Re-Gauging the Kato GP38-2 and Other Engines...

[randgust]

Wheels have to be pried out from the plastic sideframe using tweezers or a small screwdriver.

That's all there is to it.   Note the wipers on the inside of the wheels.

[strummer]

Well, that was the toughest conversion yet; and I'm not totally satisfied with the results.

There's no play in the side frames; upon re-installing the wheel sets, everything would be pressed back to where it was before, so I did have to put a spacer behind each wheel I pulled out.

It will now pass through those turnouts, but is a little rough, and I suspect I'll eventually have to do another tear-down. I think the hardest part was trying to re-assemble those d*mn MT couplers!    

Mark in Oregon

[randgust]

Yeah, exactly.    On my trackmobile, I tried everything I could think of to get some more 'slack' in that chassis to improve electrical pickup and get a little equalization, because whatever I did I still had a four-legged stool with three legs touching and it would constantly stall.    I finally gave up and had to add a pickup car as a trailer, disguised it as a scale test car.

So if you widen the gauge you tighten the bearings and decrease flexibility.  You can either experiment with bending and distorting the sideframes out a bit, or boring the holes slightly deeper, but that risks getting the frame out of square.

[nkalanaga]

Mark:  Yes, the original Kato GP38-2, also sold lettered as a GP38.  I bought half a dozen of them in BN paint when they first came out.  Like I said, I've never used them much, and tested them new, so they may have had slick wheels to start.   Also, they didn't pull poorly, I was quite satisfied them, but it was a little surprising that the Z F7 outpulled them.

On the other hand, the F7 had been around for a few years, and had some running time, so the wheels may have been rougher.  Both units ran fine, so the wheels and track weren't dirty or greasy.

Randgust:  I wired two of mine together, for the short time I used them in operations, and that mostly solved the pickup problems.  The basic design is very similar to the early Kato PA-1, but a lot lighter, which may be why it doesn't work as well.  On the other hand, I was one of the few people who never could keep a PA-1 running, which is why I ran my railroad with an ABA set of Minitrix Fs for years.  Wired together, those things never stalled.  24-wheel pickup is great...

[strummer]

Mark:  Yes, the original Kato GP38-2, also sold lettered as a GP38.  I bought half a dozen of them in BN paint when they first came out.  Like I said, I've never used them much, and tested them new, so they may have had slick wheels to start.   Also, they didn't pull poorly, I was quite satisfied them, but it was a little surprising that the Z F7 outpulled them.

I'll say. Indeed, those MT F7s are champion pullers, but I can't imagine anything out-pulling that Kato "38". I believe you, I just can't imagine it... 

As far as the little Kato steeplecab, mine runs very well; no pick-up issues. It's just that it's so light weight it can't pull more than (4) cars. I suppose I could put some weight in the cab, but I don't want to. I got it more or less as a novelty, since there is so little available in the way of "interurban" stuff in N...

Mark in Oregon

[peteski]

I always wondered what happened to the guy at Kato that designed this.   Nothing ever looked like this GP38 again.  Thank God.  The most redeeming value is that you rarely if ever have to mess with it.

That truck design used in Kato GP38-2 was used by Kato on pretty much all of their diesel and electric locos (Japanese prototype) of the same vintage and older. Atlas (Kato-made) RS-3 and RS-11) also used that truck design, and so did the Con-Cor Kato-made "SW-1500".  It all changed with the introduction of Kato U30C with the revolutionary new low-friction trucks.

Also, Kato GP38-2 had big honkin' flywheels (which I think were also first for a plastic N-scale model locomotive).

[nkalanaga]

No, the Atlas/Roco FA-1 was the first with flywheels, in 1978.  They didn't seem to do much good, and mine didn't run well enough to use regularly...

From Spookshow:  http://www.spookshow.net/loco/atlasfa.html

"This model is noteable in that it was the first N scale locomotive to employ a flywheel. We wouldn't see that particular feature again until the Kato GP38-2 (released in 1987). The mechanism is fairly impressive looking, but unfortunately it's a pretty mediocre performer. Like most Roco locos, this thing makes a lot of noise (especially the earlier Atlas releases). Pick-up is somewhat iffy (no doubt owing to the traction tires on two of the driving wheels), and the ride is just plain wobbly (once again, I blame the traction tires). Worse still, current is ferried around via wires (yuck). "

The ones on the GP38-2 made a big difference, and it would coast for some distance, once it was moving.  The problem was that it tended to lose contact when stopping, and then wouldn't restart.  But the stops were nice and smooth.

