F units

[spud7378]

Hello gang. I saw a great deal on ebay and I'm wondering. First off I'm really not experienced with the fine details of proto types. So I ask, what is the difference between an F3 and a F7 other then horse power? Now would the shell be the same ? And next question I have an athearn BB F7 that I did right up with all Road specific details. Just wondering if this shell would fit on a proto F3 frame? If not that's why I ask about the F3 to F7 comparison, if they won't fit I would re do the units over with the F3 shell.

Thanks gang

[CP_8530]

The biggest visual difference is the radiator screening: The F3 uses the earlier "chickenwire" screening, whereas the F7 has the later horizontal grills. The F3 may also have screening between the portholes, and taller radiator fans. Both would probably take more work than it's worth to convert an F3 into an F7 (unless you have a Highliners kit to build). It may be better to look for a cheap Intermountain F7A to strip and repaint (and they were originally intended to fit the Athearn chassis).

ONR never had any F3 or F7's, but if you're planning on doing a CN unit there was one ex-GTW F3 rebuilt as part of the CN 9150-series F7Au rebuild program: 9171.

I'm not sure on the P1K + Athearn frame/shell compatibility, so can't really comment on that.

[spud7378]

It was for an F7A the ONR had lots of F units. The 1500 series were all F7A's unless there is a difference between a F7 and a F7A? I did 2 units with athearn shells but only had 1 powered frame. 1 was 1520 in the chevron scheme and 1513 in the traditional green and yellow so I re powered the athearn frame and it runs great and nice and quite. So I saw the proto F3 with sound on eBay and thought the frame may fit? But I may have to look for a BB frame and re power it too. It sounds like way too much work to convert a 3 to a 7 and if a intermountain shell will fit an athearn, maybe ill look for a intermountain frame.

[CP_8530]

Actually, all of ONR's F7A's were the noticeably longer FP7 model (both Athearn and Intermountain make them). But, many people seem to make due with F7A's in their place.

The Intermountain F7A may require a bit of sanding behind the skirts to fit the Athearn frame, but when they were initially released as shells only, they were intended to be used with an Athearn chassis (among others listed in the review I read in MR).

If you want a higher level of accuracy, I'd recommend just looking for a complete Intermountain FP7 to strip and repaint, or an undec kit with drive chassis. Saves you a lot of trouble, and the F3 -> F7 thing really isn't worth it.

[spud7378]

Ok. So were they longer due to the steam generator? So there is a difference between an F7 and F7A I didn't know that. I thought the A was just because it was a cab unit.

[CP_8530]

F7 and F7A are often used interchangeably. I think officially for A-units it was just F7 without the A, and the B units merely had B added on the end (there were officially no "FP7A", "FP9A" or "FL9A" units).

The FP7 has a longer carbody, with the extra length used accommodate larger water tanks in the carbody IIRC. B-units often had that excess water capacity located where the cab would have gone, thus there's no "FP7B" units. Regular F7's could have steam generators as well, just not as large a water capacity.

[spud7378]

Well thanks for the lesson in F units. Ill just keep looking!!!

[jakeloyst]

the Athearn shell is pretty wide open, and it mounts using 2 slots in the fuel tanks, so there is no protrutions inside to block the proto frame, Athearn uses small tabs on the bottom of the frame itself to make it sit level under the F7 shell. I haven't seen the proto frame, but it should be easy enough as the entire piece fits inside the F7 body, unlike road units, where the frame thickness oftern interferes with the walkway. The F3 and F7 have the same wheel base, so the difference would be the road specific fuel tanks. On the body itself, the differences are the porthole locations and louvres, as well as the grills that run along the top. The roof top fans came in two heights, depending on the year of the unit, and wether or not the units were rebuilt at some time during their lives. Depending on your version of the F3, originally the number boards wer mounted to the side of the nose, while later units were moved more towards the front, and were larger. Both the F3 and the F7 were availiable with dynamic brakes, and steam generators. The FP7 and FP9 models were designed for a much larger steam generator with more water storage capacity to deal with larger passenger cars and train lengths, and this resulted in the extra 4 ft of length in the unit. These are all A-units. The B-units already had the space availiable for the lager tans as they did not have the engineers cab to deal with .....

