Assistance/Advice on 'modifying' Lionel Prewar 021 Switches(worried about contact rollers)

Lets back up some. First verify that the drivers are not 'fat-driver' pre-war. 

  Fat driver wheels have the larger diameter molded gear that is even with the flange in outer diameter, creating a fat flange, and a wider flange clearance to be needed.  These type of drivers use turnouts without guide rails and wheel gaps. Other turnouts would be needed.

Too narrow of wheel gauge can also cause bumping. Verify the issue vs waste time modding if not needed.

Look for evidence of flanges clipping edges and points too. 

I will post some pics or a drawing on fat wheels later. Once I start typing, I can't move to my camera, and back here again.

You need to create a triangle-ish/diamond filler that blocks a roller from dropping in.

When a roller drops into a gap the angle they sit at can catch at a harsh angle on the surface and that causes the next rise and or a pole vaulting the engine/car, slightly at least, on the front roller arm.  (My k-line car rollers can drop into a Sakia 90° crossing gap and stop the whole train like it hit a brick wall. These have a circle in the center vs a diamond and an O ring popped over this inner guide, fills the gap in a hair and and still leaves room for flanges.).

You might try wood, styrene (laminated to form a block to sand/file/shape and/or an L bracket shape,  etc.) or even sculpt a blob of 5-min JB Weld in plastic wrap as it firms. Peel plastic off once set and sand/file to fit then glue/tape that in place. 

It will have to sit either on the drop off section of the center rail against it's bend, and leave a slot for flanges to pass along each "red rail".   OR mounted on the horizontal web/bracket tying and mounting the red rails, and cantelevering over the drop-center rail & hole if needed

  I would shape and test with two sided tape and once it seems ok, then attach with epoxy or gel super glue or goo, etc.

#1 has to clear flanges.

#2 form a gap filler that would keep a roller from dropping as far down, maybe stop it from dropping at all.  It might be 1/4" - 1¼" long eyeballing it. It should sit even or just slightly lower than red rails. 1/4"- 7/16" inch tall?... (you can't make it taller once short )

The wood and plastic added are softer than metal. The plastic/wood wear out, not the metal. An extra red rail would be great to work into the materials used, lol...(?)  (I had a pair of these as a kid but got new 1122s... flood ate em. I have never seen a good close up until today...thanks.)

You could argue about wood's oils and organics contacting on metal, or something trival, but we'll likely be long dead before it matters.

I'll post a pic of a Marx fat wheel 0-27 turnout for you to see too. Others mentioned may be needed for wider turns though, I don't know that layout well.

Sparking where?

Is everything super clean?

Roller pits/wear ? Roller Axle/ rivet/ pivots clean? (flush with Wd-40, solvent, or electrical contact cleaner, etc.)

Wheel tarnish or crud?

Does it effect motor operation or flicker lights?

And how many power feeds? (ideally 1power drop to each leg of a turnout (3).

I'm seeing a few possibilities as to the bump. The red rail alignment doesn't look great. 

There is a green, red, and purple outline on shapes , the green diamond being fixed in place for sure.  Pins of plastic, metal(?), toothpick/dowel ?

Now, The Marx 0-27 that has a roller drop issue fixed with pins, and by design will pass far wheels shown below that.(& Marx fat next to Marx double reduction gear drive with normal flange & gear wheel...others used fat wheels too .)   (The turnout an excellt freebie from Pingman 😎)

Both sides of the points move; like a spinning bow tie ( pivoting) and each rail changes polarity by sliding on contact pads.  Very smooth for wheels, stable for rollers, shoes, & button griders so far.

This lower, curved point rail needs tweaking to the inside. I need to vacuum.

Notice width won't make some gaps, including some uncoupling tracks.

Steve,

My friend Adriatic is giving you some great advice...I also saw this on another website if it helps...skip to the bottom posting.

http://cs.trains.com/ctt/f/95/t/29203.aspx 

Tom 

Thanks so much @Adriatic and @PRR8976!! I appreciate you taking the time to explain this to me in such detail- I really do. I did give it a good cleaning and the sparking has certainly lessened but as you both point out that center rail gap needs to be rectified. Oddly enough, when I ran the 254E and Ives 3250 on the aforementioned 042 switches last night- it went more smoothly than it ever had before -and the 254E has deep flanges with large gears as opposed to the Ives which can run on O-27 track and is smaller.

regardless, once I get home ill be able to look at all of this advice more and get to fixing things. Thank you again, so much for all of your help.

Steve

Sometimes old track takes some being put to use again to wake it up too. I also forgot; if you look real close by there is a 3rd pin in the thru exits rail between the other 2 pins that only sticks out about 1/16th inch. The edge was ever so slightly raised and digging at the copper shoes. I rounded&tapered it slightly and deburred the tube i.d. a touch with a wide/shallow 4-flute countesink bit in my fingers. It was a loud click there until I added that pin you can barely see.