Squeaking ConCor/Kato S-2 Northern

[mmagliaro]

I asked about this once before on the forums, I believe, but I think I'll give it another go.

As long as I've owned the Kato S2 northern (which is my SP&S #700), it has had this annoying
squeak when it goes over turnout frogs or around certain curves.   I have tried oiling and polishing
wheels and drivers and never been able to get rid of it.  I have removed the pilot and trailing trucks and
run it without them, and it still squeaks.  Running it slowly over a turnout, I can quite surely tell that it is
coming from the drivers (not the tender).   

I have tried polishing the treads and flanges with 1000 grit sandpaper.  It made no difference.  And it happens
on the non-diverging route through the turnout, so it doesn't need to be on a curve.

I think it has something to do with the drivers or their flanges going through the frog (and whatever it is,
it has it in common with something that happens on certain curves).

It makes me think the flanges rub on the sides of the frog, but wow... it's quite persistent.

I am soliciting suggestions.  Also, has anyone else with a ConCor/Kato 4-8-4 ever heard this?
(I know one other person, and he has never been able to get rid of the noise either).

[peteski]

Max, I do remember you describing this problem here in the past. 

Do you have (or had) other examples of this model?  Is/was this the only one with the squeak?

Could you put a coat of light oil (maybe even WD-40) on the rails of that turnout and then run the loco trough it?  If the squeak is still there that would mean that the mechanism is making the noise (not wheels contacting the rail)

[mmagliaro]

I have had one other S2 and it did not make the noise (although I don't own it now).
My friend still has his and it still squeaks.

Tonight, I did a lot of watching and thinking.  It happens every single time it goes through the frog of a certain
turnout (and several others).   I did think about the oil idea.   Of course, then I have to clean the track in that area
and the drivers, but it would tell me that is where the noise comes from for sure.

I could dip a small brush in light oil and brush it around the driver and flange on the front set and try that.
That would also tell me that driver is the problem if the noise goes away.

Oil on the wheels and on the track.  Ick.

[peteski]

Oil on the wheels and on the track.  Ick.

This thing has been bugging you for a long time. What is a little oil on the wheels/track if it will help to solve the mystery (at least I hope).

Naphtha will clean it off easily.  I like the idea of coating the wheel threads/flanges instead of the track. Don't forget to also oil the back of the flange.

[Doug G.]

Does the S-2 have simulated brake hangers/brakes hanging down between the drivers like the Hudson? If so, they can rub on the drivers and squeak. It happened on one of my Hudsons and only on curves.

Doug

[mmagliaro]

Well, the oil had no effect at all.  (I was shocked, frankly).
As far as the brake shoes, yes, it has that detail, but they really do not look like they could be rubbing.  I
can watch it with optivisors on when it goes through a switch.  And it does it even when it is running
straight through a switch frog (not the diverging route).  It also does it sometimes on curves, but not nearly
as often as at the frogs. 

I think I may have to take some close-up video of it going over a frog and post it.  It will be easier to understand once
you see it.   Heck, looking at close-up video may allow me to see something I don't see live.

Next up, I may pull the front drivers, just to see.  If it stops doing it, I'm not sure I've proven it's the front wheels.
But if it doesn't stop doing it, that would be a good clue.

[peteski]

Well, the oil had no effect at all.  (I was shocked, frankly).

I think I may have to take some close-up video of it going over a frog and post it.  It will be easier to understand once
you see it.   Heck, looking at close-up video may allow me to see something I don't see live.

Next up, I may pull the front drivers, just to see.  If it stops doing it, I'm not sure I've proven it's the front wheels.
But if it doesn't stop doing it, that would be a good clue.

Well then, I think it is fairly safe to conclude that it is not the wheels against the track that squeak.

As far as pulling the front driver, that might not be as conclusive. If the squeak stops it might be because you've changed the geometry of the running gear, not because it was the front driver squeaking. 

[mmagliaro]

Exactly.
But if I pull the front driver and the noise is still there, then I have eliminated that component from consideration.

Doug: Your suggestion about the brake shoes was a good one.
When I originally made this engine, I widened the drivers to be correctly in gauge.  The stock S-2, like many engines,
was so narrow that it would bump through switches.  After I did that, I had to file the brake shows to clear the
drivers.  But apparently I did not do it enough, because when I removed the cover plate today, I could definitely
see curved driver marks on the backs of some of the brake shoes (just blackening, but it was an unmistakable
arc shape that matched the wheel).

