JNJ CF7 Mechanism Suggestions

[bman]

So has anyone ever worked with one of these? I came across one for a couple of bucks and said "why not?" My internet search only came up with a quick note of someone building one using a heavily modified LikeLike GP20 mechanism. Of course no description of the process of actually heavily modifiying it. I actually have an spare GP20 mech and I can get it to fit over the mech, but the steps on the front and rear porches will never clear on curves on most model railroads. I thought about using either of the plastic framed LifeLike F units or GP38-2 and shortening the frames to fit. Thought I'd ask here to before I go that route for some insighty. 
Thanks.

[thomasjmdavis]

According to Walthers, JNJ once marketed a frame kit for the CF-7
https://www.walthers.com/chassis-kit-cf7-includes-frame-motor-trucks-flywheel

I can't speak to this specifically, because I haven't done (or even seen) a JNJ CF-7, but the most likely possibility that occurs to me is the then common Atlas-Kato frame and mechanism for the RS-3 and similar one for the GP7/9 (the only difference I am aware of between the two is the truck sideframes, both carry the number 17708 cast into the frame). 
http://www.spookshow.net/loco/atlasgp79.html   the Atlas-Kato units mentioned near the top of the page

While would need to measure, I think this might be a case where the short wheelbase of the Atlas-Kato Geep could be to your advantage because the CF7 wheelbase was a bit shorter than a GP7 (IIRC).  And without putting calipers on it, hard to say for sure, but probable that the front nose would fit over the frame, since the frame was originally designed to fit under the front hood of an RS-3 shell, which while not "low nose" is a lot lower than a GP7.

Wheelbase of the GP-7 notwithstanding, in their day those were one of the best commonly available mechanisms available, and a lot of shells were built to fit them.

[thomasjmdavis]

I pulled the mechanism (Atlas Kato RS-3 with 17708 frame) out of one of my JNJ sharks.  At the nose, base of the frame to the top of the largest blob of solder on the lightboard is 0.531.  Overall length 3.5".
Width under hood 0.434".  It has a "flange" all the way around to support the walkway- 0.677 wide there and under the cab (see the spookshow photo linked above).  There are also castings that fit under the cab walkways and stairs that you might have to grind away to get the CF7 stairs/cab to fit.  Truck centers 2.2" (approx), overall wheelbase c to c-  2.92 (eyeballing the wheel centers so I don't have to take it apart).

[mu26aeh]

Not sure how it sizes to @randgust CF7 kits, but that uses a GP7/9 chassis under it.

[jcox3751]

I would look into using an Atlas GP15-1 chassis. I believe the wheel base is closest to an F7 and it is a great runner.

Remove the fuel tank and use an F unit fuel tank and you will have a great start on that shell.

Is yours an angled cab or a rounded cab shell?

Joe Cox
Austin, Texas

[randgust]

I even have one of those JnJ CF7 shells, believe it or not.   It's actually pretty crude.    I offered my photoetchings (handrails and details) for the JnJ as a separate sale for years and never had one taker, so there are darn few out there.  I studied it and decided it wasn't worth the fight.  I can see why they never appear to have got the mechanism to market as a feasible product and the shell had no usable commercial chassis as it is just so short.   I've never measured it out but it has so many glitches to begin with.

And this is the classic case of 'the enemy of good is perfect'.   The GP15 may have the right wheelbase, but that mechanism has a cast metal fuel tank that has to be almost completely ground off to be narrower to work with the proper side sills and fuel tank.   And, it doesn't have pickup wipers - the pickup goes through the truck sideframes to the frame.

I actually did one for my CF7 kit just to see if it was actually worth it visually; ground off the tank.    I was very dissapointed by the pickup issues and after a couple years I sold the mechanism and replaced it with the new Atlas GP7 mech, which is quiet, smooth and dependable and is also pretty much ready to go with DCC.

I've left this online because I do fully intend to do another run, as soon as Atlas puts it on the production schedule again:  http://www.randgust.com/prod07.htm
But for right now, I'm out of etchings and making another run of those is a significant investment unless chassis are available.

So yeah, the wheelbase is about a foot too long, I extended the area right behind the cab 6", and took the other six inches up on the spacing of the trucks behind the end sills.    And you're more than welcome to find a better, affordable solution - mine goes right over top a new-issue Atlas chassis with no mods except switching ends on the light board assembly and relocating the headlight.

I just got a communication from Atlas today that they are probably rerunning the GP7 in 2021, maybe, and that's why I didn't do another run of my photoetchings when no current-run chassis was available - it's just SO much better than the Classics it's not even funny between the slow-speed motor and the improved universal.   That's the first ray of hope for me rerunning my CF7's again that I've had in over a year.

Way back in the 80's I scratchbuilt a CF7 for JnJ on request as a resin master after my first scratchbuilt one was published in RMC.   That first pair was actually over Roco/Atlas GP9's (the ones introduced about '76).   They had it over a year and told me it was unsuitable and had never used it.  Another year passed as I complained that I never got it back.... and when I finally got it back there were traces of molding rubber all over it and it had obviously been used to make molds.   I had to give then legal notice that if if showed up on the market it was grounds for action...  and after than the other resin shell showed up that's out there now, including wrong steps, etc.   And, that's why everything I do, to this day, is copyrighted, lesson learned.