[jagged ben]

My first decent locomotive was a Kato GP50, same mech as the GP38-2.  I wish locos were still made with that type of metal frame and flywheels.

[strummer]

Please note I have changed the title of this thread to be a bit more inclusive, as there are some other locos I (and others) may have questions about, so let's talk Kato F units...

I have 4 of them; 3 A's and a B. Some have the blue box liners and some are green: dunno if that matters.  I have added either MT or Red Caboose couplers in all of them, and before I begin to take these apart for re-gauging I wonder if those couplers will stay intact when I pull the side frames. It seems like they should, but since I find messing with those tiny coupler parts the most frustrating thing in all of N scale, I thought it prudent to ask first.

Also, one of them (an F7, I think) is really noisy, unlike the other 3; anything in particular I should look for?

Thank you...

Mark in Oregon

[trainforfun]

Just a note on re-gauging :
Yesterday I went operating on my friend layout . He is on code 55 ME tracks and turnouts .
My layout is on code 80 with Atlas , Peco and Kato turnouts .
I never had to re-gauge the loco wheels but yesterday on his layout it was a necessity  !!!

When my friend said we will have to re-gauge the wheels if you want to operate here and have fun , it was derailing on all turnouts ...
I said to myself , oh no , we will have to remove the trucks and all ....

It took 2 minutes !!!
He inserted a small flat screwdriver between the wheels and the trucks and used an NMRA gauge to check frequently , that was it !!!
If you push the wheels too much outside press the side of the trucks toward inside by hand to bring it back , that's it that's all .
 

[strummer]

Indeed that is one way to do it.

FWIW, I find that a more complete "tear down" allows me to do a bit of cleaning and oiling as well, if needed.

But whatever works for you is the best way! 

Mark in Oregon

[mmagliaro]

After you spread the wheels to get it in gauge, are the outside wheel FACES rubbing on the inside of the sideframes,
or is it that the pointed ends of the axles are simply now pressing too hard into the cone-shaped holes?

If the faces are rubbing, you can pop off that sideframe assembly and then patiently flat-file in the inside of the sideframes
until you thin them out and make room for the newly-widened wheels.  I've had to do this on plenty of engines.
A diamond flat file works best on that Delrin stuff because it chews through the Delrin much more easily and doesn't clog up.

If the axle points are pressing to tight into the holes, then yes, I think I'd use a pin vise with a small bit, something like a #72,
and drill down into the cup a little on each end until the wheelset frees up.  You have to hold your breath and go slow here,
or you might drill right through the cup and ruin it.  I have had to fix a few engines this way too.

[peteski]

When the wheelsets are widened in gauge and the total axle length becomes too wide and it binds in the bearing cups, I take the wheelset apart and press the half-axles inwards, then reassemble and reinstall them. I also fabricate thin washers and place them on the half-axles against the wheel backs before reassembling the wheelset. That prevents them wheels from moving inwards and going out-of-gauge.

There is a thread on doing this: https://www.therailwire.net/forum/index.php?topic=33107

[nickelplate759]

When the wheelsets are widened in gauge and the total axle length becomes too wide and it binds in the bearing cups, I take the wheelset apart and press the half-axles inwards, then reassemble and reinstall them. I also fabricate thin washers and place them on the half-axles against the wheel backs before reassembling the wheelset. That prevents them wheels from moving inwards and going out-of-gauge.

There is a thread on doing this: https://www.therailwire.net/forum/index.php?topic=33107

So what did you do on the Aerotrain, where the wheels and half-axles are a solid piece?   Ream the axle cups a little?

[peteski]

So what did you do on the Aerotrain, where the wheels and half-axles are a solid piece?   Ream the axle cups a little?

LOL, I haven't  forgotten about that -  I'll post the details (hopefully soon). I was going to do it last week but the snow storm (and 2 days without electricity) delayed everything.