Intermountain F7 modifications

[Cajonpassfan]

A while back, several years, there was a discussion about lowering the Intermountain F7 shells on the body which I can’t seem to be able to find. Can someone please direct me to the thread? I recall it involved minor modifications to the body, and now that I have three ABBA sets entering service, I’d.like to make them look right...
Thanks,
Otto K.

[kiwi_al]

Hi Otto,
Try these links:

https://www.therailwire.net/forum/index.php?topic=32859.15

and this one
https://www.trainboard.com/highball/index.php?threads/n-scale-lowering-intermountain-f7-carbody-and-coupler-height-adjustment-sizemore.34111/#post-437791

Forgive the Trainboard sidepost   

https://www.trainboard.com/highball/index.php?threads/im-f-7-lowering-ride-height.26107/#post-321091
Pictures are hard to come by!!!

The links embedded in the TB post appear to be no longer available...

[Cajonpassfan]

Thanks Kiwi! Some good info, but a lot of it unfortunately lost...a byproduct of the digital era. Now you see it, and poof, now you don’t.
But I learned about raccoons
Otto K.

[randgust]

One of my favorite lines is "How's your wife?" when the answer is "compared to what?"

And that applies here.

If you couple a Kato F-unit back to back with a stock Intermountain, you'll see there's only about a 3-5" height difference at the back of the roof with the Kato slightly lower.   But if you look down at the truck area, that gap under the frame to the trucks is what makes it look the way it does - sitting high on the trucks with the frame gap in there.   The Kato shell 'appears' to sit lower on the trucks because that frame gap isn't there.

The Intermountain F I have measures 14' 5" to top of roof and and Kato measures about 14'1" from what I can tell.

Body panel height on both is 8'6" from bottom edge to top of grilles but at the bottom edge of the panel there's a good 6" difference between shells that really shows and that's where this comes from...some of it is in the roof curve profile, too.

It's noticeably in the truck sideframes.   Kato's are higher, and block the gap.  IM's are lower, and leave a big gap.   I don't know who is right, just an observation.  That final carbody height is not entirely the problem here.

So, visually, what you really have here is a gap problem more than a height problem; the shell height isn't as bad as the frame gap from the difference in truck designs.

Going back to when I still had hair and was running Rapido GP7's and 30's (and THAT was a gap!!) I put an additional strip across the bottom of the frame and painted it either the body shell color or grimy black to make it look a little less wacky.   On the IM it looks like about .040 would do it.   Visual block.

This also depends on whether you are repainting an IM shell (which is it's own exercise in frustration, I've done it) or not.  ATSF has that yellow stripe across the bottom on a freight unit, and the skirt was gone on most of them by the 70's anyway.

In the end, after measuring things, I just left mine alone as trying to lower the shell seemed like just too much work for the benefit. 

I'm just sayin'  Otto, before you charge into this, do the back-to-back thing and see what you think.   My reaction was a most certain 'huh....'....

And you've got 12 of them to do....

I'm not against doing terrible stuff to Intermountains, I swapped the SD45-2 stock chassis with a Kato SD40-2 simply to improve the performance and it was worth it, very much so.   The IM F7 replace a thoroughly worn-out Trix F-unit I'd painted, and compared to THAT, the IM was a huge improvement.

[Cajonpassfan]

Thank you, Randy, for your thoughtful writeup, and useful dimensions. it’s much appreciated. Your suggestion that I maybe leaving good enuff alone is the way to go struck a cord with me because in addition to these these twelve Catwhiskers a have a bunch of Warbonnets, too. What can I say, a Santa Fe all the way guy...

But of course I had to look into it on my own, and after some messing around with fitting the shells, this is what I found: The coupler mounting pads have a rounded outer edge that is supposed to fit into a rounded cutout at the each end of the shell. There is a little horizontal shelf at each end of the body for it to rest on. See pics 1 and 2.

But when I measured the distances between the outer rounded surfaces of the mounting pads and the inner rounded cutout, I found the shell dimension about .4mm too short. In addition, my shells don’t have a clean cutout, preventing them from seating properly against the shelf, pic 3. Filing the pads back is not possible because of the coupler mounting screws’ proximity, so I took a small rotary tool and an Xacto blade to open up the “cutout”, and voila, the shell now drops well into the body, pic 4. And it makes a hell of a difference, see pic 5: IM on the left, Kato on the right. (Please ignore the coupler mismatch, it’s a problem on the talgo mounted Kato truck; the IM is just right). The IM is now just ever so slightly lower than the Kato.

