slop in drive box to frame

[squandt]

how much "slop" can you have in your drive box to frame? by that I mean side to side, up an down , I have .020 on side to side, and .010 up and down. I get some bind ,never any were the drive wheel's stay up when I run a low spot.

[Fred_V]

Is this an engine you are building? What do you mean by "up and down"? Side to side you should be be able to move the driver a total of 1/16". This allows the drivers to offset when going around a curve. Fore/aft clearance should be around .006" to prevent the rods from binding when one axle goes over a bump or dip.

[squandt]

I do not have any rod bind. By up and down I mean the drive box/wheel set, as you point out ,moving back and forth. This is on a 4-8-4 in 3/4 " scale built from a Little Engine set of casting's.