I have had an issue with my 50" Z8s lower rear bushings because of the manufacturer drilled two sets of holes in each tube for grease fittings. One was used for the grease fitting but the other when welded to the rest of the a-arm pointed into the tube headed to the knuckle. When greasing, no grease made it to the bushings - just went up the tube. Before I pulled it apart I thought they must have pierced it welding it but all four tubes? Then when the bushing seizes to the sleeve and started rotating in the tubes making a god-awful squeaking (
which you can hear in one of my last videos) I found this out. I then glued steel plugs (cut off nail heads) in the holes, cleaned-up and had to plasti-weld the bushing into the tubes because they didn't fit tight anymore. I also discovered that on all the lower bushings including the knuckle side, the mount had to compress the bushing quit a bit before making contact with the sleeve. That put pressure on the bushing and forced it to actually start rotating in the tube sooner and bind against the mount. So, I machined the bushing end down enough that about 5-thousands of an inch of the sleeve stuck out past the bushing on each side. That took the pressure off the bushing and actually made the suspension work freely...and much smoother....and trust me ...the short a-arms of the 50" need to move nice and easy
I also decided to go with a graphite based high pressure grease because reports show it works better on these types of applications.
I don't have much time on this fix, but so far I love it. It's ride is much improved and..of course that squeaking is gone.