I recently opened a box of locos from my childhood and found a Bachmann 4-8-4 Northern, Burlington Route w/ smoke.  This has been in abox for about 15-18 years and I suspect that the engine was purchased about 22-25 years ago.  In the box I found a little note that I left myself that read "Rear axle broken...again.  Look in white parts box"   I found another wheel set with a broken plastic rear axle.  It appears that the replacement 'part' was the entire set of drivers.   Does anyone know if the new drivers will fit this old model?   I had great memories of this loco and woud like to salvage it if possible, but also wondering if the cost/time is worth it?     Thoughts or ideas??
The next step is to dig deeper in the myriad of boxes to look for the tiny wrenches.... 

Ok, my layout from my childhood is long gone, but I'm unearthing boxes of old stuff (20-35 years old) and I am nearing completion of a new small layout for my sons.   Many of the locos are great and ready to roll but I'm sure many of the old large steam will not run on the new layout due to size.
For this first new layout I used 18" radius as I wanted to keep it relatively small and portable (wife wants to move soon....) and it's really for the boys (although I guess I'm still 'a boy', so......
What is the largest steam engine that will run reliably on a 18".
I'm considering a new DCC w/ sound 'for dad', but it would be nice to run it on this as well as the proposed new layout.

Does the N scale EZ track only come in the 2 radii?   I only see the 11.25 and 19".    In addition to an HO layout, I was considering a small N scale layout for an area that is 34"  One seems unneccessarily tight and the other just a bit too large to stay within the limit.
Do you just use lots of flex track & cork roadbed?   Does Bachmann make any or do I just go to Atlas?

Thanks for all of the great advice so far.   I'll have to check and see if I can make a 5' work to use the 28" radius.  The notes about the access and width are well founded.  We had a variety of 'hard to reach' areas on our layout as a kid, but I was much smaller and more nimble then too.
I had been thinking of either an L configuration of about 2 4x8 sheets in a corner or I also have a long 16' wall that I could work along but it might limit my width as it is in a narrow part of the basement.
I'll check out some of the sites with plans that were mentioned in the other thread.
I also need to check the boxes and see if there was any track packed away worth using or if I'm starting from scratch for track.  If I am starting over on the track, does anyone have any recommendations to do this on a budget?   The EZ track looks like a quick and easy way to start as it allows for some quick experimentation before getting more permanent, but it also looks like it will add up quickly as each small section of track adds up $$.   What is the going rate for the nickel slilver flex track these days?   It seems to be my dad always bought bulk boxes of it in long lengths as well as cork roadbed?   (and what is prefered lately, cork or this 'new' foam that I see now?)

Sorry for yet more questions....

Thanks.
Erich

As a kid, we had a large HO gauge layout that took up 1/2 the basement.... (must have been about 5 4x8 sheets, 3 levels and 2 turntables w/roundhouses).  My parents moved years ago and it's long gone (the family that bought the house wanted it all torn out.) but all of the locomotives and rolling stock and some buildings are in boxes and my oldest son is now infatuated with trains (imagine that!). 
I need to start over and need some recommendations.

1. What is a good minimum track radius to keep to for main line?   Keep in mind that my father, son & I all love the large steam locos....   (I'm pretty sure there is a Big Boy, Mallet and perhaps Challenger class in those boxes among others).  Even if I can't run the big articulateds, I still would like to be able to run some nice 4-8-4's and similar....
2. I like the idea of the new DCC, but how do I best run some of my old stuff and gradually integrate the new?   Will I need to replace my old transformers?  Will my old engines run on the new systems?  Will a new DCC equiped run on my old equipment until I upgrade?
3. Does anybody have a good layout plan that might be contained to roughly 2 4x8 sheets, but would allow for possible addition later?  I like multi level and some mountain scenery (bridges, tunnels, etc).  Initially, I'd like to look for a good long runner and can always add switching yards later.
4.All this new fast track looks like a quick way to get something my son would enjoy, but I'm leaning toward the more traditional track on roadbed.   I'm just not sure I have the free time with work and two little ones.   Does anyone have thoughts on pro's & cons of either approach?   Can you start with the fast track and replace it sectionally?  Does someone make a 'transition piece' or can you just but the fast track & traditional roadbeds and work your way around as you 'upgrade'?   ...or just stay away from the 'click & go' all together?

Sorry for the barrage of questions, but it's been a long time and I appreciate any & all input.
Thanks,
Erich