Key Imports C-9

[woodone]

That screw is insulated from the frame with a shouldered bushing. The screw goes thought the bushing with a shouldered length. The shoulder fits through the bushing and rest against a washer that a nut is used to hold all together.
The screw/bushing/flat washer can be tightened up into the hole in the frame. There for leaving the screw/nut able to tighten up into the hole still keeping the screw insulated from the frame.

[robert3985]

Thanks Peteski.  That doesn't sound too awful, lol!  It's just getting a bit harder at 60+.

Only 60+???  I'll be 74 this year...guess I'm lucky with steady hands and one good eye!

Cheerio!
Bob Gilmore

[ATSF_Ron]

Both eyes and hands still work, but not without the trusty Optivisor!!  Can't believe I used to work on these locos without one.

[ATSF_Ron]

I'm waving the white flag on the C-9.  Max, I checked for light between the driving wheels and the rails.  Nada.  But upon closer inspection it seems as though the traction tires are deteriorating.  Ugh!  That's not in my wheelhouse to fix!

Max or Peteski, do either of you do repair work on these locos?  I've seen your handiwork on this forum and am more than happy to part with some cash for your efforts!  I feel like I'm close to having this thing running like it should, but what I have left to do is beyond my skill set, I feel.

[mmagliaro]

Replacing a traction tire may or may not be hard to do.
The rod comes off the traction tire driver in that model with a hex-head bolt, and the brass makers usually include a small matching wrench nut driver to remove that screw.

All you need to do is take that screw out, the rod will fall out of the way, and then you can pull out the old tire with some tweezers and scrape the channel clean with a jeweler's screwdriver.  Then you pop a new tire on there (LoveTrainHobbies has a wide array of tires), and put the rod back on with the hex crank screw.

Since all the drivers go around on the rods except the main geared one, you can't mess up the quartering by removing that screw.  And there are no other rods attached to it (it's the front driver that has the tire, right? - wouldn't be my first choice, but oh well).

As for doing repairs, I retired from doing that 7-8 years ago (I forget exactly when).  It was just too intrusive on my own family and hobby time.

[ATSF_Ron]

Max, thank you for your reply and for mentioning LoveTrainHobbies.  I didn't know about this resource for traction tires.  I guess I need to have a bit more confidence in my abilities to fix this thing.  Yes, it's the front driver that has the rotting traction tires.  I was thinking I'd have to remove the entire set of drivers and take off all the rods, a daunting task for me!  Sadly there was no hex wrench tool included in the box when
I received it, although there is the non-traction tired driver in there.  Odd.  I'll contact Key Imports and see if they have one.  If not, do you know of any source for micro tools like that?  Micro Mark perhaps...

Hopefully I'll have this little loco's performance dialed in soon.  Thanks again for all of your help.

[mmagliaro]

I would not expect Key Imports will have ANYTHING in the way of tools or parts.  They never did in the past even when those models were recent releases.
I don't know the size of the hex bolts on that engine.  But I would guess they are pretty large compared to scale.
Woodland Scenics markets hex wrenches for 00-90 size and 0-80 size (and a whole set of 4). Walthers and Micro-Mark also sell what appears to be the exact same set.  It's been around for years.
I would HOPE one of those would fit.
Wiha sells a 1.5mm nut driver... but I have no idea what size your hex head is.  That might work.
https://www.wihatools.com/products/precision-nut-driver-1-5-x-60mm

To go spendy... this little tool has a spring-loaded pair of jaws with a notch so it can grab onto almost anything.
https://model-motorcars.myshopify.com/collections/the-tool-shop/products/nut-holder-2-tool-shop
It's 23 bucks, though...

That same store (model motorcars) has the 00-90 and 0-80 nut drivers for $7.50

[ATSF_Ron]

While waiting for my traction tires, I'm going to start a separate thread on my Pecos River 4-6-2.  It also has the potential to run like a fine watch.  The gremlins are making me crazy!

