Originally Posted By jb500
Originally Posted By busboy
"Rocker shafts undersized for roller/needle bearings" ?? Can you elaborate?


The shaft needs to be a true .8750 dia (can't recall tolerances) with a hardness in the upper 50's/lower 60's. The reason is to distribute the load evenly to all the needles (no slop) and the hardness is needed to prevent the rollers from digging into the shaft.

I found out all this info after the needles in my 440S rockers let go. Stock OEM style shafts were supplied in my kit.

To the OP: Remember....cheap parts cost less up front, but twice as much when they fail and even more to clean up the mess. Don't skimp on the rockers.


Looked up NSK specs for J-146 bearings (the type listed as being used) and the tolerances are +0.000/-0.0005 on shaft diameter. My theory on the cage failures are both due to small shafts and lack of hardness. Undersized lets the needles in the 4-8 o'clock position concentrate the load on the shaft. And with the shaft being softer the needles begin to develop a groove and any side to side movement causes the needle to catch the edge. The drawn cups are no match for that type of force and then you get confetti.

If 440S rockers used shafts from Harland Sharp (or made to bearing specs), they may live well into the sunset. However, that is a science experiment that I will never make.