I still need to test run it to make sure there isn’t another issue, but if this is all it takes to lower the body and “close the gap”, it would seem well worth a relatively small investment in time and effort.
Am I missing anything?
Otto K.

[Cajonpassfan]

BTW, I’m using FVM 51060 bodymount couplers, below, (which I believe are clones of the old Unimates) inbetween semipermanetly coupled F units. I’ve done this before, but always had a MT coupler on one unit and an Unimate on the other. Here the 51060’s are screwed in tight and will mate with each other and neither will swing (hmm, that came out so wrong). Will this be a problem on curves and crossovers? I’d rather not have them flop around because the screws will eventually get too loose. Anyone here have useful experience with this?
Thanks for your feedback,
Otto K.

[keeper]

This is well worth checking and it is not that much work if it is that problem.

Off to grab all IM F's.

Thomas

[arbomambo]

I vote for avoiding all this by only using Kato F3s and 7s!

[Cajonpassfan]

Well, to each his own. I like the IM’s, and the effort required to lower the shell is minuscule.
Besides, Kato never made Catwhiskers...or freestanding handrails, or etched grilles, or opaque cigar band yellow...
YMMV, and obviously does...
Otto

[mark.hinds]

A while back, several years, there was a discussion about lowering the Intermountain F7 shells on the body which I can’t seem to be able to find. Can someone please direct me to the thread? I recall it involved minor modifications to the body, and now that I have three ABBA sets entering service, I’d.like to make them look right...
Thanks,
Otto K.

I lowered mine, and also semi-permanently coupled them at the correct distance.  IIRC, it required major surgery to get down to the correct 14-scale-foot height.  It's not just a screw or coupler change.  Even then, the shells are held in place by friction and gravity at the moment.

BTW, Kato's are the correct scale height; for dimensions of the prototype, see http://www.nprha.org/Diesel%20Diagrams/Forms/Thumbnails.aspx#InplviewHash765015e9-c63e-4284-b03c-fc91800bb2bd=Paged%3DTRUE-p_SortBehavior%3D0-p_FileLeafRef%3DEMD%2520F%252d3%2520Freight%25206000B%252d6005C%2520Mx%252045%252ejpg-p_ID%3D76-PageFirstRow%3D31.

Looking at my IMR F7s, the process included:
1)  Grinding a recess in the bottom of the shell under the end doors at each end, to mate with the existing "coupler mounting pads".  These pads are attached to the frame, and are extensions of the end spacers between the 2 frame sides.  The pads need to be sunk slightly into the structure under the end doors, and it needs to be done precisely, as this is what determines the final height at each end.  The weight of the shell is supported on these countersunk pads.  If you grind too far into the shell, you can glue in a small sliver of plastic and try again.
2)  Lowering the fuel tank assembly closer to the railhead.  This requires the side clips on the tank assembly to be clipped off, so that it can be lowered, and spacers to be inserted inside the tanks to keep them at a fixed distance from the protruding fuel tank portion of the metal frame.  The whole thing needs to be held in place somehow; I drilled and tapped into the bottom of the frame for a single flat-head screw.  Be sure to keep metal fragments out of the mechanism when you do this.
3)  On "A" units, you need to cut away parts of the green cab detail assembly, as it otherwise keeps the shell on that end from being lowered sufficiently.
4)  There may need to be some trimming of plastic "catches" inside the shell itself, although I no longer remember whether this is needed.
5)  WRT close coupling, there was a guy on another Forum who used HOn3 couplers from "Rail Line"; part number #116.  They are a soft-ish plastic, and you cut the shaft to the desired length, and drill a mounting hole.  I modified his design by putting a Micro Trains spring on the mounting screw, as you can't torque it down for obvious reasons.  I also carved off the top portion of the coupler to get the look I wanted for N-scale; note how the side-view image of the couplers looks flat on top.  The close-coupling couplers can be substituted for the standard Micro Trains couplers on the Intermountain F-units, at any time desired.  So, if I want 2 A-units back-to-back, I can switch them out appropriately.  BTW, these can't be uncoupled during an operating session, so are most appropriate for multi-unit diesel sets, such as 1950s-era F-units, which the prototype operated in sets. 