[ATSF_Ron]

I ordered a 4 driver set from MicroMark, figuring one of them had to work.  WRONGO!  Even the 00-90 was too big.  So I did what I should've done before I ordered and measured the nut with my digital caliper.  Looks to be 1.5mm.  Max, I just ordered it from Wiha.  Thanks for that reference!  Now, as I wait for this tool to arrive, I noticed with the 00-90 that it wouldn't fit under the other rod guide parts above the nut like you see in the pic.  Unless the Wiha has a super thin fitting on the end, I don't know how I'm going to access that nut.  We're talking thousandths of an inch clearance here.  It also doesn't appear that the front wheel set drops out independently of the rest.

[mmagliaro]

If you really can't weasel the nut driver under there and get on the bolt at an angle but enough to break it free...
Here are a few techniques I have used.

You take a slim strip of steel (brass from the hobby shop if you have to, but steel is better because is hard).
and with a jeweler's file, you file a slim 1.5mm wide slot into the end of it.  You make a home-made 1.5mm open-end wrench.
Then you use that to break the bolt free a half turn or so.  The slot must be VERY precise at sizes like this.
Then you can use the nut driver because even if you have
to only get over the head on an angle to stay clear of the valve gear, that will be enough to quickly spin out the bolt
once you have broken it loose.

I also use fine, serrated needlenose pliers (not big ham-fister hardware store ones, but the slim ones that places like Xuron sell).
You can get on that bolt and turn it out while you hold the driver still with your thumb.  It takes guts, because if you slip, you'll
mangle the head of the bolt or break something on the engine.  So it has to be placed in a foam cradle just right, with good light,
so you can get a gentle but firm grip on the bolt and turn it out.
You may not want to attempt this.  I think making a wrench is safer.

[ATSF_Ron]

Yikes!  Well thanks for that tidbit, Max.  We'll see what happens when the tool arrives.

[peteski]

Or if the tool is too large in diameter, just grind down its diameter. The force involved in loosening/tightening the crankpin aren't very high. It isnot like the thinner walls of the socket will break.

Since only one driver is geared, I was going to suggest just removing the bottom plate which holds the driver would allow lifting the driver to work on it. No quartering and gear alignment to worry about.  But then I remember all the tiny springs in the driver axle suspension - that might get ugly.  Never mind.   Servicing N scale steam locos (just like  getting old) is not for sissies. 

[mmagliaro]

...
Since only one driver is geared, I was going to suggest just removing the bottom plate which holds the driver would allow lifting the driver to work on it. No quartering and gear alignment to worry about.  But then I remember all the tiny springs in the driver axle suspension - that might get ugly.  Never mind.   Servicing N scale steam locos (just like  getting old) is not for sissies. 

Actually not a bad idea.  The springs are UNDER the bearing blocks when the engine is on its back, and they are usually firmly planted into the frame in tiny holes so they don't come flying out all that easily when you lift out an axle.
I think that will work on this Samhongsa engine. 
But as a general rule...  on some brass steam, the drivers don't come out at all if you take off the bottom plate!  The axles go through the frame and the drivers are pressed on, so you can't even lift out the axles.  I hate engines like that.

So, ATSF_Ron, yes, if you want to try that approach, you won't need any special tool other than your nut driver.  Engine on back, remove plate, and you can lift up the axle enough to get the nut driver on it the bolt.  Just do watch out for the tiny springs under the bearing blocks.   As you lift a driver axle out, you will see them underneath, between the block and the frame.  Losing those is not cool.
They are a very tiny diameter spring.

