To avoid or reduce axle and U-Joint failure, position the steering arm on top and allow more clearance between the springs and steering linkage.
Parts Mike™ offers new APM cast Dana 44 replacement "flattop" knuckles that position the steering arm .500" higher then stock GM/FSJ "flattop" knuckles. Parts Mike™ APM knuckles are cast without the normal steering arm found on OEM knuckles and are drilled to use front and rear turning radius stops. This will reduce axle and U-Joint failure.
The failure occurs when the ujoint angle is allowed to go past its working limit. This is a problem with stock knuckles that only have a single stop at the front or rear or when there are no "stops" being used.
The ujoint failure under hard usage usually occurs in the knuckle that is being turned away from the stop. Left wheel turned right and vice versa.
I have witnessed this on numerous occasions and it made me start looking at the dynamics of why this was occurring. I began noticing that just before the the "ping, pop or bang" that accompanies the breakage the outside tire had been moving from side to side in what looks like a shimmy motion.
The reason for this is that without a stop the weight of the tire and its motion against the axle shaft U-Joint assembly causes the tierod or other steering linkage components to flex. This allows the U-Joint to surpass and exceed its angularity limitations.
The result is broken parts that may include the balljoints that retain the knuckle. This is caused when the axles and ujoint "blowup" and "bind" creating enough pressure to force the knuckle out away from the housing.
Parts Mike™ APM knuckles have now incorporated 2 stops to help reduce this problem.
