how to repair Kato gs-4 cracked axle centers

[victor miranda]

I made a promise to the nice fellow at Kato.
here is the fix.

Kato GS-4 axles sometimes crack.
there are a lot of reasons.

the one to watch is the traction tire axle.
If you lose a tire, the axle is in danger.

and gluing the tire in place can cause the axle to break
because there is no relief should the axle get a good load.
and pop the axle.

reasons aside.
here is the fix.

k&s #9833 brass tubing.
it is 2.5mm outside diameter.

all the axles have plastic centers, they are a around 2.5mm.
overall, the idea is cut a pair of collars off the tubing.
cut/file the plastic center on each end of the axle center to snug fit
into the collars.
red loc-tite the axles back together.

here is a cracked gear axle center. look at about 4 oclock.


here  is the axle just before assembly.



as always the devil is in the details.

first, this repair is not a high precision job.

I made 1mm collars.  Longer is ok, the ends should not  edge out past the plastic
when you are done. Cut them longer and file them down a bit.
Chamfer the inside corner.

the plastic has the hole for the axles and this repair does not touch that place.
I strongly recommend a rotating tool be used because the collar should just fit
and wittling will leave small gaps. but if you are brave that could work....

drill, moto-tool, lathe.
get the ends to snug into the collars

at this point you should have 2 collars and the plastic axle cut down
enough to just fit into the chamfered collars.
and the two drives with bearings and axles.
OIL THE BEARINGS !!!  and then clean off the axles, I use acetone.
  leave the oil on the bearings.
loc-tite has to have a clean surface to stick.
you want the oil to protect the bearing from the loc-tite.

red loc-tite expands a little as it cures.
the collars are required to hold the tension when the red loc-tite
sets to grip the axles.

I use brass dust (from the collar filing)
to wipe the insides of the plastic axle centers.
I read that loc-tite needs metal to cure.

right side leading and I quartered by eye.
make sure to get the loc-tite inside the joint.
when you are finished assembly, sop up the extra loc-tite.

You may want to check all the axles for cracks.
two locos I repaired needed collars on all 4 axles.

victor

[delamaize]

Well damn, I gotta put that one in my box of tricks, especally since I have 3 GS4s, 2 are still GS' and the last is my A4....

[peteski]

Thanks for the info Victor.
Your method is much less complicated than what Richie is doing to his GS-4 in https://www.therailwire.net/forum/index.php?topic=27691.0

It would also be nice if Kato redesigned those axles in the future GS-4 releases, but I doubt that this will ever happen.

[Lemosteam]

Nice writeup Victor!  Seems like this is something one should do to prevent cracking in advance of it happening.

Question for you- does the GS4 use octagonal axle shafts like the Mike? (I don't own a GS4).

[rogergperkins]

Thank you for sharing.
I am disappointed that with Kato USA's knowledge of the design problem that they are not correcting it and offering a repair solution.
I have three of these locomotives and would not wish to tackle this repair myself.

[peteski]

Question for you- does the GS4 use octagonal axle shafts like the Mike? (I don't own a GS4).

No, they use round axles, thinner than the Mikado's hexagonal octagonal axles. I suspect Kato did that to minimize friction of the mechanism.

EDIT: fixed mistake -  thanks John!

[Lemosteam]

Thanks Peteski,  I'm pretty sure that Mike shaft is otagonal though for quartering...  This is a Mike driver:

[robert3985]

Since I've got the tools (lathe, mill) I think I'm gonna do this on my son's five GS4's, one of which may already have a cracked axle, one more on the bench being turned into a GS3.

Looks to me like this would be an easy "fix" if ya have a lathe, and just a little more work if you don't.

Very innovative, and good thinking!!

Thanks Victor! 

[brokemoto]

What??  A KATO axel CRACKED????  Sorry, not possible, never happen, inconceivable, not allowed, ___________________(fill in the blank).............


And here I thought that only Bachmann axels cracked, even though B-mann has made some major improvements.  The axle on the lead driver pair on my recent edition USRA 0-6-0 did crack and come apart, but I expect that it will not be a difficult fix, as I have more than one of the older versions of this thing in my various parts boxes.  If those do not fit, I expect that a piece of stiff plastic tubing exists somewhere that would fit.

Kato seems to have had its problems lately, witness this and the NW-2 running gear problems.  I understand that there was also a problem with this thing on DCCl, but, as I am not a DCC user, I can not comment.

Good idea for a fix that might apply to other power, as well, such as my Bachpersonn  USRA 0-6-0.

[eja]

Kato seems to have had its problems lately, witness this and the NW-2 running gear problems. 

Not to hijack this thread....

but what was the problem with the NW-2 and does anyone know if it has been fixed in the latest releases ?

[VonRyan]

Not to hijack this thread....

but what was the problem with the NW-2 and does anyone know if it has been fixed in the latest releases ?

In some instances the gearbox would make little or no contact with the driveshaft thus the engine would not move, yet the motor is running.
This usually results from excessive shaking of the engine, or from disassembling the engine completely. It doesn't always happen, if great care is taken, but caution is advised if you are someone who likes to take your locos apart even before you've had the chance to test run them.

As far as I know there is no solution to the problem, and whether or not the problem has been addressed in the latest run has yet to be confirmed.

I have one that I bought up at springfield this year (40% off of $80, and it's in PRR), put a decoder in, and it runs with no problems.
The story of its problems can make a potential buyer quite afraid to buy one (like I was) but these little locos are great runners with all the kato quailty expected out of any other loco.


-Cody F.

[peteski]

Going by the latest info from Kato, they listened to their customers and totally redesigned the GS4 9and FEF) driver axles.  No more broken axle-tubes or quartering issues.  Big Kudos for Kato!

[up1950s]

Thanks Pete , I ordered the replacement set for the GS-4 chassis under Jasons FEF-1 . Just maybe the exhumed can breathe again  .

[victor miranda]

oh, breathe it will.

I've been looking at the photo on Kato's web site
(and the one here...)
there is little doubt the axles in the photo are more robust.

with the bearings going from 1mm to what looks like 2mm
there will be a small performance hit.

.... a little less smooth and uses a little more power.

I wonder if anyone will notice?

I suspect they will notice the lack of paint on the tires.
(I can see that is missing.)
think the center stars are still there?


victor

[mmagliaro]

If anyone does these swap-outs and wants to send me their cracked/messed up axles and drivers,
I would like to try some evil experiments on them in my la-BOR-a-tory, and I'm sure I could make good
use of them on a kitbash someday.   Just shoot me a PM if you are at all interested.

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