Intermountain shell FP9 and Kato chassis FP7

[medvedyt]

Hello was wondering if that transition can be done? and if both frame are similars in lenght and width?

[Lackawannae8]

worst thing you can do is try? lol

[thomasjmdavis]

I think if you have an IM shell and a Kato chassis, it will only take 10 minutes to try it on your own and see what will need to be done.  Definitely not direct replacements, but probably do-able with some work.  If you have an IM shell, and are just wondering, I would recommend finding an IM chassis.

I did try this with an IM F7 shell and a Kato F unit chassis, and the fit was not good 'out of the box'.  The Kato F unit chassis is wider than the IM F unit chassis, so the IM shell was too tight.  I probably could have shaved a bit of metal off the Kato chassis and got it together, but I went the easy route, found a Kato shell for the Kato chassis, and an IM chassis for the IM shell, and ended up with two locos.  I model AT&SF, so there is no such thing as too many F units.

[Caddy58]

There was an article on fitting an IM F3 shell on a Kato mechanism in N Scale Railroading, issue 130
Same principles could be applied to an FP swap.

Cheers
Dirk

https://nscalerailroadingmagazine.com/wp-content/uploads/2021/03/130-01-42-2021-MAR-A.pdf

[kiwi_al]

Now that was well worth downloading - thanks Dirk - was that your article?

[medvedyt]

thank you very much guys. very helpful.

[Tad_T]

Very nice article.

How about going the other way?

I have a bunch of Intermountain F Units that I picked up cheaply. I also have a bunch of Kato shells that I have considered putting on them. What does a fellow have to do to make that happen?

Thanks,

Tad

[Caddy58]

Now that was well worth downloading - thanks Dirk - was that your article?

Yes, it was 

[thomasjmdavis]

There was an article on fitting an IM F3 shell on a Kato mechanism in N Scale Railroading, issue 130
Same principles could be applied to an FP swap.

Cheers
Dirk

https://nscalerailroadingmagazine.com/wp-content/uploads/2021/03/130-01-42-2021-MAR-A.pdf

That is a great article.  I wish I'd had it handy when I was looking at my own project.  I may find a use for it yet, as I do have some IM shells with no chassis to put under them, and do have some spare Kato frames- so I may make dummies.

However, for the OP project, involving FPs (not Fs), the chassis is much different than the 1987 vintage Kato chassis in the article (note the original design trucks, and full metal chassis).  The FP-7 chassis is made much like the current run F units- which is to say, a lot more plastic, and more delicate with brass strip contacts and such.  See here for a look at the FP-7 chassis- http://www.spookshow.net/loco/katofp7.html .
My guess is that the same basics apply- the frame will need to be made a bit narrower, but the specifics will be somewhat different.  And since the FP frame is longer than an F frame, the chassis are not interchangeable.