6.5 ft. diameter without modifications to the coal pile.
5 ft. diameter (using the long drawbar connection) by modifying the coal pile (see archives for directions)
8 ft. diameter using the close drawbar connection

  Are your gears damaged? The main problem that the 2-8-0 had was loose motor mounts. Tightening the screws as the "fix" instructs should solve your problem unless the teeth were damaged while running loose.

Honestly, I'd check with Dave Goodson at NWRCS (425-823-3507) as he is one of the top experts on r/c battery installations with Bachmann products! He would be able to give you a difinitive answer.

Hey Bach-man,
  Please pass on our kudos to the guys in Philly! The offerings for 2008 are going to bring a lot of smiles to large scaler's faces! Oh, since this is a thread about future products and someone intimated that it would be nice to see some more road names for the Annie, I thought I'd remind you of a beauty that was done by David Fletcher about five years ago: the E&P #6 Reveille which is a stablemate of the Eureka but instead of being a 4-4-0 American, it's a 2-6-0 Mogul! It's a perfect fit for someone that already has a Eureka and wants a Mogul! The beauty of it is that the cab color is different and there are some minor detailings that would have to be added but other than that the engines are almost identical!

Here is David Fletcher's version from his website on 4largescale.com:

Hmmm.... looks like a cross between one of those old Spectrum 2-4-2T Coal crek #3 , the Spectrum 1:20.3 Porter and an Indie! (Not a bad idea....)

Guys,
  The simple reality is that R1 curves were never designed for 1:20.3 (Fn3) scaled engines and rolling stock! LGB went to some incredible lengths to get their stuff to go around R1 curves but LGB was nominally 1:22.5 and wasn't into "scale models" but toy train carricatures.
  It simply isn't fair to ask Bachmann to compromise with their attention to scale fidelity by having them modify their engines and rolling stock to handle R1 curves! Fn3 is considerably LARGER than G! Don't be fooled because smaller Fn3 prototypes will run with G scale cars. These newest Spectrum engines have been modeled after LARGE prototypes! 8ft diameter curves as a minimum are about the best we can expect in all fairness.

  Removing the springs would seem to leave the same problem as his springs are already totally compressed! The answer seems obvious: get new springs! Unfortunately, this might be one of those trial and error kind of situations. I would recommend going to a well stocked hobby shop and try and match the spring. This has happened to me on several occasions over the years and this is what I had to do.
   One caveat: You don't want to get the springs too stiff or your problem won't be solved! Good luck.

The warning against using "Pulse" should indeed be heeded when running LGB locomotives! I have heard horror stories about internal circuitry burnouts. You should have no trouble with Bachmann trains however! As far as pure DC is concerned, one power pack is pretty much as good as another. What you need to look at is the amperage rating (i.e. is it BIG enough to handle the draw?) If you are planning on running multiple locomotives or are contemplating expanding your layout considerably, I would recommend at least a 10 amp power supply!

  Make that three people that have a Coal Creek #3 that is still plugging away! I have had mine for the last eight years and it is still running smoothly. Of course, I heard the warnings and lubed the gears rather liberally and have never over-worked it! In fact, I was able to get one off of ebay a couple of years ago for a pittance to use as a "parts unit" should my first one ever give out.
  I ran my 2-4-2T with the new 1:20.3 side tank Porter and the Porter is definitely superior in detailing and running characteristics (i.e. smoothness and robustness) but the 2-4-2T is also a decade older! With that taken into consideration, the 2-4-2T holds it's own and is not completely outclassed! The main sticking point is the fragile gearing though! If you have to pay more than $50 for one I would seriously consider something newer and more robust! If, however, you are looking for an unusual engine that is pleasing to the eye in 1:22.5 scale (yes, I know the ads stated 1:20.3 but it really looks dinky in that scale!) then this may be the engine you are looking for! Just remember: Caveat Emptor! 

Cool! I'm glad it's working for you! It would seem we now have another option when adding sound to a small switcher...

  That's strange. I have a #463 that has a Sierra sound system in it and the Phoenix 2K2 uses the same kind of triggers....oh wait! Now I remember! The optical chuff trigger was junked and mine has the old tried and true magnetic reed switch to make it work! Come to think of it, did anybody ever get that optical chuff to work properly with Phoenix or Sierra sound systems?

Well, give her a try and report how it's working! Like I said, I'm sure somebody has tried it!

  The short answer is "no." That is what Soundtraxx's Sierra units are for! Now, the 0-4-0 is a small engine and probably would never pull more than an amp but I have to admit that I'm not an expert. I'm sure someone has tried it before....

You're welcome! Actually, I had this problem with a 2nd gen. Big-Hauler back in 1999 and some people were kind enough to help me out! I'm just passing along their help!

  There are a couple of things you can do to help with this problem. First, have you lubricated the area where the pilot "slides" side to side in an arc? Second, loosen the bolt so the pilot moves more freely. Third, add weight to the pilot (which you apparently already have done.) Fourth, (and this may be a big one) check the gauge of the pilot wheels. You may find that this is the reason the pilot keeps derailing. Lastly, if all else fails, contact Barry Olson at Barry's Big Trains as he has an aftermarket replacement for the pilot mounting that pretty much eliminates any problems!