[ATSF_Ron]

Thank you guys, especially Peteski and Max for all the assistance on my C9.  The traction tire change was a relative breeze with that Wiha tool.  What made my heart skip a beat was when I gingerly lifted out the front driver set looking for those tiny springs.  Then I turned over the driver set and found them inside what I guess are the bearing blocks, resting on tiny little stubs.  Thankfully they stayed put while I swapped out the tires.  Now the strange part.  Even with brand new traction tires this little guy can barely pull 4 cars!  WTH??  Yes, I again checked for daylight between the rails and the drivers using a very powerful flashlight.  Everything looks to be normal.  When I had the shell off before, I noticed there was a fairly hefty weight in the boiler area.  I'm not sure if there's room, but possibly I could stash more weight in that area.  If that won't work then I guess this loco is limited to VERY short locals, lol!  Or some "fake" double heading.  For the most part, I'd say this was a success.  I'm very happy with the running quality and smoothness.  Pulling power is the only downside at this point.

Here's one more final bit that is indeed strange.  I also have an Oriental UP 2-8-0.  I believe these were about the same era as the C9 in terms of production.  The SP loco weighs 2.25oz, has traction tires, and pulls 4 40' cars on level track.  The UP loco weighs 2.22oz, has NO traction tires and pulls at least 14 cars before slipping.  That doesn't seem like a significant weight difference.  I also weighed each tender.  The SP tender was 0.97oz and the UP was 0.81oz.  Both are free rolling.  I even swapped tenders and it made zero difference for the C9.  This is odd.  Something seems to be stealing power from the SP steamer.

Max or Peteski, there's one more thing I just thought of while typing this up.  In an earlier post I mentioned that the screw which holds the motor to the torque arm is missing.  Could that in some way be robbing the SP loco of some pulling power?  I have not replaced it as it seems I'd need to remove the motor from its mount in order to screw it down from above.  Is that a big deal, or would it also involve separating the worm drive?  I'm rather hesitant to mess with that.

[peteski]

Congratulations on successful TT replacement.  The warning about those tiny springs was just a heads-up, so you were prepared for small parts to to fall out.  But yes, in many brass models there is a small finger in each bearing slot to retain those springs.  Sometimes those springs are actually glued into the bearing slot.  Bit sometimes the are loose or the spring remains in the hole in the bearing, to fall out later when you don't expect it.  Plus you ended up losing that insulating washer, so it was fair to warn you about those springs.   

What is the symptom when you add  more than 4 cars to that loco?  Does it start slipping with the wheels spinning in place, or do the wheels stop moving?

If the wheels stopped moving then that would be motor issue.  But (as I suspect) if the wheels are spinning (slipping) that is a traction issue.  After all, smooth metal wheel treads are riding on smooth metal rails - there isn't much friction there.

Traction can be increased by adding more weight (mass) to the model. And as you will see below, traction tires are the additional step that is taken to increase traction.

I think this example will show you what the model is experiencing. I don't know where you live but where I live, during the snowy winters I remember back in the days of rear-wheel-drive trucks, they would have a hard time not slipping in the snow. That is because their rear end was very light (empty bed, plus the heavy engine up front making things worse). To increase their traction owners would load the bed with cinder blocks, rocks, sand, or anything that would put more weight over the rear wheels.  If that wasn't enough, they would also add snow-chains  to the rear tires to further increase traction.

Same applies to N scale locos. Adding as much weight  as possible will increase the traction. If that alone doesn't work, adding traction tires (equivalent of tire chains) will further increase traction. 

The other problem in N scale steam locos is the rigid wheelbase (those driver suspension springs are too stiff to actually provide any equalization). The other problem is weight contribute over the drivers.  If most of the loco's weight is supported by the non-TT drivers, then the TT-driver will not contribute much traction.

So you are correct, adding as much weight over the TT driver (making the model "TT driver heavy) would increase the traction.  Another trick would be to have the TT driver sitting a scoobitch lower than the other driver (so grater portion of the models weight would be supported by that driver, greatly increasing traction).  Kind of like having a truck with cinder blocks *AND* tire chains.    But in N scale, finding the right distance the TT-driver should sit lower is tricky.  And in the model lowering the TT driver would usually have to be done by raising some of the other drivers. Could be a lot of trial and error experimenting.  Hopefully this puts some light on your locos situation.