[tjkorinek]

EMC/EMD :
F7A locomotive 1500 hp
F7AA locomotive 3000 hp
F7ABA locomotive 4500 hp
F7ABBA locomotive 6000hp ... the more units, the more horsepower. A very flexible
and highly addaptible system. The customer (RRs) could purchase locomotive based
on their particular horsepower needs. That need was to be a single locomotive of mul-
tiple units. This was marketing of the erea. A/cab, B/cabless, later by Roads termed
booster. EMDs mechanical up grades did little to change "F"s appearance over all models ( numbered) beyond the "FT"s ; 3,5,7,9. BIGGEST factor in appearance came
from customers with the purchase. Railroads employed their own mechanical and de-
sign departments. General Motors offered an extensive array of accessories, which
these departments would use to taylor locomotives. Both for service and its own look.
A happy customer would be a return customer. As diesel detailers are awear.
PAINTschemes also weigh in heavily where customization. Design and color, go the
distance, to identify a railroads equiptment and domain. Hope this sheads a little factual
light on your research. Liberaries are another great source. Glad to share. TJK 2013

[tjkorinek]

P.S. Live it up! YOUR "F3" is worth all the effort you care to invest. AND the work is
easier when doing multiples, think A,B,B,A... Now think FOUR sets! Sell 3 and yours
paid for itself. Athearn shells are cheap and easily cut up. Excellent for learning the
material and tools. (TIP HERE) My "F3" sets were built with three tools ;
A, coping saw ( teeth toward handle ) pulling better control
B, 6'' file ( flat smooth cut )
C, #11 exacto knife ( as scraper to clean and sharpen corners )
the sharper the better... CAREFUL!
My start was four shells to produce one... lots of do overs to get it right...just more practice
the work is the fun, the effort well worth every minute (and all the shells). TJK 2013

[spud7378]

Thanks guys for the help

[tjkorinek]

Four sets(ABBA)/ four locomotives/ sixteen units total.
What are your roads needs roster wise?  Total here...
24000 hp in fun! Love it when people think BIG. TJK 2013

[dablaze]

I went the same route on ONR F units, I have one each of blue and yellow, older green and even did a very weathered Northlander F unit...all on Athearn models. Then when the Atlas/roco FP-7's came out, I started again and have a couple of green units. (at this point my bout of rivititis-countagen disease kicked in and I could not bring myself to put them on the layout anymore) Then intermountain came out...and my Rocos are still valid, but sitting on the back burner.

If you want an inexpensive solution, haunt Ebay for some Roco FP-7's, they can be had pretty cheap sometimes, they come up often, so pass on any that go too high. Also, watch carefully and you can find the Rocos without dynamic brakes which will be more correct. That being said, I don't know exactly what the physical differences are, I think it might just be the lack of the forward most roof fan?

Someone will have to clear one thing up for me, I know that the ONR purchased F7b units from Milwaukee Road, but I believe I heard they were simply run for the steam generator units, and may not even have been powered...I don't know how steam generators work...

I can't remember who was doing a thread on an ONR FP7 2000 series cat build, I would love to have seen that thread finished with the final result!

Craig

[spud7378]

Thanks Craig. The ex Milwaukee road b units were used for shell and trucks only. They were converted to APU (aux power units) they were never powered by the ONR as a true B unit. I believe they had purchased 5 but only converted 3 202,204,205 I think. The remaining 2 sat on the deadline for a few years. The one unit I did with the athearn frame and shell but re powered with an a line motor runs great I think I may so that with the second unit. I did a shell but its powered with the athearn motor. Too noisey. Sow I saw a deal on an f3 and thought it might fit. But I think going to so the repower on the other unit as well it may be easier.