I have a 2000 pontiac bonneville ssei and sometimes whenever I am driving it it shifts hard but most of the time it shifts smoothly. Is there something wrong with my transmission that it shifts hard sometimes? The transmission is an automatic.
If it not the mounts look into converting to Dextron VI and installing a shift kit. 11 months ago I was convinced I needed to rebuild the trans, did the Dextron VI and the shift kit- and the trans is running better every day- 30k miles later.
If it engages into D and R hard to it could be a vacuum problem. I had hard engagement into D and R also 1-2 shifts were pretty hard and 2-3 shifts a little harder than normal. after a brief look under hood I found vacuum line had been totally knocked off trans. Stuck it back on fine ever since.