Author Topic: Re-powering a OMI Brass AC6000CW with a Kato chassis?  (Read 2107 times)

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kiwi_bnsf

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Re-powering a OMI Brass AC6000CW with a Kato chassis?
« on: July 24, 2013, 11:55:19 PM »
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Hi there,

I'm the proud owner of an Overland Models Brass Union Pacific AC6044CW (or C6044AC as UP would call it).

I figure that this is unlikely to be produced in the near future by a mainstream manufacturer as they were only used by two roads, so I splurged.

The shell is nice, and will look great once the grills are weathered. However, as expected, the chassis and performance are very basic.

I've completely disassembled everything including the tucks, gear towers, universals etc. It's all be thoroughly cleaned, and carefully lubed. It is much less of a coffee grinder now, but want a loco that runs well - not a shelf queen.

The chassis has a number of issues that annoy me:
  • three-pole super-speed motor
  • mis-aligned universal shafts
  • mis-aligned idler cogs in the gear towers
  • coarse wheelsets that cannot be replaced with Atlas or Kato parts
  • basic wipers for electrical pickup with crude sprung contact with the body

I began looking at re-motoring and putting in new universals last night, but that won't solve the issues in the gear towers or the trucks.

I got thinking that it is most likely much easier to purchase a Kato AC4400CW chassis, and modify the frame to fit the AC6000 shell. A quick check of the width indicates some narrowing of the Kato frame will be required, but it doesn't look impossible. The Kato GE trucks look better than the brass ones, and DCC would be simpler too.

My main concern before commencing is how best to insulate the frame from the Brass shell. Does anyone here have any experience with this? Is it simply a case of appropriate use of kapton tape / insulation tape between the frame and shell? Is it a good idea to paint the Kato frame exterior?

Any input / experience would be most appreciated.

Cheers

Tim






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Tim

Modelling Tehachapi East Slope in N scale circa 1999

u18b

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #1 on: July 25, 2013, 12:58:17 AM »
+1
I started the same exact project.

Kapton tape inside tbe shell provides insulation.
Ron Bearden
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"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.

u18b

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #2 on: July 25, 2013, 02:09:35 AM »
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I have a bit more time for a more thorough answer.

1.  The hardest part of shell prep is just behind the cab on the inside roof.  The is a LARGE round brass pad that is the base (with screw in the middle) for mounting the roof circuit board.  The round brass must be removed 100% completely.  And you have to do it without damaging those grills on the fireman's side (left).  Very delicate motor tool grinding work.

2.  Of course the edge where the walkway meets the shell must be smooth, with no sharp or rough edges.

3. The fuel tank is a problem.  DO NOT just press the shell onto the chassis.  On the CSX model, there is some kind of filter that projects down from the walkway between the air tanks on the left side.  Mine busted off when the Kato fuel tank hit it.  You need to cut a slot in the plastic fuel tank for it.

4.  The chassis needs a LITTLE bit of metal removed.  Obviously, those shell locking bumps have to go flat.  And then, the very highest rectangles above the front on the motor need to be trimmed from back to forward about 1/4 ".  Basically, where the roof on the shell behind the cab steps down.  You have to make room for that stepdown.

5.  Height is not a problem.  With the brass circle completely removed, the shell sits right on the chassis (obviously, no light board.).  The shell height appears pretty good to me.

6.  Trucks.  The first AC6000s (or AC60) on the CSX had the trucks that are the brass sideframes.  But later, they changed them out to the big steerable kind.
Like this:  http://www.trainweb.org/csxrailfan/nov99/ac60/truck.jpg
Kato did me a favor by making a GEVO with this truck.

7.  All Kato GEs and the SD70MAC use the same chassis.  The problem is that it is TOO SHORT for the AC60.   So far, I don't know of a better chassis, so that means that one day I will need to CUT the chassis and stretch it rearward a few feet.

8.  As for insulation, I see I have Kapton tape on the INSIDE of the shell, under the walkway,
AND on the side and top edges of the chassis (remember the shell will sit ON the chassis (roof/inside to chassis).


This project has been on the back burner for me.
One day I will get back to it and stretch the chassis.

