Upgrading the N scale Intermountain SD45-2 with a Kato chassis

[GM50 4164]

Kato trucks are not interchangeable. Intermountain use the Atlas HT-C Truck which has a different bolster post/spur gear design.

I have seen some people graft sections of Kato trucks onto the Atlas/IMRC HT-C to improve looks (especially where the traction motors should be hanging).


@randgust Thanks for posting your SD45-2 Kato conversion. It looks very nice — especially the lovely replacement handrails

I see you managed to achieve this using a Kato SD40-2 Early chassis. That's where I started, but I found that the frame sat quite high on the chassis supports where the pickup strips are retained. In reality in your photo it looks very good.

The Kato Mid Production is still a better option for my purposes as it includes a nice subframe and it has more room for a speaker.

The ride height works out pretty well (next to a Rapido Centerbeam with correct 36" wheels):

(Attachment Link)



In terms of weight, the Kato Mid frames are denser that the IMRC, and so my converted SD45-2s end up within 1 gram of the original IMRC loco even after milling and installing capacitors and speakers:

(Attachment Link)

The stock Kato SD40-2 is slightly more than 10% heavier, but I've not encountered any issues with pulling power.


I've ended up making use of the void at the end of the long hood that is created by converting to the shorter SD40-2 chassis. This has yielded a 9x16mm speaker chamber with more than 1.8 cubic centimetres, and it has a nice clean low end when run at low volume:

(Attachment Link)


A capacitor really is a must if you are running sound like I am, and I'm happy to sacrifice a couple of grams for the big improvement in reliability — in this case I've used an ISE Power Keeper:

(Attachment Link)


ESU has recently re-mastered their EMD 20-645 sound file and included a low idle, so I'm a happy camper:

https://projects.esu.eu/projectoverviews/search?cat=18&type=all&q=20-645



The only thing remaining now is to try one of the new CUI 9x25mm speakers to see how this compares:

(Attachment Link)


Then I'm onto "mass production" of the dozen or so units that myself and my Clinchfield friend @Doug W require.

Cheers

Tim, I am really intrigued with the large speaker enclosure you've designed for the conversion of the SD45-2. Do you have a YouTube page or video of it running anywhere? I would love to hear it with either speaker.

[kiwi_bnsf]

Tim, I am really intrigued with the large speaker enclosure you've designed for the conversion of the SD45-2. Do you have a YouTube page or video of it running anywhere? I would love to hear it with either speaker.

I hope to post some comparison videos in the next 3-6 months. My 3D printing and frame milling has taken a hiatus for the last 18 months due to a fairly significant re-model of my layout space. This has involved a lot of messy tasks including plaster, paint, and woodwork, during which I lost my test track, work bench, and programming space.

The remodel is now in its final stages, and I should have a modelling space again in the next month or so.

I will be sure to post some updates once things are back on track!

Cheers