mixing 2 rail and 3 rail rolling stock?

I run some old Kusan 2 rail cars on my 3 rail layout occasionally. Electrically there should be no problem. However if you have scale wheels, they may not track well on a round head rail such as tubular track or Fastrack. Your coupler height may be lower on the scale cars than on the three rail ones too. 

 

If you use insulated outer rails for block control or signal activation, the two rail cars will not activate them. 

 

J White

 

Electrically you would be OK but I do not think the scales  2 rail wheel would ride on the tubular track very well, might be ok on higher end track.

 

Electrically, you are correct. Mechanically, the scale size of 2-Rail wheels will generally NOT properly track thru most tubular turnouts. My layout is all Atlas O solid nickel silver "T section" track, and I thus have no problems operating 2-Rail pieces of freight rolling stock. The scale flanges do tend to make a bit of noise when going thru the frogs, but since I have modified each guard rail at the switch frogs, I have no derailments.

I haven't tried this since I installed Atlas instead of Fastrack.  Then, I had three 2R flatcars that I bought used for very little $$ - beautiful cars.  They caused no electrical problems - you are right about that -  but cbojaowner is  correct about the scale wheels.   My flatcars would de-rail on O-60 curves and tighter curves all the time, and sometimes on O-72.  There was no hope going through switches.  

 

Atlas track has a different, squarer profile, but I replaced the trucks on the cars with Atlas trucks from my  LHS, so I can't see if they would run on that any better.  I imagine they'd do a bit better - but not good enough.

I've got 2 old Atlas, 1 AHM and 2 old Roco cars... that were 2 rail. I started swapping out the trucks on the AHM since the coupler was no good for the rest of my rolling stock...had to mod the frame a tad to get the body back down but it worked out well. I think there's a possiblity of swapping out the plastic low flange 2 rail wheels out for high flange 3 rail ones....just haven't gotten to it yet.

THanks guys. I'm looking for a Ballantine Ale reefer, and found it in 2R. I will hold off. Time will provide a 3R, or a squirrel will distract me...

Does the 2r equipment work well on gargraves 3r track?

In my experience, the "track" is not really the issue. The "turnouts" are the issue involving 2-Rail SCALE wheel sets. As a member of the Independent Hi-Railers, Midwest Division, I have run some 2-Rail SCALE cabooses on our Gargraves/Ross modular layout, but the 2-Rail wheels do NOT like to make reverse movements through the turnouts.

If the price is right, it's easy enough to change the trucks and remove the 2R couplers. You can resell the leftovers to a 2-railer.