The primary cause of a transmission to experience hard shifting is low fluid. Fluid is the life of a transmission and operates most of its functions.
A bad transmission gear can cause your 1999 Nissan frontier to shift hard. Low transmission fluid can also cause the transmission to shift hard.
Possibly low fluid.
Has recent work been performed?
Have the transmission checked for codes. That will tell you the possible causes.
check fluid in tranie....and LUCAS tranie lube
electronic solenoid
The most common reason for an automobile transmission to shift hard is low transmission fluid. Make sure the transmission fluid is at the appropriate level.
The transmission may shift hard due to it beginning to fail. However, it may also be due to low transmission fluid.
modulator valve on the transmission.
Check the transmission fluid on the 1995 Nissan Altima. Bad fluid can cause the transmission to shift harder on parts that are more worn.
More likely it has something to do with pressure problems in your transmission, check the fluid and replace the transmission filter. If the problem is not fixed check the vaccum lines running to the transmission and the vaccum off the engine.
lack of tranny oil would probably be the culprit. if not tranny fluid then you are probably in need of a transmission overhaul.