Pre-war Trains and Fastrack Switches

I have found most prewar engines and cars have no problem with Fastrack. The only issue may be steam loco's that have the same diameter gear as the wheel. Marx steam locos and some inexpensive Lionel 4 wheel steamers may have issues. The same type of problem as running them through O gauge 022's.

I never had many issues. Basically if it was a loco or car that didn't like a traditional switch it didn't like FasTrack either.

My 763E did prefer FasTrack switches which I always found odd but I chalk that up my o72 traditional switches being a little worn.

I tried Fastrack switches and had nothing but problems with them when running my prewar trains. The only loco that ran right through them was my 763e Hudson. My others (260e, 263e, 249e etc) all had trouble getting through the frog without a noticeable "bump" or even sometimes a derailment. If you can find them, the K-Line /O Line Reproductions super snap switches are tough to beat. I'm using them on my layout and have had no issues with any of my trains, old or modern; everything rolls right through them. You will still probably have a challenge with Marx locos due to the large gears.

I've also had issues with Locomotives with large gears going through not only FasTrack switches, but also FasTrack Grade Crossings.  They usually stall on the grade crossings due to lack of electrical contact with the outside rails.