So my conclusion was the same as yours.  I own a full AC6000 for CSX.  Beauty.  But not as smooth running as I would like.

Then one day about 2 or 3 years ago, just a CSX shell came up on ebay- no chassis.  And I won it- for something like $80.  I was shocked and VERY pleased.

So unlike you, I have a whole brass model AND just a shell.   So I have experimented with the shell.

And yes, that shell riding on a Kato GEVO mechanism -- even though it is a couple of feet too short, sure looks pretty cool quietly running down the track.

Hope some of that helps.

« Last Edit: July 25, 2013, 02:14:19 AM by u18b »
Ron Bearden
CSX N scale Archivist
http://u18b.com

"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.

kiwi_bnsf

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #3 on: July 25, 2013, 06:41:35 AM »
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Hi Ron,

Wow - thanks for the quick and thorough reply!

I will pay special attention when grinding down the light board nub, and with clearance around fuel tank area. I'm used to careful dremelling required on the inside of plastic Dash 9 shells, so hopefully I won't break anything!


With regards to the length issue, I had completely overlooked this. The only dimensional info I had found so far had the AC6000CW as 2' longer in overall length than the AC4400CW, but having the same truck centers (66'-02"):

http://www.thedieselshop.us/DataAC6000.HTML

http://www.thedieselshop.us/DataAC4400.HTML

I realise you are correct though - comparing the Kato AC4400CW chassis with the OMI chassis shows the clear wheelbase discrepancy :(

I'm going to have to do some further testing with Kato GE trucks, and the SD70MAC and SD9043MAC shells, but I think I'll end up with the same compromise as you… still I'd rather have a smooth runner with 2mm incorrect truck spacing, than a coffee grinder that jumps my turnout frogs!

Thanks again for your time.

Cheers

Tim
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Tim

Modelling Tehachapi East Slope in N scale circa 1999

Leggy

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #4 on: July 25, 2013, 07:34:39 AM »
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I've been keen on getting a C60AC for years now, being freelance tho I've got very specific details in mind....the thought of cutting a brass one up to put on a teardrop cab doesn't really appeal to me as much as I'd like...

Good to know that the mods aren't as severe as I thought, just remember with that 2mm shorter wheelbase the overhangs will be greater so it's best to keep that in mind!

Catt

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #5 on: July 25, 2013, 10:06:23 AM »
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The trucks for the KATO U30-C and C30-7 have offset bolsters and can be reversed to stretch the wheelbase (worked great for getting a good chassis for the Bachmann Dash 8 40C). I don't know if the newer KATO GEs have this or not but it may be worth checking out.
Johnathan (Catt) Edwards
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ljudice

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #6 on: July 25, 2013, 06:43:27 PM »
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I had a Hallmark C40-8W (Conrail) some years ago and turned the thing into a dummy....


kiwi_bnsf

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #7 on: July 25, 2013, 08:04:50 PM »
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I had considered making the AC6000CW a dummy, but I would still need to address the wheel sets - as these are too coarse to run through my Fast Tracks turnouts smoothly.

Swapping in Atlas or Kato wheelsets isn't an option as the diameter of the OMI axles is considerably narrower, and I would have to modify the trucks (removing the option to ever use the original OMI chassis again). I've emailed NWSL, and most of their range is now no longer produced. I guess I could try and turn the wheels down, but the OMI wheels are pretty crude.

The dummy idea was what triggered me to think about using Kato trucks, and then why not the whole Kato chassis?

I think I'm going to focus on testing the SD70M chassis, and check if the the SD70ACe and SD9043MAC chassis are even an option with the older-style GE trucks.

Cheers

Tim
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Modelling Tehachapi East Slope in N scale circa 1999

Leggy

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Re: Re-powering a OMI Brass AC6000CW with a Kato chassis?
« Reply #8 on: July 25, 2013, 09:36:47 PM »
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From messing about I know the new GE bogies fit the SD80/SD90 mech but will need the GE mech worms (otherwise it makes a real grinding sound). Might be easier to shorten a SD80/SD90 mech than lengthen a SD70/AC44 mech?