The final product should be checked with some sort of gauge capable of measuring the height above the railhead (at *both* ends); I used this:

[sizemore]

Holy Crap, something I did 14 years ago still being used! Glad to help.

The S.

PS. While I haven't posted, still into trains, just dont post much, focused on working on my house, and other projects.

[ncbqguy]

The Fox Valley dummy knuckle couplers are not clones of the Red Caboose / Precision Masters originals; they were part of the tooling that Matt acquired from Red Caboose/InterMountain. 
Charlie Vlk

[Cajonpassfan]

I lowered mine, and also semi-permanently coupled them at the correct distance.  IIRC, it required major surgery to get down to the correct 14-scale-foot height.  It's not just a screw or coupler change.  Even then, the shells are held in place by friction and gravity at the moment.

BTW, Kato's are the correct scale height; for dimensions of the prototype, see http://www.nprha.org/Diesel%20Diagrams/Forms/Thumbnails.aspx#InplviewHash765015e9-c63e-4284-b03c-fc91800bb2bd=Paged%3DTRUE-p_SortBehavior%3D0-p_FileLeafRef%3DEMD%2520F%252d3%2520Freight%25206000B%252d6005C%2520Mx%252045%252ejpg-p_ID%3D76-PageFirstRow%3D31.

Looking at my IMR F7s, the process included:
1)  Grinding a recess in the bottom of the shell under the end doors at each end, to mate with the existing "coupler mounting pads".  These pads are attached to the frame, and are extensions of the end spacers between the 2 frame sides.  The pads need to be sunk slightly into the structure under the end doors, and it needs to be done precisely, as this is what determines the final height at each end.  The weight of the shell is supported on these countersunk pads.  If you grind too far into the shell, you can glue in a small sliver of plastic and try again.
2)  Lowering the fuel tank assembly closer to the railhead.  This requires the side clips on the tank assembly to be clipped off, so that it can be lowered, and spacers to be inserted inside the tanks to keep them at a fixed distance from the protruding fuel tank portion of the metal frame.  The whole thing needs to be held in place somehow; I drilled and tapped into the bottom of the frame for a single flat-head screw.  Be sure to keep metal fragments out of the mechanism when you do this.
3)  On "A" units, you need to cut away parts of the green cab detail assembly, as it otherwise keeps the shell on that end from being lowered sufficiently.
4)  There may need to be some trimming of plastic "catches" inside the shell itself, although I no longer remember whether this is needed.
5)  WRT close coupling, there was a guy on another Forum who used HOn3 couplers from "Rail Line"; part number #116.  They are a soft-ish plastic, and you cut the shaft to the desired length, and drill a mounting hole.  I modified his design by putting a Micro Trains spring on the mounting screw, as you can't torque it down for obvious reasons.  I also carved off the top portion of the coupler to get the look I wanted for N-scale; note how the side-view image of the couplers looks flat on top.  The close-coupling couplers can be substituted for the standard Micro Trains couplers on the Intermountain F-units, at any time desired.  So, if I want 2 A-units back-to-back, I can switch them out appropriately.  BTW, these can't be uncoupled during an operating session, so are most appropriate for multi-unit diesel sets, such as 1950s-era F-units, which the prototype operated in sets. 

The final product should be checked with some sort of gauge capable of measuring the height above the railhead (at *both* ends); I used this:

Thanks for your input, very useful. As to the tanks, I lowered them by clipping the the tabs and holding the plastic tank casting in place by a piece of 3M mounting squares cut to size. It dropped  the tank assembly by about 10” and took about two minutes to do. Kato on left, IM right; close enough for me...
Love the raccoon...
Otto K.

[NorsemanJack]

BTW, I’m using FVM 51060 bodymount couplers, below, (which I believe are clones of the old Unimates) inbetween semipermanetly coupled F units. I’ve done this before, but always had a MT coupler on one unit and an Unimate on the other. Here the 51060’s are screwed in tight and will mate with each other and neither will swing (hmm, that came out so wrong). Will this be a problem on curves and crossovers? I’d rather not have them flop around because the screws will eventually get too loose. Anyone here have useful experience with this?
Thanks for your feedback,
Otto K.

Back in the day, I did convert an ABBA set of IMR F3's to unimates.  I believe that I gutted a MT 1015 coupler box, drilled out the "post," and used it to mount the unimates.  That allowed me to tighten the screws securely, but allow for free rotation of the unimates.  I would never simply mount them with a screw.