Thank you John and Peter,
disassembled the rear lower wishbone yesterday evening, put in the grease nipple, greased it completely and assembled it again. I will see if the noise is gone this afternoon.
After complete dismanteling i saw that the rose joint in the lower wishbone to rear frame bearing had lots of rust, water and showed some wear.
I will replace it during the winter but have not found the correct rose bearing today.
Can someone bring up a source or part number for the rose bearing?
One of the two O-rings was splitted and i measured the other one, it should be 30mm x 5mm.
The rose bearing ring has 39.98mm outer dia and a width of 11.01mm, the ball has a 26.06mm inner dia and a 17.40mm width.
BTW, i used self tapping/forming, hardened, 90 degree grease nipples, no need to tap a thread into the hole.
Thanks for your support,
Uwe