Which chassis do you prefer to modify?

[Dreyfusshudson]

In Japan, there's lots of old Kato/Micro Ace steamers to modify(making 1880 diameter 4-8-4).
Which chassis do you prefer? Rivarossi? Model Power? Minitrix?

[timwatson]

Kato chassis are really pretty good. They have a nice cordless motor now some of the older versions didn’t and weren’t quite as good as the chassis now. I hope that helps.

[JMaurer1]

Don't really understand why you are asking the question, but the Rivarossi frames are known for frame rot. Both the Riv and Minitrix are using really old school motors and large flanges. The MP at least uses more modern manufacturing and motors but are no longer in production. The Micro Ace/Kato's run like a Kato, but they are very distinctly a Japanese and/or Chinese prototype (although the streamline versions are rather nice to look at). I guess it depends on what you are planning on doing with it...

[thomasjmdavis]

Am I correct to assume that "1880 diameter" is 1880mm, which in US loco dimensions would be a 74 inch driver?

I am not aware of any US prototype x-8-x locomotives available with 74" drivers.  The Bachmann 4-8-2's and N&W J,and the new BLI Reading T1, and all the Berkshires are based on prototypes with 69" or 70" drivers. The Bachmann ATSF, Kato and BLI 4-8-4s, and the BLI PRR M1, are based on locos with 79-80" drivers.

The most common locomotives with 73" drivers are the various models of USRA Pacifics. But to stretch those to become a 4-8-4 would probably require a new frame and a whole lot of work.

I need a 4-8-4 chassis with 73" drivers myself, so if I am wrong in my statements above, somebody please let me know.  My easiest route would appear to be heavily modifying a BLI T1, and accepting the 3" difference in driver diameter, and a few inches in overall wheelbase. 

[kiwi_al]

For 73 inch spoked drivers stretch the Bachmann 4-6-2 - Bachmann has made the drivers 73 inches, however the mechanism is a bit high and there is a limited amount of metal you can mill off before compromising the motor housing. For Bokpok drivers the latest Bachmann 4-8-4 Northern (clear crystal box version - stay away from white box or earlier) has the 73 inch drivers. It also should be noted that model manufacturers rarely make steam drivers of the correct prototypical size for the model they are producing, this is just my opinion after measuring a fair chunk of steam drivers.   

[mmagliaro]

I'll say at the outset that I have used all of these at one time or another, except the Model Power, but that's a function
of when I did them and what was available.

Rivarossi, Minitrix  - No because they aren't split frame, the wheels have huge flanges, and Rivarossi doesn't even have axle bearings.  So for a new kitbash, I would avoid these, even aside from the Rivarossi frame rot problem.

Model Power - No.  Much nicer, finer-looking parts, but the slippy driver/axle connections and contact wipers even on the drivers rule
these out for me.

Kato - Always a good choice.  Their engineering is simply excellent at any era of their production.  It's not just that their engines run well.  Nor do I really worry about the motor for something like a kitbash since that can always be changed.
The big thing is that the parts are designed to fit better, and they tend to only go together one way.  For example, when you put some chassis together, people play tricks like "loosen this screw one turn" to alleviate a bind.  That sort of thing belies a design that is not precise or parts that do not fit precisely.  I don't tend to have to play games like that on a Kato chassis.  They go together and everything should just be tight and that's that.

Broadway Limited is one you didn't have on your list.  I don't own a one.  And until they stop making solid non-see-thru drivers, I never will.  I would not invest all the effort to kitbash a steam model with solid drivers.

[Dreyfusshudson]

Old Rivarossi has Chassis rot problem?
Since I don't have it, I didn't aware of that.
Kato ot Microace will be best solution.
Did someone have walkthrough of making 4-8-4 chassis?

[mmagliaro]

Old Rivarossi has Chassis rot problem?
Since I don't have it, I didn't aware of that.
Kato ot Microace will be best solution.
Did someone have walkthrough of making 4-8-4 chassis?

Oh yeah.  The Rivarossi / Atlas N Scale steam locos are the venerable granddaddy of the Zamac contamination problem ("zinc rot", "zinc pest", whatever you call it).  I think they are the most famous N Scale loco of all time to suffer from that issue.  Through the 1980s and 1990s for sure, engines that were seemingly clean for 30 years would start showing the problem. 
It doesn't happen to all of them.   There are plenty of 50 year old Rivarossi frames around that have not crumbled or warped.  And the longer time goes on, the more sure you can be that if you find a frame and it's clean, it won't suffer the problem.

But even without that, the design is just.... old.  No axle bearings, deep flanges, no split frame so one-side pickup only.  I am all for fixing them up and running them just as they are.  But I don't think they are worth investing kitbash time to make a new engine.

[thomasjmdavis]

For 73 inch spoked drivers stretch the Bachmann 4-6-2 - Bachmann has made the drivers 73 inches, however the mechanism is a bit high and there is a limited amount of metal you can mill off before compromising the motor housing. For Bokpok drivers the latest Bachmann 4-8-4 Northern (clear crystal box version - stay away from white box or earlier) has the 73 inch drivers. It also should be noted that model manufacturers rarely make steam drivers of the correct prototypical size for the model they are producing, this is just my opinion after measuring a fair chunk of steam drivers.   

I guess it should not surprise me that the Bachmann 4-8-4 drivers are 7 scale inches too small (they should be 80"), so I'll take your word for it. Something to do with early versions of the loco having huge flanges, I assume?

If someone here has a "post 2005 in plastic box" version of the Bachmann 4-8-4, can you tell me what the measurement is between axle centers of the 1st and 4th driver? (inches or mm whichever is more convenient for you)  I know what it should be, but if the drivers are smaller, I wonder if the wheelbase changed (not a bad thing for my purposes if it shrunk a little bit.)

Thanks in advance.

[mike_lawyer]

If you can use a Kato chassis, that is my number one choice.  The engineering is excellent, and the parts fit together well.  You can save a lot of troubleshooting and headaches by starting with a solid chassis.  Pick a Kato if one is available.

[kiwi_al]

I guess it should not surprise me that the Bachmann 4-8-4 drivers are 7 scale inches too small (they should be 80"), so I'll take your word for it. Something to do with early versions of the loco having huge flanges, I assume?

If someone here has a "post 2005 in plastic box" version of the Bachmann 4-8-4, can you tell me what the measurement is between axle centers of the 1st and 4th driver? (inches or mm whichever is more convenient for you)  I know what it should be, but if the drivers are smaller, I wonder if the wheelbase changed (not a bad thing for my purposes if it shrunk a little bit.)

Thanks in advance.

If you are wanting close to 80 inch drivers then you'd be better to use a Kato FEF-3 4-8-4, that has 78 inch drivers (Bokpok) Ideal for Santa Fe Northerns - 3751, 2900 and 3776 classes.

[thomasjmdavis]

If you are wanting close to 80 inch drivers then you'd be better to use a Kato FEF-3 4-8-4, that has 78 inch drivers (Bokpok) Ideal for Santa Fe Northerns - 3751, 2900 and 3776 classes.

I am looking specifically for 73" drivers.  An earlier post ID'd the Bachmann Santa Fe Northern as having 73" drivers.  I am aware of the 80" drivers being correct for the 2900 and 3776 classes (and the post-rebuild 3751 class), which is why I was surprised that Bachmann made them so much smaller.  My guess is that the Bachmann frame will still be too long, but I didn't want to dismiss it, hence my asking about the axle centers.