I'm trying to determine which linkages go on my 4*60 ailerons. The kit has a 4-40 set for the ailerons and a 2-56 set for the rudder/elev. but I don't know which is which. Are the 4-40s the larger diameter linkages??

Yes. The 4-40 is really a #4 screw size, with 40 threads per inch. The 2-56 is a #2 screw size, 56 threads per inch (56 TPI). The bigger the number, the bigger the screw.


Mark

i would think the bigger rods would go on the rudder/elevator.

For a 60 size plane you will want to put the 4 40 (larger) linkages on the elevator and rudder. You could probably get away with 2 56, but in general each aileron will come under less stress than the rudder and elevator so smaller linkages can be used on the ailerons.