Model Power Pacific 4-6-2 Improvement: Fixing a Disaster and making a Pearl

[samusi01]

@u18b

Very good work there. Makes me happy that steam represents a tiny portion of my fleet.

[Dwight in Toronto]

Ron, as always, that was an incredibly comprehensive and instructive tutorial.  Thank you for taking the (substantial) time to post all the pics, and compose the commentary.

I’ve had one of these Model Power locos for a good 10 years or so.  I outfitted it with DCC quite a while back, but then put in an ESU 58731 sound decoder (and a 0402 LED) two years ago.  The model has always run fairly well, but I did have to fabricate new axle wipers for the tender at one point.

Anyway, here’s a short video demonstrating the DCC/sound upgrade:

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[u18b]

Thank you for posting Dwight.

You wouldn't happen to have a photo of the LED would you?

[u18b]

Knowing that my primary road is CSX, some might wonder about my interest in a Pacific.

Actually, it's personal.  Because one ran on CSX!
@chessie system fan and I and the rest of the family road on a special excursion in the 1990s.

The lead loco was an Atlanta and West Point Pacific number 290.
I'd like to build this loco one day.

This project makes it closer.

[sd45elect2000]

All I can think is , good god, I have 16 of these !

Randy

[u18b]

All I can think is , good god, I have 16 of these !

Randy

Well, as was said in one of the first posts.....

When they are good.... they are good.   

I hope all of yours are good.   

But if one goes bad....      you can know what to look for.
 

[spookshow]

If it was me, I'd go looking for one of BLI's 4-6-2's in lieu of any of these Ajin models. Much less insanity there, especially if you go with a non-BLI decoder.

-Mark

[mmagliaro]

Ron,
I thoroughly enjoyed this, first for your good work, and second, because it reminds me of how painful these are to work on.
The big "if" with these engines is the tenuous grip the drivers have on those axles.  No splines.  No flatted-half-axle ends, not keyed square ends.  It's just a "sort of tight" fit, and prayers.  As you found out, you can correct the quartering just by holding a wheel still with a thumb and rotating the opposite side.  While that makes quartering them easier, it does not bode well for them to not gradually move out of quarter over time.

I have a question about the gear mesh issue.  Instead of filing or machining the axle slots and then padding them to push the drivers up, couldn't you just flat-file the whole top of that frame so that when it is mounted under the boiler, it moves up a little closer?

As for the motor... it suddenly dawns on me... that motor may well be the one I was purchasing in bulk to harvest the armatures for my Rivarossi motor rebuilds.  It looks exactly like it in size and the color of the armature wire. The dual-shaft version was still around for a while, but it is no longer on eBay or aliexpress, where it used to be $2-$3... if you are ever in a pinch and want to just change out the whole motor.  Amazon has them for about $12.   You need to look for mabuchi FT-010SA, and ideally, the "type A",  FT-010SA-07300, which is 21000 rpm at 12v instead of the type "B" which is 28,000 rpm.  Since the ebay/aliexpress source has dried up, I suspect there aren't many left floating around.

I just found some on aliexpress for $2.64/ea   (look for "010 train motor") .  They are the 010 size, and they are the slower "A" type, but the dual shafts are shorter... bummer... about 4mm instead of 7mm.   The armature skew is less pronounced than on the MP motor.  But who knows?  It might be worse or better.  Of course, I had to order 5 to find out!

[Rasputen]

Filing the top of the frame would only change the mesh between the worm and the worm gear.

My friend has been able to pin the drivers on HO steamers by drilling a small hole radially down through the driver, into the axle, and then pressing in a steel pin. 
I want to try this on my MP 4-6-2's before they slip out of quarter.

[jwaldo]

Oh my gosh.  This is bad.   I never saw Spookshow mention this problem of motor caps falling out.

But wait!   This Ajin motor is the same as used in the brass Little Joe.  Since I remotored one for a customer, I still had an old motor.  Great.  I’ll just swap them.

But I was shocked to see that it had the SAME problem.   There is a pattern here. 



So I have come to a conclusion.  Heat from soldering alters the composition of this plastic.   The plastic doesn’t just melt, it burns and CHANGES composition into a crumbling mess.

The first-version Athearn F59PHIs had this motor too. Even after I managed to get the decoder wires on without ruining the housing it's still a mediocre motor. And for whatever reason after an hour or so of continuous running it starts screeching and binding until I let it cool down.

[u18b]

Max,
Thank you.

Rasputan beat me to it.

The need for tighter mesh is between the worm gear and the middle driver.  The driver bearing fits into a slot which provides an upper limit.  So making it tighter on the bottom has no effect.   I wanted to raise the bearing on the driver.

In the photo below, the only way to increase the mesh at the blue arrow is to cut the bearing channel higher.



My work with a file was pretty primitive, but it worked.

[mmagliaro]

Sorry!  I misread your post.  I thought the problem was between the motor worm and worm gear.  Now I see. It is between the driver gear and the one above it.

And regarding your son's admonishment about you getting a lathe, for this particular job, what you really want is a mill, not a lathe.
Putting that frame on its side under a mill would allow making short work of cutting those slots just "N thousandths" higher.  And a sideways
cut with the right diameter cutter would leave a nice rounded top to the slot ta-boot.

[u18b]

There will be a lot to report in the coming posts.

Having pretty much completed the first Pacific, I now turned to the second.

I did the modular spring treatment as before.

I then decided to mod the tender.  One of the disappointments of the Model Power Pacific is the primitive pick-up scheme in the tender.   So my goal was to add needle bearing trucks from Kato or Bachmann.   It turned out I had a surplus Bachmann tender so I used those trucks.

I took the stock tender and unsoldered the wires.






I cut slots in the plastic frame for the pickups.

Now I had a problem.  The hole on the Bachmann trucks was too large.  In the following photo, the MP truck is left with small hole and the Bachmann truck is right.  I needed a bushing to fill the hole and receive the screw.



Going thru my parts box I found a Kato GP30/35 u-joint filled the hole but the hex pattern was bad.   I then saw that the joint from an Atlas SD26 filled the hole perfectly.   I could just drill out the center and trim it into a bushing (or fat washer).

I shimmed the trucks to raise the platform a bit.  It all worked.



I trimmer the truck pick ups contacts because they stuck up too high.

I then installed the springy strips that touch the trucks contacts and built a circuit board.  This time I used larger and cheaper plugs and sockets.  The blue plug is the analog plug.




I did have to add extra weight because I lost the original weight with my mod.  The tender was too light otherwise.




Took the loco for a test run and all ran pretty well. (more in a moment).

The stock model picks up electricity from 5 wheels per side (3 drivers and 2 tender.  By using the Bachmann trucks, the locomotive now gets power from 7 wheels per side (a 40% increase!)



This was a good change.

[u18b]

By the way, the second mechanism did NOT have gears go out of mesh- so I did not cut on the bearing slots.

[u18b]

I did encounter one awful pesky thing.   This second Pacific had a defective piston rod/valve assembly.   It looks like it corroded in the ocean for a decade or so.   Look at how pitted and rough the part is!  I could not help but think that this roughness would add friction to the loco.





The third Pacific was painted for Southern and was trash from a very bad sound installation (the frame was cut to run headlight wires- terrible!).

So I decided to use that loco as a parts source.  The side rods and valve gear were all better, so I did a swap.