speed of 280 sMPH, it will creep at a decent slow speed with no issues on speed step 1 and be very quiet.  The one issue is that at moderate throttle speeds it makes a horrendous rattling/vibrating noise.  It goes away near max throttle. 

This noise happens whether running the entire train, or just the power car alone. Removing the plastic shell doesn't help.  Pushing down on the top of the car or providing some resistance makes it go away or greatly reduce.  It seems like some metal pieces are vibrating against each other (maybe the spring loaded axle pickup bars?).  I initially had added just a drop of Labelle 108 at the trucks, worm, and motor bushings, before swapping the decoder.  After the decoder swap and trying to solve the noise, I added Labelle 106 grease in a number of areas to see if it could dampen whatever was vibrating.  This did not help.  I've since fully stripped every thing down, including full truck disassembly. the motor has very slight movement in the frame, but it is not loose and if you shake the frame and motor (with trucks removed), there is no rattling noise.

Any suggestion to quiet this noise would be very appreciated.

As a side note, when fixing the poor pickup issue, we lost one of the power car truck springs.  After spending an hour + in vain looking for it, we pulled the truck pickup springs out of one of the other cars.  They seem very slightly less stiff (.009" wire vs .011" wire diameter), but this noise issue was happening before and after the spring swap.  I couldn't find anywhere to source replacement springs, except ebay for $35 a piece!  We don't need pickup in the middle cars, so not a big deal, but are there domestic (USA) sources for Tomix spare parts?  I didn't find any.

Peteski, I don't think this is really an electronics issue, or a DCC issue, I think it is a mechanical issue, but figured to start the thread here and please move if it should be discussed elsewhere.

[peteski]

Like you mentioned, I don't believe it is a DCC  issue.  Probably not even needed to remove the decoder (a major paint I'm sure) to eliminate the decoder as the culprit.

I have that exact set in for repair. In the one I have the plastic end of the motor where the brushes are is partially melted. The motor overheated while running at high speed for a rather long time on an NTRAK layout.  But the train already had some high mileage on it before that happened, so the commutator might have already been affected by the segment gaps being clogged with conductive brush dust.  With the crazy prices out there I'm also having problem finding replacement motor, but that is not related to your problem.

Can you give a better description of the noise?  How loud? Could the noise be coming from inside of the motor?  When starting from a stop, at what speed does the noise start?  Does it start gradually, or there is no noise, then it starts full blast at some certain speed? Does its pitch (tone) change with the speed), or just a constant rattle with no discernible pitch? Does the noise also happen while you hold the power car in your hand, upside down and finding a way to power it without running on tracks?

[PanAmShay]

Quick summary, I was able to get it solved!

I checked each component for noise working my way back from full assembly to the motor by itself.  There was a little bit of noise coming from just the motor in the frame, so re-lubed the motor bushings and put a piece of kapton tape on either side of the motor to prevent it from rattling at all.  The most noise (a frequency dependent buzzing) was from the worm/black worm housing/white drive shaft.  If you touched the black worm housing while it was running, the buzzing would get really loud.  At first I thought I needed to dampen the worm housing, so put some heavy marine grease in the slots in the frame.  This calmed the buzzing feeling in your finger, but not the noise.  I then put a drop of Labelle 108 oil in the drive shaft to the worm gear housing (See arrow in pic).  What was interesting was it didn't make it instantly go away, but buzzed for a few seconds and as the oil started to work itself out of the u-joint there was a step function and the buzzing went away.  I did this one at a time for each worm gear housing. It was sort of like there was some burr that needed to wear away, but without the oil it wouldn't.  I can't fully explain it, but am very happy to have it all back together and running nicely, ready for running on an nTrak layout in a few weeks, where hopefully it won't melt the motor!

The loco seems pretty easy to work on with the exception of removing or installing the trucks, which feels like I am about to break them each time (and once removed them find the pickup springs deformed.)

Tried posting a video to show the noise, but I guess it makes sense not to allow video uploads.

Where do you send yours for repair?

[Englewood]

I highly recommend jnsforum.com for information on Japanese prototypes. Lots of good information there.

[PanAmShay]

Englewood, thanks!  This is our first model of a Japanese prototype, and I hadn't thought to look for other resources.  Appreciate the link

[peteski]

The fastest spinning metal parts of the mechanism (basically either motor or worm shafts, or both) usually emit speed dependent screeching noise at certain speeds.   The plastic universals usually don't make that kind of noise. I'm really surprised that it did make that noise, and adding lubricant (Heavy marine grease is just a touch of an overkill for N scale model    ) applied there quieted it down.  Or maybe I'm not reading your post correctly.