Upon close examination of the engine on its back, I could indeed see that some drivers could still hit the brakeshoes
at the extreme ends of their lateral play.

So I filed the backs of the brake shoes very VERY thin.  The engine does seem to glide through certain curves more easily than it did before, which is a good thing.  And as I expected, this made no difference at all to the squeak.
The sound really REALLY sounds like metal-on-metal.  I don't think any slippery Delrin part rubbing on anything could
make a noise like this.

I shall report back after I try unpinning and removing various drivers.

[sizemore]

What about leading and trailing trucks? Maybe the back of the flange hitting the frogs? I would think that the weight on the drivers themselves would squash any resonance from a squeak unless it was bone dry in the bearing blocks.

The S.

[peteski]

What about leading and trailing trucks? Maybe the back of the flange hitting the frogs? I would think that the weight on the drivers themselves would squash any resonance from a squeak unless it was bone dry in the bearing blocks.

The S.

Max mentioned removing those early on during testing. I assume that they are still off the loco.

[mmagliaro]

Max mentioned removing those early on during testing. I assume that they are still off the loco.

They are not off the loco.  But yes, I have already tried that and it never helped.  Removing them and running
the engine without them did nothing to alleviate the squeak.

[kornellred]

According to Mark Peterson's (Spookshow) N Scale Locomotive Encyclopedia, the ConCor/Kato S2 has a coined brass chassis, while the later Rail Baron (China) S2 has a zinc alloy chassis.  Neither model has bearing blocks on the driver axles, so there is constant (rotating) metal-to-metal contact between the drivers and the chassis halves.  Maybe (just a WAG) the brass chassis halves can sing a song when the pressure angle of the driver axle(s) changes ever so slightly.  Without question, this happens on curves.  It is not beyond possibility that such a change could occur when driver axles are passing through frogs.

[mmagliaro]

It is correct that the Kato version (mine) has a coined brass chassis, and no bearings.
The later Con-Cor one does have bearings, however (which doesn't matter since that's not what I have).

I long thought that the wheel nubs sliding in that bare metal frame channel could make noise,
but I had tried oiling those channels many times and never had any change in the behavior.

I did figure something out today, however.
I pulled drivers 1 and 4 and the pilot and trailing trucks.  So now the engine ran on only the center two drivers
(2 and 3).  And still it squeaked.  Not only that, but occasionally, I found that I could slide the engine through
a turnout and make the noise, so it therefore has nothing to do with any internal moving parts because the
wheels were not rotating when I slid it through.

Figuring that it simply must be drivers 2 and 3, I focused on them.   They definitely had some very faint
scoring on them.   I don't know if that was always there, if I put them it there on my various polishing attempts,
or if I did it when I lightly sanded them to blacken them (which is all worn off the treads now anyway because
I've been tinkering).  This is nothing I haven't done on other engines.   1000 grit sandpaper is mighty
darn fine.

But I went at those wheels with 1000 grit again, but this time, focusing only on the treads and making nice circular
motions with the sandpaper so I was sure to not introduce more score lines, but instead, polished them out.

Ta-da, the noise is massively reduced.  It still does it at a few spots on the layout, but many of the places where
it did it every time are gone. 

My theory:
The wheels are squeaking then they slide laterally across the railhead.  Those score lines, faint as they are,
must be chattering/dragging across the rail.   If I did some more polishing (I think polishing compound next, to really
get them mirror smooth), I am hopeful I can get rid of it completely.
At a turnout frog, the guard rails pull the driver set one way or the other to guide it past the frog, so... squeak.
On a curve, or coming out of a a curve, the drivers are sliding laterally all over the place, so... squeak.

Even the places where it still squeaks are greatly less intense now.   
Just one of those things.  The drivers didn't really look that bad.  I've seen way worse and never had this problem.
But it is probably just dumb luck, the metal the drivers are made of, who knows?

I think the compound is the logical next step.

[nscaleSPF2]

Glad that you are making progress, Max.

Your local auto parts store should have 1500 and 2000 grit sandpapers, for an even smoother finish.  A drop of water on the paper also helps.  This may avoid the mess that polishing compound makes.

Regards,

[strummer]

This may be a dumb question, but won't "super-polishing" your drive wheels effect the engine's traction? i.e. ability to pull?

Mark (also) in Oregon