The OP should've mentioned that the 4wd vehicles in question are DHK Razr's. These do not have a center differential, they have a center spool. Simply taking the front center shaft out will make them 2wd with no need to lock anything. The front axles are cvd's according the to the manual I found online, not dog bones. This makes it more involved to disassemble and remove the front axles which I'm not sure will make any difference for what you're looking for. Might as well leave them in so you don't lose the parts for when they get over the donuts.
I'm guessing they're the brushed versions if they can't slide them around. I normally have no problem sliding around a brushless 4wd and the 4wd makes it easier to control the vehicle, sliding or not. Something to keep in mind when they get older or if you upgrade.
Last edited by Maj_Overdrive; 12-29-2014 at 09:55 AM.