Exactly where did you apply the LaBelle light oil and where was the grease applied?

I doubt that a burr would have cause the noise or that there even was a burr.  The rapidly spinning metal shafts in dry bearings (plastic or metal bearings) generate horrible noise and some light oil quiets them down.

If the "send for repair" question was directed at me, the answer is "me". I do all of my (and many of my friends) repairs and DCC installs. I'm also a traveling N scale mechanic, servicing models of my fellow NTRAK members at the train shows I attend.

As for lubricants, for years I have been using Woodland Scenics Hob-E-Lube 7-pack of oils and greases. Those are geared towards model railroading. I made my own hypodermic needle applicators.
https://woodlandscenics.woodlandscenics.com/show/item/HL650

[PanAmShay]

Peteski--sorry for confusion and it was sort of an odd sequence of events.  At the very beginning, I applied the labelle 108 oil to a couple of moving spots (truck gears, then universal and motor bushings) after wiping the old residue off from 10 years of sitting.  This was before I had even removed the Digitrax decoder and was just trying to get it to run.  When I heard the buzzing noise, I first suspected it was the black plastic worm housings so I put some labelle 106 light grease between the worm housings and the die cast chassis.  This didn't help so I tried adding 106 grease to the universals--just trying options to see if anything made an effect. It didn't really make a big improvement, and now since I had more 106 grease than desired and didn't want to be picking up dirt and debris, I did a full deep clean (at which point I lost one of the collector springs trying to stretch it out just a bit more for more consistent pickup), disassembling the trucks, worms, motor, everything.  I just wiped it all down with a lint free piece of towel. I didn't use a solvent or cleaner, believing that any small residual would be a good base starting point.  At this point I reassembled and the buzzing was way worse than ever, and I put the first post yesterday on the topic.  Thiis morning before breakfast, I tore down again, testing the noise at each step.  This is where I added blue marine grease between the black worm housing and the die cast frame, since I could feel these parts buzzing relative to each other.  There is no relative movement here though, so adding the marine grease here wouldn't cause any friction.  It is nice because it doesn't wash out typically with heat, so should stay in place.  Agreed it would be terrible for an n scale gear/universal/etc moving joint. At this point I added the labelle 108 to the plastic universal and plastic cup pressed on the metal worm shaft, and the noise went away after a few seconds of running.  I believe it is a plastic/plastic interface, and buzzing is the best descriptor here. I'm just glad it's gone now (fingers crossed it says that way).

I misread your message about your Dr Yellow "set in for repair"--I read as "sent in for repair".  Makes way more sense now!

Thanks for the suggestion on the Woodland Scenics kit.

[peteski]

Thanks for the explanation PanAmShay.  Buzzing is not a noise that would be generated by dry metal shaft bearings (motor and worm). That is more of a screech.   In this case it seems that the ball on the end of the plastic drive shaft fits loosely enough into the cup of the U-joint and it starts trashing around causing noise. In that case some grease will dampen the vibration.

Are both universals making the noise or just one?  I'm also wondering if the drive shafts are slightly bowed (not straight) causing them to be out of balance.  Also I wonder if there is too much fore/aft play in the worm shaft riding in its bearings?  That could cause the worm itself (and the U-joint cup) to shift  back and forth a bit.

[PanAmShay]

Peteski--both universals were making the buzzing noise.  It does seem like there was some free play fore/aft of the worm in the housing--but I believe the housing does not control it, since then it would be an over constraint on the snap fit universal joints at the motor and worm.  Worm fore/aft play seems more dictated by free play in the universals, but I'm not sure the designed tolerance stack up loop here.

Thankfully the noise is resolved though, so unless (until) it comes back, we'll just happy to have a new train to our fleet.  We even have Dr Yellow and our TVG Lyria Euroduplex speed matched now and just to test things out had them running in a consist spaced halfway apart on our loop.  The loop function on our Speedstick V5 worked great for high speed top speed setting as it is more consistent than direct sMPH readings at these elevated speeds.

It sounds like there isn't any real source for replacement parts, other than ebay--is that correct?

[peteski]

It sounds like there isn't any real source for replacement parts, other than ebay--is that correct?

Tomix only sells replacement parts in Japan for Japan.  Some Japanese online shops like Hobby Search (www.1999.co.jp) sell spare parts for Kato and Tomix, but often not the specifics we are looking for.