Four years ago I changed the worn out rubber suspension bushes on the 308 to more modern polyurethane alternatives. The polyurethane bushes are more rigid than the rubber versions and were quite a common ‘upgrade’ back when I fitted them.
Today even after multiple disassemblies and lubrications, they have started squeaking… again… Warning: the video below is extremely irritating.
Time, then, to go back to the OEM rubber ‘silentbloc’ bushes, which are, as the name suggests, silent. Furthermore the polyurethane bushes actually wear as the bush rotates against the suspension arms. Even with lubrication, if two parts are moving against each other, one of them is going to wear. It is this rotation that’s the source of the squeak. The silentblocs work differently… the rubber twists inside the inner and outer surfaces but is bonded to both surfaces so there is no wear. The problem with the rubber bushes is that eventually the rubber perishes and the bush becomes loose. However, I doubt they deteriorate faster than the poly bushes wear out. If I change them now, I won’t have to change them again.
Installation is unfortunately more involved than the poly bushes: the old silentblocs need to be first ground and then pressed out, the new ones need to be tack-welded in. Finally each bush can only be properly torqued with all four wheels on the ground with suspension loaded which is considerably more work.