started with groaning sounds when steering hard at low speeds,seemed to be in the front(wheel bearings and cv joints checked good)then problem escalated to vibration(the faster you go the worse it is).sound is definitely coming from rear-end.also fuel economy has dropped drastically coinciding with this issue.
whats causing my element to vibrate and make excessive noise from the rear end? on 2004 Honda Element
agree with #1 and poss eng or trans mounts
2 more answers
Use only Honda 'Dual-pump' fluid. Depending on how degraded the fluid is (or if there's much left in the diff.)you may need to do more than one 'drain&fill' before 'BURNISHING' the clutches will have the desired results.IT"S NOT gear noise , it's 'clutch chatter' that you're experiencing..............Note to fancy473......If I'm correct , you're thinking of S/B #07-024 , however that (the burnishing) procedure only applied to CR-Vs due to contaminated fluid from the factory.No TSBs came out on the elements for the rear diff judder , although it's the same root cause.....HAPPY HONDA DAYS!!
It sounds like you need a rear differential deburniishment .. it is avalaible at your local honda dealer , your differential fluid has broken down and is no longer lubricating the gears properly