Gen 1 FJR (53K miles) when at any speed has a grinding sound when the clutch gets pulled in and the bike is turned. I replicate this by traveling 20 mph(32KLM) moving side to side hearing it best when the clutch is pulled in. The sound is still there with out the clutch being pulled in, its just more noticeable. Just replaced the bearings to remove one suspect although they had some lose play and needed to be replaced. Road the bike and the sound is still there. Removed all the drive line components and inspected; Output shaft bearing(no abnormal play or sound), Ujoint( little cap play not enouph to replace. I should here clunking sound at low speeds), Differential( could be culprit, BUT bearings feel tight with no abnormal movement from any thing that spins) there are two versions of spacers and bearings for these rear ends. Clutch hub in question on this machine has one bearing and a long spacer. The spacer doesn't exactly fit tight inside the differential as it allows the internal gear to spin. It pushes against the spacer that is pressed into the Differentials body. When all the components are put together the wheel has just the smallest amount of flexion. It moves ever so slightly. Not a click, but a bend like movement. Subtle. To me the long spacer insert allows the differential to float a little. It doesn't seat inside the difs internal. Not sure about the inside pieces and the gaps they should have. There is play in the swing arm where it pivots to the frame so that will have to be addressed. If every thing tight, there should be zero movement and no sound changes in the rear end when the bike is in a turn??? Tire wear is normal. Not sure what a bad Differential would sound like if it was going bad. Any positive input would be appreciated. Any one pull their clutch in and sway bike side to side? If so what did or didn't you hear. To me the sound isn't normal.