Fest,
Did the cracking start after the cylinder was rebuilt and reinstalled back in the machine?
I'm wondering if the new bushings might be the culprits, especially if they are a close fit on the pins. If the two cylinder pins aren't dead nuts parallel when everything is assembled, there will be some HUGE bending forces generated as the cylinder is extended or retracted and the pin tries to rotate in the bores.
To check this out isn't an easy job as you will have to pull the cylinder back out of the machine. You would then get a couple of rods the same size as the pins and about 3 feet long. Put one in each end of the cylinder eyes, centered, and level them both with a good high precision level. Then measure from rod to rod at each end and see if the measurements are the same. If they are, the rod end centerlines are parallel. If not, then you might have some fixing to do, especially if the measurements are out by a lot.
You should do the same checking on the pin bores in the machine frame and the lift arms to ensure they are also parallel to each other. I'm not sure how easy this will be given the tight clearances where those pinholes live.
If this all started with the installation of the new bushings, they could have been machined with the ID's out of line with the OD's--I can't see that with OEM or good quality repair parts but if they were made by someone who may have been careless when machining the bushings the bores could have been machined out of line with the bushing OD's.
I might have my head up my butt with this theory but don't ask me how I know about pins and misalignment!! The tip of my left FU finger is a little shorter because of misaligned bores on a Hyundai 290 hydraulic thumb!!
.
Jon.
