Kato SD40-2 frame change ? Probably old news....

[mu26aeh]

I received a newer run SD40-2 from Kato today from a eBay win.  As soon as I took it out of the box, both trucks hit the floor.  Nothing new, took a rough ride in USPS.  So I went downstairs and took shell off, and everything hit the work bench.  After I took the fuel tank off, everything seperated as there is nothing holding the frame halves together.  Took me about 15 minutes to get everything back together and shell back on.  How many models have frames like this ?  Every locomotive I've ever had are held together with screws.

[peteski]

Several Kato models (including GG-1) have that screw-less frame. I think all the models which use the new fine-pitch gears and sprung center axle in the 3-axle trucks.   But I also seem to recall that Kato did revert to the older proven design using screws and slightly more coarse gears on some of the new models (like SDP40F).

[daniel_leavitt2000]

I think the changeover was in 2009 to the new system. In addition to no screws, the work is mounted to the truck. This was supposedly done to speed up assembily. There was a problem with trucks popping loose with the first run. I don't know if they package them differently now or they made improvements but newer releases have not had the same problems. Also note that the center axle in each truck is "sprung" in that the needle cup is cut in such a way to allow a little flex. Never saw any major improvements with the new system and it is more fragile.

[sundowner]

I should had pack those truck better. Currently all SD70ACe, second run of Flare Radiator SD70M and the short nose Mid-Prod SD40-2 are the ones that have trucks that pop out easy. All cowl units don't used screws but they used tabs to hold the trucks in so for the most part they stay on.

[mu26aeh]

I should had pack those truck better. Currently all SD70ACe, second run of Flare Radiator SD70M and the short nose Mid-Prod SD40-2 are the ones that have trucks that pop out easy. All cowl units don't used screws but they used tabs to hold the trucks in so for the most part they stay on.

I don't blame you sundowner.      I was more wondering what the situation was on the frames.  It was driving me nuts trying to get everything back in there.  I would flip the mechanism over to get the trucks in and the damn gears and shafts would fall out, and of course that damn little brass ring on end of worm would fly off and I spend 5 minutes trying to find it again.  I got it back together and damn it if I didn't flip it over again 

Now I am once again back to point where I need more decoders.  I knew I wouldn't stay 100% DCC for long 

[C855B]

I first encountered the screw-less Kato chassis with the NW2 in 2007 or 8, so at least it goes back that far. I wasn't (and am still not) a fan; reassembly after DCC left it running bunches less than smooth. There are a lot of bits to keep in place and in alignment while trying to get the shell back on. Maybe it's a matter of practice, and I should dig it out of the stash and try again.

[peteski]

Hint: unlike the frames where screws are used, these screw-less chassis should be fully assembled (sans trucks), then the trucks (with the drive shafts attached to the worm coupling need to be installed in the assembled chassis.  You guide the drive shaft's hex flywheel coupling up int the chassis close to the opening in the flywheel, then snap the truck into place.  That is why these trucks come out so easily - they are designed to be snapped in and out of the assembled chassis.

If you try to reassemble those new frames the old-fashioned way you end up needing 5 hands!   

[Scottl]

I've dealt with a few of these frames and have no complaints.  It is the most refined n scale frame I have seen.  I have heard issues reported, but it is far from universal.

[mu26aeh]

On a related, but different topic.  I wish I had won the other auction.  It was #8100, which I captured prototype on the Hanover Sub.  It would have been right at home on my model Hanover Sub

[sundowner]

SD40-2 are cool, I saw the extremely rare to see FEC 718 last week sandwich between a FEC GEVO and GP40 and I though about finding a snoot to paint.
 I painted seven of the mid-pro because I got tire of waiting for Kato to do them in CSX YN3 with the ditch lights. Since I change roads I am down to two that I am keeping, sold four and repainted one into FEC 714. Too bad CSX are putting that ugly cab on them because they do look great in dark blue.

[peteski]

I've dealt with a few of these frames and have no complaints.  It is the most refined n scale frame I have seen.  I have heard issues reported, but it is far from universal.

The new mechanism is even smother-running than the previous iteration, but those fine-tooth gears are very unforgiving when they pick up even a small piece of debris.  The layout needs to be kept really clean.  One easy solution is to cover the openings in the bottom of the truck with a piece of masking tape. There is enough clearance so the gears do not rub against the tape, and it seals the most likely point of debris incursion.

[Scottl]

I agree that it is a really smooth mechanism.  The best in my experience.  Good point though about fouling the gears, I think I will protect my units.

[mu26aeh]

The new mechanism is even smother-running than the previous iteration, but those fine-tooth gears are very unforgiving when they pick up even a small piece of debris.  The layout needs to be kept really clean.  One easy solution is to cover the openings in the bottom of the truck with a piece of masking tape. There is enough clearance so the gears do not rub against the tape, and it seals the most likely point of debris incursion.

Added value from sundowner, as he already had the openings taped up ! 

[jagged ben]

Here is how you're supposed to disassemble the 'mid-production' version of the SD40-2:
http://www.katousa.com/N/SD40-2/maint/disassembly.html

This type of mechanism dates to 2006.  Note that it wasn't exactly a 'switchover' for the SD40-2 because Kato has continued to produce new models with the old mechanism.  The clue is if it's a model with ditchlights; in that case it has the new screwless mechanism, which appears to have been designed partly with the purpose of making room for the ditchlight light pipes.  Otherwise it has the original mechanism (i.e. 'Early' SD40-2 models, or snoots). 

I could be wrong but I believe the SD70M has also been produced with two different mechs.   Other models either were designed with the new style mech or were not.    The instructions linked to above should generally apply, as far as principles, to the various new style mechs. 

[Ngineer]

I agree that it is a really smooth mechanism.  The best in my experience.

Not true regarding the NW2. Sorry to say that, but I have two and they both have issues.

The NW2 is a rather bad runner.

The new mechanism works for heavy locos like the GG1, the E8 etc. and the SD40-2, but not for light locos IMHO.

   Javier