Transmission Shifts Gears Hard

[ESHyatt]

Recently my Bonneville's transmission began shifting into each gear hard while in route (not the gear shift). She mainly does it when she is hot. What could cause this? And yesterday the "check gas cap" light came and she started to run really rough. I don't suppose these are related? Does anyone have any feedback? Please address each issue if they are unrelated. THANKS!

[SPLLOUDER]

you need to drop pan do new filter and fluid . and install a shift kit .

this will help some .

fuel cap issue . Common solution = buy new fuel cap , old one has a bad seal .

[nos4blood70]

Yup. Some fresh fluid and shift kit will just about eliminate the harsh shifts.

[Mark Fahey]

Having just done the shift kit, keep in mind there are no instructions with the Transgo kit. There is a picture and for the most part, that's enough but based on the lecture I got from the Technical Support person, the kit is not intended for us mere amateurs.
You will find that about half of the parts will be thrown away since if you're like me, you have no intention of dropping the subframe to access the side cover.

[ESHyatt]

Thank you so much fellas. I feel so much better knowing a little of what I'm facing. Walking into a repair shop as a women is like saying its "open season". I refuse to let that happen on my watch!