The other day i heard strange sounds like grinding from beneath my miata. this was only under full throttle in first gear. i beleave its the differential that is dying. what do you guys think. this only happens under hard acceleration in first and second gear. i rotated the driveshaft and it seems to have a lot of play with respect to the differential.

 

so i lifted the miata. i then had a friend accelerate and put in gear the miata. i checked was was this noice its making and based on what i saw it seems the rear driverside upper differential mounts are making a metal to metal contact. it seems that the plastic mount inserted in there is not working. i tightened the bolt but it seems tight. are there mounting bushings of hard plastic that insert in there that i can buy if yes what are they called or what else can i do.

 

mazdaspeed differential mount bushing