[/quote]Not always, if the inner part of the Birfield broke but the outter bell stayed intacted it will not turn hard nor will the wheel lock up.]

Just pulled my Birfs back out for better inspection outer
race is cracked on right side just enough to only clank and chatter whenlocked in If I just locked in one side actually almost didnt notice it, as soon as both wheels where locked sounded and felt as if I shatterd the pinion. With the locker up front truck is very hard to steer " when locked " sometimes makes for a long day on the trail!!!